WO2016010383A1

WO2016010383A1 - Test socket

Info

Publication number: WO2016010383A1
Application number: PCT/KR2015/007408
Authority: WO
Inventors: Young Bae Chung
Original assignee: Isc Co., Ltd.
Priority date: 2014-07-17
Filing date: 2015-07-16
Publication date: 2016-01-21
Also published as: KR101573450B1; TWI555984B; TW201606311A

Abstract

A test socket is configured to be disposed between a test target device and a test apparatus for electrically connecting terminals of the test target device to pads of the test apparatus. The test socket includes: a support sheet formed of an insulative material and including penetration holes at positions corresponding to the terminals of the test target device; inserts including first conductive parts and elastic insulative parts, wherein the first conductive parts are disposed in the penetration holes of the support sheet and formed by arranging a plurality of first conductive particles in an insulative elastic material in a thickness direction of the support sheet, and the elastic insulative parts are formed of an insulative elastic material and disposed between the first conductive parts and inner walls of the penetration holes to surround the first conductive parts; and an anisotropic sheet including second conductive parts and an insulative support part, wherein the second conductive parts are disposed under the first conductive parts and formed by arranging a plurality of second conductive particles in an insulative elastic material in a thickness direction of the anisotropic sheet at positions corresponding to the penetration holes, and the insulative support part is disposed under the support sheet to support and insulate the second conductive parts.

Description

TEST SOCKET

One or more exemplary embodiments relate to a test socket, and more particularly, to a test socket that is configured to minimally damage terminals of test target devices and has improved resistance characteristics and an increased thickness.

In general, stable electric connection between a device and an inspection apparatus is necessary when electric characteristics of the device are inspected. To this end, a test socket is generally used to connect a test apparatus to a device to be tested.

The function of the test socket is to connect terminals of a device to pads of a test apparatus to allow two-way transmission of electric signals between the device and the test apparatus. For this, an elastic conductive sheet or pogo pins are used in a test socket as contact parts. An elastic conductive sheet is used to bring elastic conductive parts into contact with terminals of a device to be tested, and pogo pins, in which springs are disposed, are used to connect a device to be tested to a test apparatus while buffering any mechanical impact that may occur when making the connection. Such elastic conductive sheets or pogo pins are used in most test sockets.

FIG. 1 illustrates an exemplary test socket 20 of the related art. The test socket 20 includes: conductive silicone parts 8 formed at positions to which ball leads 4 of a ball grid array (BGA) semiconductor device 2 may be placed; and an insulative silicon part 6 formed as an insulative layer in a region not making contact with the ball leads (lead terminals) 4 of the semiconductor device 2 so as to support the conductive silicone parts 8. The conductive silicone parts 8 electrically connect the lead terminals 4 of the semiconductor device 2 to contact pads 10 of a socket board 12 for testing the semiconductor device 2, and conductive rings 7 are respectively mounted on upper surfaces of the conductive silicone parts 8.

The test socket 20 may be useful for a test apparatus making contact with a semiconductor device by pushing the semiconductor device toward the test apparatus. Particularly, since the conductive silicone parts 8 are configured be individually pushed, it may be easy to perform a test process according to the flatness of peripheral devices. In other words, the conductive silicone parts 8 may have improved electric characteristics. Furthermore, the conductive rings 7 prevent spreading of the conductive silicone parts 8 when the conductive silicone parts 8 are pushed by the lead terminals 4 of the semiconductor device 2, and thus the conductive silicone parts 8 may be less deformed and thus may be stably used for a long time.

FIG. 2 illustrates another exemplary test socket 20 of the related art. Referring to FIG. 2, a method such as a plating, etching, or coating method is used to form conductors 22 on upper surfaces of conductive silicone parts 8 that electrically connect contact pads 10 of a socket board 12 to lead terminals 4 of a semiconductor device 2 to be tested.

since the conductors 22 formed on the upper surfaces of the conductive silicone parts 8 by a method such as a plating, etching, or coating method are relatively rigid, the elasticity of the conductive silicone parts 8 may be lowered as compared with the case of not using the conductors 22. That is, although the function of the conductive silicone parts 8 is to elastically connect the lead terminals 4 of the semiconductor device 2 to the contact pads 10 of the socket board (test board) 12, the elasticity of the conductive silicone parts 8 is lowered. In addition, the conductors 22, the lead terminals 4 of the semiconductor device 2, or the contact pads 10 of the test board 12 may be damaged if contacting actions are frequently carried out, and contaminants may be accumulated thereon.

To address such problems, a test socket shown in FIG. 3 has been proposed. The test socket includes: conductive silicone parts 8 formed of a mixture of silicone and conductive metal powder and disposed at positions where ball leads 4 of a BGA semiconductor device 2 may be placed; and an insulative silicon part 6 formed in a region not making contact with the ball leads (lead terminal) 4 of the semiconductor device 2 for supporting the conductive silicone parts 8. A conductivity enhancing layer 30 having a conductive metal powder density greater than that of the conductive silicone parts 8 is formed on upper surfaces of the conductive silicone parts 8. The test socket shown in FIG. 3 improves conductivity.

However, the above-described techniques of the related art may have the following problems.

First, the test socket of the related art shown in FIG. 3 is limited to increasing the thickness of the conductivity enhancing layer 30 formed on the upper surfaces of the conductive silicone parts 8. Since conductive powder is densely included in such a conductivity enhancing layer, the amount of silicon rubber used to maintain the shape of the conductive powder is relatively small. In this case, if the conductivity enhancing layer is formed thick, the shape of the conductivity enhancing layer may not be stably maintained.

Therefore, it is difficult to increase the thickness of the conductivity enhancing layer, and in this case, pressure applied by ball leads of a semiconductor device is concentrated to lower sides of the conductive silicon parts 8.

In addition, when a conductivity enhancing layer having a high density of conductive particles (powder) is formed, it is difficult to increase the density of the conductive particles to a certain level or higher because the amount of silicon rubber is reduced if the density of the conductive particles is increased. Therefore, it is difficult to obtain a maximized degree of conductivity.

According to one or more exemplary embodiments, a test socket is configured to be disposed between a test target device and a test apparatus for electrically connecting terminals of the test target device to pads of the test apparatus, the test socket including: a support sheet formed of an insulative material and including penetration holes at positions corresponding to the terminals of the test target device; inserts including first conductive parts and elastic insulative parts, wherein the first conductive parts are disposed in the penetration holes of the support sheet and formed by arranging a plurality of first conductive particles contained in an insulative elastic material in a thickness direction of the support sheet, and the elastic insulative parts are formed of an insulative elastic material and disposed between the first conductive parts and inner walls of the penetration holes to surround the first conductive parts; and an anisotropic sheet including second conductive parts and an insulative support part, wherein the second conductive parts are disposed under the first conductive parts and formed by arranging a plurality of second conductive particles contained in an insulative elastic material in a thickness direction of the anisotropic sheet at positions corresponding to the penetration holes, and the insulative support part is disposed under the support sheet to support and insulate the second conductive parts.

The first conductive particles may not be in the elastic insulative parts.

The first conductive particles may be included in the elastic insulative parts in an amount of 10 volume% or less.

The elastic insulative parts may be integrally coupled to the first conductive parts and the support sheet.

The elastic insulative parts may be more elastic than the first conductive parts and the support sheet.

The first conductive particles may be more densely arranged than the second conductive particles.

The support sheet may be formed of a material that is harder than the insulative support part.

The penetration holes of the support sheet may have a downwardly decreasing inner diameter.

According to one or more exemplary embodiments, a test socket is configured to be disposed between a test target device and a test apparatus for electrically connecting terminals of the test target device to pads of the test apparatus, the test socket including: a support sheet formed of an insulative material and including penetration holes at positions corresponding to the terminals of the test target device; first conductive parts disposed in the penetration holes of the support sheet and formed by arranging a plurality of first conductive particles contained in an insulative elastic material in a thickness direction of the support sheet, the first conductive parts having an outer diameter that is smaller than an inner diameter of the penetration holes; and an anisotropic sheet including second conductive parts and an insulative support part, wherein the second conductive parts are disposed under the first conductive parts and formed by arranging a plurality of second conductive particles contained in an insulative elastic material at positions corresponding to the penetration holes, the second conductive particles being less densely arranged than the first conductive particles, and the insulative support part is disposed under the support sheet to support and insulate the second conductive parts.

The insulative support part may include an upper insulative support part and a lower insulative support part disposed under the upper insulative support part, and the upper insulative support part and the lower insulative support part may have different degrees of hardness.

The upper insulative support part may be formed of a material that is softer than the lower insulative support part.

The second conductive parts may include second upper conductive parts and second lower conductive parts disposed under the second upper conductive parts, and a content of the second conductive particles in the second upper conductive parts may be different from a content of the second conductive particles in the second lower conductive parts.

The second conductive particles may be less densely arranged in the second upper conductive parts than in the second lower conductive parts.

According to the exemplary embodiments, the density of the conductive parts of the test socket may be improved to obtain high-current and high-resistance characteristics.

In addition, according to the exemplary embodiments, the thickness of the first conductive parts in which conductive particles are very densely arranged may be increased owing to the elastic insulative parts.

In addition, according to the exemplary embodiments, the size of the penetration holes of the support sheet may be increased regardless of the outer diameter of the first conductive parts, and thus terminals of test target devices may be minimally damaged by contact with the support sheet.

In addition, according to the exemplary embodiments, the insulative support part of the test socket may have regions having different degrees of hardness, and thus a pressing force that will be applied to the insulative support part may be adjusted.

FIGS. 1 to 3 are views illustrating text sockets of the related art;

FIG. 4 is a view illustrating a test socket according to an exemplary embodiment;

FIG. 5 is a view illustrating how the test socket illustrated in FIG. 4 is operated;

FIG. 6 is a view illustrating an exemplary case in which a device to be tested is not properly placed on the test socket illustrated in FIG. 4;

FIG. 7 is a view illustrating the test socket according to another exemplary embodiment; and

FIG. 8 is a view illustrating the test socket according to another exemplary embodiment.

Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the exemplary embodiments are merely described below, by referring to the figures, to explain aspects of the present description. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

Hereinafter, test sockets will be described in detail with reference to the accompanying drawings according to exemplary embodiments.

According to an exemplary embodiment, a test socket 100 is disposed between a test target device 140 to be tested and a test apparatus 150 so as to electrically connect terminals 141 of the test target device 140 to pads 151 of the test apparatus 150. The test socket 100 includes a support sheet 110, inserts 120, and an anisotropic sheet 130.

Penetration holes 111 are formed in the support sheet 110 at positions corresponding to the terminals 141 of the test target device 140, and the support sheet 110 is formed of an insulative material. The support sheet 110 may be attached to an upper surface of the anisotropic sheet 130. In detail, the support sheet 110 may be integrally attached to an insulative support part 132 of the anisotropic sheet 130. The support sheet 110 supports the inserts 120 (described later).

It may be preferable that the support sheet 110 be formed of a material having high elasticity and resilience. In addition, the support sheet 110 may be formed of a material selected according to requirements such as heat resistance or insulative properties. For example, the support sheet 110 may be formed of silicone, urethane, or any other elastic material by taking into consideration required degrees of elasticity and resilience. In addition, when heat resistance and insulative properties are taken into account, the support sheet 110 may be formed of a synthetic resin such as polyimide (PI), polycarbonate (PC), polypropylene (PP), polyethylene terephthalate (PET), or polymethylmethacrylate (PMMA). Particularly, the support sheet 110 may be formed of a material that is harder than the insulative support part 132 of the anisotropic sheet 130, so as to protect the insulative support part 132.

The penetration holes 111 of the support sheet 110 may be formed using a laser. However, the penetration holes 111 are not limited thereto. For example, the penetration holes 111 may be formed through a machining process.

The inserts 120 are inserted into the penetration holes 111 of the support sheet 110. The inserts 120 include first conductive parts 121 and elastic insulative parts 122.

The first conductive parts 121 are disposed in the penetration holes 111 of the support sheet 110. The first conductive parts 121 are formed by arranging a plurality of first conductive particles 1211 contained in an insulative elastic material in the thickness direction of the support sheet 110. The first conductive parts 121 have an outer diameter that is smaller than the inner diameter of the penetration holes 111. For example, the outer diameter of the first conductive parts 121 may be equal to or less than 0.9 times the inner diameter of the penetration holes 111. Preferably, the outer diameter of the first conductive parts 121 may be 0.85 times the inner diameter of the penetration holes 111. If the outer diameter of the first conductive parts 121 is smaller than the inner diameter of the penetration holes 111, as described above, even if the terminals 141 of the test target device 140 are not placed at center regions of the first conductive parts 121 but are placed at edge portions of the first conductive parts 121, the terminals 141 of the test target device 140 may not be directly in contact with the support sheet 110, and thus the surfaces of the terminals 141 of the test target device 140 may not be damaged. For example, even when the support sheet 110 is formed of a relatively hard material such as polyimide (PI), the terminals 141 of the test target device 140 may not be directly in contact with the support sheet 110.

Preferably, the insulative elastic material used for forming the first conductive parts 121 may be a heat-resistant, cross-linked polymer. The heat-resistant, cross-linked polymer may be obtained from various curable polymer forming materials, preferably such as liquid silicone rubber. The liquid silicone rubber may be addition-cure or condensation-cure liquid silicone rubber. For example, addition-cure liquid silicone rubber may be used. Preferably, the first conductive parts 121 may be formed using a cured product of a liquid silicone rubber (hereinafter referred to as a cured silicone rubber) having a compression set of 10% or less, more preferably 8% or less, and even more preferably 6% or less, at 150ㅀC. If the compression set of the cured silicon rubber is greater than 10%, the first conductive particles 1211 of the first conductive parts 121 may be in disorder after the first conductive parts 121 are repeatedly used at high temperatures, and the conductivity of the first conductive parts 121 may be lowered below a required level.

Preferably, the first conductive particles 1211 of the first conductive parts 121 may be arranged more densely than second conductive particles 1311 of second conductive parts 131 of the anisotropic sheet 130.

Preferably, the first conductive particles 1211 of the first conductive parts 121 may be formed by coating magnetic core particles with a highly conductive metal. The highly conductive metal may have a conductivity of 5 x 10⁶ Ω/m or greater at 0ㅀC. Preferably, the magnetic core particles for forming the first conductive particles 1211 may have a number average particle diameter of 3 μm to 40 μm. The number average particle diameter of the magnetic core particles is measured by a laser diffraction scattering method. Examples of a material that may be used to form the magnetic core particles may include iron, nickel, cobalt, and materials formed by coating copper or a resin with the metals. Preferably, the magnetic core particles may be formed of a material having a saturation magnetization of 0.1 Wb/m² or greater, more preferably 0.3 Wb/m² or greater, and even more preferably 0.5 Wb/m². For example, the magnetic core particles may be formed of iron, nickel, cobalt, or an alloy thereof.

Examples of the highly conductive metal for coating the magnetic core particles include gold, silver, rhodium, platinum, and chromium. Preferably, gold may be used as the highly conductive metal because gold is chemically stable and highly conductive.

The elastic insulative parts 122 are disposed between the first conductive parts 121 and inner walls of the penetration holes 111 and surround the first conductive parts 121. Preferably, the elastic insulative parts 122 may be integrally coupled to the first conductive parts 121 and the support sheet 110. However, the elastic insulative parts 122 are not limited thereto. For example, there may be gaps between the elastic insulative parts 122 and the first conductive parts 121 and/or between the elastic insulative parts 122 and the support sheet 110. Preferably, the elastic insulative parts 122 may be formed of an insulative elastic material. Preferably, the elastic insulative parts 122 may be more elastic than the first conductive parts 121 and the support sheet 110. For example, the elastic insulative parts 122 may be formed of a relatively soft material such as silicone rubber or urethane. The function of the elastic insulative parts 122 is to connect the first conductive parts 121 having a certain degree of conductivity to the support sheet 110, and since the elastic insulative parts 122 are formed of a relatively soft material, the first conductive parts 121 may be vertically movable relative to the support sheet 110. That is, the elastic insulative parts 122 may allow individual movements of the first conductive parts 121. Preferably, the first conductive particles 1211 may not be included in the elastic insulative parts 122. However, the elastic insulative parts 122 are not limited thereto. For example, the first conductive particles 1211 may be included in the elastic insulative parts 122 in a small amount of 10 volume% or less.

Since the elastic insulative parts 122 are disposed between the first conductive parts 121 and the inner walls of the penetration holes 111 of the support sheet 110, it may be easy to individual move the first conductive parts 121, and the penetration holes 111 may be formed to have a large size through a manufacturing process so as to prevent the surfaces of the terminals 141 of the test target device 140 from being damaged by the support sheet 110.

The anisotropic sheet 130 includes: the second conductive parts 131 disposed under the first conductive parts 121 and formed by arranging the second conductive particles 1311 contained in an insulative elastic material in the thickness direction of the anisotropic sheet 130 at positions corresponding to the penetration holes 111; and the insulative support part 132 disposed under the support sheet 110 to support and insulate the second conductive parts 131.

The insulative elastic material used to form the second conductive parts 131 may be identical or similar to the insulative elastic material used to form the first conductive parts 121, and thus a detailed description thereof will not be repeated. A material used to form the second conductive particles 1311 of the second conductive parts 131 may be identical or similar to a material used to form the first conductive particles 1211, and thus a detailed description thereof will not be repeated. However, it may be preferable that the second conductive particles 1311 have an average particle diameter that is greater than that of the first conductive particles 1211, and the ratio of the second conductive particles 1311 per unit area of the second conductive parts 131 be less than the ratio of the first conductive particles 1211 per unit area of the first conductive parts 121. That is, the second conductive particles 1311 may be less densely arranged than the first conductive particles 1211.

In addition, it may be preferable that the insulative support part 132 supporting and insulating the second conductive parts 131 be formed of the same insulative elastic material as the insulative elastic material used to form the second conductive parts 131. However, the insulative support part 132 is not limited thereto. That is, the insulative support part 132 may be formed of another material. For example, the insulative support part 132 may be formed of a material having a higher degree of elasticity than the insulative elastic material of the second conductive parts 131.

The test socket 100 of the exemplary embodiment may have the following operational effects.

As shown in FIG. 4, after the test socket 100 is placed on the test apparatus 150, the test target device 140 is moved to a position above the test socket 100. Then, the test target device 140 is lowered to bring the terminals 141 of the test target device 140 into contact with the first conductive parts 121 as shown in FIG. 5. If the test target device 140 contacting the first conductive parts 121 is further pushed down, the first conductive parts 121 and the second conductive parts 131 are compressed in the thickness direction thereof by the terminals 141 of the test target device 140, and thus the first conductive particles 1211 and the second conductive particles 1311 are brought into contact with each other. As a result, the first conductive parts 121 and the second conductive parts 131 are electrically connected to each other. Thereafter, an electric signal input from the test apparatus 150 is transmitted to the test target device 140 through the second conductive parts 131 and the first conductive parts 121. In this manner, an electric test may be performed.

FIG. 6 illustrates a case in which the terminals 141 of the test target device 140 are not placed at the centers of upper surfaces of the first conductive parts 121 but are placed slightly away from the centers. Even if the terminals 141 of the test target device 140 are placed slightly away from the centers of the first conductive parts 121 as described above, the terminals 141 of the test target device 140 are not directly brought into contact with the support sheet 110 but may be brought into contact with the elastic insulative parts 122, and thus the surfaces of the terminals 141 may be minimally damaged. For example, if the support sheet 110 is formed of a relatively hard material such as polyimide by taking into consideration the heat resistance of the support sheet 110, the surfaces of the terminals 141 may be damaged (scratched) by contact with inner surfaces (particularly, edges) of the penetration holes 111. However, according to the exemplary embodiment, the elastic insulative parts 122 formed of a relatively soft material are disposed between the inner surfaces of the penetration holes 111 and the first conductive parts 121, and thus the surfaces of the terminals 141 may be minimally damaged.

Furthermore, in the related art, if the terminals 141 of the test target device 140 have different heights, for example, different protruding heights, some of the terminals 141 of the test target device 140 may not be in contact with the first conductive parts 121. However, according to the exemplary embodiment, since the elastic insulative parts 122 are disposed between the first conductive parts 121 and the support sheet 110, the first conductive parts 121 may be vertically moved relative to the support sheet 110.

In addition, the thickness of the first conductive parts 121 may be increased. For example, in the related art, it may be difficult to increase the thickness of the first conductive parts 121 because the amount of the insulative elastic material used to maintain the shape of the first conductive particles 1211 of the first conductive parts 121 is adjusted to be small for increasing the density of the first conductive particles 1211. However, according to the exemplary embodiment, since the elastic insulative parts 122 securely surround the first conductive parts 121, the thickness of the first conductive parts 121 may be sufficiently increased. Therefore, high-current and high-resistance characteristics may be obtained.

The test socket 100 of the exemplary embodiment may be modified as shown in FIGS. 7 and 8.

In the exemplary embodiment shown in FIGS. 4 to 6, the insulative support part 132 is formed of the same insulative elastic material. However, the exemplary embodiments of the present disclosure are not limited thereto. For example, the insulative support part 132 may be formed in a plurality of layers having different characteristics. For example, as shown in FIG. 7, an insulative support part 232 may include an upper insulative support part 2321 and a lower insulative support part 2322 disposed under the upper insulative support part 2321, and the upper and lower

insulative support parts

2321 and 2322 may have different degrees of hardness. For example, the upper insulative support part 2321 may be formed of a relatively soft material compared to the lower insulative support part 2322. As described above, if the insulative support part 232 is formed in a plurality of layers having different characteristics, a pressure applied to the test socket 100 may be varied.

In the exemplary embodiment shown in FIGS. 4 to 6, the second conductive particles 1311 of the second conductive parts 131 have uniform density. However, the exemplary embodiments of the present disclosure are not limited thereto. For example, as shown in FIG. 8, each of second conductive parts 331 may include a second upper conductive part 3311 and a second lower conductive part 3312 disposed under the second upper conductive part 3311, and the content of second conductive particles in the second upper conductive part 3311 may be different from the content of second conductive particles in the second lower conductive part 3312. Particularly, the second conductive particles of the second upper conductive part 3311 may be less densely arranged than the second conductive particles of the second lower conductive part 3312. As described above, if the second conductive parts 331 are formed in a plurality of layers having different densities, the characteristics of the test socket 100 may be improved.

In the above-described exemplary embodiments, the penetration holes 111 of the support sheet 110 have a vertically uniform inner diameter. However, the exemplary embodiments of the present disclosure are not limited thereto. For example, the penetration holes 111 of the support sheet 110 may have a downwardly decreasing inner diameter. That is, as shown in FIG. 9, penetration holes 411 of a support sheet 410 may have a downwardly decreasing inner diameter. In this case, even if terminals of a test target device are brought into contact with upper ends of the penetration holes 411 of the support sheet 410, the surfaces of the terminals of the test target device may be minimally damaged.

It should be understood that exemplary embodiments of the test socket described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each exemplary embodiment should typically be considered as available for other similar features or aspects in other exemplary embodiments.

Claims

A test socket configured to be disposed between a test target device and a test apparatus for electrically connecting terminals of the test target device to pads of the test apparatus, the test socket comprising:

a support sheet formed of an insulative material and comprising penetration holes at positions corresponding to the terminals of the test target device;

inserts comprising first conductive parts and elastic insulative parts, wherein the first conductive parts are disposed in the penetration holes of the support sheet and formed by arranging a plurality of first conductive particles contained in an insulative elastic material in a thickness direction of the support sheet, and the elastic insulative parts are formed of an insulative elastic material and disposed between the first conductive parts and inner walls of the penetration holes to surround the first conductive parts; and

an anisotropic sheet comprising second conductive parts and an insulative support part, wherein the second conductive parts are disposed under the first conductive parts and formed by arranging a plurality of second conductive particles contained in an insulative elastic material in a thickness direction of the anisotropic sheet at positions corresponding to the penetration holes, and the insulative support part is disposed under the support sheet to support and insulate the second conductive parts.
The test socket of claim 1, wherein the first conductive particles are not in the elastic insulative parts.
The test socket of claim 1, wherein the first conductive particles are included in the elastic insulative parts in an amount of 10 volume% or less.
The test socket of claim 1, wherein the elastic insulative parts are integrally coupled to the first conductive parts and the support sheet.
The test socket of claim 1, wherein the elastic insulative parts are more elastic than the first conductive parts and the support sheet.
The test socket of claim 1, wherein the first conductive particles are more densely arranged than the second conductive particles.
The test socket of claim 1, wherein the support sheet is formed of a material that is harder than the insulative support part.
The test socket of claim 1, wherein the penetration holes of the support sheet have a downwardly decreasing inner diameter.
A test socket configured to be disposed between a test target device and a test apparatus for electrically connecting terminals of the test target device to pads of the test apparatus, the test socket comprising:

a support sheet formed of an insulative material and comprising penetration holes at positions corresponding to the terminals of the test target device;

first conductive parts disposed in the penetration holes of the support sheet and formed by arranging a plurality of first conductive particles contained in an insulative elastic material in a thickness direction of the support sheet, the first conductive parts having an outer diameter that is smaller than an inner diameter of the penetration holes; and

an anisotropic sheet comprising second conductive parts and an insulative support part, wherein the second conductive parts are disposed under the first conductive parts and formed by arranging a plurality of second conductive particles contained in an insulative elastic material at positions corresponding to the penetration holes, the second conductive particles being less densely arranged than the first conductive particles, and the insulative support part is disposed under the support sheet to support and insulate the second conductive parts.
The test socket of claim 9, wherein the insulative support part comprises an upper insulative support part and a lower insulative support part disposed under the upper insulative support part, and

the upper insulative support part and the lower insulative support part have different degrees of hardness.
The test socket of claim 10, wherein the upper insulative support part is formed of a material that is softer than the lower insulative support part.
The test socket of claim 9, wherein the second conductive parts comprise second upper conductive parts and second lower conductive parts disposed under the second upper conductive parts, and

a content of the second conductive particles in the second upper conductive parts is different from a content of the second conductive particles in the second lower conductive parts.
The test socket of claim 12, wherein the second conductive particles are less densely arranged in the second upper conductive parts than in the second lower conductive parts.