KR101498996B1 - Complex Sheet - Google Patents

Abstract

A composite sheet used in a thermo-compression process, which is one of the manufacturing processes of electronic devices, comprises a heat-resistant resin film and a sheet composed of a silicone rubber-based composition formed on both sides of the heat-resistant resin film, And the cerium oxide is contained in an amount of 1 to 20 parts by weight based on 100 parts by weight of the silicone rubber.

Description

Complex Sheet {Complex Sheet}

The present invention relates to an electronic device, particularly a flat panel display (FPD), and more particularly to a compact TFT liquid crystal module, a color STN liquid crystal module plasma display panel (PDP) And more particularly,

Conventionally, in a manufacturing process of an electronic device, a compression process as shown in Figs. 1 to 3 is performed. Fig. 1 is an overall view, Fig. 2 is an enlarged view of a portion A in Fig. 1, viewed in a direction of an arrow X, and Fig. 3 is an enlarged view of a portion B in Fig. 1, . However, FIG. 1 shows the state before the pressing, and FIGS. 2 and 3 show the state after the pressing.

Reference numeral 1 in the figure denotes a glass substrate on which the first electrode 2 is formed. One end of the flexible printed board (FPC) 3 is laminated to the end of the glass substrate 1 by thermocompression bonding. Here, the FPC 3 has a film 5 on which the driver IC 4 is formed and a second electrode 6 formed on one side of the film 5. The heater 8 having the release sheet 7 at the lower end is disposed on the thermocompression bonding portion between the glass substrate 1 and the FPC 3. [ The other end of the FPC 3 is laminated with a PCB (printed circuit board) substrate 10 having a third electrode 9 formed at an end thereof by thermocompression bonding. The heater 12 having the release sheet 11 at the lower end is disposed on the thermocompression bonding portion between the PCB substrate 10 and the FPC 3. [ Reference numeral 13 denotes an anisotropic conductive film (ACF), and 14 denotes a sealing material. The thickness of the third electrode 9, the second electrode 6, and the first electrode 2 is set to be thin in this order.

1, an ACF 13 is interposed between the first electrode 2 of the glass substrate 1 and the second electrode 6 of the FPC 3, The first electrode 2 of the glass substrate 1 and the second electrode 6 of the FPC 3 are bonded to each other by thermocompression bonding the release sheet 7 between the heater 8 and the heater 8, And the like. The FPC 3 and the heater (not shown) on the ACF 13 are interposed between the third electrode 9 of the PCB substrate 10 and the second electrode 6 of the FPC 3 with the ACF 13 interposed therebetween. The third electrode 9 of the PCB substrate 10 and the second electrode 6 of the FPC 3 are electrically connected to each other by thermocompression bonding the release sheet 11 with the heater 12, Connection.

However, the release sheets 7 and 11 used in the pressing process are required to have releasability with respect to the ACF 13 pushed at the time of pressure bonding, as well as cushioning for uniform pressure bonding. Particularly, the portion (B portion) where the third electrode 9 of the PCB substrate and the second electrode 6 of the FPC 3 are connected requires greater cushioning property than the release sheet for the glass substrate. Conventionally, a silicone rubber sheet, a fluororesin film having releasability, a composite sheet of a silicone rubber and a fluororesin film, and the like have been proposed and used variously.

Conventionally, as a rubber composite sheet having the same purpose as the release sheet, for example, Japanese Patent Application Laid-Open No. 2004-55687 has been proposed. The rubber composite sheet is composed of a resin film, a fluororesin layer formed on one side (flexible substrate side) of the resin film, and a rubber layer formed on the other side of the resin film, And the like.

However, in recent years, in order to shorten the compression cycle and improve the productivity, the material of the ACF is replaced with the low-temperature short-time type, and it is required to maintain and improve the connection reliability. Also, the pressing process using an ACF is used for various purposes, and it is difficult to say that the proposed release sheet provides satisfactory release characteristics and repeated service life.

It is an object of the present invention to provide a heat resistant resin film and a sheet made of a silicone rubber composition formed on both sides of the film and to provide a silicone rubber composition of the sheet with a specific composition to form various anisotropic conductive films Which is suitable for a pressing process to be used, has a long repeated service life, and has good releasability characteristics.

The composite sheet of the present invention comprises a heat-resistant resin film and a sheet composed of a silicone rubber-based composition formed on both sides of the heat-resistant resin film, in the composite sheet used in the thermo- The silicone rubber composition of the present invention is a silicone rubber composition in which the amount of silica powder is 2 to 100, carbon black is 0 to 200, magnesium oxide is 10 to 1000, iron oxide is 0 to 20, and cerium oxide is 0.1 to 0.5, .

In the present invention, the heat-resistant resin film may be a film made of a heat-resistant resin selected from polyimide resin, aromatic polyamide resin, polyether ether ketone resin, polyether sulfone resin and polyphenylene sulfide resin. And is not particularly limited.

In the present invention, the silica powder is used in an amount of 2 to 100 parts by weight based on 100 parts by weight of the silicone rubber for the following reasons. That is, when the amount of the silica powder is less than 2 parts by weight, the rubber hardness becomes low and the residual compression distortion becomes large. When the amount of the silica powder exceeds 100 parts by weight, the rubber hardness becomes too high, resulting in poor cushionability and poor moldability.

In the present invention, the carbon black is set to 0 to 200 parts by weight based on 100 parts by weight of the silicone rubber. When the amount of the carbon black exceeds 200 parts by weight, the electric conductivity is not increased and the antistatic property is less improved. It is because it gets worse.

In the present invention, magnesium oxide is used in an amount of 10 to 1000 parts by weight based on 100 parts by weight of the silicone rubber for the following reasons. That is, when the amount of the magnesium oxide is less than 10 parts by weight, the heat conduction rate is low and it takes time to raise the temperature. If the amount of the magnesium oxide exceeds 1,000 parts by weight, the heat conduction rate is not increased and the effect on the increase of the filling amount can not be obtained. In addition, the moldability is deteriorated and the rubber after curing becomes brittle.

In the present invention, the amount of the iron oxide is 0 to 20 parts by weight based on 100 parts by weight of the silicone rubber. When the amount of the iron oxide exceeds 20 parts by weight, the reduction in molecular weight of the silicone polymer under high temperature and pressure can not be suppressed, Because.

In the present invention, cerium oxide is used in an amount of 0.1 to 0.5 parts by weight based on 100 parts by weight of the silicone rubber for the following reasons. That is, when the amount of cerium oxide is less than 0.1 parts by weight, the molecular weight of the silicone polymer under high temperature and pressure is increased, and the residual compression distortion is large. When the cerium oxide exceeds 0.5 parts by weight, the lower molecular weight of the silicone polymer under high temperature and pressure can not be suppressed and the residual compression distortion can not be lowered.

In the present invention, the total thickness is preferably 0.01 to 5 mm. If the total thickness is less than 0.01 mm, the service life is not satisfied due to insufficient strength, and if the total thickness exceeds 5 mm, the thermal conduction speed is low and it takes time to press.

According to the present invention, it is possible to obtain a composite sheet suitable for a pressing process using various anisotropic conductive films, having a long repetitive service life and having good releasing characteristics.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a composite sheet according to each embodiment of the present invention will be described with reference to the drawings. The first to eighth embodiments described below are composite sheets used for pressing the electrodes in the portion A in Fig. The ninth and tenth embodiments described below relate to a composite sheet used for bonding between electrodes in a portion B in Fig.

(First Embodiment)

Please refer to Fig.

Reference numeral 21 in the figure denotes a heat resistant resin film (polyimide film) made of polyimide and having a thickness of 50 占 퐉. The roughened surfaces 21a and 21b roughened by the corona discharge treatment are formed on both surfaces of the polyimide film 21, respectively. The black sheets 22a and 22b made of the silicone rubber composition are formed on both sides of the polyimide film 21 on which the uneven surfaces 21a and 21b are formed. The sheets 22a and 22b were prepared by mixing 12 parts by weight of silica powder, 42 parts by weight of carbon black, 260 parts by weight of magnesium oxide, 2 parts by weight of iron oxide, and 0.1 part by weight of cerium oxide with 100 parts by weight of organopolysiloxane (silicone rubber) And then the mixture is uniformly mixed, and the resulting composition is laminated, dried and cured.

Next, a method of manufacturing the composite sheet of Fig. 4 will be described.

(1) First, a polyimide film having a thickness of 50 탆 was used as a substrate. This polyimide film was coated on both sides with a polyalkoxysilane, a platinum compound and tetraethoxysilane dissolved in n-nucleic acid as primers, and dried at room temperature for 10 minutes. The deposition amount at this time was 2.0 g / m 2 on one side. Apart from this, 12 parts by weight of silica powder, 42 parts by weight of carbon black, 260 parts by weight of magnesium oxide, 2 parts by weight of iron oxide, and 0.1 part by weight of cerium oxide were uniformly mixed with 100 parts by weight of organopolysiloxane, Thereby obtaining a rubber-based composition.

(2) Next, the silicone rubber composition was dissolved in a toluene solvent, and a white gold vulcanizing agent was added to prepare a rubber paste. Subsequently, the rubber paste was coated on one side of a polyimide film having a thickness of 50 占 퐉 and subjected to the primer treatment, and then vulcanized at 170 占 폚 for 10 minutes by a hot vulcanization furnace. Subsequently, this process was repeated on the other side of the polyimide film to obtain a structure in which the core material of the polyimide was the middle and the upper and lower sides were symmetrical. Further, secondary vulcanization was carried out by treatment in a hot-air drying furnace at 200 占 폚 for 4 hours to obtain a composite sheet coated with a silicone rubber composition having a total thickness of 200 占 퐉.

According to the first embodiment, a polyimide film 21 having uneven surfaces 21a and 21b and sheets 22a and 22b made of a silicone rubber composition having a predetermined composition and formed on both surfaces of the polyimide film 21 The composite sheet 23 is constituted. Therefore, the composite sheet 23 of the present invention is suitable for a pressing process using various anisotropic conductive films, has a long repetitive service life, and has excellent releasing characteristics.

In fact, the thickness reduction ratio (%) of the composite sheet was tested using a testing machine as shown in Fig. This test is performed by placing the composite sheet 32 on the heater lower plate 31 and pressing the composite sheet 32 with the heated upper plate 33 to measure the rate of decrease in the thickness of the composite sheet 32 . The compression durability of the composite sheet was tested using a testing machine as shown in Fig. In this test, the composite sheet 32 is placed on the heated lower heater board 31 by successively sandwiching the printed board 34a, the anisotropic conductive film 35 and the copper-deposited polyimide film 34b not patterned , And pressing the composite sheet 32 with the heated upper side plate 33.

The thickness reduction rate was obtained as follows: press pressure: 4 MPa; heater upper half temperature: 300 占 폚; heater lower half temperature: room temperature; press retention time: 10 sec; press interval: 5 sec;

The compression durability was evaluated as follows: press pressure: 3 MPa; heater upper half temperature: 280 占 폚; heater lower half temperature: 45 占 폚; press holding time: 15 sec; press number: 20, 40, 60, 80 times Confirmed by conduction after the compression test).

(Embodiments 2 to 8 and Comparative Examples 1 to 3)

A composite sheet was obtained in the same manner as in the first embodiment except that the mixing ratio of the components of the raw material composition was changed. However, the polyimide film is not used for the comparative example 3.

Table 1 below shows the compositions of the raw materials of the first embodiment 1 to 8 and the comparative examples 1 to 3, the thickness reduction rate, the heating rate, the antistatic property, the molding processability and the compression durability (20 times, 40 times, 60 times , ≪ / RTI > 80 times). In Table 1, the rate of rise in temperature, the antistatic property, the moldability and the compression durability are indicated by a double circle, the best one being a double circle, the ordinary one being a triangle, and the poor ones being indicated by x. In Table 1, the thicknesses of the sheets 22a and 22b of Examples 1 to 8 and Comparative Examples 1 and 2 are 75 μm, respectively, and the thickness of the rubber layer of Comparative Example 3 is 200 μm.

 Raw material Mixing ratio
(Parts by weight) Embodiment Comparative Example 1 2 3 4 5 6 7 8 One 2 3 Silicone rubber 100 100 100 100 100 100 100 100 100  100 100 Silica powder 2-100 12 5 2 2 5 20 30 100 2 150 10 Carbon black 10 to 200 42 10 70 60 55 25 10 200 5 250 40 Magnesium oxide 10 to 1000 260 30 10 50 120 500 700 1000 10 1500 250 Iron oxide 0 to 20 2 0 One One One 4 6 20 0 30 2 Cerium oxide 0.1 to 0.5 0.1 0.1 0.3 0.3 0.3 0.3 0.3 0.5 0.05 One 0.3 Thickness reduction rate 0.5 1.3 1.3 1.1 0.9 0.8 1.3 0.3 1.4 1.4 2.2 Heating rate ◎ △ × △ ○ ◎ ◎ ◎ × × ◎ Antistatic property ◎ △ ◎ ◎ ◎ ◎ △ ◎ × × ◎ Moldability ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ Crimp durability (number of times) 20 ○ ○ ○ ○ ○ ○ ○ ○ - - × 40 ○ × ○ ○ ○ ○ ○ × - - - 60 ○ - × × ○ ○ ○ - - - - 80 ○ - - - × ○ ○ - - - -

Good heat conduction and extremely short compression time; Good thermal conductivity; Good compression time; Good thermal conductivity; Good compression time; Good thermal conductivity. Respectively, indicating insufficient shortening of the compression time.

Good: It is highly conductive and prevents the electrification very good.: Good: It is neutral and good. Prevention of electrification.?: Low electrification and prevention of electrification. X: Good electrification and poor electrification failure.

Good: Good moldability in molding processability.

In the compression durability,?: Good conduction, and X: poor conduction.

The composite sheets of the first embodiment 1 to 8 and the comparative examples 1 to 3 based on Table 1 are as follows.

In the case of the first embodiment, it was confirmed that the temperature raising rate, the antistatic property, the molding processability, and the press durability as characteristics were set to be well balanced and the characteristics required for the thermocompression-bonded sheet used for pressing the ACF were satisfied.

In the case of the second embodiment, the rate of temperature rise is low thermal conductivity and shortens the pressing time, and the antistatic property has low conductivity, but prevents electrification. However, the strength of the coating layer made of the silicone rubber composition was lowered, and it was confirmed that the compression durability was insufficient.

In the case of the third embodiment, the rate of temperature rise is about the thermal conductivity, the shortening of the pressing time is insufficient, and the antistatic property is good for high conductivity. In addition, it was confirmed that the coating layer made of the silicone rubber composition showed a slight decrease in strength, and the compression durability was insufficient.

In the case of the fourth embodiment, the temperature raising rate is low heat conductivity, shortening the pressing time, and the antistatic property is very good with high conductivity. However, it was confirmed that the coating layer made of the silicone rubber composition showed a slight decrease in strength, and the compression durability was insufficient.

In the case of the fifth embodiment, the rate of temperature rise is intermediate heat conduction, the compression time is shortened favorably, and the antistatic property is very good with high conductivity. However, a slight decrease in strength was observed in the coating layer made of the silicone rubber composition, and it was confirmed that the compression durability was also slightly lacking.

In the case of the sixth embodiment, the heating rate is a middle heat conduction and the pressing time is extremely shortened, and the electrification preventing property is low, but the electrification is prevented. Further, it was confirmed that the coating layer made of the silicone rubber composition showed no reduction in strength, and that the compression durability was also sufficient.

In the case of the seventh embodiment, the rate of temperature rise is high heat conductivity and the compression time is extremely shortened. Also, since the antistatic property is low, the antistatic property is poor. Further, it was confirmed that the coating layer made of the silicone rubber composition showed no reduction in strength, and that the compression durability was also sufficient.

In the case of the eighth embodiment, the temperature raising rate is high heat conductivity, the pressing time is extremely shortened, and the antistatic property is extremely high, which is very good. However, the strength of the coating layer made of the silicone rubber composition is lowered, and the compression durability is also insufficient. Further, although the moldability is not impaired, it is confirmed that the composite sheet lacks flexibility because of the large amount of components, and uncertainty remains in the compression of a sound ACF.

In the case of Comparative Example 1, the rate of temperature rise is about the thermal conductivity, the shortening of the pressing time is insufficient, and the antistatic property is the electrification preventing property. Further, since the strength of the coating layer made of the silicone rubber composition was remarkably lowered, it was confirmed that the amount of deformation was large and repetitive pressing was impossible.

In the case of Comparative Example 2, it was confirmed that the amount of components to be compounded was too large and molding was impossible.

In the case of Comparative Example 3, the rate of temperature rise is high thermal conductivity, the compression time is extremely shortened, and the antistatic property is extremely high. However, since the strength of the coating layer made of the silicone rubber composition remarkably decreased, it was confirmed that the amount of deformation was large and repetitive pressing was impossible.

(Ninth embodiment)

See FIG. Further, in the case of the composite sheet of the ninth embodiment and the tenth embodiment to be described later, since it is assumed that the unevenness of the terminal portion of the FPC is used for a large use, the thickness of the first and second sheets is formed to be sufficiently thick have. Here, in FIG. 7, the composite sheet is set so that the first sheet 42a is on the ACF side and the second sheet 42b is on the heater side.

Reference numeral 41 in the figure denotes a heat-resistant resin film (polyimide film) made of polyimide and having a thickness of 25 占 퐉. On both sides of the polyimide film 41, uneven surfaces 41a and 41b having a surface roughness (Ra) of 1.4 which is roughened by a corona discharge treatment are formed. On both sides of the polyimide film 41 on which the uneven surfaces 41a and 41b are formed, a black first sheet (210 占 퐉 thick) 42a made of a silicone rubber composition and a second sheet of gray Thickness 115 mu m) 42b are formed.

The first sheet 42a was prepared by mixing 12 parts by weight of silica powder, 42 parts by weight of carbon black, 262 parts by weight of magnesium oxide, 2 parts by weight of iron oxide, And 0.1 part by weight of cerium are uniformly mixed with each other, followed by laminating, drying and curing. The second sheet 42b was prepared by uniformly mixing 31 parts by weight of silica powder, 698 parts by weight of magnesium oxide, 6 parts by weight of iron oxide and 0.1 part by weight of cerium oxide with 100 parts by weight of an organopolysiloxane (silicone rubber) Based composition is laminated, dried, and cured. Table 2 shows the mixing ratios of the respective raw materials, the thicknesses of the first and second sheets, the thickness reduction rate, the heating rate, the antistatic property, the molding processability, and the compression durability ( 20 times, 40 times, 60 times, and 80 times, respectively). In Table 2, the rate of rise in temperature, the antistatic property, the moldability and the compression durability were indicated by a double circle, the best one being a double circle, the ordinary one being a triangle, and the poor ones being indicated by x.

Raw material Ninth Embodiment
(First sheet / second sheet) Tenth Embodiment
(First sheet / second sheet) Silicone rubber 100/100 100/100 Silica powder 12/31 12/12 Carbon black 42/0 42/42 Magnesium oxide 262/698 262/262 Iron oxide 2/6 2/2 Cerium oxide 0.1 / 0.1 0.1 / 0.1 Thickness (㎛) 210/115 150/150 Thickness reduction rate 0.6 0.4 Heating rate ◎ ◎ Antistatic property ○ ◎ Moldability ○ ○ Crimp durability
(Number of times) 20 ○ ○ 40 ○ ○ 60 ○ ○ 80 ○ ○

However, in the heating rate,?: High thermal conductivity and very good compression time

And can be shortened.

In the antistatic property, & cir &: Highly conductive and highly antistatic,

O: Represents neutral conductivity and good antistatic property, respectively.

Good: Good moldability in molding processability.

Good: Excellent in compression durability.

Next, a manufacturing method of the composite sheet 43 of Fig. 7 will be described.

(1) First, a polyimide film having a thickness of 25 mu m was used as a substrate. Further, 12 parts by weight of silica powder, 42 parts by weight of carbon black, 262 parts by weight of magnesium oxide, 2 parts by weight of iron oxide and 0.1 part by weight of cerium oxide were uniformly mixed with 100 parts by weight of organopolysiloxane to obtain a silicone rubber composition.

(2) Next, the silicone rubber composition was dissolved in a toluene solvent, and a platinum vulcanizing agent was added to prepare a rubber paste. Subsequently, the rubber paste was coated on one side of a polyimide film having a thickness of 25 占 퐉 and subjected to the primer treatment, and then vulcanized at 170 占 폚 for 10 minutes by a hot vulcanization furnace. Subsequently, this process was repeated on the other side of the polyimide film to obtain a double-sided structure having a core of polyimide as the middle. Further, secondary vulcanization was carried out by treatment in a hot-air drying furnace at 200 占 폚 for 4 hours to obtain a composite sheet 43 coated with a silicone rubber composition having a total thickness of 350 占 퐉.

According to the ninth embodiment, the thickness of the polyimide film 41 having the uneven surfaces 41a and 41b and the thickness of the silicone rubber-based composition having a predetermined composition formed on one side of the polyimide film 41 is 210 And a second sheet 42b having a thickness of 115 mu m each formed of a silicone rubber composition having a predetermined composition and formed on the other surface of the polyimide film 41, . Therefore, the composite sheet 43 of the present invention not only achieves the same effects as those of the first embodiment, but also has the effect described below.

That is, depending on the application, the degree of cushioning required for the composite sheet is different. For example, for applications requiring cushioning, it is necessary to increase the thickness of the sheet. Here, if the thickness of the first and second sheets on both sides is increased, the cushioning property can be imparted. However, do. Thus, by increasing the thickness of the first sheet 42a contacting the work (flexible substrate) and reducing the thickness of the second sheet 42b, the cushioning property can be imparted without damaging the thermal conductivity. In the case of the ninth embodiment, since the thickness of the first sheet 42a is 210 占 퐉 and the thickness of the second sheet 42b is 115 占 퐉, the thermal conductivity of the composite sheet 43 is not impaired , And cushioning properties can be imparted. In the composite sheet 43 shown in Fig. 5, the first sheet 42a is necessary for the purpose of functioning, and the second sheet 42b is necessary for preventing warpage.

Further, if the sheets of the same color are formed on both sides of the polyimide film, it is impossible to visually recognize the front and back sides of the composite sheet 43. Therefore, in the ninth embodiment, the color of the first sheet 42a is made black and the color of the second sheet 42b is made gray, so that the identification of the front and back of the composite sheet 43 is facilitated . Further, since the polyimide film has a thickness of 25 占 퐉, the thermal conductivity can be improved as compared with the first embodiment.

Thus, the composite sheet of the ninth embodiment is suitable for use in which the rate of temperature rise is improved, the antistatic property, the molding processability, and the compression durability are set to be well balanced, and the cushioning property is required in comparison with the first embodiment.

(Tenth Embodiment)

See FIG. 7 are denoted by the same reference numerals, and a description thereof will be omitted.

As shown in Table 2, the first sheet 52a is black with a thickness of 150 占 퐉, and the second sheet 52b has the same thickness and color as the first sheet 52a. Therefore, the mixing ratio of the first sheet 51a and the second sheet 52b is the same. The manufacturing method of the composite sheet 53 according to the tenth embodiment is the same as that of the ninth embodiment.

According to the tenth embodiment, it is possible to obtain a composite sheet in which the rate of temperature rise is improved, the antistatic property, the molding processability, and the compression durability are set to be well balanced, and the thickness reduction rate and thermal conductivity are slightly improved as compared with Example 1.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an explanatory diagram of a case where thermocompression bonding of an electrode terminal portion of a circuit board to a glass substrate and a conductive portion of a PCB substrate is performed using a release sheet. Fig.

Fig. 2 is an enlarged view of the main part of Fig. 1, viewed from the direction of arrow X. Fig.

Fig. 3 is an enlarged view of the main part of Fig. 1 and viewed in the Y-arrow direction. Fig.

4 is a schematic cross-sectional view of the composite sheet according to the first embodiment of the present invention.

5 is an explanatory diagram of a test apparatus for testing the thickness reduction ratio of the composite sheet of the present invention.

6 is an explanatory diagram of a test apparatus for testing the compression durability of the composite sheet of the present invention.

7 is a schematic cross-sectional view of a composite sheet according to a ninth embodiment of the present invention.

8 is a schematic cross-sectional view of a composite sheet according to a tenth embodiment of the present invention.

Claims (5)

In a composite sheet used in a thermo-compression process, which is one of the manufacturing processes of electronic devices, Heat-resistant resin film and two sheets of a silicone rubber-based composition formed on both sides of the heat-resistant resin film, The thicknesses of the two sheets are different from each other, Wherein each of the silicone rubber compositions of the two sheets is in a weight ratio of 2 to 100 in terms of silica powder to 100 in silicone rubber, 0 to 200 in carbon black, 10 to 1000 in magnesium oxide, 0 to 20 in iron oxide, : 0.1 to 0.5. The method according to claim 1, Wherein the composition of the two sheets is different. The method according to claim 1, The one sheet of the silicone rubber composition of the two sheets contains silica powder 12, carbon black 42, magnesium oxide 262, iron oxide 2, and cerium oxide 0.1 in a weight percentage with respect to the silicone rubber 100, Wherein the other sheet of the two sheets of the silicone rubber composition comprises, by weight, the silica powder 100, the silica powder 31, the carbon black 0, the magnesium oxide 698, the iron oxide 6, and the cerium oxide 0.1 Composite sheet. 4. The method according to any one of claims 1 to 3, Wherein the heat resistant resin film is made of a heat resistant resin selected from the group consisting of a polyimide resin, an aromatic polyamide resin, a polyether ether ketone resin, a polyether sulfone resin, and a polyphenylene sulfide resin. 4. The method according to any one of claims 1 to 3, And a total thickness of 0.01 to 5 mm.

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