JPH0722147A - Manufacture of anisotropic conductive sheet - Google Patents

Abstract

PURPOSE:To establish a method for manufacturing an anisotropic conductive sheet with a low compressive load which can inspect IC's through simply and stably connecting a small-pitch. small area outer lead electrode of a surface mount type IC with the pattern electrode of a circuit board and which is free from deformation of the outer lead electrode at the time of connecting. CONSTITUTION:An alternate woven fabric 3 consisting of thin conductive wires 1 and water soluble, electrically insulative thin wires 2 is affixed to an electric insulative elastomer layer in sheet form. Thereafter the water soluble wires 2 are dissolved away, and a number of first composite sheets obtained 6 are laminated in consolidation, and the resultant laminate 8 is cut into sheet form perpendicular to the direction in which the conductive thin wires 1 are stretching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an anisotropic conductive sheet used for electrical connection between various circuit boards or between electronic parts and circuit boards, and more particularly, a pitch of a surface mount type IC (hereinafter referred to as IC). And a method for manufacturing an anisotropic conductive sheet suitable for connecting an outer lead electrode having a small area (hereinafter referred to as a lead electrode) to a pattern electrode on a circuit board of an inspection device so as to face each other.

[0002]

2. Description of the Related Art With the progress of semiconductors and semiconductor-related technologies, high-performance IC chips have been developed, and the mounting technology that enables them to be mounted on a circuit board at high density has been improved.
It greatly contributes to high integration, weight reduction, and compactness of various electronic devices such as word processors, personal computers, and memory cards. Although these ICs are properly designed and manufactured in a controlled process, sometimes they may cause malfunctions. Therefore, highly integrated ICs that require high reliability must be fully inspected. Is common. Since various IC resin packages have been diversified, IC sockets, anisotropic conductive sheets and the like have been conventionally used for inspection and mounting of these.

[0003]

Normally, an IC socket is
Polybutylene terephthalate (PBT), polysulfone (PSF), polyether sulfone (PES), etc. glass fiber-added engineering plastics are injection-molded into the socket body, and copper such as phosphor bronze or beryllium copper is plated on the socket body. A large number of contacts made of an alloy spring material are press-fitted and fixed, and the lead electrodes of the IC mounted in the IC socket and the pattern electrodes of the circuit board are electrically connected via these contacts. Therefore, the contactor is provided with a bent portion that causes elasticity in order to maintain a predetermined contact pressure when the contactor is connected to the lead electrode of the IC.

Such an IC socket is widely used because it has a stable connection and high reliability in a heat resistance test such as an IC burn-in test, but it has the following problems. In other words, with the high integration of ICs, the number of lead electrodes has been reduced and the pitch has been reduced. Currently, the lead electrodes have advanced to a pitch of about 0.3 mm, so they have become thinner and thinner than before, and their strength has decreased. When an IC socket is used to inspect an IC having such a lead electrode, the lead electrode is easily deformed or damaged due to lack of strength against the applied contact pressure.

Particularly, when the IC is set in the IC socket, since it is dropped by using the tapered guides at the four corners, a slight misalignment causes bending in the floating direction (vertical direction), and the connection becomes unstable, resulting in reliability. Is reduced. Further, the socket body is manufactured by injection-molding the engineering plastic as described above. However, when it comes to an IC having a low pitch lead electrode as described above, the partition plate (separator) of the socket body becomes very thin. For,
Molding dies become more precise and complex, resulting in very high costs and increased costs. Due to the above-mentioned problems, the conventional IC socket cannot handle ICs having low pitch lead electrodes under the present circumstances.

Recently, ICs for processing high-frequency signals have been frequently used in mobile phones, communication devices, computers, etc., but when these ICs are inspected by conventional IC sockets, the contacts are bent. Since it has a portion, the conduction path is long, and the inductance increases, which often causes malfunction.

Next, the anisotropic conductive sheet has a structure in which a large number of thin metal wires are embedded in a sheet-like electrically insulating elastomer layer in parallel with the thickness direction, and the sheet is faced with IC lead electrodes and circuits. It is sandwiched between pattern electrodes such as a substrate and electrically connected to each other to inspect an IC and the like, and it has been used as a device capable of improving the problems of the IC socket.

In order to obtain the anisotropic conductive sheet having the above-mentioned structure, one method is as follows: (a) After the metal thin wires are arranged and fixed at a constant pitch on one surface of the sheet-like electrically insulating elastomer layer, A large number of composite sheets are laminated and integrated so that the fine metal wires are parallel to each other and the electrically insulating elastomer layers and the fine metal wires are alternately laminated, and this laminate is cut into a sheet shape at right angles to the fine metal wires. As another method, (b) one is a fine metal wire and the other is polyethylene terephthalate (PET)
An electrically insulating thin wire (hereinafter referred to as an insulating thin wire) made of a monofilament or the like is woven into a mesh shape, and a composite woven fabric is bonded to a sheet-shaped electrically insulating elastomer layer to form a composite. A method is adopted in which a large number of thin wires are laminated in parallel so that the electrically insulating elastomer layer and the thin metal wires are alternately overlapped with each other, and this laminated body is cut into a sheet shape at right angles to the direction of the thin metal wires.

However, in the method (a), it takes a lot of time to regularly arrange the thin metal wires on the sheet-like electrically insulating elastomer layer, and it is extremely difficult to arrange them at a low pitch. . The method (b) has an advantage that the thin metal wires can be arranged more easily than the method (a) and can be arranged at a low pitch, but since the resulting anisotropic conductive sheet contains the insulating thin wires, Of the anisotropic conductive sheet cannot be used for an IC having a lead electrode with a low pitch, and the contact pressure when connecting the lead electrode of the IC and the pattern electrode of the circuit board becomes large. Since the cut portion of the insulating thin wire remains, the contact with the lead electrode of the IC or the pattern electrode of the circuit board becomes unstable, and there is a problem that the reliability of the connection decreases.

[0010]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and easily and stably connects the lead electrodes of the surface mount type IC having a small pitch and area to the pattern electrodes of the circuit board. It is an object of the present invention to provide a method for manufacturing an anisotropic conductive sheet with a low compression load that can inspect an IC by using the above method and does not deform the lead electrode of the IC during connection.

The present invention achieves this object, which is characterized by comprising the following first to fifth steps:
In particular, the gist is a method of manufacturing an anisotropic conductive sheet for connecting the outer lead electrodes of the surface-mount type IC and the pattern electrodes of the circuit board so as to face each other. First Step A mesh-like woven cloth is formed from conductive thin wires (preferably warp threads) and water-soluble electrically insulating fine wires (preferably weft threads). Second step The first composite sheet is formed by bonding and fixing the above-mentioned interwoven fabric on the electrically insulating elastomer layer formed on the base material. Third Step The water-soluble electrically insulating thin wire in the first composite sheet is dissolved and removed with water or warm water to form a second composite sheet. Fourth step: Removing the base material from the large number of second composite sheets and stacking them so that the conductive directions of the conductive thin wires are aligned and preferably parallel, and the electrically insulating elastomer layer and the conductive thin wires are alternately superposed. They are integrated to form a laminated body. Fifth step The laminated body is cut into a sheet at a predetermined plane in the conductive direction of the conductive thin wire, preferably at a right angle to form a sheet. In addition, after the 1st to 5th steps, it is optional to add metal plating to the portions of the conductive thin wires protruding on both cut surfaces of the 6th step sheet.

Next, each step of the method for producing an anisotropic conductive sheet of the present invention will be described with reference to the drawings. First step As shown in FIGS. 1 (a) and 1 (b), a conductive thin wire 1 used as a warp in a warper and an insulating thin wire 2 used as a weft in a warper are woven into a mesh shape. The mixed woven fabric 3 is obtained. Although a general-purpose weaving machine can be used for weaving, the conductive thin wire 1 can be made as fine as about 300 mesh by using a weaving machine that produces a screen printing mesh. As the conductive thin wire 1, a metal wire, a conductive synthetic resin wire, a carbon fiber, a wire made of a conductive elastomer, or a metal-plated wire of these or glass fibers can be used, but it can be thinned and has high conductivity. Bronze wire and beryllium copper wire, which have high strength and are advantageous in terms of cost, are desirable. The wire diameter is not particularly limited, but is preferably 10 to 50 μm in order to reduce the mesh thickness of the interwoven cloth 3 and to obtain a stable contact with the lead electrode and the like, and to minimize the compressive load when connecting. . If necessary, the surface of this product is treated with an adhesive before use. A synthetic resin wire such as water-soluble polyvinyl alcohol is used as the insulating fine wire 2, and a water-soluble vinylon monofilament or multifilament having a strength suitable for weaving is preferable.

Second Step Next, as shown in FIG. 1 (c), the base material 4 is prepared by using a calender molding machine, a T-die extrusion molding machine, and various coating machines when the material is liquid, as shown in FIG. 1 (c).
By processing the above into a thin film to form the electrically insulating elastomer layer 5, and laminating it with the above-mentioned interwoven fabric 3,
The first composite sheet 6 is obtained. As the electrically insulating elastomer, natural rubber, synthetic rubber, thermoplastic elastomer and the like can be used, but silicone rubber having high heat resistance and easy to be formed into a sheet is most preferable. It is optional to add an adhesive component therein in order to improve the adhesiveness with the conductive thin wire 1. When silicone rubber is used as the electrically insulating elastomer, the first composite sheet 6
Is a base material 4 such as a PET sheet produced by a calender molding machine.
It is easily obtained by forming a silicone rubber layer in the form of a sheet by topping on the top and laminating this with the woven cloth 3.

Third Step Next, the water-soluble insulating thin wire 2 in the first composite sheet 6 is treated with water or hot water or steam (a small amount of a solvent such as methanol or ethanol added as necessary, which has a strong polarity). Mixing is acceptable. A surfactant may be used in combination so long as the electrical characteristics are not deteriorated.
The second composite sheet 7 shown in (d) can be easily obtained.

Fourth Step Next, after the second composite sheet 7 is cut into a predetermined size and the base material 4 is peeled and removed, as shown in FIG. 1 (e), the conductive direction of the conductive thin wire 1 is changed. A large number of laminated bodies 8 which are aligned, preferably parallel to each other, and in which the electrically insulating elastomer layers 5 and the conductive thin wires 1 are alternately arranged and integrally molded, are formed.
To get The conductive thin wire 1 constantly changes its direction in a wavy shape because it is a warp yarn, and this conductive direction is the direction of the averaged alternate long and short dash line shown in the figure.

Fifth Step Subsequently, the laminated body 8 is cut into a sheet shape in a predetermined plane in the conductive direction of the conductive thin wire 1, preferably a vertical surface, and the conductive thin wire 1 is formed in the electrically insulating elastomer layer 5. An anisotropic conductive sheet 9 of the present invention (see FIG. 1 (f)) in which only one is embedded is obtained.

Step 6 Further, if necessary, in order to improve the reliability of the connection and stabilize the connection resistance value, gold or the like is applied to the portion of the conductive thin wire 1 protruding on both cut surfaces of the obtained sheet. By carrying out the metal plating treatment (1), an anisotropic conductive sheet having a more stable connection resistance value can be obtained.

The anisotropic conductive sheet 9 thus obtained is shown in FIG.
As shown in (f), both electrodes are connected by being sandwiched between the lead electrode 11 of the IC 10 and the pattern electrode 13 on the circuit board 12.

[0019]

According to such a manufacturing method of the present invention, since the interwoven cloth woven by the conductive thin wires and the insulating thin wires is attached to the sheet-like electrically insulating elastomer layer, the step of arranging the conductive thin wires can be performed. It is possible to obtain an anisotropic conductive sheet which is simplified and can be easily arranged at high density and which can be connected to an IC having lead electrodes having a small pitch and area.

Further, since the insulating thin wire is not included inside the anisotropic conductive sheet, the compressive load applied to the lead electrode when connecting the lead electrodes of the IC becomes small, and the lead electrodes having a small pitch and area are bent. It is possible to connect and inspect the IC without causing damage. Furthermore, since the conductive path of the anisotropic conductive sheet is shorter than that of the IC socket, the anisotropic conductive sheet can be used for inspection of ICs that process high frequency signals.

[0021]

【Example】

First step Using a phosphor bronze wire with a diameter of 40 μm for the warp and a water-soluble vinylon fiber monofilament ML type (product of Nichibi Co., Ltd.) of 30 denier for the weft and plain weaving with a screen mesh weaving machine, 2 bronze
A 50-mesh, water-soluble vinylon fiber 100-mesh interwoven fabric was obtained.

Second step Next, P having a thickness of 50 μm is formed.
On the glossy surface of the ET sheet, 100 parts by weight of silicone rubber compound KE-702BU (trade name, manufactured by Shin-Etsu Chemical Co., Ltd.) having a hardness of 68 ° H, and a peroxide-based vulcanizing agent C-3 ( Shin-Etsu Chemical Co., Ltd., trade name) 3
The silicone rubber composition obtained by adding and kneading parts by weight was dispensed to a thickness of 100 μm by a calender molding machine. Then, the above-mentioned interwoven fabric was laminated and laminated on the silicone rubber composition to prepare a first composite sheet.

Third step: The water-soluble vinylon fibers on the surface of the woven fabric of the first composite sheet are dissolved and removed by using hot water at 80 ° C., and then dried to remove water, thereby obtaining a second composite sheet. It was

Fourth Step Next, this second composite sheet was cut into 100 mm in length and width, the PET substrate was peeled off, and a laminating machine was used to make it parallel to the conductive direction of the phosphor bronze wire and the silicone rubber composition layer and phosphorus. 500 sheets were laminated so that the bronze wires were alternately laminated. Then, this laminated block 16
Heat press molding at 0 ° C. and 1.0 kgf / cm ² for 5 hours,
A laminate having a height of about 50 mm was produced.

Fifth Step The laminate thus produced is cut into a sheet shape perpendicular to the conductive direction of the phosphor bronze wire by a slicer using a rotary blade, and the pitch of the phosphor bronze wire is 100 μm in length and width. A 0.5 mm thick sheet was obtained.

Step 6 Next, 180
After heat treatment for 2 hours at ℃, the metal bromide, reducing agent, complexing agent, buffer,
Nickel was plated to a thickness of 1 μm and gold to a thickness of 0.3 μm successively by an electroless plating method using a plating solution containing a stabilizer to obtain a final anisotropic conductive sheet.

[0027]

[Comparative Example] A conventional anisotropic method in which a monofilament of PET having a diameter of 30 μm was used for the weft and the same processing as in the example was carried out by omitting the step of dissolving and removing the weft, and leaving the weft in the electrically insulating elastomer layer. A conductive sheet was produced.

The two types of anisotropic conductive sheets thus obtained were used. The gold-plated PC plate and the area of the tip were 0.2 m.
FIG. 2 shows the relationship between the compression amount and the compression load when the space between the m ² pin-shaped gold-plated lead electrodes is compressed. FIG. 3 shows the relationship between the compressive load and the connection resistance value by the four-terminal method. It was confirmed that the anisotropic conductive sheet of the example can be connected by a low compressive load as compared with the comparative example. Also,
FIG. 4 shows the distribution of the connection resistance values, and it was confirmed that the anisotropic conductive sheets of the examples had a lower connection resistance value and less variation than the comparative example.

[0029]

As described above, according to the present invention, the step of arranging the conductive thin wires on the electrically insulating elastomer layer is simplified, and the conductive thin wires can be arranged at a high density. I with lead electrodes with small pitch and area
An anisotropic conductive sheet capable of connecting C and a circuit board is obtained.

In addition, since the finally obtained anisotropic conductive sheet does not contain insulating thin wires, the anisotropic conductive sheet itself becomes soft, and it becomes a lead electrode when the lead electrode of the IC is connected to the pattern electrode. The compressive load applied becomes small, and even in an IC with a small pitch and area of lead electrodes, the IC can be inspected by connecting without causing bending or damage of the lead electrodes. Further, unlike the comparative example, since the cut portion of the insulating fine wire does not project on both cut surfaces of the anisotropic conductive sheet, the contact between the lead electrode of the IC and the pattern electrode of the circuit board becomes stable, and the connection reliability is improved. The property is improved.

Moreover, the obtained anisotropic conductive sheet is used for IC
When the inspection is performed by connecting the lead electrode of the above-mentioned to the pattern electrode of the circuit board, the conductive path of the anisotropic conductive sheet is shorter than that of the IC socket, so that it can be used for the inspection of the IC that processes a high frequency signal. .

[Brief description of drawings]

FIG. 1 shows a process for producing an anisotropic conductive sheet of the present invention, in which (a) is a plan view of a mixed woven fabric obtained in the first step,
(B) is a cross-sectional view taken along line XX of (a), and (c) is a second view.
Sectional drawing of the 1st composite sheet obtained by the process, (d)
Is a cross-sectional view of the second composite sheet obtained in the third step,
(E) is a cross-sectional view of the laminated body obtained in the fourth step,
(F) is explanatory drawing of the usage of the anisotropic conductive sheet obtained by the method of this invention.

FIG. 2 is a graph showing a relationship between a compression amount and a compression load of anisotropic conductive sheets obtained in Examples and Comparative Examples.

FIG. 3 is a graph showing the relationship between the compressive load and the connection resistance value of the anisotropic conductive sheets obtained in Examples and Comparative Examples.

FIG. 4 is a graph showing a distribution state of connection resistance values of anisotropic conductive sheets obtained in Examples and Comparative Examples.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Conductive thin wire 2 ... Insulating thin wire 3 ... Interwoven cloth 4 ... Base material 5 ... Electrically insulating elastomer layer 6 ... First composite sheet 7 ... Second composite sheet 8 ... Laminated body 9 ... Anisotropic conductive sheet 10 ... IC 11 ... Lead electrode 12 ... Circuit board 13 ... Pattern electrode

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[Procedure amendment]

[Submission date] July 29, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

The present invention achieves this object, which is characterized by comprising the following first to fifth steps:
In particular, the gist is a method of manufacturing an anisotropic conductive sheet (such as a pressure contact pinching type connector) for connecting the outer lead electrode of the surface mount type IC and the pattern electrode of the circuit board so as to face each other. First Step A mesh-like woven cloth is formed from conductive thin wires (preferably warp threads) and water-soluble electrically insulating fine wires (preferably weft threads). Second step The first composite sheet is formed by bonding and fixing the above-mentioned interwoven fabric on the electrically insulating elastomer layer formed on the base material. Third Step The water-soluble electrically insulating thin wire in the first composite sheet is dissolved and removed with water or warm water to form a second composite sheet. Fourth Step On the second composite sheet, while removing the base material of the plurality of second composite sheets, the conductive directions of the conductive thin wires are aligned, preferably parallel, and electrically conductive with the electrically insulating elastomer layer. After the thin wires are alternately laminated to form a laminated body to form a laminated body, the base material of the lowest second composite sheet is removed. Fifth Step The second composite sheet or laminate from which the base material has been removed is cut at a constant angle, preferably at a right angle, with respect to the conductive direction of the conductive thin wire to form a sheet. After the first to fifth steps, metal plating is applied to the portions of the conductive thin wires protruding on both cut surfaces of the sixth step sheet. Is optional.

[Procedure 3]

[Document name to be amended] Statement

[Name of item to be corrected] 0015

[Correction method] Change

[Correction content]

Fourth Step Next, the second composite sheet 7 is cut into a predetermined size, and a plurality of second composite sheets are cut on the base material 4 while the base material 4 is removed therefrom, as shown in FIG. 1 (f). Like conductive thin wire 1
Of the second composite sheet at the lowest position after forming a plurality of layers by aligning the conductive directions of the two, preferably in parallel, and alternately laminating the electrically insulating elastomer layer 5 and the conductive thin wire 1 alternately. The material is removed to obtain the laminated body 8. The conductive thin wire 1 constantly changes its direction in a wavy shape because it is a warp yarn, and this conductive direction is the direction of the average dot-dash line shown in the figure. The base material 4 of the lowest second composite sheet may be peeled and removed after the second composite sheet from which the base material has been removed is laminated thereon.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

Fifth Step Next, the second composite sheet 7 from which the base material 4 has been removed (see FIG. 1)
(See (e)) or the laminated body 8 (see FIG. 1 (f)),
An electrically insulating elastomer layer 5 is obtained by cutting the conductive thin wire 1 into a sheet at a certain angle, preferably perpendicular to the conductive direction.
The anisotropic conductive sheet 9 of the present invention in which only the conductive thin wire 1 is embedded is obtained.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

Sixth step Further, if necessary, in order to improve the reliability of the connection and stabilize the connection resistance value, gold or the like is applied to the portion of the conductive thin wire 1 protruding on both cut surfaces of the obtained sheet. By carrying out the metal plating treatment (1), an anisotropic conductive sheet having a more stable connection resistance value can be obtained. In the anisotropic conductive sheet according to the present invention, in order to prevent buckling of both sides of the anisotropic conductive sheet during compression connection and to stabilize the connection with the electrode, as shown in FIG. 5A, an electrically insulating elastomer is used. It is optional to provide the support member 14 made of (1) by bonding or adhering. In order to manufacture such an anisotropic conductive sheet, sheet-like support members made of an electrically insulating elastomer are bonded and formed integrally on both surfaces of the laminate with an adhesive layer, and then the conductive thin wires are electrically conductive. It can be obtained by cutting into a sheet at an angle to the direction, preferably at a right angle. Such an anisotropic conductive sheet is suitable for connection between circuit boards. This electrically insulating elastomer is used by appropriately selecting the hardness, thickness, material and the like from conventionally known support members of this type.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

As shown in FIG. 5 (b), the anisotropic conductive sheet 9 obtained in FIG. 1 (f) is sandwiched between the pattern electrodes 13 on the opposing circuit board 12 to connect the electrodes.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 shows a process for producing an anisotropic conductive sheet of the present invention, in which (a) is a plan view of a mixed woven fabric obtained in the first step,
(B) is a cross-sectional view taken along line XX of (a), and (c) is a second view.
Sectional drawing of the 1st composite sheet obtained by the process, (d)
Is a cross-sectional view of the second composite sheet obtained in the third step,
(E) is a cross-sectional view of the second composite sheet with the base material removed,
(F) is a cross-sectional view of the laminated body obtained in the fourth step.

FIG. 2 is a graph showing a relationship between a compression amount and a compression load of anisotropic conductive sheets obtained in Examples and Comparative Examples.

FIG. 3 is a graph showing the relationship between the compressive load and the connection resistance value of the anisotropic conductive sheets obtained in Examples and Comparative Examples.

FIG. 4 is a graph showing a distribution state of connection resistance values of anisotropic conductive sheets obtained in Examples and Comparative Examples.

5A is a perspective view of an anisotropic conductive sheet provided with a support member, and FIG. 5B is an explanatory view of a usage state of the anisotropic conductive sheet.

[Explanation of Codes] 1 ... Conductive thin wire 2 ... Insulating thin wire 3 ... Interwoven cloth 4 ... Base material 5 ... Electrically insulating elastomer layer 6 ... First composite sheet 7 ... Second composite sheet 8 ... Laminated body 9 ... Anisotropic conductive sheet 10 ... IC 11 ... Lead electrode 12 ... Circuit board 13 ... Pattern electrode 14 ... Support member

[Procedure Amendment 7]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure Amendment 8]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Added

[Correction content]

[Figure 5]

Claims (1)

[Claims] 1. A method of manufacturing an anisotropic conductive sheet, comprising the following first to fifth steps. First Step A mesh-like interwoven cloth is formed from conductive thin wires and water-soluble electrically insulating thin wires. Second step The first composite sheet is formed by bonding and fixing the above-mentioned interwoven fabric on the electrically insulating elastomer layer formed on the base material. Third Step The water-soluble electrically insulating thin wire in the first composite sheet is dissolved and removed with water or warm water to form a second composite sheet. Fourth step: Removing the base material from the large number of second composite sheets, aligning the conductive directions of the conductive thin wires, and laminating and integrating them so that the electrically insulating elastomer layers and the conductive thin wires are alternately laminated to form a laminated body. To do. Fifth step The laminate is cut into a predetermined plane in the conductive direction of the conductive thin wire to form a sheet.