JPH05304229A - Terminal for ic socket - Google Patents

Abstract

PURPOSE:To stabilize contact resistance over a long term by forming a conductive film, in which transition of Sn or Pb to be applied on an IC lead is retarded, on the end face of a terminal. CONSTITUTION:IC socket terminal 3 made of beryllium copper has a terminal end face 3a contacting with an IC wherein the terminal end face 3a is applied with a conductive film composed of one or more of Ru, Rh, Pt, Ir, Re, W, Mo, Cr, Ta, Nb, V, Al or alloys thereof or nitride, carbide, silicide, or aluminium compound of transition metal. The film is deposited by 50nm-20mum through normal film deposition technology, e.g. thermal CVD method or plasma method. The film is conductive in any case and also hard except in case of Al. The film has such properties as diffusion is suppressed with respect to Cu, Sn, or Pb, wettability is low, and transition of Sn or Pb is retarded. When such conductive film is employed in the terminal of IC socket, oxide film is not formed on the end face and initial conditions are sustained for a long term resulting in a prolonged service life.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC (Integrated Circuit) socket terminal, and more particularly to a long-life terminal assembled to a test IC socket used for various IC tests such as burn-in test or operation test. ..

[0002]

2. Description of the Related Art Inspection of ICs is carried out for all products or for each lot for the purpose of removing initial failure products and short-life products caused by inherent defects of manufactured ICs and product variations. Among these inspections, for example, IC burn-in is
The inspection is a test for heating the IC to remove defective products, and the operation test is a test for giving a signal to the IC to confirm the operation.

Here, the inspection of the IC is usually carried out by using an IC socket as shown in FIG. 1. After the test, the IC is removed, and a non-defective product is shipped as a product or stored. It Here, IC burn-in is
This is performed using an IC socket as shown in FIG. In FIG. 1, an IC socket 1 is composed of a socket body 1a and a lid 1b, and the hinge 2 serves as an axis, and the socket body 1a
The lid 1b is openable and closable. Then, the terminals 3, 3 having an integrally formed shape as shown in FIG. 2 are assembled to the bottom of the socket body 1a. Here, the socket body 1
The a and the lid 1b are usually made of poniphenylene sulfide, which is excellent in heat resistance, and the terminals 3 and 3 are made of beryllium copper, which is also excellent in heat resistance and spring properties. Then, the end surface 3a of the terminal 3 is plated with Ni as an underlayer and then plated with Au.

By the way, the mounting of the IC in the test socket is performed as follows. Terminal 3 in IC socket 1
The lead 4a of the IC 4 to be tested is placed on the end surface 3a of the device, the lead 4a is pressed by the pressing portion 5a of the movable pressing plate 5, and the lid 1b is covered in this state, and the mounting of the IC in the test socket is completed. To do. When performing a burn-in test, an electric load is applied to the IC 4 for at least several hours in a high-temperature atmosphere usually exceeding 100 ° C. to operate the IC, and whether the operation is normal or abnormal is determined. Further, when performing an operation inspection, a signal is input to the IC and an operation signal is used to determine whether the operation is normal or abnormal.

[0005]

By the way, for example, an IC
The surface of the lead is usually covered with Sn or a Sn alloy (solder or the like). Therefore, IC in the IC socket
In the process of inserting and removing the cable and repeating the test operation such as burn-in test, the thermal and mechanical action such as heating, pressurizing, rubbing, etc., or their combined action with Au of the terminal end surface is performed. , Sn and Sn alloy components on the IC lead surface are transferred to the contact side.

That is, on the terminal end surface of the IC socket,
Sn, which is a coating component of the IC lead, and Pb in the solder adhere, and these are oxidized and converted into an oxide film. As a result, the contact resistance between the IC lead and the end face of the terminal increases, which interferes with the measurement test. When a measurement current is applied to the contact surface on which the oxide film is formed, even if the area of the mechanical contact between the IC lead and the terminal end surface is wide, Since the area is small, the measured current flows intensively in that portion to generate Joule heat, and the generated heat softens the Sn or Sn alloy on the IC lead surface, and the further transition to the terminal end face proceeds. In this way, when the IC test operation is repeated, the oxide film of Sn or Pb gradually grows on the terminal end face, and the contact resistance between the IC lead and the terminal end face increases.

However, it is very difficult to remove the above-mentioned Sn or Pb oxide film. Therefore,
When the contact resistance value between the IC lead and the terminal end face exceeds the allowable limit in the test, the IC socket is no longer usable and is discarded. In general, this service life is significantly shorter than that of a contact between Au platings in a normal connector or the like.

[0008]

In order to achieve the above object, according to the present invention, Ru, R are attached to at least a terminal end face which is assembled to an IC socket and which is in contact with the IC.
h, Pt, Ir, Re, W, Mo, Cr, Ta, Nb,
At least one selected from the group consisting of V, Al or alloys thereof, or at least one selected from the group consisting of nitrides, carbides, borides, silicides and aluminides of transition metals is formed. An IC socket terminal is provided.

In the terminal of the present invention, at least the end surface of the terminal which comes into contact with the IC lead is covered with a conductive film described later. The material forming the terminal body may be any material used as a terminal material, for example,
Beryllium copper can be mentioned as a typical example, but nickel beryllium alloy, spinodal alloy (CuNiSn), titanium copper alloy, etc. can be mentioned.

As the material for forming the conductive film formed by covering at least the end face of the terminal, Ru, Rh, Pt,
Ir, Re, W, Mo, Cr, Ta, Nb, V, Al metals, Pt-Ir alloy, Pt-Ru alloy, Pt-Rh
An alloy composed of two or more of the above-mentioned respective metals such as an alloy can be given. These may be used alone or in appropriate combination of two or more kinds.

Further, as the material for forming the conductive film, for example, nitrides of transition metals such as TiN, VN, NbN and TaN; carbides of transition metals such as TiC, TaC and WC; TiB ₂ And transition metal borides such as PtSi ₂ , TiSi ₂ , and MoSi ₂ ; transition metal aluminides such as TiAl and PtAl. These may be used alone or in appropriate combination of two or more kinds.

These conductive films are formed, for example, by thermal CVD.
Method, plasma CVD method, ECRCVD method, ion plating method, sputtering method, vacuum deposition method, IVD method, wet plating method or the like may be applied to the terminal end face. The thickness of these films is appropriately selected according to the usage conditions of the socket in which the terminals are assembled. However, if the film thickness is less than 50 nm, it is difficult to form a film that sufficiently covers the end face, and if the film thickness is more than 20 μm, the residual stress in the formed film causes
Since fine cracks may occur in the coating, the thickness of the coating is set within the range of 50 nm to 20 μm. The preferred film thickness is 0.5 to 2.0 μm.

The above coating may be formed directly on the end face of the terminal, or may be formed on the Au plating layer after the end face is plated with, for example, Ni undercoat or Au.

[0014]

[Function] All of these conductive films are conductive,
And all except Al are hard. Moreover, Cu and S
Difficult to diffuse between n and Pb, wet poorly, Sn,
It has the property that transfer of Pb and the like is unlikely to occur. Therefore, when it is used as a terminal of an IC socket, the formation of an oxide film on the terminal end face as described above does not occur, and the terminal end face always maintains a state close to the initial state.

[0015]

EXAMPLES Example 1 An IC socket terminal 3 made of beryllium copper as shown in FIG. 2 was ultrasonically cleaned with acetone for 5 minutes. In addition, on the surface of the terminal 3, a Ni undercoat layer and an Au plating layer are formed thereon.

This terminal was set in a vacuum chamber, the interior of the chamber was evacuated to 1 × 10 ⁻³ Pa or less using a turbo molecular pump, and then the terminal was heated to 150 ° C. Then, the valve of the turbo molecular pump is opened halfway to reduce the exhaust conductance, and the inside of the chamber is 1 × 10 ⁻¹ Pa.
Ar gas was introduced until. A voltage of about -1 kV was applied to the terminal, a high frequency of 1 kW was generated from the RF antenna in the chamber and discharged, and the surface of the terminal was washed.

Then, the voltage applied to the terminals is lowered to -200 V, and in that state, Ru is evaporated from the crucible set in the chamber by the electron beam evaporation method to form a film at a deposition rate of 2 n.
A Ru film having a thickness of 0.5 μm was formed on the surface of the terminal at m / sec. Example 2 As a material for a terminal, a Ni undercoat layer, Au was formed on the surface of the terminal.
A Ru-coated terminal was manufactured in the same manner as in Example 1 except that one having no plated layer was used and the film thickness was 2 μm.

Example 3 Example 3 was carried out except that titanium copper having neither a Ni undercoating layer nor an Au plating layer formed on the surface was used as the terminal material, and the thickness of the film was 2 μm. A Ru-coated terminal was manufactured in the same manner as in Example 1. Example 4 An IC socket terminal made of beryllium copper was ultrasonically cleaned with acetone for 5 minutes. In addition, on the surface of this terminal, a Ni undercoat layer and an Au plating layer are formed thereon.

This terminal was set in a vacuum chamber, the interior of the chamber was evacuated to 1 × 10 ⁻³ Pa or less using a turbo molecular pump, and then the terminal was heated to 100 ° C. Then, the valve of the turbo molecular pump was opened halfway to reduce the exhaust conductance, and Ar gas was introduced until the inside of the chamber became 1 Pa. A voltage of about -800 kV was applied to the terminal, and the surface of the terminal was cleaned by reverse sputtering.

Then, the flow rate of Ar gas was adjusted to maintain the pressure in the chamber at 0.3 Pa, and a voltage was applied to the Ru target set in the chamber to cause discharge, and the reactive DC magnetron sputtering method was used. Deposition rate 3 nm /
In 2 sec, a Ru film having a thickness of 2 μm was formed on the surface of the terminal. Example 5 As a terminal material, a Ni undercoat layer, Au was formed on the surface of the terminal.
A Ru-coated terminal was manufactured in the same manner as in Example 4, except that the plated layer was not applied.

Example 6 A Ru-coated terminal was prepared in the same manner as in Example 4 except that titanium copper having neither a Ni undercoat layer nor an Au plating layer formed on the surface was used as the terminal material. Manufactured. Example 7 Example 1 except that the material to be deposited was Rh.
A Rh-coated terminal was manufactured in the same manner as in.

Example 8 A Rh-coated terminal was manufactured in the same manner as in Example 4, except that the material to be sputtered was Rh. Example 9 Example 1 except that the material to be deposited was Pt.
A Pt-coated terminal was manufactured in the same manner as in.

Example 10 A Pt-coated terminal was manufactured in the same manner as in Example 4, except that the material to be sputtered was Pt. Example 11 A Pt-Ir alloy-coated terminal was manufactured in the same manner as in Example 1, except that the material to be deposited was Pt-Ir alloy.

Example 12 A Pt-Ir alloy-coated terminal was manufactured in the same manner as in Example 4, except that the material to be sputtered was Pt-Ir alloy. The above 12 types of terminals are set in the IC socket as shown in FIG. 1, the IC lead is placed on the end face of the terminal and pressed, and a current (I) of 10 mA is applied between the IC lead and the terminal in the atmosphere at a temperature of 170 ° C. Then, the voltage drop (V) was measured, and the contact resistance was calculated every 100 hours with R (Ω) = V / I. All of the example terminals exhibited the same behavior. The results are shown in Fig. 3 as-○ -marks.

For comparison, beryllium copper and Ni were used.
Base plating layer (thickness 5 μm) and Au plating layer (thickness 0.5)
The same burn-in test was also performed on the conventional terminal (Comparative Example 1) in which (μm) was sequentially applied, and the result was-●-
It is shown in FIG. 3 as a mark. Examples 13 to 23 Under the same conditions as in Example 1, a conductive film having the indicated thickness was formed on the surface of the terminal material shown in Table 1.

After mounting these terminals in an IC socket in the same manner as in Examples 1 to 12, IC leads were placed on the end faces of the terminals and pressed, and insertion and removal were repeated 50,000 times. During this insertion / removal, a current (I) of 10 mA is passed between the terminals, a low level voltage (V) is measured, and the contact resistance R
(Ω) = V / I was calculated. All of the example terminals exhibited the same behavior. The results are shown in Fig. 4 as-○ -marks.

For comparison, the same burn-in test was performed on the terminals of Comparative Example 1, and the results are shown in FIG. 4 as-●-marks. Further, the terminal of the first embodiment and the first embodiment
The burn-in test was repeated 20 times by inserting the IC into each of the 20 IC sockets in which terminals 3 to 23 were set, heating at 200 ° C. for 28 hours, and then cooling and pulling out the IC. After that, the contact resistance of the IC socket is measured, and when the measured value is 1Ω or more, it is considered as a socket failure, and when it is less than 1Ω, the socket is judged as good, and the socket failure rate (%) for each terminal is determined. ) Was calculated. The above results are collectively shown in Table 1.

[0028]

[Table 1]

Examples 24 to 39 By using the materials shown in Table 2 as a target during the reactive DC magnetron sputtering in Example 4, a conductive film having the indicated thickness was formed on the surface of the terminal material shown in Table 2. Formed. After these terminals were set in the IC socket in the same manner as in Examples 13 to 23, the IC lead was placed on the terminal end face and pressed, and insertion / removal was repeated 50,000 times, and 10 mA was inserted between the terminals during this insertion / removal. When the contact resistance R (Ω) = V / I was calculated by flowing the current (I) of (1) and measuring the low level voltage (V), all the example terminals exhibited substantially the same behavior. The tendency was almost the same as in FIG.

A burn-in test was conducted under the same conditions as in Examples 13 to 23 to calculate the socket failure rate. The above results are collectively shown in Table 2.

[0031]

[Table 2]

Example 40 An IC socket terminal 3 made of beryllium copper as shown in FIG. 2 was ultrasonically cleaned with acetone for 5 minutes. In addition, on the surface of the terminal 3, a Ni undercoat layer and an Au plating layer are formed thereon. This terminal was set in a vacuum chamber, the interior of the chamber was evacuated to 1 × 10 ⁻³ Pa or less using a turbo molecular pump, and then the terminal was heated to 100 ° C. Then, the valve of the turbo molecular pump is opened halfway to reduce the exhaust conductance, and the inside of the chamber is 1 × 1.
Ar gas was introduced until it reached 0 ⁻¹ Pa. -1k to the terminal
A voltage of about V was applied, a high frequency of 1 kW was generated from the RF antenna in the chamber, and discharge was performed to clean the terminal surface.

Next, the introduced gas was a mixed gas of Ar and N ₂ (mixing ratio 1: 1), and the pressure in the chamber was 8 × 10 ^-2.
The voltage applied to the terminal is lowered to -200 V by holding at Pa, and in that state, Ti is evaporated from the crucible set in the chamber by the electron beam evaporation method, and the film formation rate by the RF ion plating method is 2 nm / sec. A TiN film having a thickness of 0.5 μm was formed on the surface of the terminal.

Example 41 As a terminal material, a Ni undercoat layer, Au was formed on the surface of the terminal.
A TiN-coated terminal was manufactured in the same manner as in Example 40, except that one having no plated layer was used and the thickness of the coating was 2 μm. Example 42 Example 40 was repeated except that titanium copper on which neither a Ni undercoat layer nor an Au plating layer was formed was used as the material for the terminal, and the thickness of the film was 2 μm. A TiN-coated terminal was manufactured in the same manner as in.

Example 43 An IC socket terminal made of beryllium copper was ultrasonically cleaned with acetone for 5 minutes. In addition, on the surface of this terminal, a Ni undercoat layer and an Au plating layer are formed thereon. Set this terminal in the vacuum chamber and set the inside of the chamber to 1 x 10
After vacuum evacuation to ⁻³ Pa or less using a turbo molecular pump, the terminals were heated to 150 ° C. Then, the valve of the turbo molecular pump was opened halfway to reduce the exhaust conductance, and Ar gas was introduced until the inside of the chamber became 1 Pa. A voltage of about -800 kV was applied to the terminal, and the surface of the terminal was cleaned by reverse sputtering.

Next, a mixed gas of Ar and N ₂ (mixing ratio 2: 1) was used as an introduction gas, and the flow rate was adjusted to adjust the inside of the chamber to 0.
Ti pressure set in the chamber is kept at 3 Pa.
A voltage was applied to the target to generate a discharge, and a TiN film having a thickness of 2 μm was formed on the surface of the terminal at a film forming rate of 3 nm / sec by the reactive DC magnetron sputtering method. Example 44 As a terminal material, a Ni undercoat layer, Au was formed on the surface of the terminal.
A TiN-coated terminal was manufactured in the same manner as in Example 43, except that one having no plated layer was used.

Example 45 A TiN-coated terminal was prepared in the same manner as in Example 43, except that titanium copper having neither a Ni undercoating layer nor an Au plating layer formed on its surface was used as the terminal material. Manufactured. The above 6 types of terminals are integrated as shown in FIG.
Set it in the socket, put the IC lead on the end face of the terminal and press it, and put 1 between the IC lead and the terminal in the atmosphere at 170 ℃.
A current (I) of 0 mA was applied, the voltage drop (V) was measured, and the contact resistance was calculated every 100 hours as R (Ω) = V / I. All of the example terminals exhibited the same behavior.
The results are shown in Fig. 5 as-○ -marks.

For comparison, the same test was conducted on the terminal of Comparative Example 1, and the results are shown in FIG. 5 as-●-marks. Examples 46 to 57 By using the materials shown in Table 2 as the material to be vaporized by the electron beam at the time of RF ion plating in Example 40, the conductive film having the indicated thickness is formed on the surface of the terminal material shown in Table 3. Formed.

After these terminals were set in the IC socket in the same manner as in Examples 13 to 23, the IC leads were placed on the end faces of the terminals and pressed, and insertion and removal were repeated 50000 times. A current (I) of 10 mA is applied between them, and a low level voltage (V) is measured to measure the contact resistance R
When (Ω) = V / I was calculated, all of the example terminals exhibited substantially the same behavior. The results are shown in Fig. 6 as-○-.

A burn-in test was conducted under the same conditions as in Examples 13 to 23 to calculate the socket failure rate. The above results are collectively shown in Table 3.

[0041]

[Table 3]

Examples 58 to 65 Various conductive coatings having the indicated thickness were formed on the surfaces of terminals made of beryllium copper only by the method shown in Table 4. Each of these terminals was assembled in an IC socket in the same manner as in Examples 40 to 45, and a burn-in test was performed to obtain the initial contact resistance and 10
The contact resistance after 000 hours was measured. In addition, the contact resistance was measured after repeating insertion and extraction 50000 times as in Examples 46 to 57. The results are collectively shown in Table 4.

[0043]

[Table 4]

[0044]

As is apparent from the above description, the terminal of the present invention has a conductive film formed on the end face thereof, which is less likely to transfer Sn, Pb, etc., which are the coating components of the IC lead, and therefore can be used for a long period of time. The contact resistance is stable over the entire range.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a test IC socket.

FIG. 2 is a side view of an IC socket terminal.

FIG. 3 is a graph showing changes in contact resistance between a terminal of the present invention and a conventional terminal.

FIG. 4 is a graph showing changes in contact resistance between a terminal of the present invention and a conventional terminal.

FIG. 5 is a graph showing changes in contact resistance between a terminal of the present invention and a conventional terminal.

FIG. 6 is a graph showing changes in contact resistance between a terminal of the present invention and a conventional terminal.

[Explanation of symbols]

 1 IC Socket 1a Socket Body 1b Lid 2 Hinge 3 Terminal 3a Terminal End Surface 4 IC 4a IC Lead 5 Movable Pressing Plate 5a Pressing Part

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[Procedure amendment]

[Submission date] February 12, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

Claims (1)

[Claims] 1. A Ru, Rh, Pt, Ir, Re, W, Mo, attached to an IC socket or an LCD socket, and at least a terminal end face which comes into contact with the IC or LCD,
At least one selected from the group of Cr, Ta, Nb, V, Al or alloys thereof, or at least one selected from the group of nitrides, carbides, borides, silicides and aluminides of transition metals. An IC socket terminal having a conductive film formed thereon.