Solder ball, solder joint, and joining method
10780530 · 2020-09-22
Assignee
Inventors
- Hiroki OSHIMA (Tokyo, JP)
- Takeo Saitoh (Tochigi, JP)
- Takahiro Nishizaki (Campbell, CA, US)
- Tomohisa Kawanago (Tochigi, JP)
- Masato Shiratori (Tochigi, JP)
- Kaichi Tsuruta (Tochigi, JP)
Cpc classification
B23K35/00
PERFORMING OPERATIONS; TRANSPORTING
B23K35/262
PERFORMING OPERATIONS; TRANSPORTING
H05K3/3457
ELECTRICITY
H05K3/3463
ELECTRICITY
B23K35/26
PERFORMING OPERATIONS; TRANSPORTING
B23K35/3093
PERFORMING OPERATIONS; TRANSPORTING
B23K35/0244
PERFORMING OPERATIONS; TRANSPORTING
B23K35/30
PERFORMING OPERATIONS; TRANSPORTING
International classification
B23K35/00
PERFORMING OPERATIONS; TRANSPORTING
B23K35/30
PERFORMING OPERATIONS; TRANSPORTING
Abstract
A solder ball according to the present invention contains 0.2 to 2.2% by mass of Zn, and a balance of Sn, and has a spherical diameter of 0.1 to 120 m and a yellowness (b*) in an L*a*b* color system of 2.70 or more and 9.52 or less. An oxide film is formed by performing aging treatment. By producing a solder ball having a yellowness of 2.70 or more and 9.52 or less, it is possible to suppress the growth of a Cu.sub.3Sn layer and/or a CuZn(Sn) layer during joining.
Claims
1. A solder ball comprising: 0.2 to 2.2% by mass of Zn; and a balance of Sn, wherein the solder ball has a spherical diameter of 0.1 to 120 m, and wherein the solder ball has a yellowness (b*) in an L*a*b* color system of 2.70 or more and 9.52 or less and/or a thickness of an oxide film on a surface of the solder ball is 1.5 nm or more and 10.7 nm or less.
2. The solder ball according to claim 1, further comprising at least one element selected from a group consisting of Ag, Cu, Bi, In, Ni, Sb, Co, Fe, Ge, and P, wherein content of Ag is 0 to 4% by mass; content of Cu is 0 to 1.0% by mass; content of Bi, In or Sb is 0 to 3% by mass in total; and content of Ni, Co, Fe, Ge or P is 0 to 0.1% by mass in total.
3. The solder ball according to claim 1, having an dose of 0.0200 cph/cm.sup.2 or less.
4. The solder ball according to claim 2, having an dose of 0.0200 cph/cm.sup.2 or less.
5. A joining method comprising the steps of: arranging a plurality of the solder balls on electrodes, each solder ball containing 0.2 to 2.2% by mass of Zn; and a balance of Sn, wherein the solder ball has a spherical diameter of 0.1 to 120 m, and wherein the solder ball has a yellowness (b*) in an L*a*b* color system of 2.70 or more and 9.52 or less and/or a thickness of an oxide film on a surface of the solder ball is 1.5 nm or more and 10.7 nm or less; and melting the plurality of solder balls arranged on the electrodes using an organic acid gas.
6. The joining method according to claim 5 comprising the steps of: arranging a plurality of the solder balls on electrodes, each solder ball further containing at least one element selected from a group consisting of Ag, Cu, Bi, In, Ni, Sb, Co, Fe, Ge, and P, wherein content of Ag is 0 to 4% by mass; content of Cu is 0 to 1.0% by mass; content of Bi, In or Sb is 0 to 3% by mass in total; and content of Ni, Co, Fe, Ge or P is 0 to 0.1% by mass in total; and melting the plurality of solder balls arranged on the electrodes using an organic acid gas.
7. The joining method according to claim 5 comprising the steps of: arranging a plurality of the solder balls on electrodes, each solder ball having an dose of 0.0200 cph/cm.sup.2 or less; and melting the plurality of solder balls arranged on the electrodes using an organic acid gas.
8. The joining method according to claim 6 comprising the steps of: arranging a plurality of the solder balls on electrodes, each solder ball having an dose of 0.0200 cph/cm.sup.2 or less; and melting the plurality of solder balls arranged on the electrodes using an organic acid gas.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1)
(2)
DETAILED DESCRIPTION OF PREFERRED EMBODIMENT
(3) The following will describe preferred embodiments of the present invention more in detail with reference to the drawing. The solder ball according to the present invention is mainly composed of Sn, containing 0.2 to 2.2% by mass of Zn, and having a spherical diameter of 0.1 to 120 m and a yellowness in the L*a*b* color system of 2.70 or more and 9.52 or less. In the present invention, the solder ball has an oxide film having a predetermined thickness on its surface. The oxide film is formed by performing any aging treatment. Examples of the aging treatment include exposure to the atmosphere (standing) and heat treatment. According to the present invention, a solder ball having a yellowness of 2.70 or more and 9.52 or less is produced, thereby making it possible to suppress the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining. The following will describe each of the components in detail.
(4) (1) Zn: 0.2 to 2.2% by Mass
(5) The content of Zn in the solder ball is 0.2 to 2.2% by mass. By setting the content of Zn to 0.2% by mass or more, a constant amount of Zn can be secured, so that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer can be surely suppressed. In addition, by setting the content of Zn to 2.2% by mass or less, the growth of the oxide film can be suppressed within a certain range, so that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer can be suppressed without reducing the wettability of the solder. That is, according to the above range of the Zn content, any aging treatment is applied to an SnZn-based lead-free solder ball in the formation of solder bumps, thereby making it possible to enrich Zn preferentially on the surface of the solder ball. As a result, during solder joining, the CuZnSn compound is formed preferentially to the CuSn compound by a reaction of Sn in the solder, Zn enriched on the solder surface, and Cu on the electrode side. Since the CuZnSn compound is less likely to grow than the CuSn compound, it allows the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer to be suppressed.
(6) (2) Spherical Diameter of Solder Ball: 0.1 to 120 m
(7) The spherical diameter of the solder ball is 0.1 to 120 m. This is because, if the spherical diameter of the solder ball exceeds 120 m, it is difficult to solder with a fine pitch, so that it is impossible to cope with the demand for the miniaturization of the substrate and the narrowing of the electrodes of the electronic components. The lower limit value is set to 0.1 m or more, as the limit of the spherical diameter of the solder ball that can be technically used for solder bump formation. As described above, by setting the spherical diameter of the solder ball within the range of 0.1 to 120 m, it is possible to cope with the miniaturization and high integration of the electronic components. Furthermore, the above-described effect of suppressing the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer is exhibited as the particle diameter of the solder ball decreases, and the spherical diameter of the solder ball is preferably 120 m or less, more preferably 80 m or less, still more preferably 50 m or less, most preferably 30 m or less.
(8) (3) Yellowness in L*a*b* Color System: 2.70 or More and 9.52 or Less
(9) The yellowness in the L*a*b* color system of the solder ball is 2.70 or more and 9.52 or less. If the yellowness is 2.70 or more and 9.52 or less, it is possible to suppress the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining. More preferably, the yellowness is 2.70 or more and 4.00 or less. When the solder ball is subjected to any aging treatment at a predetermined temperature for a predetermined time, an oxide film containing a large amount of zinc oxide (ZnO) is formed on the surface of the solder ball, so that an enrichment phenomenon occurs in which the concentration of Zn on the surface of the solder ball increases. Even when the Zn content is as low as 0.2 to 2.2% by mass as in the present invention, the concentration of Zn on the solder ball surface can be increased by intentionally oxidizing the solder ball surface, whereby the effect of suppressing the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer can be obtained. Here, it is considered that, if the solder ball is excessively oxidized to increase the concentration of Zn on the surface of the solder ball, the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer can be suppressed more effectively. However, in a solder ball having a spherical diameter of 120 m or less, the influences of the oxide film are particularly great, thereby causing a problem of reduction in reliability during solder joining. Therefore, it is necessary to manage the oxide film thickness so as to satisfy both of the conditions for the oxide film thickness in consideration of the solderability and the conditions for the oxide film thickness in consideration of the suppression of the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer by enrichment of Zn. Therefore, in the present invention, in order to manage the thickness of the oxide film formed on the surface of the solder ball simply and quickly, the yellowness in the L*a*b* color system is adopted, and a solder ball having a yellowness of 2.70 or more and 9.52 or less in the L*a*b* color system is produced, thereby realizing a solder ball having a predetermined oxide film thickness. If the yellowness is less than 2.70, Zn is not enriched, so that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer cannot be effectively suppressed during solder bump formation. On the other hand, if the yellowness exceeds 9.52, the wettability of the solder during solder ball joining may be impaired. As a result, it is possible to provide a solder ball capable of effectively suppressing the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer without reducing the solder wettability.
(10) (4) Addition of at Least One Element Selected from a Group Consisting of: Ag, Cu, Ag, Bi, in, Sb, Ni, Co, Fe, Ge and P and Ag: 0 to 4% by Mass; Cu: 0 to 1.0% by Mass; Bi, in or Sb: 0 to 3% by Mass in Total; and Ni, Co, Fe, Ge or P: 0 to 0.1% by Mass, in Total
(11) The solder ball that constitutes the present invention may contain Ag, Cu, Bi, In, Ni, Sb, Co, Fe, Ge, and/or P in the above-described ranges. This enables the joining reliability to be improved. The contents of Ag, Cu, Bi, In, Ni, Sb, Co, Fe, Ge and/or P are preferably set: Ag: 0 to 4% by mass; Cu: 0 to 1.0% by mass; Bi, In or Sb: 0 to 3% by mass in total; and Ni, Co, Fe, Ge or P: 0 to 0.1% by mass in total, since a reaction between Zn and the joining member must not be disturbed.
(12) (5) Sn as Main Component
(13) The main component of the solder ball according to the present invention is Sn, and the content thereof is always highest among the metal elements in the solder ball. In addition, the solder ball according to the present invention may contain inevitable impurities. Even when the solder ball contains inevitable impurities, the above-described effects are not affected.
(14) (6) Alpha () Dose: 0.0200 cph/cm.sup.2 or Less
(15) The dose of the solder ball according to the present invention is 0.0200 cph/cm.sup.2 or less from the viewpoint of suppressing soft errors. This is an dose such that soft errors would not become a problem in high-density mounting of the electronic components. The dose is more preferably 0.0010 cph/cm.sup.2 or less from the viewpoint of suppressing soft errors in higher-density mounting.
(16) (7) Method for Manufacturing Solder Ball
(17) First, a solder ball having a spherical diameter of 0.1 to 120 m and containing 0.2 to 2.2% by mass of Zn is produced. As a method of producing the solder ball, a known method such as a dropping method in which a molten solder is added dropwise and processed into a spherical shape or a gas atomizing method can be adopted. One or more elements selected from a group consisting of Ag, Cu, Bi, In, Ni, Sb, Co, Fe, Ge, and P may be added to the solder ball.
(18) Next, the solder ball thus produced is subjected to any aging treatment to form an oxide film on the surface of the solder ball, thereby controlling the concentration of Zn on the surface of the solder ball to be high. In the aging treatment, the heating temperature and the heating time are set so as to attain an oxide film thickness such that the yellowness of the solder ball is 2.70 or more and 9.52 or less. Also, as other methods for controlling the concentration of Zn to be high, there are indicated: storing the solder ball in a state of being exposed to the atmosphere at room temperature for a long time; aging by increasing the oxygen concentration during ball formation; and oxygen plasma irradiation at least either during ball formation or after ball formation. Thus, it is possible to produce a solder ball in which an oxide film having a certain thickness is formed on its surface.
(19) The solder ball according to the present invention can also be used to form a solder joint for joining electrodes. In the present invention, for example, a structure in which a solder bump is mounted on an electrode of a printed board is referred to as solder joint. The solder bump means, for example, a structure in which a solder ball is mounted on an electrode of a semiconductor chip.
(20) The solder ball according to the present invention can also be applied to a joining method without using any flux. For example, a plurality of solder balls subjected to any aging treatment are placed on electrodes of a substrate, and then the plurality of solder balls placed thereon are melted using an organic acid gas, thereby forming a solder bump. As the solder balls, used are 50 solder balls, an arithmetic mean of the measured values of diameters of which is 120 m. Also in this case, the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer can be effectively suppressed.
EXECUTED EXAMPLES
(21) First, SnZn solder balls each having a spherical diameter of 120 m and having the alloy composition shown in each of the Executed Examples were prepared. Next, each of the prepared solder balls was subjected to any aging treatments in advance under different conditions, and the surface of each of the solder balls was intentionally oxidized to increase the concentration of Zn on the surface thereof, thereby preparing solder balls having formed thereon an oxide film containing a high concentration of zinc oxide (ZnO). Subsequently, the oxide film thickness and yellowness of each of the solder balls, and the concentration of Zn on the surface of each of the solder balls were measured, and the thicknesses of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer were evaluated.
(22) (1) Measurement of Thickness of Oxide Film Formed on Each of the Solder Balls
(23) The thickness of the oxide film formed on each of the solder balls was measured using a FE-AES measuring device of ULVAC PHI700. The acceleration voltage of the measuring device was set to 10 kV, and the irradiation current was set to 10 nA. The oxide film thickness (depth) was obtained from the speed (etching rate) at which the surface of a sample was scraped with an ion (Ar), and the etching depth which was a peak value of the intensity derived from oxygen was used as an approximate value of the oxide film thickness. The etching rate is an SiO.sub.2-conversion value converted in terms of a speed at which an SiO.sub.2 standard sample is scraped.
(24) (2) Measurement of Yellowness of Each of the Solder Balls
(25) The yellowness of each of the solder balls was measured using CM-2600d spectrophotometer manufactured by Konica Minolta, Inc.
(26) (3) Measurement of Concentration on Surface of Each of the Solder Balls
(27) The concentration of Zn on the surface of each of the solder balls was analyzed qualitatively with a field emission electron probe microanalyzer (FE-EPMA), and a semi-quantitative analysis value was quoted. For the concentration of Zn on the surface of each of the solder balls, a semi-quantitative analysis value was calculated in order to make comparison in terms of the concentration change.
(28) (4) Evaluation of Total Thickness of Cu.sub.3Sn Layer and/or CuZn(Sn) Layer
(29) Flux WF-6317 (manufactured by Senju Metal Industry Co., Ltd.) was printed on an electrode pad of Bare-Cu (bare copper) formed on a substrate, and each of the solder balls was mounted thereon. The temperature of the electrode pad on which the solder ball was mounted was increased from 25 C. to 250 C. in an N.sub.2 atmosphere at a temperature increase rate of 5 C./sec, and then reflow soldering was performed for 1 minute. After the reflow soldering, the joined body was cut for each substrate, and the joining interface (cut surface) between the solder ball and the electrode was observed in an SEM image to measure the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer. Then, based on the evaluation of the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer of each of the solder balls of the Comparative Examples shown in the tables, the solder balls having the same alloy composition in each of Tables 1 to 6 were evaluated as follows on the basis of the solder balls not subjected to any aging treatments.
(30) (i) When the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer in the Executed Example (Comparative Example) is less than the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer in the Comparative Example not subjected to any aging treatment, the symbol o (good) is shown the tables.
(31) (ii) When the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer in the Example (Comparative Example) is not less than the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer in the Comparative Example not subjected to any aging treatment: the symbol x (bad) is shown the tables.
(32) Table 1 indicates the measurement results and evaluation results of the solder balls in each of which the alloy composition is Sn-0.2% by mass Zn.
(33) TABLE-US-00001 Oxide film Semi-quantitatively Whether IMC layers became Aging condition Alloy thickness Yellowness analyzed Zn thinner than those of No. Temperature/time composition (nm) (b*) (% by mass) Comparative Example EXECUTED Normal temperature/3 days Sn0.2Zn 1.5 2.77 0.463 EXAMPLE 1 EXECUTED Normal temperature/7 days Sn0.2Zn 2.0 2.81 0.471 EXAMPLE 2 EXECUTED 200 C./0.5 min Sn0.2Zn 2.1 2.97 0.492 EXAMPLE 3 EXECUTED 200 C./1 min Sn0.2Zn 2.1 3.52 0.556 EXAMPLE 4 EXECUTED 200 C./1.5 min Sn0.2Zn 2.3 3.41 0.549 EXAMPLE 5 EXECUTED 200 C./2 min Sn0.2Zn 2.3 3.43 0.547 EXAMPLE 6 EXECUTED 200 C./5 min Sn0.2Zn 2.7 3.48 0.531 EXAMPLE 7 EXECUTED 200 C./10 min Sn0.2Zn 3.0 3.45 0.617 EXAMPLE 8 EXECUTED 200 C./30 min Sn0.2Zn 3.7 3.99 0.735 EXAMPLE 9 EXECUTED 200 C./60 min Sn0.2Zn 4.1 3.99 0.902 EXAMPLE 10 EXECUTED 200 C./90 min Sn0.2Zn 4.3 4.08 0.926 EXAMPLE 11 EXECUTED 200 C./120 min Sn0.2Zn 4.5 4.13 0.915 EXAMPLE 12 EXECUTED 200 C./300 min Sn0.2Zn 4.7 4.48 0.938 EXAMPLE 13 EXECUTED 200 C./1800 min Sn0.2Zn 9.1 5.76 0.978 EXAMPLE 14 EXECUTED 200 C./2880 min Sn0.2Zn 9.5 6.50 1.007 EXAMPLE 15 COMPARATIVE 0 Sn0.2Zn 0.7 2.45 0.247 EXAMPLE 1
(34) In Comparative Example 1, solder balls of Sn-0.2% by mass Zn, which were not subjected to any aging treatment, were used. In Comparative Example 1, when the solder ball having a yellowness of 2.45 was selected, the oxide film thickness thereof was 0.7 nm, and the concentration of Zn on the surface of the solder ball was 0.247% by mass. In Table 1, since the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining in Comparative Example 1 was a reference for evaluation, it was indicated as -, not x.
(35) In Executed Example 1, respective solder balls of Sn-0.2% by mass Zn were subjected to aging treatment involving continuous exposure to the atmosphere at normal temperature of 20 C. to 30 C. for 3 days. According to Executed Example 1, when the solder ball having a yellowness of 2.77 was selected, the oxide film thickness thereof was 1.5 nm, and the concentration of Zn on the surface of the solder ball was 0.463% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(36) In Executed Example 2, respective solder balls of Sn-0.2% by mass Zn were subjected to aging treatment involving continuous exposure to the atmosphere at normal temperature of 20 C. to 30 C. for 7 days. According to Executed Example 2, when the solder ball having a yellowness of 2.81 was selected, the oxide film thickness thereof was 2.0 nm, and the concentration of Zn on the surface of the solder ball was 0.471% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(37) In Executed Example 3, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 0.5 minutes. According to Executed Example 3, when the solder ball having a yellowness of 2.97 was selected, the oxide film thickness thereof was 2.1 nm, and the concentration of Zn on the surface of the solder ball was 0.492% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(38) In Executed Example 4, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 1 minute. According to Executed Example 4, when the solder ball having a yellowness of 3.52 was selected, the oxide film thickness thereof was 2.1 nm, and the concentration of Zn on the surface of the solder ball was 0.556% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(39) In Executed Example 5, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 1.5 minutes. According to Executed Example 5, when the solder ball having a yellowness of 3.41 was selected, the oxide film thickness thereof was 2.3 nm, and the concentration of Zn on the surface of the solder ball was 0.549% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(40) In Executed Example 6, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 2 minutes. According to Executed Example 6, when the solder ball having a yellowness of 3.43 was selected, the oxide film thickness thereof was 2.3 nm, and the concentration of Zn on the surface of the solder ball was 0.547% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(41) In Executed Example 7, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 5 minutes. According to Executed Example 7, when the solder balls having a yellowness of 3.48 was selected, the oxide film thickness thereof was 2.7 nm, and the concentration of Zn on the surface of the solder ball was 0.531% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(42) In Executed Example 8, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 10 minutes. According to Executed Example 8, when the solder ball having a yellowness of 3.45 was selected, the oxide film thickness thereof was 3.0 nm, and the concentration of Zn on the surface of the solder ball was 0.617% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(43) In Executed Example 9, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 30 minutes. According to Executed Example 9, when the solder ball having a yellowness of 3.99 was selected, the oxide film thickness thereof was 3.7 nm, and the concentration of Zn on the surface of the solder ball was 0.735% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(44) In Executed Example 10, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 60 minutes. According to Executed Example 10, when the solder ball having a yellowness of 3.99 was selected, the oxide film thickness thereof was 4.1 nm, and the concentration of Zn on the surface of the solder ball was 0.902% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(45) In Executed Example 11, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 90 minutes. According to Executed Example 11, when the solder ball having a yellowness of 4.08 was selected, the oxide film thickness thereof was 4.3 nm, and the concentration of Zn on the surface of the solder ball was 0.926% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(46) In Executed Example 12, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 120 minutes. According to Executed Example 12, when the solder ball having a yellowness of 4.13 was selected, the oxide film thickness thereof was 4.5 nm, and the concentration of Zn on the surface of the solder ball was 0.915% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(47) In Executed Example 13, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 300 minutes. According to Executed Example 13, when the solder ball having a yellowness of 4.48 was selected, the oxide film thickness thereof was 4.7 nm, and the concentration of Zn on the surface of the solder ball was 0.938% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(48) In Executed Example 14, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 1800 minutes. According to Executed Example 14, when the solder ball having a yellowness of 5.76 was selected, the oxide film thickness thereof was 9.1 nm, and the concentration of Zn on the surface of the solder ball was 0.978% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(49) In Executed Example 15, respective solder balls of Sn-0.2% by mass Zn were heat-treated at 200 C. for 2880 minutes. According to Executed Example 15, when the solder ball having a yellowness of 6.50 was selected, the oxide film thickness thereof was 9.5 nm, and the concentration of Zn on the surface of the solder ball was 1.007% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 1 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(50) Table 2 indicates the measurement results and evaluation results of the solder balls each of which the alloy composition is Sn-0.6% by mass Zn.
(51) TABLE-US-00002 Oxide film Semi-quantitatively Whether IMC layers became Aging condition Alloy thickness Yellowness analyzed Zn thinner than those of No. Temperature/time composition (nm) (b*) (% by mass) Comparative Example EXECUTED Normal temperature/3 days Sn0.6Zn 1.6 2.71 0.627 EXAMPLE 16 EXECUTED Normal temperature/7 days Sn0.6Zn 2.3 2.85 0.639 EXAMPLE 17 EXECUTED 200 C./0.5 min Sn0.6Zn 2.3 3.15 0.677 EXAMPLE 18 EXECUTED 200 C./1 min Sn0.6Zn 2.3 3.68 0.552 EXAMPLE 19 EXECUTED 200 C./1.5 min Sn0.6Zn 2.3 3.70 0.531 EXAMPLE 20 EXECUTED 200 C./2 min Sn0.6Zn 2.3 3.50 0.507 EXAMPLE 21 EXECUTED 200 C./5 min Sn0.6Zn 2.6 3.64 0.623 EXAMPLE 22 EXECUTED 200 C./10 min Sn0.6Zn 2.9 3.68 0.773 EXAMPLE 23 EXECUTED 200 C./30 min Sn0.6Zn 4.0 4.14 0.757 EXAMPLE 24 EXECUTED 200 C./60 min Sn0.6Zn 4.9 4.36 1.171 EXAMPLE 25 EXECUTED 200 C./90 min Sn0.6Zn 5.2 4.55 1.249 EXAMPLE 26 EXECUTED 200 C./120 min Sn0.6Zn 5.4 4.78 1.261 EXAMPLE 27 EXECUTED 200 C./300 min Sn0.6Zn 5.5 4.96 1.456 EXAMPLE 28 EXECUTED 200 C./1800 min Sn0.6Zn 9.7 8.09 2.078 EXAMPLE 29 EXECUTED 200 C./2880 min Sn0.6Zn 10.6 9.52 2.116 EXAMPLE 30 COMPARATIVE 0 Sn0.6Zn 0.7 2.51 0.443 EXAMPLE 2
(52) In Comparative Example 2, solder balls of Sn-0.6% by mass Zn, which were not subjected to any aging treatment, were used. In Comparative Example 2, when the solder ball having a yellowness of 2.51 was selected, the oxide film thickness thereof was 0.7 nm, and the concentration of Zn on the surface of the solder ball was 0.443% by mass. In Table 2, since the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining in Comparative Example 2 was a reference for evaluation, it was indicated as -, not x.
(53) In Executed Example 16, respective solder balls of Sn-0.6% by mass Zn were subjected to aging treatment involving continuous exposure to the atmosphere at normal temperature of 20 C. to 30 C. for 3 days. According to Executed Example 16, when the solder ball having a yellowness of 2.71 was selected, the oxide film thickness thereof was 1.6 nm, and the concentration of Zn on the surface of the solder ball was 0.627% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(54) In Executed Example 17, respective solder balls of Sn-0.6% by mass Zn were continued to be exposed to the atmosphere at normal temperature of 20 C. to 30 C. for 7 days. According to Executed Example 17, when the solder ball having a yellowness of 2.85 was selected, the oxide film thickness thereof was 2.3 nm, and the concentration of Zn on the surface of the solder ball was 0.639% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(55) In Executed Example 18, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 0.5 minutes. According to Executed Example 18, when the solder ball having a yellowness of 3.15 was selected, the oxide film thickness thereof was 2.3 nm, and the concentration of Zn on the surface of the solder ball was 0.677% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(56) In Executed Example 19, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 1 minute. According to Executed Example 19, when the solder ball having a yellowness of 3.68 was selected, the oxide film thickness thereof was 2.3 nm, and the concentration of Zn on the surface of the solder ball was 0.552% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(57) In Executed Example 20, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 1.5 minutes. According to Executed Example 20, when the solder ball having a yellowness of 3.70 was selected, the oxide film thickness thereof was 2.3 nm, and the concentration of Zn on the surface of the solder ball was 0.531% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(58) In Executed Example 21, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 2 minutes. According to Executed Example 21, when the solder ball having a yellowness of 3.50 was selected, the oxide film thickness thereof was 2.3 nm, and the concentration of Zn on the surface of the solder ball was 0.507% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(59) In Executed Example 22, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 5 minutes. According to Executed Example 22, when the solder ball having a yellowness of 3.64 was selected, the oxide film thickness thereof was 2.6 nm, and the concentration of Zn on the surface of the solder ball was 0.623% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(60) In Executed Example 23, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 10 minutes. According to Executed Example 23, when the solder ball having a yellowness of 3.68 was selected, the oxide film thickness thereof was 2.9 nm, and the concentration of Zn on the surface of the solder ball was 0.773% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(61) In Executed Example 24, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 30 minutes. According to Executed Example 24, when the solder ball having a yellowness of 4.14 was selected, the oxide film thickness thereof was 4.0 nm, and the concentration of Zn on the surface of the solder ball was 0.757% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(62) In Executed Example 25, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 60 minutes. According to Executed Example 25, when the solder ball having a yellowness of 4.36 was selected, the oxide film thickness thereof was 4.9 nm, and the concentration of Zn on the surface of the solder ball was 1.171% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(63) In Executed Example 26, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 90 minutes. According to Executed Example 26, when the solder ball having a yellowness of 4.55 was selected, the oxide film thickness thereof was 5.2 nm, and the concentration of Zn on the surface of the solder ball was 1.249% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(64) In Executed Example 27, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 120 minutes. According to Executed Example 27, when the solder ball having a yellowness of 4.78 was selected, the oxide film thickness thereof was 5.4 nm, and the concentration of Zn on the surface of the solder ball was 1.261% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(65) In Executed Example 28, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 300 minutes. According to Executed Example 28, when the solder ball having a yellowness of 4.96 was selected, the oxide film thickness thereof was 5.5 nm, and the concentration of Zn on the surface of the solder ball was 1.456% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(66) In Executed Example 29, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 1800 minutes. According to Executed Example 29, when the solder ball having a yellowness of 8.09 was selected, the oxide film thickness thereof was 9.7 nm, and the concentration of Zn on the surface of the solder ball was 2.078% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(67) In Executed Example 30, respective solder balls of Sn-0.6% by mass Zn were heat-treated at 200 C. for 2880 minutes. According to Executed Example 30, when the solder ball having a yellowness of 9.52 was selected, the oxide film thickness thereof was 10.6 nm, and the concentration of Zn on the surface of the solder ball was 2.116% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 2 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(68) Table 3 indicates the measurement results and evaluation results of the solder balls each of which the alloy composition is Sn-2% by mass Zn.
(69) TABLE-US-00003 Oxide film Semi-quantitatively Whether IMC layers became Aging condition Alloy thickness Yellowness analyzed Zn thinner than those of No. Temperature/time composition (nm) (b*) (% by mass) Comparative Example EXECUTED Normal temperature/3 days Sn2Zn 1.6 2.70 0.635 EXAMPLE 31 EXECUTED Normal temperature/7 days Sn2Zn 2.5 2.93 0.651 EXAMPLE 32 EXECUTED 200 C./0.5 min Sn2Zn 2.5 3.12 0.693 EXAMPLE 33 EXECUTED 200 C./1 min Sn2Zn 2.5 3.61 0.669 EXAMPLE 34 EXECUTED 200 C./1.5 min Sn2Zn 2.5 3.48 0.701 EXAMPLE 35 EXECUTED 200 C./2 min Sn2Zn 2.5 3.57 0.743 EXAMPLE 36 EXECUTED 200 C./5 min Sn2Zn 2.8 3.72 0.981 EXAMPLE 37 EXECUTED 200 C./10 min Sn2Zn 3.2 3.81 1.034 EXAMPLE 38 EXECUTED 200 C./30 min Sn2Zn 4.2 4.05 1.165 EXAMPLE 39 EXECUTED 200 C./60 min Sn2Zn 5.0 4.28 1.200 EXAMPLE 40 EXECUTED 200 C./90 min Sn2Zn 5.5 4.48 1.286 EXAMPLE 41 EXECUTED 200 C./120 min Sn2Zn 5.7 4.42 1.523 EXAMPLE 42 EXECUTED 200 C./300 min Sn2Zn 5.9 4.79 1.855 EXAMPLE 43 EXECUTED 200 C./1800 min Sn2Zn 9.9 6.33 2.199 EXAMPLE 44 EXECUTED 200 C./2880 min Sn2Zn 10.7 7.33 2.217 EXAMPLE 45 COMPARATIVE 0 Sn2Zn 0.9 2.55 0.492 EXAMPLE 3
(70) In Comparative Example 3, solder balls of Sn-2% by mass Zn, which were not subjected to any aging treatment, were used. In Comparative Example 3, when the solder ball having a yellowness of 2.55 were selected, the oxide film thickness thereof was 0.9 nm, and the concentration of Zn on the surface of the solder ball was 0.492% by mass. In Table 3, since the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining in Comparative Example 3 was a reference for evaluation, it was indicated as -, not x.
(71) In Executed Example 31, respective solder balls of Sn-2% by mass Zn were subjected to aging treatment involving continuous exposure to the atmosphere at normal temperature of 20 C. to 30 C. for 3 days. According to Executed Example 31, when the solder ball having a yellowness of 2.70 was selected, the oxide film thickness thereof was 1.6 nm, and the concentration of Zn on the surface of the solder ball was 0.635% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(72) In Executed Example 32, respective solder balls of Sn-2% by mass Zn were subjected to aging treatment involving continuous exposure to the atmosphere at normal temperature of 20 C. to 30 C. for 7 days. According to Executed Example 32, when the solder ball having a yellowness of 2.93 was selected, the oxide film thickness thereof was 2.5 nm, and the concentration of Zn on the surface of the solder ball was 0.651% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(73) In Executed Example 33, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 0.5 minutes. According to Executed Example 33, when the solder ball having a yellowness of 3.12 was selected, the oxide film thickness thereof was 2.5 nm, and the concentration of Zn on the surface of the solder ball was 0.693% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(74) In Executed Example 34, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 1 minute. According to Executed Example 34, when the solder ball having a yellowness of 3.61 were selected, the oxide film thickness thereof was 2.5 nm, and the concentration of Zn on the surface of the solder ball was 0.669% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(75) In Executed Example 35, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 1.5 minutes. According to Executed Example 35, when the solder ball having a yellowness of 3.48 was selected, the oxide film thickness thereof was 2.5 nm, and the concentration of Zn on the surface of the solder ball was 0.701% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(76) In Executed Example 36, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 2 minutes. According to Executed Example 36, when the solder ball having a yellowness of 3.57 was selected, the oxide film thickness thereof was 2.5 nm, and the concentration of Zn on the surface of the solder ball was 0.743% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(77) In Executed Example 37, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 5 minutes. According to Executed Example 37, when the solder ball having a yellowness of 3.72 was selected, the oxide film thickness thereof was 2.8 nm, and the concentration of Zn on the surface of the solder ball was 0.981% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(78) In Executed Example 38, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 10 minutes. According to Executed Example 38, when the solder ball having a yellowness of 3.81 was selected, the oxide film thickness thereof was 3.2 nm, and the concentration of Zn on the surface of the solder ball was 1.034% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(79) In Executed Example 39, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 30 minutes. According to Executed Example 39, when the solder ball having a yellowness of 4.05 was selected, the oxide film thickness thereof was 4.2 nm, and the concentration of Zn on the surface of the solder ball was 1.165% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(80) In Executed Example 40, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 60 minutes. According to Executed Example 40, when the solder ball having a yellowness of 4.28 was selected, the oxide film thickness thereof was 5.0 nm, and the concentration of Zn on the surface of the solder ball was 1.200% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(81) In Executed Example 41, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 90 minutes. According to Executed Example 41, when the solder ball having a yellowness of 4.48 was selected, the oxide film thickness thereof was 5.5 nm, and the concentration of Zn on the surface of the solder ball was 1.286% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(82) In Executed Example 42, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 120 minutes. According to Executed Example 42, when the solder ball having a yellowness of 4.42 was selected, the oxide film thickness thereof was 5.7 nm, and the concentration of Zn on the surface of the solder ball was 1.523% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(83) In Executed Example 43, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 300 minutes. According to Executed Example 43, when the solder ball having a yellowness of 4.79 was selected, the oxide film thickness thereof was 5.9 nm, and the concentration of Zn on the surface of the solder ball was 1.855% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(84) In Executed Example 44, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 1800 minutes. According to Executed Example 44, when the solder ball having a yellowness of 6.33 was selected, the oxide film thickness thereof was 9.9 nm, and the concentration of Zn on the surface of the solder ball was 2.199% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(85) In Executed Example 45, respective solder balls of Sn-2% by mass Zn were heat-treated at 200 C. for 2880 minutes. According to Executed Example 45, when the solder ball having a yellowness of 7.33 was selected, the oxide film thickness thereof was 10.7 nm, and the concentration of Zn on the surface of the solder ball was 2.217% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 3 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(86) Table 4 indicates the measurement results and evaluation results of the solder balls each of which the alloy composition is Sn-2.2% by mass Zn.
(87) TABLE-US-00004 Oxide film Semi-quantitatively Whether IMC layers became Aging condition Alloy thickness Yellowness analyzed Zn thinner than those of No. Temperature/time composition (nm) (b*) (% by mass) Comparative Example EXECUTED Normal temperature/3 days Sn2.2Zn 1.8 2.73 0.651 EXAMPLE 46 EXECUTED Normal temperature/7 days Sn2.2Zn 2.5 3.03 0.673 EXAMPLE 47 EXECUTED 200 C./0.5 min Sn2.2Zn 2.5 3.21 0.705 EXAMPLE 48 EXECUTED 200 C./1 min Sn2.2Zn 2.5 3.68 0.710 EXAMPLE 49 EXECUTED 200 C./1.5 min Sn2.2Zn 2.5 3.42 0.733 EXAMPLE 50 EXECUTED 200 C./2 min Sn2.2Zn 2.6 3.55 0.762 EXAMPLE 51 EXECUTED 200 C./5 min Sn2.2Zn 2.9 3.74 1.114 EXAMPLE 52 EXECUTED 200 C./10 min Sn2.2Zn 3.2 3.77 1.132 EXAMPLE 53 EXECUTED 200 C./30 min Sn2.2Zn 4.1 4.12 1.227 EXAMPLE 54 EXECUTED 200 C./60 min Sn2.2Zn 5.2 4.28 1.286 EXAMPLE 55 EXECUTED 200 C./90 min Sn2.2Zn 5.5 4.30 1.358 EXAMPLE 56 EXECUTED 200 C./120 min Sn2.2Zn 5.7 4.51 1.649 EXAMPLE 57 EXECUTED 200 C./300 min Sn2.2Zn 5.8 4.69 1.863 EXAMPLE 58 EXECUTED 200 C./1800 min Sn2.2Zn 10.1 6.28 2.216 EXAMPLE 59 EXECUTED 200 C./2880 min Sn2.2Zn 10.6 7.40 2.284 EXAMPLE 60 COMPARATIVE 0 Sn2.2Zn 0.9 2.53 0.509 EXAMPLE 4
(88) In Comparative Example 4, solder balls of Sn-2.2% by mass Zn, which were not subjected to any aging treatment, were used. In Comparative Example 4, when the solder ball having a yellowness of 2.53 was selected, the oxide film thickness thereof was 0.9 nm, and the concentration of Zn on the surface of the solder ball was 0.509% by mass. In Table 4, since the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining in Comparative Example 4 was a reference for evaluation, it was indicated as -, not x.
(89) In Executed Example 46, respective solder balls of Sn-2.2% by mass Zn were subjected to aging treatment involving continuous exposure to the atmosphere at normal temperature of 20 C. to 30 C. for 3 days. According to Executed Example 46, when the solder ball having a yellowness of 2.73 was selected, the oxide film thickness thereof was 1.8 nm, and the concentration of Zn on the surface of the solder ball was 0.651% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(90) In Executed Example 47, respective solder balls of Sn-2.2% by mass Zn were subjected to aging treatment involving continuous exposure to the atmosphere at normal temperature of 20 C. to 30 C. for 7 days. According to Executed Example 47, when the solder ball having a yellowness of 3.03 was selected, the oxide film thickness thereof was 2.5 nm, and the concentration of Zn on the surface of the solder ball was 0.673% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(91) In Executed Example 48, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 0.5 minutes. According to Executed Example 48, when the solder ball having a yellowness of 3.21 was selected, the oxide film thickness thereof was 2.5 nm, and the concentration of Zn on the surface of the solder ball was 0.705% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(92) In Executed Example 49, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 1 minute. According to Executed Example 49, when the solder ball having a yellowness of 3.68 was selected, the oxide film thickness thereof was 2.5 nm, and the concentration of Zn on the surface of the solder ball was 0.710% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(93) In Executed Example 50, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 1.5 minutes. According to Executed Example 50, when the solder ball having a yellowness of 3.42 was selected, the oxide film thickness thereof was 2.5 nm, and the concentration of Zn on the surface of the solder ball was 0.733% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(94) In Executed Example 51, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 2 minutes. According to Executed Example 51, when the solder ball having a yellowness of 3.55 was selected, the oxide film thickness thereof was 2.6 nm, and the concentration of Zn on the surface of the solder ball was 0.762% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(95) In Executed Example 52, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 5 minutes. According to Executed Example 52, when the solder ball having a yellowness of 3.74 was selected, the oxide film thickness thereof was 2.9 nm, and the concentration of Zn on the surface of the solder ball was 1.114% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(96) In Executed Example 53, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 10 minutes. According to Executed Example 53, when the solder ball having a yellowness of 3.77 was selected, the oxide film thickness thereof was 3.2 nm, and the concentration of Zn on the surface of the solder ball was 1.132% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(97) In Executed Example 54, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 30 minutes. According to Executed Example 54, when the solder ball having a yellowness of 4.12 was selected, the oxide film thickness thereof was 4.1 nm, and the concentration of Zn on the surface of the solder ball was 1.227% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(98) In Executed Example 55, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 60 minutes. According to Executed Example 55, when the solder ball having a yellowness of 4.28 was selected, the oxide film thickness thereof was 5.2 nm, and the concentration of Zn on the surface of the solder ball was 1.286% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(99) In Executed Example 56, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 90 minutes. According to Executed Example 56, when the solder ball having a yellowness of 4.30 was selected, the oxide film thickness thereof was 5.5 nm, and the concentration of Zn on the surface of the solder ball was 1.358% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(100) In Executed Example 57, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 120 minutes. According to Executed Example 57, when the solder ball having a yellowness of 4.51 was selected, the oxide film thickness thereof was 5.7 nm, and the concentration of Zn on the surface of the solder ball was 1.649% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(101) In Executed Example 58, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 300 minutes. According to Executed Example 58, when the solder ball having a yellowness of 4.69 was selected, the oxide film thickness thereof was 5.8 nm, and the concentration of Zn on the surface of the solder ball was 1.863% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(102) In Executed Example 59, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 1800 minutes. According to Executed Example 59, when the solder ball having a yellowness of 6.28 was selected, the oxide film thickness thereof was 10.1 nm, and the concentration of Zn on the surface of the solder ball was 2.216% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(103) In Executed Example 60, respective solder balls of Sn-2.2% by mass Zn were heat-treated at 200 C. for 2880 minutes. According to Executed Example 60, when the solder ball having a yellowness of 7.40 was selected, the oxide film thickness thereof was 10.6 nm, and the concentration of Zn on the surface of the solder ball was 2.284% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 4 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(104) Table 5 indicates the measurement results and evaluation results of the solder balls in each of which the alloy composition is Sn-0.6% by mass Zn-1.0% by mass Ag-0.5% by mass Cu.
(105) TABLE-US-00005 TABLE 5 Oxide film Semi-quantitatively thickness YeIlowness analyzed Zn Comparison in IMC with No. Aging condition (nm) (b*) (% by mass) Comparative Example EXECUTED Normal temperature 7 days 2.3 2.76 0.652 EXAMPLE 61 EXECUTED 200 C. 5 min 2.7 3.53 0.619 EXAMPLE 62 EXECUTED 200 C. 10 min 3.1 3.59 0.745 EXAMPLE 63 EXECUTED 200 C. 60 min 4.8 4.20 1.211 EXAMPLE 64 COMPARATIVE 0 0 0.8 2.43 0.428 EXAMPLE 5
(106) In Comparative Example 5, solder balls of Sn-0.6% by mass Zn-1.0% by mass Ag-0.5% by mass Cu, which were not subjected to any aging treatment, were used. In Comparative Example 5, when the solder ball having a yellowness of 2.43 was selected, the oxide film thickness thereof was 0.8 nm, and the concentration of Zn on the surface of the solder ball was 0.428% by mass. In Table 5, since the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining in Comparative Example 5 was a reference for evaluation, it was indicated as -, not x.
(107) In Executed Example 61, respective solder balls of Sn-0.6% by mass Zn-1.0% by mass Ag-0.5% by mass Cu were subjected to aging treatment involving continuous exposure to the atmosphere at normal temperature of 20 C. to 30 C. for 7 days. According to Executed Example 61, when the solder ball having a yellowness of 2.76 was selected, the oxide film thickness was 2.3 nm, and the concentration of Zn on the surface of the solder ball was 0.652% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 5 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(108) In Executed Example 62, respective solder balls of Sn-0.6% by mass Zn-1.0% by mass Ag-0.5% by mass Cu were subjected to aging treatment involving continuous exposure to the atmosphere at 200 C. for 5 minutes. According to Executed Example 62, when the solder ball having a yellowness of 3.53 was selected, the oxide film thickness thereof was 2.7 nm, and the concentration of Zn on the surface of the solder ball was 0.619% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 5 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(109) In Executed Example 63, respective solder balls of Sn-0.6% by mass Zn-1.0% by mass Ag-0.5% by mass Cu were subjected to aging treatment involving continuous exposure to the atmosphere at 200 C. for 10 minutes. According to Executed Example 63, when the solder ball having a yellowness of 3.59 was selected, the oxide film thickness thereof was 3.1 nm, and the concentration of Zn on the surface of the solder ball was 0.745% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 5 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(110) In Executed Example 64, respective solder balls of Sn-0.6% by mass Zn-1.0% by mass Ag-0.5% by mass Cu were subjected to aging treatment involving continuous exposure to the atmosphere at 200 C. for 60 minutes. According to Executed Example 64, when the solder ball having a yellowness of 4.20 was selected, the oxide film thickness thereof was 4.8 nm, and the concentration of Zn on the surface of the solder ball was 1.211% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 5 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(111) Table 6 indicates the measurement results and evaluation results of the solder balls in each of which the alloy composition is Sn-0.6% by mass Zn-0.5% by mass Cu.
(112) TABLE-US-00006 TABLE 6 Oxide film Semi-quantitatively thickness Yellowness analyzed Zn Comparison in IMC with No. Aging condition (nm) (b*) (% by mass) Comparative Example EXECUTED Normal temperature 7 days 2.5 2.97 0.661 EXAMPLE 65 EXECUTED 200 C. 5 min 2.8 3.72 0.640 EXAMPLE 66 EXECUTED 200 C. 10 min 3.3 3.78 0.794 EXAMPLE 67 EXECUTED 200 C. 60 min 5.9 4.57 1.237 EXAMPLE 68 COMPARATIVE 0 0 0.7 2.56 0.467 EXAMPLE 6
(113) In Comparative Example 6, solder balls of Sn-0.6% by mass Zn-0.5% by mass Cu, which were not subjected to any aging treatment, were used. In Comparative Example 6, when the solder ball having a yellowness of 2.56 was selected, the oxide film thickness thereof was 0.7 nm, and the concentration of Zn on the surface of the solder ball was 0.467% by mass. In Table 6, since the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining in Comparative Example 6 was a reference for evaluation, it was indicated as -, not x.
(114) In Executed Example 65, respective solder balls of Sn-0.6% by mass Zn-0.5% by mass Cu were subjected to aging treatment involving continuous exposure to the atmosphere at normal temperature of 20 C. to 30 C. for 7 days. According to Executed Example 65, when the solder ball having a yellowness of 2.97 was selected, the oxide film thickness thereof was 2.5 nm, and the concentration of Zn on the surface of the solder ball was 0.661% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 6 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(115) In Executed Example 66, respective solder balls of Sn-0.6% by mass Zn-0.5% by mass Cu were subjected to aging treatment involving continuous exposure to the atmosphere at 200 C. for 5 minutes. According to Executed Example 66, when the solder ball having a yellowness of 3.72 was selected, the oxide film thickness thereof was 2.8 nm, and the concentration of Zn on the surface of the solder ball was 0.640% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 6 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(116) In Executed Example 67, respective solder balls of Sn-0.6% by mass Zn-0.5% by mass Cu were subjected to aging treatment involving continuous exposure to the atmosphere at 200 C. for 10 minutes. According to Executed Example 67, when the solder ball having a yellowness of 3.78 was selected, the oxide film thickness thereof was 3.3 nm, and the concentration of Zn on the surface of the solder ball was 0.794% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 6 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(117) In Executed Example 68, respective solder balls of Sn-0.6% by mass Zn-0.5% by mass Cu were subjected to aging treatment involving continuous exposure to the atmosphere at 200 C. for 60 minutes. According to Executed Example 68, when the solder ball having a yellowness of 4.57 was selected, the oxide film thickness thereof was 5.9 nm, and the concentration of Zn on the surface of the solder ball was 1.237% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 6 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(118) Table 7 indicates the measurement results and evaluation results of the solder balls in each of which the alloy composition is Sn-0.6% by mass Zn-0.5% by mass Bi-0.5% by mass Sb-0.001% by mass Co.
(119) TABLE-US-00007 TABLE 7 Oxide film Semi-quantitatively thickness Yellowness analyzed Zn Comparison in IMC with No. Aging condition (nm) (b*) (% by mass) Comparative Example EXECUTED Normal temperature 7 days 2.3 2.91 0.675 EXAMPLE 69 EXECUTED 200 C. 5 min 2.8 3.82 0.636 EXAMPLE 70 EXECUTED 200 C. 10 min 3.0 3.90 0.791 EXAMPLE 71 EXECUTED 200 C. 60 min 5.2 4.59 1.257 EXAMPLE 72 COMPARATIVE 0 0 0.8 2.68 0.481 EXAMPLE 7
(120) In Comparative Example 7, solder balls of Sn-0.6% by mass Zn-0.5% by mass Bi-0.5% by mass Sb-0.001% by mass Co, which were not subjected to any aging treatment, were used. In Comparative Example 7, when the solder ball having a yellowness of 2.68 was selected, the oxide film thickness thereof was 0.8 nm, and the concentration of Zn on the surface of the solder ball was 0.481% by mass. In Table 7, since the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining in Comparative Example 7 was a reference for evaluation, it was indicated as -, not x.
(121) In Executed Example 69, respective solder balls of Sn-0.6% by mass Zn-0.5% by mass Bi-0.5% by mass Sb-0.001% by mass Co were subjected to aging treatment involving continuous exposure to the atmosphere at normal temperature of 20 C. to 30 C. for 7 days. According to Executed Example 69, when the solder ball having a yellowness of 2.91 was selected, the oxide film thickness thereof was 2.3 nm, and the concentration of Zn on the surface of the solder ball was 0.675% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 7 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(122) In Executed Example 70, respective solder balls of Sn-0.6% by mass Zn-0.5% by mass Bi-0.5% by mass Sb-0.001% by mass Co were subjected to aging treatment involving continuous exposure to the atmosphere at 200 C. for 5 minutes. According to Executed Example 70, when the solder ball having a yellowness of 3.82 was selected, the oxide film thickness thereof was 2.8 nm, and the concentration of Zn on the surface of the solder ball was 0.636% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 7 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(123) In Executed Example 71, respective solder balls of Sn-0.6% by mass Zn-0.5% by mass Bi-0.5% by mass Sb-0.001% by mass Co were subjected to aging treatment involving continuous exposure to the atmosphere at 200 C. for 10 minutes. According to Executed Example 71, when the solder ball having a yellowness of 3.90 was selected, the oxide film thickness thereof was 3.0 nm, and the concentration of Zn on the surface of the solder ball was 0.791% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 7 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(124) In Executed Example 72, respective solder balls of Sn-0.6% by mass Zn-0.5% by mass Bi-0.5% by mass Sb-0.001% by mass Co were subjected to aging treatment involving continuous exposure to the atmosphere at 200 C. for 60 minutes. According to Executed Example 72, when the solder ball having a yellowness of 4.59 was selected, the oxide film thickness thereof was 5.2 nm, and the concentration of Zn on the surface of the solder ball was 1.257% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 7 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(125) Table 8 indicates the measurement results and evaluation results of the solder balls in each of which the alloy composition is Sn-0.6% by mass Zn-0.5% by mass In-0.01% by mass Ni-0.01% by mass Fe.
(126) TABLE-US-00008 TABLE 8 Oxide film Semi-quantitatively thickness Yellowness analyzed Zn Comparison in IMC with No. Aging condition (nm) (b*) (% by mass) Comparative Example EXECUTED Normal temperature 7 days 2.5 2.75 0.682 EXAMPLE 73 EXECUTED 200 C. 5 min 3.3 3.71 0.633 EXAMPLE 74 EXECUTED 200 C. 10 min 3.9 3.82 0.804 EXAMPLE 75 EXECUTED 200 C. 60 min 6.1 4.78 1.349 EXAMPLE 76 COMPARATIVE 0 0 1.0 2.48 0.508 EXAMPLE 8
(127) In Comparative Example 8, solder balls of Sn-0.6% by mass Zn-0.5% by mass In-0.01% by mass Ni-0.01% by mass Fe, which were not subjected to any aging treatment, were used. In Comparative Example 8, when the solder ball having a yellowness of 2.48 was selected, the oxide film thickness thereof was 1.0 nm, and the concentration of Zn on the surface of the solder ball was 0.508% by mass. In Table 8, since the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining in Comparative Example 8 was a reference for evaluation, it was indicated as -, not x.
(128) In Executed Example 73, respective solder balls of Sn-0.6% by mass Zn-0.5% by mass In-0.01% by mass Ni-0.01% by mass Fe were subjected to aging treatment involving continuous exposure to the atmosphere at normal temperature of 20 C. to 30 C. for 7 days. According to Executed Example 73, when the solder ball having a yellowness of 2.75 was selected, the oxide film thickness thereof was 2.5 nm, and the concentration of Zn on the surface of the solder ball was 0.682% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 8 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(129) In Executed Example 74, respective solder balls of Sn-0.6% by mass Zn-0.5% by mass In-0.01% by mass Ni-0.01% by mass Fe were subjected to aging treatment involving continuous exposure to the atmosphere at 200 C. for 5 minutes. According to Executed Example 74, when the solder ball having a yellowness of 3.71 was selected, the oxide film thickness thereof was 3.3 nm, and the concentration of Zn on the surface of the solder ball was 0.633% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 8 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(130) In Executed Example 75, respective solder balls of Sn-0.6% by mass Zn-0.5% by mass In-0.01% by mass Ni-0.01% by mass Fe were subjected to aging treatment involving continuous exposure to the atmosphere at 200 C. for 10 minutes. According to Executed Example 75, when the solder ball having a yellowness of 3.82 was selected, the oxide film thickness thereof was 3.9 nm, and the concentration of Zn on the surface of the solder ball was 0.804% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 8 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(131) In Executed Example 76, respective solder balls of Sn-0.6% by mass Zn-0.5% by mass In-0.01% by mass Ni-0.01% by mass Fe were subjected to aging treatment involving continuous exposure to the atmosphere at 200 C. for 60 minutes. According to Executed Example 76, when the solder ball having a yellowness of 4.78 was selected, the oxide film thickness was 6.1 nm, and the concentration of Zn on the surface of the solder ball was 1.349% by mass. In addition, it was confirmed that the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining were thinner than those of the solder ball of Comparative Example 8 which was not subjected to any aging treatment, and that the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer was suppressed.
(132) Table 9 indicates the measurement results and evaluation results of the solder balls each of which the alloy composition is Sn-0.0001% by mass Zn.
(133) TABLE-US-00009 Oxide film Semi-quantitatively Whether IMC layers became Aging condition Alloy thickness Yellowness analyzed Zn thinner than those of No. Temperature/time composition (nm) (b*) (% by mass) Comparative Example COMPARATIVE Normal temperature/3 days Sn0.0001Zn 1.0 3.36 0.000 X EXAMPLE 9 COMPARATIVE Normal temperature/7 days Sn0.0001Zn 1.2 3.36 0.000 X EXAMPLE 10 COMPARATIVE 200 C./0.5 min Sn0.0001Zn 1.2 3.37 0.000 X EXAMPLE 11 COMPARATIVE 200 C./1 min Sn0.0001Zn 1.4 3.37 0.000 X EXAMPLE 12 COMPARATIVE 200 C./1.5 min Sn0.0001Zn 1.6 3.41 0.000 X EXAMPLE 13 COMPARATIVE 200 C./2 min Sn0.0001Zn 1.8 3.43 0.000 X EXAMPLE 14 COMPARATIVE 200 C./5 min Sn0.0001Zn 2.2 3.44 0.000 X EXAMPLE 15 COMPARATIVE 200 C./10 min Sn0.0001Zn 2.3 3.92 0.000 X EXAMPLE 16 COMPARATIVE 200 C./30 min Sn0.0001Zn 3.5 5.34 0.000 X EXAMPLE 17 COMPARATIVE 200 C./60 min Sn0.0001Zn 12.5 15.23 0.000 X EXAMPLE 18 COMPARATIVE 200 C./90 min Sn0.0001Zn 14.0 19.04 0.000 X EXAMPLE 19 COMPARATIVE 200 C./120 min Sn0.0001Zn 17.3 22.07 0.000 X EXAMPLE 20 COMPARATIVE 0 Sn0.0001Zn 0.7 3.34 0.000 EXAMPLE 21
(134) In Comparative Example 21, solder balls of Sn-0.0001% by mass Zn, which were not subjected to any aging treatment, were used. In Comparative Example 21, when the solder ball having a yellowness of 3.34 was selected, the oxide film thickness thereof was 0.7 nm. On the other hand, it was confirmed that, since only a very small amount of Zn was added to the solder ball, the concentration of Zn on the surface of the solder ball was 0.000% by mass, and that the growth of the Cu.sub.3Sn layer during joining was not suppressed. No CuZn(Sn) layer was seen probably because the content of Zn was very small. In Table 9, since the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining in Comparative Example 21 was a reference for evaluation, it was indicated as -, not x.
(135) In Comparative Examples 9 to 20, an oxide film having a predetermined thickness was formed on the surface of each of the respective solder balls according to the conditions for the aging treatments, and the yellowness according to the oxide film thickness was measured. When the aging treatment time was 60 minutes or more as in Comparative Examples 18 to 20, the oxide films were significantly thickened, and it was confirmed that the yellowness increased as the oxide film thickness increased. On the other hand, since only a very small amount of Zn was added to the solder ball, the concentration of Zn on the surface of the solder ball was 0.000% by mass in all of Comparative Examples 9 to 20, and it was confirmed that the growth of the Cu.sub.3Sn layer during joining was not suppressed as in Comparative Example 21.
(136) Table 10 indicates the measurement results and evaluation results of the solder balls each of which the alloy composition is Sn-0.7% by mass Cu.
(137) TABLE-US-00010 Oxide film Semi-quantitatively Whether IMC layers became Aging condition Alloy thickness Yellowness analyzed Zn thinner than those of No. Temperature/time composition (nm) (b*) (% by mass) Comparative Example COMPARATIVE Normal temperature/3 days Sn0.7Cu 0.9 3.71 0.000 X EXAMPLE 22 COMPARATIVE Normal temperature/7 days Sn0.7Cu 1.2 3.71 0.000 X EXAMPLE 23 COMPARATIVE 200 C./0.5 min Sn0.7Cu 1.2 3.70 0.000 X EXAMPLE 24 COMPARATIVE 200 C./1 min Sn0.7Cu 1.4 3.71 0.000 X EXAMPLE 25 COMPARATIVE 200 C./1.5 min Sn0.7Cu 1.5 3.76 0.000 X EXAMPLE 26 COMPARATIVE 200 C./2 min Sn0.7Cu 1.8 3.69 0.000 X EXAMPLE 27 COMPARATIVE 200 C./5 min Sn0.7Cu 2.0 3.70 0.000 X EXAMPLE 28 COMPARATIVE 200 C./10 min Sn0.7Cu 2.1 3.83 0.000 X EXAMPLE 29 COMPARATIVE 200 C./30 min Sn0.7Cu 3.3 5.27 0.000 X EXAMPLE 30 COMPARATIVE 200 C./60 min Sn0.7Cu 12.3 15.00 0.000 X EXAMPLE 31 COMPARATIVE 200 C./90 min Sn0.7Cu 13.8 18.88 0.000 X EXAMPLE 32 COMPARATIVE 200 C./120 min Sn0.7Cu 17.1 21.54 0.000 X EXAMPLE 33 COMPARATIVE 0 Sn0.7Cu 0.7 3.72 0.000 EXAMPLE 34
(138) In Comparative Example 34, solder balls of Sn-0.7% by mass Cu, which were not subjected to any aging treatment, were used. In Comparative Example 34, when the solder ball having a yellowness of 3.72 was selected, the oxide film thickness thereof was 0.7 nm. On the other hand, since no Zn was added to the solder ball, the concentration of Zn on the surface of the solder ball was 0.000% by mass, and it was confirmed that the growth of the Cu.sub.3Sn layer during joining was not suppressed. The CuZn(Sn) layer was not seen because Zn was not contained. In Table 10, since the total thickness of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining in Comparative Example 34 was a reference for evaluation, it was indicated as -, not x.
(139) In Comparative Examples 22 to 33, an oxide film having a predetermined thickness was formed on the surface of each of the respective solder balls according to the conditions for the aging treatment, and the yellowness according to the oxide film thickness was measured. When the aging treatment time was 60 minutes or more as in Comparative Examples 31 to 33, the oxide films were significantly thickened, and it was confirmed that the yellowness increased as the oxide film thickness increased. On the other hand, since no Zn was added to the solder ball, the concentration of Zn on the surface of the solder ball was 0.000% by mass in all of Comparative Examples 22 to 33, and it was confirmed that the growth of the Cu.sub.3Sn layer during joining was not suppressed as in Comparative Example 34.
(140) From the above results, it was confirmed that, in the case of solder balls having a Zn content of 0.2 to 2.2% by mass and a spherical diameter of 120 m or less, aging treatment was performed to produce solder balls having a yellowness of 2.70 or more and 9.52 or less or an oxide film thickness of 1.5 nm or more and 10.7 nm or less, whereby Zn was enriched on the surface of each of the solder balls. It was also confirmed that, as a result, the oxide film containing zinc oxide (ZnO), which was formed on the surface of each of the solder balls, functioned as a protective film, whereby the growth of new Cu.sub.3Sn layer and/or CuZn(Sn) layer on the oxide film containing zinc oxide (ZnO) could be suppressed as compared with general solder ball not subjected to any aging treatment.
(141) The following will describe the joining interface between the solder ball and the electrode when soldering was performed using the solder ball of Sn-2.0% by mass Zn subjected to aging treatment in Executed Example 31 and the solder ball of Sn-2.0% by mass Zn not subjected to any aging treatment in Comparative Example 3 with reference to SEM images.
(142)
(143) In comparison in terms of the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer at the joining interface between the solder ball and the electrode, because of a high Zn content of 2.0% by mass in Executed Example 31 and Comparative Example 3, the CuZn(Sn) layer was formed in both cases. The thickness of the CuZn(Sn) layer was 1.34 m in Executed Example 31 shown in
(144) From the above, it was found that, in the case of solder ball having an oxide film thickness within the range of 1.5 nm or more and 10.7 nm or less, a yellowness of 2.70 or more and 9.52 or less and a spherical diameter of 0.1 to 120 m, even when the solder ball had a composition containing 0.2 to 2.2% by mass of Zn, the enrichment of Zn on the surface thereof made it possible to more effectively suppress the growth of the Cu.sub.3Sn layer and/or the CuZn(Sn) layer during joining. Although only the comparative photographs of the solder balls each having a composition of Sn-2.0% by mass Zn are shown in
(145) Next, the doses when solder balls of Sn-0.2% by mass Zn, Sn-0.6% by mass Zn, Sn-2.0% by mass Zn and Sn-2.2% by mass Zn, which had been subjected to aging treatment, having different purities of Zn were respectively measured.
(146) Measurement of Dose
(147) The dose of each of the solder balls was measured using an -ray measuring device of a gas flow proportional counter. Each measurement sample was a sample obtained by spreading solder balls on a bottom of a flat shallow container of 300 mm300 mm until the bottom could not be seen. The measurement sample was placed in the -ray measuring device and allowed to stand for 24 hours under PR-10 gas flow, and then the dose was measured. In addition, the PR-10 gas (argon 90%-methane 10%) used for the measurement was a PR-10 gas after the lapse of 3 weeks or more from filling in a gas cylinder. The reason for using the cylinder after the lapse of 3 weeks or more was that the measurement was made in accordance with the JEDEC (Joint Electron Device Engineering Council) STANDARD-Alpha Radiation Measurement in Electronic Materials JESD221, as defined by the JEDEC, so as to prevent the generation of a rays by radon in the atmosphere entering the gas cylinder.
(148) Table 11 indicates the relationship among the purity of Sn, the purity of Zn and the dose in the solder balls. In Table 11, for the purities of Sn and Zn, 3N indicate 99.9% by mass and 5N indicate 99.999% by mass.
(149) TABLE-US-00011 TABLE 11 dose, No. Composition Sn purity Zn purity cph/cm2 EXECUTED Sn0.2Zn 5N 5N <0.0010 EXAMPLE 77 EXECUTED Sn0.6Zn 5N 5N <0.0010 EXAMPLE 78 EXECUTED Sn2.0Zn 5N 5N <0.0010 EXAMPLE 79 EXECUTED Sn2.2Zn 5N 5N <0.0010 EXAMPLE 80 COMPARATIVE Sn0.2Zn 5N 3N >1 EXAMPLE 35 COMPARATIVE Sn0.6Zn 5N 3N >1 EXAMPLE 36 COMPARATIVE Sn2.0Zn 5N 3N >1 EXAMPLE 37 COMPARATIVE Sn2.2Zn 5N 3N >1 EXAMPLE 38
(150) When the purity of Sn was 5N and the purity of Zn was 5N, as indicated in Executed Examples 77 to 80 in Table 11, the dose of each Executed Example was 0.0010 cph/cm.sup.2 or less, which was below the required 0.0200 cph/cm.sup.2. On the other hand, when the purity of Sn was 5N and the purity of Zn was 3N, as indicated in Comparative Examples 35 to 38, the dose of each Comparative Example exceeded 1, which could not satisfy the required condition of 0.0200 cph/cm.sup.2. Thus, it was confirmed that the condition for dose could be satisfied by selecting solder balls wherein the purity of Sn was 5N and the purity of Zn was 5N. Even when producing solder balls having added thereto Ag, Cu, Bi, In, Sb, Ni, Co, Fe, Ge, and/or P other than Sn and Zn, the dose of each of the solder balls would be 0.0200 cph/cm.sup.2 or less if the respective elements used have high purity and provide an dose of 0.0200 cph/cm.sup.2 or less.
(151) The technical scope of the present invention is not limited to the above-described embodiment, and includes various modifications added to the above-described embodiments without departing from the scope of the present invention.
(152) The terms and expressions which have been employed in the foregoing description are used therein as terms of description and not of limitation, and these are no intention, in the use of such terms and expressions, of excluding equivalent of the features shown and described or portions thereof, it being recognized that the scope of the invention is defined and limited only by the claims.
(153) It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof.