JP2003059607A - Ic socket - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an IC socket keeping stable properties against repeated burn-in, having an electric contact with a durable plated layer. SOLUTION: The IC socket, for testing an IC having many electrodes, is mounted on a test device through a socket board. the IC socket has many electric contacts 20 which electrically connect the electrodes of the IC to a test device through an electric circuit formed to a socket board, and the electric contacts 20 have nickel palladium plating layer at a contact point 20a contacting the electrode of the IC.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC having a large number of electrodes arranged on a test apparatus via a socket board.
IC socket for testing

[0002]

2. Description of the Related Art It is common practice to burn-in an IC by itself and forcibly cause a failure factor in a short time to screen an IC having an initial failure. Such burn-in of ICs is performed by mounting the ICs on a board called a socket board or burn-in board having a large number of IC sockets mounted thereon, and setting the boards on which these ICs are mounted in a burn-in device. . This burn-in device has an IC of, for example, 1
A high voltage of about 1.2 to 1.6 times the rated voltage / signal is applied through a substrate and an IC socket at a high temperature of about 25 ° C. In this way, by burn-in the IC alone, the IC having the initial failure can be discriminated and eliminated in advance, and the cost can be suppressed to be lower than the burn-in for each expensive board on which the IC is mounted.

The burn-in IC socket is formed corresponding to the shape of the IC, and the electric contacts of the IC socket are arranged corresponding to the electrodes of the IC. These electrical contacts generally have a gold-plated layer on the underlying nickel-plated layer at the contact point with the whole of the base material made of phosphor bronze or beryllium copper or the electrode of the IC.

[0004]

In such an IC socket, when the burn-in of the IC is repeated, the gold-plated layer at the contact portion becomes so high that the temperature becomes particularly high because of the softness inherent in the gold itself. Impurities of the electrodes of the IC are likely to adhere. Further, by repeating the burn-in, the gold plating layer is easily peeled off from the underlying nickel plating layer or the base material, and there is a problem in the durability of the electrical contact and eventually the IC socket.

The present invention has been made to solve the above problems, and provides an IC socket provided with an electric contact having a plating layer having stable characteristics and having stable characteristics even after repeated burn-in. The purpose is to

[0006]

In order to solve the above problems, the inventors of the present invention have diligently studied in order to obtain an optimum plating layer, and nickel palladium plating is extremely durable as a contact of an IC socket. Therefore, the present invention has been completed based on these findings. That is, the IC socket of the present invention is installed in a test device via a socket board to test an IC in which a large number of electrodes are arranged. The IC socket has a large number of electrical contacts for electrically connecting the electrodes of the IC to the testing device via an electrical circuit formed on the socket board, and these electrical contacts are contact portions that come into contact with the electrodes of the IC. It has a nickel-palladium plating layer on its surface.

Further, in the IC socket of the present invention, it is preferable that the nickel palladium plating layer has a ratio of nickel and palladium in a range of approximately 1: 9 to 4: 6.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, FIGS. 1 to 4
An open top type IC socket for burn-in and an electric contact therefor will be described as an example.

As shown in FIG. 1, the IC socket 2 is provided with a rectangular socket body 4 made of an insulating material, which is attached to a substrate (test device) (not shown) such as a socket board or a burn-in board. On the upper part of the socket body 4, a large number of small holes vertically penetrating the socket body 4 are arranged side by side in a grid pattern, and a rectangular pedestal 4a on which a rectangular IC (not shown) is mounted, and this pedestal 4a Guide part 4 that surrounds from all sides and arranges the IC in a predetermined position
and b are integrally provided.

A pair of opposed sockets which are pivotally attached to one side of the socket body 4 and are urged by a spring (not shown) toward a position for pressing the IC from the guide portion 4b to the pedestal 4a. IC holder 6 is provided.

A large number of electrical contacts 8 which are in electrical contact with the electrodes of the IC are supported by members (not shown) and are arranged on the same axis as the small holes, and the small holes are provided from the other side of the socket body 4. And the tip of the contact portion 8a is slightly projected and held.

The side surface of the socket body 4 is provided with a plurality of locking claws. A spring 10 arranged on the socket body 4 urges a predetermined portion of these locking claws in a direction away from the socket body 4 to move the pedestal 4a.
The cover 12 having an opening for attaching and detaching the IC to be positioned at is locked. This cover 12
Interlocks with the driving of these IC holders 6 to open later-described contact portions 8a of the electrical contacts 8. Further, the positioning device 14 of the IC socket 2 is locked to the predetermined portion of the locking claw from the other side.

Further, as shown in FIG. 2, the contact portion 8a of the electric contact 8 used in the IC socket 2 is I
It is formed by a pair of leaf spring-shaped arm portions in which a solder ball (not shown) forming the C electrode is sandwiched by four protrusions 8b. A nickel plating layer, for example, is formed as a base layer on the contact portion 8a with the IC of the electric contact 8 and the vicinity thereof (hatched portion in FIG. 2), and a nickel palladium plating layer made of a nickel palladium alloy is formed thereon. Have. This nickel-palladium plating layer need only be provided on the four protrusions 8b of the contact portions 8a that are in direct contact with the electrodes of the IC, but not only the four protrusions 8b but also the four protrusions 8b depending on the cost of plating. The contact portion 8a shown in FIG. 2 and its vicinity (hatched portion), or the electric contact 8 as a whole may be provided. This is because the inventors have made diligent efforts to improve the durability of the IC socket and have found that nickel-palladium plating has extremely excellent durability as a contact of the IC socket.

Incidentally, such an IC socket is not limited to the electrical contact 8 shown in FIGS.
It may also have the electrical contacts 20 shown in FIG. The electrical contact 20 is urged by a spring arm portion 24, which will be described later, to be brought into contact with an electrode of an IC having a generally flat plate-shaped electrode.

The electric contact 20 includes a hook-shaped contact portion 20a that contacts an electrode of the IC, and a base portion 26 that supports the contact portion 20a via a spring arm portion 24. The base portion 26 has two solder leg portions 28 connected to the test device on the side opposite to the contact portion 20a. Further, for example, the contact portion 2 of the electric contact 20.
0a and its vicinity (hatched portion in FIG. 3) have, for example, a nickel plating layer formed as a base layer and a nickel palladium plating layer made of a nickel palladium alloy thereon.

The IC socket may also have the electrical contact 30 shown in FIG. 4 (a). The electrical contact 30 includes a contact portion 30a that comes into contact with an electrode of an IC, that is, a solder ball, a base portion 32 that is laterally displaced from the contact portion 30a, and a connecting portion 34 that connects the contact portion 30a and the base portion 32. Have. The contact point portion 30a is formed in a tuning fork shape in which the tip portion is branched into two forks and has an arm portion, and the tip end surface that contacts the solder ball of the IC is formed by two inclined surfaces that are inclined in opposite directions. Also,
For example, a nickel plating layer is formed as a base layer on the contact portion 30a and the vicinity thereof (hatched portion in FIG. 4A) of the electrical contact 30, and nickel palladium plating made of nickel palladium alloy is formed thereon. With layers.

The IC socket may have the electrical contact 40 shown in FIG. 4 (b). Similar to the electrical contact 20 shown in FIG. 3, the electrical contact 40 is urged and brought into contact with an electrode of an IC having a generally plate-like electrode by a spring arm portion 42 described later.

The electrical contact 40 has a contact portion 40a that contacts the electrode of the IC, and a base portion 44 that supports the contact portion 40a via a spring arm portion 42. The spring arm portion 42 includes a connecting portion 46 that forms a curved spring portion that extends from one end of the base portion 44, an arm 48 that extends substantially straight from the connecting portion 46, and an arm at the tip of the arm 48. It consists of a tip 50. Further, for example, a nickel plating layer is formed as a base layer on, for example, the contact portion 40a and the vicinity thereof (hatched portion in FIG. 4B) of the electrical contact 40, and nickel made of nickel palladium alloy is formed thereon. It has a palladium plating layer.

An example in which the electric contact 20 shown in FIG. 3 is arranged in a predetermined IC socket will be described below. The base material of this electric contact 20 is, for example, about 0.25 m.
Beryllium copper having a thickness of m is used at 315 ° C.,
Heat treatment is performed for 2 hours.

The nickel-palladium plating layer included in the electrical contact 20 has a nickel plating layer thickness of 1.
The thickness of the nickel palladium plating layer is about 0 μm.
It is preferable that the thickness is about 0 μm and the ratio of nickel and palladium is approximately 2 to 8. Hereinafter, the ratio of nickel and palladium will be described by taking such a ratio as an example.

The durability of the IC socket provided with the electrical contact 20 having the nickel palladium plating layer on the contact portion 20a is measured by the following test. In this embodiment, one IC socket has, for example, 5
Four electric contacts 20 are juxtaposed at predetermined positions.

First, the electric contact 20 attached to the IC socket installed in the burn-in test device (not shown) is brought into an open state (initial state), and an IC (not shown) attachable to this IC socket is provided. Place it in place and attach it. Then, the contact resistance value is measured at each of the contact portions 20a in contact with the 54 electrodes formed of, for example, solder balls of this IC, and the average value thereof is taken. Next, with the IC attached, the cover of the IC socket is pressed 100 times against the biasing force of the spring.
This is one cycle of the operation test. After that, the contact resistance value is measured at each contact portion 20a of the electrical contact 20, and the average value is taken. Further, with the IC attached, the IC socket is left at 135 ° C. for 48 hours. This is one cycle of the high temperature test. After that, the contact resistance value is measured at each contact portion 20a of the electrical contact 20, and the average value is taken. Then, one cycle of each of the operation test and the high temperature test after this operation test was set as one cycle of the durability test of the IC socket simulating the burn-in of the IC, and this durability test was repeated 20 cycles. The IC used in this test is replaced with a new IC every cycle of the durability test.

For comparison with the nickel-palladium plating layer, the contact portion 20a has a sufficient hardness as compared with the gold-plating layer and the gold-plating layer, which are generally used in the past, on the nickel-plating base. The electrical contact 20 shown in FIG.
The shaded area was plated and the durability test was repeated. The gold plating layer is formed by plating gold having a thickness of approximately 0.035 μm on a nickel plating base having a thickness of approximately 1.27 μm. The nickel boron plating layer has a thickness of 2.0μ.
It has a thickness of m to 4.0 μm.

5 and 6, the vertical axis represents the contact resistance value and the horizontal axis represents the number of cycles of the operation test and the high temperature test, respectively. Further, the circle mark indicates the measurement result of the nickel palladium plating layer, the square mark indicates the measurement result of the gold plating layer, and the triangle mark indicates the measurement result of the nickel boron plating layer. As shown in FIGS. 5 and 6, in the initial state of the durability test (0 cycle on the horizontal axis in FIGS. 5 and 6), the electrical contact 2
The test results of the three types of plated layers in the contact portion 20a of 0 have almost the same contact resistance value. However, as the number of cycles of the durability test is increased, the contact portion 20a having the nickel boron plating layer and the gold plating layer is formed.
The contact resistance value of No. 2 changed largely in the direction of increasing as compared with the initial state during the process up to 20 cycles, but the contact resistance value of the contact portion 20a having the nickel palladium plating layer was almost flat, It was revealed that the change from the state was the least.

Therefore, the electrical contact having the nickel-palladium plating layer at the contact portion with the electrode of the IC can provide stable data even after repeated durability tests as compared with the electrical contact having the gold-plating layer or the nickel boron plating layer. Can be taken. Therefore, it was confirmed that the durability of the electrical contact 20 and eventually the IC socket was good.

As described above, the IC of this embodiment
According to the socket, the plating layer of the electrical contact has stable characteristics even if the burn-in of the IC is repeated, and the socket can be used for a long period of time.

The contact portions 8a shown in the present embodiment,
The electrical contacts 8, 20, 30, 40 having nickel-palladium plated layers on 20a, 30a, 40a are examples, and can be used, for example, as spring probe-shaped electrical contacts (not shown). That is, the present invention can be applied to the contact portions of all electrical contacts of IC sockets that can change depending on the burn-in IC. Further, as shown by the shaded portions in FIGS. 2, 3 and 4, the plating layer may have only the contact portion and the vicinity thereof, but only the portion contacting the electrode of the IC or the base material of the electrical contact. You may have a plating layer in the whole.

Further, in the present embodiment, the thickness of the nickel-palladium plating layer has been described by taking the above-mentioned thickness as an example, but the thickness is not limited to such a thickness and may be an appropriate value as necessary. be able to. Further, in the present embodiment, the ratio of nickel to palladium in the nickel-palladium plating layer included in the electrical contact is most preferably 2 to 8, as is clear from the above experiment, but such a nickel-palladium plating layer is preferable. As long as the above characteristics can be maintained, it can be used in the range of 1: 9 to 4: 6.

Further, in the present embodiment, the IC socket has 54 electrical contacts, but the number is not limited to this, and it can be arranged according to the number of electrodes arranged in the IC. Of course. Further, although the IC socket and the IC are described as being rectangular in the present embodiment, the present invention is not limited to such a shape and may be another shape. Further, in the present embodiment, the open top type IC socket is described as an example, but the present invention is not limited to such an IC socket, and the same can be applied to a lid type IC socket or the like.

Therefore, the following can be said about the IC socket according to the present embodiment. According to the present embodiment, as is clear from the contact resistance values of the IC socket after the operation test and after the high temperature test, the electrical contact having the nickel palladium plating layer at the contact portion is a gold plating layer or nickel boron plating at the contact portion. It has superior durability compared to electrical contacts with layers.

[0031]

As described above, according to the present invention,
It is possible to provide an IC socket having improved durability even in a test under a severe environment such as burn-in.

[Brief description of drawings]

FIG. 1 is a perspective view schematically showing an entire IC socket according to the present embodiment.

FIG. 2 is a perspective view schematically showing a contact portion of the electric contact according to the present embodiment.

FIG. 3 is a schematic diagram of an electrical contact according to the present embodiment.

4A and 4B are modifications of the electrical contacts shown in FIGS. 2 and 3.

FIG. 5 is a graph showing the average value of the contact resistance value of the contact portion of the IC socket measured after each cycle of the operation test according to the present embodiment.

FIG. 6 is a graph showing the average value of the contact resistance value of the contact portion of the IC socket measured after each cycle of the high temperature test according to the present embodiment.

[Explanation of symbols]

2 ... IC socket, 4 ... Socket body, 4a ... Pedestal,
4b ... Guide part, 6 ... IC holder, 8 ... Electric contact, 8a ... Contact part, 8b ... Projection part, 12 ... Cover, 14
... Positioning device, 20 ... Electric contact, 20a ... Contact part, 24 ... Spring arm part, 26 ... Base part, 28 ... Solder leg part, 30 ... Electric contact, 30a ... Contact part, 32 ... Base part, 34 ... Coupling part, 40 ... Electrical contacts, 40a ... Contact portion, 42 ... Spring arm portion, 44 ... Base portion, 46 ... Connecting portion, 4
8 ... Arm, 50 ... Arm tip

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2G003 AA07 AC01 AG01 AG08 AG12                       AH00                 2G011 AA14 AA15 AB01 AB06 AB07                       AC00 AC14 AE03 AF02                 5E024 CA18 CB03

Claims (2)

[Claims] 1. An IC for testing an IC having a large number of electrodes arranged in a test device through a socket board.
The socket has a large number of electrical contacts for electrically connecting the electrodes of the IC to the testing device through an electrical circuit formed on the socket board. These electrical contacts are provided with nickel at the contact portions that come into contact with the electrodes of the IC. An IC socket having a palladium plating layer. 2. The IC socket according to claim 1, wherein the nickel-palladium plating layer has a ratio of nickel and palladium in a range of approximately 1: 9 to 4: 6.