CERAMIC, PROBE GUIDING MEMBER, PROBE CARD, AND SOCKET FOR PACKAGE INSPECTION

Abstract

A ceramic according to the present invention includes, in mass %, BN: 20.0 to 55.0%, SiC: 5.0 to 40.0%, ZrO.sub.2 and/or Si.sub.3N.sub.4: 3.0 to 60.0%. The ceramic has a coefficient of thermal expansion at 50 to 500 C. of 1.010.sup.6 to 5.010.sup.6/ C., is excellent in low electrostatic properties (10.sup.6 to 10.sup.14 .Math.cm in volume resistivity) and free-machining properties, and is thus suitable to be used for, for example, a probe guiding member for guiding probes of a probe card, and a socket for package inspection.

Claims

1. A ceramic comprising, in mass %: BN: 20.0 to 55.0%; SiC: 5.0 to 40.0%; and ZrO.sub.2 and/or Si.sub.3N.sub.4: 3.0 to 60.0%.

2. The ceramic according to claim 1, wherein the ceramic has a coefficient of thermal expansion at 50 to 500 C. of 1.010.sup.6 to 5.010.sup.6/ C.

3. The ceramic according to claim 1, wherein the ceramic has a volume resistivity of 10.sup.6 to 10.sup.14 .Math.cm.

4. The ceramic according to claim 1, wherein the ceramic has a coefficient of water absorption of 0.5% or less.

5. A probe guiding member that guides probes of a probe card, the probe guiding member comprising: a plate-shaped main body that is made of the ceramic according to claim 1; and the main body includes a plurality of through holes and/or slits through which the probes are to be inserted.

6. A probe card comprising: a plurality of probes; and the probe guiding member according to claim 5.

7. A socket for package inspection, wherein the socket for package inspection is made of the ceramic according to claim 1.

8. The ceramic according to claim 2, wherein the ceramic has a volume resistivity of 10.sup.6 to 10.sup.14 .Math.cm.

9. The ceramic according to claim 2, wherein the ceramic has a coefficient of water absorption of 0.5% or less.

10. The ceramic according to claim 3, wherein the ceramic has a coefficient of water absorption of 0.5% or less.

11. The ceramic according to claim 8, wherein the ceramic has a coefficient of water absorption of 0.5% or less.

12. A probe guiding member that guides probes of a probe card, the probe guiding member comprising: a plate-shaped main body that is made of the ceramic according to claim 2; and the main body includes a plurality of through holes and/or slits through which the probes are to be inserted.

13. A probe guiding member that guides probes of a probe card, the probe guiding member comprising: a plate-shaped main body that is made of the ceramic according to claim 3; and the main body includes a plurality of through holes and/or slits through which the probes are to be inserted.

14. A probe guiding member that guides probes of a probe card, the probe guiding member comprising: a plate-shaped main body that is made of the ceramic according to claim 4; and the main body includes a plurality of through holes and/or slits through which the probes are to be inserted.

15. A probe guiding member that guides probes of a probe card, the probe guiding member comprising: a plate-shaped main body that is made of the ceramic according to claim 8; and the main body includes a plurality of through holes and/or slits through which the probes are to be inserted.

16. A probe guiding member that guides probes of a probe card, the probe guiding member comprising: a plate-shaped main body that is made of the ceramic according to claim 9; and the main body includes a plurality of through holes and/or slits through which the probes are to be inserted.

17. A probe guiding member that guides probes of a probe card, the probe guiding member comprising: a plate-shaped main body that is made of the ceramic according to claim 10; and the main body includes a plurality of through holes and/or slits through which the probes are to be inserted.

18. A probe guiding member that guides probes of a probe card, the probe guiding member comprising: a plate-shaped main body that is made of the ceramic according to claim 11; and the main body includes a plurality of through holes and/or slits through which the probes are to be inserted.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0037] FIG. 1 is a cross-sectional view illustrating a configuration of a probe card as an example.

[0038] FIG. 2 is a top view illustrating a configuration of a probe guide as an example.

[0039] FIG. 3 is a picture of Example 1 after a micromachining test.

[0040] FIG. 4 is a picture of Comparative example 6 after the micromachining test.

DESCRIPTION OF EMBODIMENTS

[0041] 1. Ceramic

[0042] A ceramic according to the present invention includes, in mass %, BN: 20.0 to 55.0%, SiC: 5.0 to 40.0%, ZrO.sub.2 and/or Si.sub.3N.sub.4: 3.0 to 60.0%. In the following description, the symbol % for contents means percent by mass.

[0043] BN: 20.0 to 55.0%

[0044] The ceramic according to the present invention is required to be a free-machining material that allows machining to be performed with a cemented carbide tool, and thus in order to give excellent free-machining properties to the ceramic, 20.0% or more of BN is contained as an essential component. However, if a content of BN is more than 55.0%, a material strength is decreased, arising a problem in machining through holes in that walls between through holes are collapsed. Accordingly, the content of BN is to range from 20.0 to 55.0%. A lower limit of the content of BN is preferably 25.0%, and more preferably 30.0%. An upper limit of the content of BN is preferably 50.0%, and more preferably 45.0%.

[0045] Note that types of BN include hexagonal BN (h-BN) and cubic BN (c-BN), but the c-BN has a high hardness, and it is thus preferable to use h-BN. Although no specific limitation is imposed on a grain diameter of BN, if BN has an excessively large grain diameter, a decrease in material strength may occur, and thus BN preferably has an average grain diameter of less than 5 m.

[0046] SiC: 5.0 to 40.0%

[0047] SiC is an essential component to adjust a volume resistivity of the ceramic such that the volume resistivity falls within a range from 10.sup.6 to 10 .Math.cm. Accordingly, a content of SiC is to be 5.0% or more. However, if the content of SiC is more than 40.0%, the volume resistivity falls below 10.sup.6 .Math.cm, which not only is an undesirable volume resistivity for the low electrostatic-property material but also raises a problem in that a material hardness increases excessively to impair the free-machining properties. Accordingly, the content of SiC is to range from 5.0 to 40.0%. A lower limit of the content of SiC is preferably 10.0%, and more preferably 15.0%. An upper limit of the content of SiC is preferably 35.0%, and more preferably 30.0%.

[0048] Although no specific limitation is imposed on a grain diameter of SiC, if SiC has an excessively large grain diameter, variations in the volume resistivity become large, and thus SiC preferably has an average grain diameter of less than 2.0 m. In addition, SiC is preferably present being dispersed in the ceramic mainly containing BN. A state of the dispersion can be checked by performing elementary analysis of Si using the energy dispersive X-ray spectrometry (EDX).

[0049] ZrO.sub.2 and/or Si.sub.3N.sub.4: 3.0 to 60.0%.

[0050] ZrO.sub.2 and Si.sub.3N.sub.4 are both components essential for enhancement in the mechanical properties of the ceramic. Accordingly, a content of ZrO.sub.2 and/or Si.sub.3N.sub.4 is to be 3.0% or more. However, if the content of ZrO.sub.2 and/or Si.sub.3N.sub.4 is more than 60.0%, the hardness increases excessively, and the free-machining properties deteriorate, which makes it impossible to form fine holes with high precision. Accordingly, the content of ZrO.sub.2 and/or Si.sub.3N.sub.4 is to range from 3.0 to 60.0%. A lower limit of the content of ZrO.sub.2 and/or Si.sub.3N.sub.4 is preferably 5.0%, and more preferably 10.0%. An upper limit of the content of ZrO.sub.2 and/or Si.sub.3N.sub.4 is preferably 55.0%, and more preferably 50.0%. In a case where ZrO.sub.2 and Si.sub.3N.sub.4 are both contained, their total content is to range from 3.0 to 60.0%.

[0051] Although no specific limitation is imposed on a grain diameter of ZrO.sub.2 and/or Si.sub.3N.sub.4, if ZrO.sub.2 and/or Si.sub.3N.sub.4 has an excessively large grain diameter, variations in the mechanical properties become large, and thus ZrO.sub.2 and/or Si.sub.3N.sub.4 preferably has an average grain diameter of less than 2 m. In addition, ZrO.sub.2 and/or Si.sub.3N.sub.4 is preferably present being dispersed in the ceramic mainly containing BN. A state of the dispersion can be checked by the elementary analysis using EDX.

[0052] The ceramic according to the present invention contains, in addition to the components described above, a sintering agent necessary to obtain a close-grained ceramic. As the sintering agent, one or more kinds selected from, for example, aluminum oxide (alumina, Al.sub.2O.sub.3), magnesium oxide (magnesia, MgO), yttrium oxide (yttria, Y.sub.2O.sub.3), oxides of lanthanoid metals, and complex oxides such as spinel, can be used. Of these, a mixture of alumina and yttria, or a mixture of alumina and yttria further containing magnesia is preferable.

[0053] No specific limitation is imposed on a content of the sintering agent, but the content is desirably 1.0 to 15.0%. If the compounding amount is excessively small, the sintering becomes insufficient, decreasing the strength of the ceramic as a sintered body. In contrast, if the compounding amount is excessively large, grain boundary phases made of glass and crystals having low strengths increase, which also incurs a decrease in the strength of the ceramic. Furthermore, because the grain boundary phases have high volume resistivities, the excessively large compounding amount incurs an increase in the volume resistivity of the ceramic, adversely affecting the low electrostatic properties. The content of the sintering agent is preferably 3.0% or more, and more preferably 5.0% or more. The content of the sintering agent is preferably 12.0% or less, and more preferably 10.0% or less.

[0054] Contents of the respective components (mass %) can be measured by the ICP emission spectral analysis.

[0055] Coefficient of Thermal Expansion at 50 to 500 C.: 1.010.sup.6 to 5.010.sup.6/ C. In a case where the ceramic according to the present invention is used for a probe guide, the ceramic is required to have a coefficient of thermal expansion as high as that of a silicon wafer on which IC chips are formed. This is because, when a temperature in the inspection changes, positions of the IC chips move with thermal expansion of the silicon wafer. At the time, in a case where the probe guide has a coefficient of thermal expansion as high as that of the silicon wafer, the probe guide moves in synchronization with expansion and contraction of the silicon wafer, which enables a high precision inspection to be kept. This also applies to a case where the ceramic according to the present invention is used for a socket for inspection. Accordingly, a reference coefficient of thermal expansion at 50 to 500 C. is 1.010.sup.6 to 5.010.sup.6/ C.

[0056] Volume Resistivity: 10.sup.6 to 10.sup.14 .Math.cm

[0057] A feature of the ceramic according to the present invention is having low electrostatic properties, and its reference volume resistivity is 10.sup.6 to 10.sup.14 .Math.cm.

[0058] Coefficient of Water Absorption: 0.5% or less

[0059] The ceramic according to the present invention is required to be close-grained so that necessary mechanical properties are obtained. Sufficient mechanical properties may not be obtained if there are a large number of residual pores, and thus a reference coefficient of water absorption is 0.5% or less.

[0060] Flexural Strength: 200 MPa or more

[0061] In a case where the ceramic according to the present invention is used for a probe guide, the ceramic is required to have mechanical properties sufficient to withstand contact and a load of probes and the like in the inspection. This also applies to a case where the ceramic according to the present invention is used for a socket for inspection. Accordingly, a reference flexural strength is 200 MPa or more.

[0062] Free-Machining Properties

[0063] Regarding free-machining properties, a machining precision of performing cutting working using a cemented carbide micro drill to form 1000 (8125 rows) through holes having diameters of 50 m and 100 m with a 60 m pitch is evaluated by observing the through holes by a vision measuring system (e.g., Quick Vision from Mitutoyo Corporation). At that time, a case where the machining precision is within 3.0 m is determined to be good in the free-machining properties.

[0064] 2. Method for Producing Ceramic

[0065] An example of a method for producing the ceramic according to the present invention will be described below.

[0066] Powders of BN, SiC, and ZrO.sub.2 and/or Si.sub.3N.sub.4 are mixed together with the sintering agent by a known method such as a method using a ball mill. That is, the powders, solvent, resin-made balls each including a ceramic-made or iron-made core therein are mixed in a container to be formed into slurry. At that time, as the solvent, water or alcohol can be used. In addition, an additive such as a dispersant and a binder may be used as necessary.

[0067] The obtained slurry is formed into grains by a known method such as spray drying and a method using a decompression evaporator. That is, the slurry is spray-dried by a spray dryer to be formed into granules or is dried by the decompression evaporator to be formed into powder.

[0068] The obtained powder is sintered under a high temperature and a high pressure by, for example, a known method such as hot pressing and hot isostatic pressing (HIP) to be formed into a sintered ceramic body. In the case of the hot pressing, the powder may be calcined in a nitrogen atmosphere or in pressurized nitrogen. In addition, a temperature of the calcination preferably ranges from 1400 to 1900 C. If the temperature is excessively low, the sintering becomes insufficient, and if the temperature is excessively high, a problem such as liquating oxide components arises.

[0069] An appropriate pressing force ranges from 15 to 50 MPa. In addition, a duration of maintaining the pressing force is normally about 1 to 4 hours, which however depends on the temperature or the dimensions. Also in a case of the HIP, calcination conditions including the temperature and the pressing force are to be set as appropriate. Alternatively, a known calcination method such as a pressureless calcination method and an atmosphere pressing calcination may be adopted.

EXAMPLE

[0070] In order to confirm the effects of the present invention, powders of BN (h-BN), SiC, and ZrO.sub.2 and/or Si.sub.3N.sub.4 were mixed together with the sintering agent (the mixture of alumina and yttria, or the mixture of alumina and yttria further containing magnesia) at various compounding ratios with water, dispersant, resin, and ceramic-made balls, and obtained slurries were each spray-dried by a spray dryer to be formed into granules. The obtained granules were charged into a graphite-made dice (mold) and subjected to hot pressing calcination in a nitrogen atmosphere, under a pressure of 30 MPa, at 1700 C., for 2 hours, to be formed into test materials being 150 mm long150 mm wide30 mm thick.

[0071] For reference, a resin to which commercial carbon fiber was added (Comparative example 8), a ceramic including commercial Al.sub.2O.sub.3 as its main phase (Comparative example 9), a ceramic including commercial ZrO.sub.2 as its main phase (Comparative example 10) were prepared as test materials.

[0072] From the obtained test materials, test specimens were taken and subjected to various kinds of tests.

[0073] <Volume Resistivity>

[0074] A volume resistivity of each of the test materials was determined in conformity with JIS C2141.

[0075] <Thermal Expansivity>

[0076] A coefficient of thermal expansion of each of the test materials at 50 to 500 C. was determined in conformity with JIS R1618.

[0077] <Coefficient of Water Absorption>

[0078] A coefficient of water absorption of each of the test materials was determined in conformity with JIS C2141.

[0079] <Flexural Strength>

[0080] A three-point flexural strength of each of the test materials was determined in conformity with JIS R1601.

[0081] <Free-Machining Properties>

[0082] Regarding free-machining properties, a machining precision of performing cutting working using a cemented carbide micro drill to form 1000 (8125 rows) through holes having diameters of 50 m and 100 m with a 60 m pitch was evaluated by performing visual observation on the through holes (a case where the machining precision was within 3.0 m was determined to be good). At that time, a case where the machining precision was within 3.0 pm was determined to be good in the free-machining properties and marked as , a case where the machining precision out of 3.0 m was marked as , and a case where the drilling failed due to a breakage of the drill or the like was marked as x, which were written in Table 1.

TABLE-US-00001 TABLE 1 Coef- ficient of Thermal Volume water expan- resis- absorp- Flexural sivity Fine hole Content (mass %) tivity tion strength (10.sup.6/ machining test Category SiC C TiO.sub.2 BN ZrO.sub.2 Si.sub.3N.sub.4 Y.sub.2O.sub.3 Al.sub.2O.sub.3 MgO (cm) (%) (MPa) C.) 50 um 100 um Example 1 8.5 36.0 48.0 5.6 1.9 9.1 10.sup.13 0.0 318 4.6 2 18.5 39.2 34.8 5.6 1.9 5.3 10.sup.13 0.0 326 3.2 3 21.3 40.0 31.2 5.6 1.9 3.9 10.sup.12 0.0 335 3.2 4 24.2 41.0 27.3 5.6 1.9 1.3 10.sup.11 0.0 329 2.8 5 10.9 38.4 43.2 5.6 1.9 1.2 10.sup.13 0.0 555 1.1 6 14.1 38.4 40.0 5.6 1.9 1.2 10.sup.13 0.0 549 1.2 7 15.2 38.4 38.9 5.6 1.9 5.9 10.sup.11 0.0 512 1.0 8 16.3 38.4 37.8 5.6 1.9 4.2 10.sup.10 0.0 503 1.1 9 17.4 38.4 36.7 5.6 1.9 8.0 10.sup.9 0.0 532 1.3 10 19.1 37.4 33.6 7.2 2.7 9.1 10.sup.8 0.0 510 1.2 11 21.2 37.4 31.5 7.2 2.7 1.1 10.sup.8 0.0 519 1.3 12 10.4 25.5 56.6 5.6 1.9 4.6 10.sup.12 0.0 611 1.6 13 22.3 51.2 16.6 5.4 2.7 1.8 6.8 10.sup.10 0.0 230 1.3 14 36.2 25.5 25.5 4.5 5.5 1.8 1.0 4.3 10.sup.6 0.0 469 3.6 15 15.0 38.8 18.8 19.9 5.6 1.9 8.5 10.sup.11 0.0 473 2.9 16 24.2 41.0 27.3 5.6 1.9 3.4 10.sup.11 0.8 253 2.7 Compar- 1 * 32.6 47.4 12.5 5.6 1.9 1.9 10.sup.15# 0.0 344 4.7 ative 2 * 47.7 44.8 5.6 1.9 2.0 10.sup.15# 0.0 447 1.4 Example 3 2.3* 34.1 56.1 5.6 1.9 7.7 10.sup.14# 0.0 322 4.8 4 43.8* 12.4* 16.5 17.4 6.3 1.8 1.8 1.6 10.sup.5# 0.0 656 3.4 x Drill Preci- broken sion 3 um 5 * 3.8 39.2 49.5 5.6 1.9 9.5 10.sup.15# 0.0 269 1.3 6 * 7.8 39.9 44.8 5.6 1.9 8.0 10.sup.6 0.0 138# 1.3 Wall Wall broken broken 7 * 23.1 69.4* 3.7 1.9 1.9 1.2 10.sup.15# 0.0 741 2.8 x x Drill Drill broken broken 8 Antistatic-measures peek (resin) 1.2 10.sup.9 0.1 142# 40.0# Wall Wall broken broken Preci- Preci- sion sion 3 um 3 um 9 Antistatic-measures Al.sub.2O.sub.3 5.6 10.sup.10 0.0 475 7.4# x x Drill Drill broken broken 10 Antistatic-measures ZrO.sub.2 9.8 10.sup.8 0.0 865 8.6# x x Drill Drill broken broken The mark * indicates that its value fell out of the range specified in the present invention. The mark # indicates that its property did not satisfy the range desired in the present invention.

[0083] FIG. 3 is a picture of Example 1 after a refining test, and FIG. 4 is a picture of Comparative example 6 after the refining test.

[0084] As shown in Table 1, Comparative examples 1 to 3 were examples in which BN was contained as their main phases, ZrO.sub.2 and/or Si.sub.3N.sub.4 were contained, but their contents of SiC were low, or they did not contain SiC, and thus their volume resistivities became excessively high. In Comparative example 4, its content of BN was excessively low, and its content of hard SiC was excessively high, and thus its free-machining properties deteriorated in a micromachining test. Comparative examples 5 and 6 were examples in which C was contained rather than SiC; in Comparative example 5, its volume resistivity was excessively high, and in Comparative example 6, its free-machining properties deteriorated. Comparative example 7 was an example in which Si.sub.3N4 was contained as its main phase, and TiO.sub.2 was contained, but its volume resistivity was excessively high, and in addition, its free-machining properties deteriorated. In Comparative examples 8 to 10, all of their free-machining properties deteriorated.

[0085] In contrast, Examples 1 to 16 were good in both the volume resistivity and the free-machining properties. Example 16 satisfied the required qualities, but its coefficient of water absorption was as high as 0.8, and its flexural strength deteriorated to some degree. In addition, in Comparative example 6, a collapse of walls between the through holes occurred in the cutting working, but in Example 1, the through holes were successfully formed with high precision without the occurrence of such collapse, as illustrated in FIG. 3 and FIG. 4.

INDUSTRIAL APPLICABILITY

[0086] The present invention makes it possible to obtain a ceramic that is excellent in low electrostatic properties (10.sup.6 to 10.sup.14 .Math.cm in volume resistivity) and free-machining properties, which is thus useful particularly to a probe guiding member, a probe card, and a socket for inspection.