Solder alloy, solder paste, and electronic circuit board

Abstract

A solder alloy substantially consists of tin, silver, indium, bismuth, and antimony. With respect to the total amount of the solder alloy, the content ratio of the silver is 2.8 mass % or more and 4 mass % or less; the content ratio of the indium is 6.2 mass % or more and 9.0 mass % or less; the content ratio of the bismuth is 0.7 mass % or more and 5.0 mass % or less; the content ratio of the antimony is 0.3 mass % or more and 5.0 mass % or less; and the content ratio of the tin is the remaining ratio and the value of A is 4.36 or less wherein A=0.87[In content ratio (mass %)]0.41[Ag content ratio (mass %)]0.82[Sb content ratio (mass %)].

Claims

1. A solder alloy consisting essentially of: tin, silver, indium, bismuth, and antimony, wherein with respect to the total amount of the solder alloy, the content ratio of the silver is 2.8 mass % or more and 4 mass % or less; the content ratio of the indium is 6.2 mass % or more and 9.0 mass % or less; the content ratio of the bismuth is 1.0 mass % or more and 5.0 mass % or less; the content ratio of the antimony is 1.0 mass % or more and 5.0 mass % or less; and the content ratio of the tin is the remaining ratio, and wherein the value of A in the following discriminant (1) is 4.36 or less,
A=0.87[In content ratio (mass %)]0.41[Ag content ratio (mass %)]0.82[Sb content ratio (mass %)](1), and wherein the solder alloy satisfies: 1) Phase Transformation ranking of A or B, wherein ranking A corresponds to A: deformation of the solder alloy was not confirmed, and ranking B corresponds to B: deformation of the solder alloy was confirmed, but a bridge between solder alloys of lands that were adjacent to each other was not confirmed; 2) a Durability of a 3216 size ranking of A, wherein ranking A corresponds to A: a proportion of a crack was 70% or less of a total length of a fillet; and 3) a Breakage of Component ranking of A or B, wherein ranking A corresponds to A: a crack did not occur in a component electrode, and ranking B corresponds to B: a crack occurred in a component electrode, but rupture did not occur.

2. The solder alloy according to claim 1, wherein the content ratio of the bismuth is 1.0 mass % or more and 3.0 mass % or less.

3. The solder alloy according to claim 1, wherein the content ratio of the antimony is 1.0 mass % or more and 3.0 mass % or less.

4. A solder alloy consisting essentially of: tin, silver, indium, bismuth, antimony, and at least one element selected from the group consisting of copper, nickel, cobalt, gallium, germanium, and phosphorus, wherein with respect to the total amount of the solder alloy, the content ratio of the silver is 2.8 mass % or more and 4 mass % or less; the content ratio of the indium is 6.2 mass % or more and 9.0 mass % or less; the content ratio of the bismuth is 1.0 mass % or more and 5.0 mass % or less; the content ratio of the antimony is 1.0 mass % or more and 5.0 mass % or less; the content ratio of the element is above 0 mass % and 1 mass % or less; and the content ratio of the tin is the remaining ratio, and wherein the value of A in the following discriminant (1) is 4.36 or less,
A=0.87[In content ratio (mass %)]0.41[Ag content ratio (mass %)]0.82[Sb content ratio (mass %)](1), and wherein the solder alloy satisfies: 1) Phase Transformation ranking of A or B, wherein ranking A corresponds to A: deformation of the solder alloy was not confirmed, and ranking B corresponds to B: deformation of the solder alloy was confirmed, but a bridge between solder alloys of lands that were adjacent to each other was not confirmed; 2) a Durability of a 3216 size ranking of A, wherein ranking A corresponds to A: a proportion of a crack was 70% or less of a total length of a fillet; and 3) a Breakage of Component ranking of A or B, wherein ranking A corresponds to A: a crack did not occur in a component electrode, and ranking B corresponds to B: a crack occurred in a component electrode, but rupture did not occur.

5. A solder paste comprising: a solder powder composed of the solder alloy according to claim 1, and a flux.

6. An electronic circuit board comprising: a soldering portion by the solder paste according to claim 5.

Description

EXAMPLES

(1) The present invention will now be described in more detail by way of Examples and Comparative Examples. However, the present invention is not limited to the following Examples. Values in Examples shown below can be replaced with the values (that is, upper limit value or lower limit value) described in the embodiment.

Examples 1 to 46 and Comparative Examples 1 to 44

(2) Preparation of Solder Alloy

(3) The powder of each of the metals described in Tables 1 to 2 was mixed at the mixing ratio described in Tables 1 to 2 and each of the obtained metal mixtures was melted to be unified in a melting furnace, thereby preparing solder alloys.

(4) In each of Examples, the value of A in the following discriminant (1) was adjusted so as to be 4.36 or less.
A=0.87[In content ratio (mass %)]0.41[Ag content ratio (mass %)]0.82[Sb content ratio (mass %)](1)

(5) The mixing ratio of tin (Sn) in each of the mixing formulations in Examples and Comparative Examples is a remaining ratio obtained by subtracting the mixing ratio (mass %) of the metals (tin (Sn), silver (Ag), indium (In), bismuth (Bi), antimony (Sb), copper (Cu), nickel (Ni), cobalt (Co), gallium (Ga), germanium (Ge), and phosphorus (P)) described in Tables 1 to 2.

(6) The solder alloy in Example 1 is obtained by blending each of the metals of Ag, In, Bi, and Sb at a ratio shown in Table 1 and defining the remaining content as Sn.

(7) Examples 2 to 3 are an example of the formulation in which the mixing ratio of Ag is increased with respect to the formulation in Example 1. Example 4 is an example of the formulation in which the mixing ratio of In is increased with respect to the formulation in Example 3.

(8) Examples 5 to 7 are an example of the formulation in which the mixing ratio of Sb is increased with respect to the formulation in Examples 1 to 3. Examples 8 to 10 are an example of the formulation in which the mixing ratio of In is increased with respect to the formulation in Examples 5 to 7. Examples 11 to 12 are an example of the formulation in which the mixing ratio of In is further increased with respect to the formulation in Examples 9 to 10.

(9) Examples 13 to 15 are an example of the formulation in which the mixing ratio of Sb is further increased with respect to the formulation in Examples 5 to 7. Examples 16 to 24 are an example of the formulation in which the mixing ratio of In is increased with respect to the formulation in Examples 13 to 15.

(10) Examples 25 to 30 are an example of the formulation in which any one of Cu, Ni, Co, Ga, Ge, and P is added at a ratio shown in Table 1 with respect to the formulation in Example 9. Example 31 is an example of the formulation in which all of Cu, Ni, Co, Ga, Ge, and P are added at a ratio shown in Table 1.

(11) Examples 32 and 36 are an example of the formulation in which the mixing ratio of Sb is increased or decreased with respect to the formulation in Example 9.

(12) Examples 33 to 35 are an example of the formulation in which the mixing ratio of Bi is increased or decreased with respect to the formulation in Example 9.

(13) Example 37 is an example of the formulation in which the mixing ratio of Bi is increased with respect to the formulation in Example 1.

(14) Example 38 is an example of the formulation in which the mixing ratio of Sb is increased with respect to the formulation in Example 1.

(15) Example 39 is an example of the formulation in which the mixing ratio of Bi is increased with respect to the formulation in Example 3.

(16) Example 40 is an example of the formulation in which the mixing ratio of Sb is increased with respect to the formulation in Example 3.

(17) Example 41 is an example of the formulation in which the mixing ratio of In is increased with respect to the formulation in Example 38.

(18) Example 42 is an example of the formulation in which the mixing ratio of Bi is increased with respect to the formulation in Example 38.

(19) Example 43 is an example of the formulation in which the mixing ratio of In is increased with respect to the formulation in Example 40.

(20) Example 44 is an example of the formulation in which the mixing ratio of Bi is increased with respect to the formulation in Example 40.

(21) Example 45 is an example of the formulation in which the mixing ratio of In and that of Bi are increased with respect to the formulation in Example 38.

(22) Example 46 is an example of the formulation in which the mixing ratio of In and that of Bi are increased with respect to the formulation in Example 40.

(23) Comparative Examples 1 to 2 are an example of the formulation in which the mixing ratio of Sb is decreased and the value of A in the above-described discriminant (1) is adjusted to exceed the above-described predetermined value with respect to the formulation in Examples 45 to 46.

(24) Comparative Examples 3 to 6 are an example of the formulation in which the mixing ratio of any one of Ag, In, Bi, and Sb is decreased to be insufficient with respect to the formulation in Example 1.

(25) Comparative Examples 7 to 10 are an example of the formulation in which the mixing ratio of any one of Ag, In, Bi, and Sb is increased to be excessive with respect to the formulation in Example 46.

(26) Comparative Examples 11 to 18 are an example of the formulation in which the mixing ratio of any one of Ag, In, Bi, and Sb is increased or decreased to be insufficient or excessive with respect to the formulation in Example 9.

(27) Comparative Example 19 is an example of the formulation in which the mixing ratio of In is increased and the value of A in the above-described discriminant (1) is adjusted to exceed 4.36 with respect to the formulation in Example 5.

(28) Comparative Example 20 is an example of the formulation in which the mixing ratio of In and that of Bi are increased and the value of A in the above-described discriminant (1) is adjusted to exceed 4.36 with respect to the formulation in Example 5.

(29) Comparative Example 21 is an example of the formulation in which the mixing ratio of In is increased and the value of A in the above-described discriminant (1) is adjusted to exceed 4.36 with respect to the formulation in Example 7.

(30) Comparative Example 22 is an example of the formulation in which the mixing ratio of In and that of Bi are increased and the value of A in the above-described discriminant (1) is adjusted to exceed 4.36 with respect to the formulation in Example 7.

(31) Comparative Example 23 is an example of the formulation in which the mixing ratio of Sb is decreased and the value of A in the above-described discriminant (1) is adjusted to exceed 4.36 with respect to the formulation in Example 23.

(32) Comparative Example 24 is an example of the formulation in which the mixing ratio of Sb is decreased or that of Bi is increased, and the value of A in the above-described discriminant (1) is adjusted to exceed 4.36 with respect to the formulation in Example 23.

(33) Comparative Examples 25 to 32 are an example of the formulation in which the mixing ratio of In is increased and the value of A in the above-described discriminant (1) is adjusted to exceed 4.36 with respect to any of the formulations in Examples 1 to 3.

(34) Comparative Examples 33 to 36 are an example of the formulation in which the mixing ratio of In is increased and the value of A in the above-described discriminant (1) is adjusted to exceed 4.36 with respect to any of the formulations in Examples 5 to 7.

(35) Comparative Examples 37 to 44 are obtained by blending each of the metals of Ag, In, Bi, and Sb at a ratio shown in Table 1, further adding Cu, Ni, and P at a ratio shown in Table 1, and defining the remaining content as Sn.

(36) Preparation of Solder Paste

(37) The obtained solder alloy was powdered so that the particle size thereof was 25 to 38 m. The obtained powder of the solder alloy was mixed with known flux, thereby obtaining a solder paste.

(38) Evaluation of Solder Paste

(39) The obtained solder paste was printed in a chip component-mounted print board and a chip component was mounted thereon by a reflow method. The printing conditions of the solder paste at the time of mounting, the size of the chip component, and the like were appropriately set in accordance with each of the evaluations to be described later.

(40) TABLE-US-00001 TABLE 1 Mixing Formulation (Mass %) No. Ag In Bi Sb Cu Ni Co Ga Ge P Discriminant A Ex. 1 2.8 6.2 1.0 0.3 4.00 Ex. 2 3.5 6.2 1.0 0.3 3.71 Ex. 3 4.0 6.2 1.0 0.3 3.51 Ex. 4 4.0 7.0 1.0 0.3 4.20 Ex. 5 2.8 6.2 1.0 1.5 3.02 Ex. 6 3.5 6.2 1.0 1.5 2.73 Ex. 7 4.0 6.2 1.0 1.5 2.52 Ex. 8 2.8 7.0 1.0 1.5 3.71 Ex. 9 3.5 7.0 1.0 1.5 3.43 Ex. 10 4.0 7.0 1.0 1.5 3.22 Ex. 11 3.5 8.0 1.0 1.5 4.30 Ex. 12 4.0 8.0 1.0 1.5 4.09 Ex. 13 2.8 6.2 1.0 3.0 1.79 Ex. 14 3.5 6.2 1.0 3.0 1.50 Ex. 15 4.0 6.2 1.0 3.0 1.29 Ex. 16 2.8 7.0 1.0 3.0 2.48 Ex. 17 3.5 7.0 1.0 3.0 2.20 Ex. 18 4.0 7.0 1.0 3.0 1.99 Ex. 19 2.8 8.0 1.0 3.0 3.35 Ex. 20 3.5 8.0 1.0 3.0 3.07 Ex. 21 4.0 8.0 1.0 3.0 2.86 Ex. 22 2.8 9.0 1.0 3.0 4.22 Ex. 23 3.5 9.0 1.0 3.0 3.94 Ex. 24 4.0 9.0 1.0 3.0 3.73 Ex. 25 3.5 7.0 1.0 1.5 1.0 3.43 Ex. 26 3.5 7.0 1.0 1.5 1.0 3.43 Ex. 27 3.5 7.0 1.0 1.5 1.0 3.43 Ex. 28 3.5 7.0 1.0 1.5 1.0 3.43 Ex. 29 3.5 7.0 1.0 1.5 1.0 3.43 Ex. 30 3.5 7.0 1.0 1.5 1.0 3.43 Ex. 31 3.5 7.0 1.0 1.5 0.2 0.2 0.2 0.2 0.1 0.1 3.43 Ex. 32 3.5 7.0 1.0 5.0 0.56 Ex. 33 3.5 7.0 0.7 1.5 3.43 Ex. 34 3.5 7.0 5.0 1.5 3.43 Ex. 35 3.5 7.0 3.0 1.5 3.43 Ex. 36 3.5 7.0 1.0 1.0 3.84 Ex. 37 2.8 6.2 5.0 0.3 4.00 Ex. 38 2.8 6.2 1.0 5.0 0.15 Ex. 39 4.0 6.2 5.0 0.3 3.51 Ex. 40 4.0 6.2 1.0 5.0 0.35 Ex. 41 2.8 9.0 1.0 5.0 2.58 Ex. 42 2.8 6.2 5.0 5.0 0.15 Ex. 43 4.0 9.0 1.0 5.0 2.09 Ex. 44 4.0 6.2 5.0 5.0 0.35 Ex. 45 2.8 9.0 5.0 5.0 2.58 Ex. 46 4.0 9.0 5.0 5.0 2.09

(41) TABLE-US-00002 TABLE 2 Dis- Mixing Formulation (Mass %) crimi- No. Ag In Bi Sb Cu Ni Co Ga Ge P nant A Comp. Ex. 1 2.8 9.0 5.0 0.3 6.44 Comp. Ex. 2 4.0 9.0 5.0 0.3 5.94 Comp. Ex. 3 2.5 6.2 1.0 0.3 4.12 Comp. Ex. 4 2.8 6.0 1.0 0.3 3.83 Comp. Ex. 5 2.8 6.2 0.5 0.3 4.00 Comp. Ex. 6 2.8 6.2 1.0 0.0 4.25 Comp. Ex. 7 4.3 9.0 5.0 5.0 1.97 Comp. Ex. 8 4.0 9.5 5.0 5.0 2.53 Comp. Ex. 9 4.0 9.0 5.5 5.0 2.09 Comp. Ex. 10 4.0 9.0 5.0 5.5 1.68 Comp. Ex. 11 2.4 7.0 1.0 1.5 3.88 Comp. Ex. 12 4.3 7.0 1.0 1.5 3.10 Comp. Ex. 13 3.5 5.9 1.0 1.5 2.47 Comp. Ex. 14 3.5 9.3 1.0 1.5 5.43 Comp. Ex. 15 3.5 7.0 0.5 1.5 3.43 Comp. Ex. 16 3.5 7.0 5.3 1.5 3.43 Comp. Ex. 17 3.5 7.0 1.0 0.1 4.57 Comp. Ex. 18 3.5 7.0 1.0 5.5 0.15 Comp. Ex. 19 2.8 7.8 1.0 1.5 4.41 Comp. Ex. 20 2.8 7.8 3.0 1.5 4.41 Comp. Ex. 21 4.0 8.4 1.0 1.5 4.44 Comp. Ex. 22 4.0 8.4 3.0 1.5 4.44 Comp. Ex. 23 3.5 9.0 1.0 2.3 4.51 Comp. Ex. 24 3.5 9.0 3.0 2.3 4.51 Comp. Ex. 25 2.8 7.0 1.0 0.3 4.70 Comp. Ex. 26 3.5 7.0 1.0 0.3 4.41 Comp. Ex. 27 2.8 8.0 1.0 0.3 5.57 Comp. Ex. 28 3.5 8.0 1.0 0.3 5.28 Comp. Ex. 29 4.0 8.0 1.0 0.3 5.07 Comp. Ex. 30 2.8 9.0 1.0 0.3 6.44 Comp. Ex. 31 3.5 9.0 1.0 0.3 6.15 Comp. Ex. 32 4.0 9.0 1.0 0.3 5.94 Comp. Ex. 33 2.8 8.0 1.0 1.5 4.58 Comp. Ex. 34 2.8 9.0 1.0 1.5 5.45 Comp. Ex. 35 3.5 9.0 1.0 1.5 5.17 Comp. Ex. 36 4.0 9.0 1.0 1.5 4.96 Comp. Ex. 37 3.5 8.0 0.5 0.5 5.12 Comp. Ex. 38 3.5 8.0 0.5 1.5 4.30 Comp. Ex. 39 3.5 8.0 0.5 3.0 3.07 Comp. Ex. 40 4.0 6.0 1.0 0.0 0.5 3.58 Comp. Ex. 41 4.0 6.0 1.0 0.0 1.0 3.58 Comp. Ex. 42 3.5 6.0 0.5 0.0 0.1 3.79 Comp. Ex. 43 3.5 6.0 0.5 0.0 0.1 3.79 Comp. Ex. 44 3.5 6.0 0.5 0.1 3.70

(42) Evaluation

(43) <Production of Electronic Circuit Board>

(44) Each of the solder pastes obtained in Examples and Comparative Examples was printed in a chip component-mounted print board and a chip component was mounted thereon by a reflow method. The printing film thickness of the solder paste was adjusted using a metal mask having a thickness of 150 m. After the printing of the solder paste, a chip condenser and a chip resistor component having a 1005 size and a 3216 size were mounted on a predetermined position of the above-described print board to be heated in a reflow furnace and then, the chip component was mounted thereon. The reflow conditions were set as follows: preheating of 170 to 190 C., peak temperature of 260 C., time for the furnace being at 220 C. or more to be 45 seconds, and cooling rate at the time when the temperature decreased from the peak temperature until 200 C. to be 3 to 8 C./sec.

(45) Furthermore, the above-described print board was subjected to a cooling/heating cycle test in which it was retained under the environment of 150 C. for 30 minutes and next, retained under the environment of 40 C. for 30 minutes.

(46) <Phase Transformation>

(47) As for the print board in which the above-described cooling/heating cycles were repeated by 3000 cycles, the appearance of a QFN land portion (0.2 mm width land, 0.2 mm width gap) at 0.4 mm pitch was observed and the obtained results were ranked in accordance with the following criteria.

(48) A: Deformation of the solder alloy was not confirmed.

(49) B: Deformation of the solder alloy was confirmed, but a bridge between the solder alloys of the lands that were adjacent to each other was not confirmed.

(50) C: A bridge was formed between the solder alloys of the lands that were adjacent to each other.

(51) <Durability>

(52) The chip condenser portions having a 1005 size and a 3216 size after the cooling/heating cycles of 3000 cycles were cut and the cross sections thereof were polished. Thereafter, the proportion of cracks that occurred in the solder fillet portion was ranked in accordance with the following criteria. The number of evaluation chips was 10 for each of the chip condensers having a 1005 size and a 3216 size. In each of the chip sizes, the ranking was performed based on the largest crack.

(53) A: The proportion of the crack was 70% or less of the total length of the fillet.

(54) B: The proportion of the crack was less than 100% of the total length of the fillet.

(55) C: The crack completely crossed the fillet portion.

(56) <Breakage of Component>

(57) The chip resistor portion having a 3216 size after the cooling/heating cycles of 3000 cycles was cut and the cross section thereof was polished. Thereafter, the degree of cracks that occurred in an electrode portion of the chip resistor component itself was ranked in accordance with the following criteria. The number of evaluation chips was 10. The ranking was performed based on the largest crack.

(58) A: A crack did not occur in the component electrode.

(59) B: A crack occurred in the component electrode, but rupture did not occur.

(60) C: Rupture occurred in the electrode portion by a crack of the component electrode.

(61) <Comprehensive Evaluation>

(62) As grading for each of the evaluations of Phase Transformation, Durability on Using Chip Having 1005 Size, Durability on Using Chip Having 3216 Size, and Breakage of Component, evaluation A was defined as two points with evaluation B as one point and evaluation C as zero point. Next, the total grading in each evaluation item was calculated. Based on the total grading, each of the solder pastes obtained by Examples and Comparative Examples was comprehensively evaluated in accordance with the following criteria.

(63) A: Highly excellent (the total grading was eight points).

(64) B: Good (the total grading was six points or seven points and evaluation C was not included).

(65) C: Bad (at least one evaluation C was included).

(66) TABLE-US-00003 TABLE 3 Phase Durability Breakage Compre- Trans- 1005 3216 of hensive No. formation Size Size Component Evaluation Ex. 1 A A B A 7, B Ex. 2 A A B A 7, B Ex. 3 A A B A 7, B Ex. 4 B A B A 6, B Ex. 5 A A A A 8, A Ex. 6 A A A A 8, A Ex. 7 A A A A 8, A Ex. 8 A A A A 8, A Ex. 9 A A A A 8, A Ex. 10 A A A A 8, A Ex. 11 B A A A 7, B Ex. 12 A A A A 8, A Ex. 13 A A A A 8, A Ex. 14 A A A A 8, A Ex. 15 A A A A 8, A Ex. 16 A A A A 8, A Ex. 17 A A A A 8, A Ex. 18 A A A A 8, A Ex. 19 A A A A 8, A Ex. 20 A A A A 8, A Ex. 21 A A A A 8, A Ex. 22 B A A A 7, B Ex. 23 A A A A 8, A Ex. 24 A A A A 8, A Ex. 25 A A A A 8, A Ex. 26 A A A A 8, A Ex. 27 A A A A 8, A Ex. 28 A A A A 8, A Ex. 29 A A A A 8, A Ex. 30 A A A A 8, A Ex. 31 A A A A 8, A Ex. 32 A A A B 7, B Ex. 33 A A B A 7, B Ex. 34 A A A B 7, B Ex. 35 A A A A 8, A Ex. 36 A A A A 8, A Ex. 37 A A B B 6, B Ex. 38 A A A B 7, B Ex. 39 A A B B 6, B Ex. 40 A A A B 7, B Ex. 41 A A A B 7, B Ex. 42 A A A B 7, B Ex. 43 A A A B 7, B Ex. 44 A A A B 7, B Ex. 45 A A A B 7, B Ex. 46 A A A B 7, B

(67) TABLE-US-00004 TABLE 4 Phase Durability Breakage Compre- Trans- 1005 3216 of hensive No. formation Size Size Component Component Comp. Ex. 1 C A B B 4, C Comp. Ex. 2 C A B B 4, C Comp. Ex. 3 A B C A 5, C Comp. Ex. 4 A B C C 3, C Comp. Ex. 5 A B C A 5, C Comp. Ex. 6 B B C A 4, C Comp. Ex. 7 A B C B 4, C Comp. Ex. 8 A B C B 4, C Comp. Ex. 9 A A B C 5, C Comp. Ex. 10 A A A C 6, C Comp. Ex. 11 A B C A 5, C Comp. Ex. 12 A B C A 5, C Comp. Ex. 13 A A B C 5, C Comp. Ex. 14 C A B A 5, C Comp. Ex. 15 A B C A 5, C Comp. Ex. 16 A A B C 5, C Comp. Ex. 17 C B C A 3, C Comp. Ex. 18 A A B C 5, C Comp. Ex. 19 C A A A 6, C Comp. Ex. 20 C A A A 6, C Comp. Ex. 21 C A A A 6, C Comp. Ex. 22 C A A A 6, C Comp. Ex. 23 C A A A 6, C Comp. Ex. 24 C A A A 6, C Comp. Ex. 25 C A B A 5, C Comp. Ex. 26 C A B A 5, C Comp. Ex. 27 C A B A 5, C Comp. Ex. 28 C A B A 5, C Comp. Ex. 29 C A B A 5, C Comp. Ex. 30 C A B A 5, C Comp. Ex. 31 C A B A 5, C Comp. Ex. 32 C A B A 5, C Comp. Ex. 33 C A A A 6, C Comp. Ex. 34 C A A A 6, C Comp. Ex. 35 C A A A 6, C Comp. Ex. 36 C A A A 6, C Comp. Ex. 37 C C C A 2, C Comp. Ex. 38 B C C A 3, C Comp. Ex. 39 A C C A 4, C Comp. Ex. 40 A A C C 4, C Comp. Ex. 41 A A C C 4, C Comp. Ex. 42 A B C C 3, C Comp. Ex. 43 A B C C 3, C Comp. Ex. 44 A B C C 3, C

(68) While the illustrative embodiments of the present invention are provided in the above description, such is for illustrative purpose only and it is not to be construed as limiting the scope of the present invention. Modification and variation of the present invention that will be obvious to those skilled in the art is to be covered by the following claims.

INDUSTRIAL APPLICABILITY

(69) The solder alloy, the solder composition, and the solder paste of the present invention are used in an electronic circuit board used for electrical and electronic devices or the like.