JP2006142611A - Composite sheet for thermal press bonding and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composite sheet for thermal press bonding having good cushioning properties, heat conductivity and mold releasability and hard to cause thermal deformation or ply separation, and its manufacturing method. <P>SOLUTION: The composite sheet for thermal press bonding is constituted of a metal foil 12, the mold release layer 11, which contains a fluoroplastic resin and has a thickness of 3-20 μm, provided on one side thereof and the heat conductive rubber layer 13 with a thickness of 30-200 μm provided on the other surface of the metal foil. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention is used for bonding by thermocompression bonding of electronic / electronic device parts, particularly liquid crystal displays, plasma displays, etc., and a thermocompression bonding composite sheet for transferring heat of a thermocompression bonding plate to a member to be bonded, and its manufacture. Regarding the method.

  2. Description of the Related Art Conventionally, in an electronic device manufacturing process using the above components, a thermocompression bonding operation using the apparatus shown in FIG. 2 or the like is performed according to the process shown in FIG. This process includes 1) a panel transporting process for transporting the liquid crystal panel 1, 2) a temporary press-bonding process for temporarily attaching the anisotropic conductive film 2 (ACF) to the electrode forming portion 1a of the liquid crystal panel 1, and 3) TAB3 (or COG). 4) a mounting step of mounting at a position where the bonding is performed, and 4) a main pressing step with the anisotropic conductive film 2.

  3 to 5 show typical films (including sheets, the same applies hereinafter) and composite sheets used in this step. At present, a thermocompression bonding method using these films or the like is performed. The anisotropic conductive film 2 is thermocompression bonded by the thermocompression bonding plate 4 to electrically connect the electrodes 3a of the TAB 3 and the electrodes 1a of the liquid crystal panel 1 positioned above and below.

  What is shown in FIG. 3 is a composite sheet (for example, refer to Patent Document 1) in which a PTFE film 21 or a metal foil is integrated by applying a fluororesin coat.

  4 shows a combination of PTFE film 21 and silicone rubber sheet 22, or a composite sheet in which PTFE film 21 and silicone rubber sheet 22 are integrated (see, for example, Patent Document 2).

  What is shown in FIG. 5 is a combination sheet of polyimide film 23, silicone rubber sheet 22, and glass cloth impregnated cloth 24, or an integrated composite sheet.

  However, the type shown in FIG. 3 is disadvantageous in that it cannot be used for large-sized components because when electronic component components become large as in recent years, unevenness occurs at the time of thermocompression bonding.

  4 and 5 that use a plurality of films, etc., require a feeding and winding device for each film, etc., so that if each film does not have a certain degree of strength, the film is wound. It can't stand taking and tears. Moreover, since air intervenes between the films (sheets), the thermal conductivity is deteriorated, and it is necessary to increase the pressure bonding temperature or to increase the heating time. Therefore, there are problems from the viewpoint of productivity and energy saving. Further, since the films (sheets) are used in an overlapping manner, the films (sheets) are likely to be wrinkled, resulting in a decrease in the effective usage rate of the films (sheets) and a decrease in product yield. Furthermore, since the material used must have a thickness that can withstand the take-up and winding device, it is not economical.

On the other hand, among the types shown in FIGS. 4 and 5, those using a composite sheet in which a plurality of films and the like are integrated cause problems of adhesion between layers and thermal conductivity due to increase in thickness. easy. In particular, the type shown in FIG. 4 is composed only of a resin or a rubber material, so that a problem of thermal deformation is likely to occur.
JP 2003-100807 A JP-A-5-315401

  Accordingly, an object of the present invention is to provide a thermocompression bonding composite sheet that has good cushioning properties, thermal conductivity, and releasability, and that hardly causes thermal deformation or delamination, and a method for manufacturing the same.

  As a result of intensive research to achieve the above object, the present inventors achieved the above object by bringing the release layer and the rubber layer into a predetermined range while adhering and integrating the release layer and the rubber layer through a metal foil. The present inventors have found that this can be done and have completed the present invention.

  That is, the composite sheet for thermocompression bonding of the present invention has a metal foil, a release layer having a thickness of 3 to 20 μm, which is provided on one surface side and contains a fluorine-based resin, and the other surface side of the metal foil. And a thermally conductive rubber layer having a thickness of 30 to 200 μm provided.

  According to the composite sheet for thermocompression bonding of the present invention, since the metal foil is interposed between the release layer and the rubber layer, thermal deformation and delamination are unlikely to occur at the time of compression bonding, and the thermal conductivity can be improved. In addition, since a release layer having an appropriate thickness containing a fluororesin is provided on one surface side of the metal foil, the release property can be improved while maintaining thermal conductivity. Furthermore, since the heat conductive rubber layer having an appropriate thickness is provided on the other surface side of the metal foil, the heat conductivity and the cushioning property can be improved. Therefore, unevenness does not easily occur at the time of thermocompression bonding, and it can be used for large parts.

  In the above, the rubber layer preferably contains silicone rubber and metal compound particles. Silicone rubber has good heat resistance, and the thermal conductivity can be improved by containing metal compound particles.

  In addition, since the composite sheet for thermocompression bonding of the present invention uses a metal foil, the antistatic function is excellent, but in order to further improve this function, carbon black is added to the release layer. Thus, the antistatic function can be improved. The antistatic function can effectively prevent problems such as damage caused by static electricity of electronic parts and the like and adhesion of dust.

  On the other hand, in the method for producing a thermocompression bonding composite sheet according to the present invention, a dispersion containing a fluororesin is applied to one surface side of a metal foil, and the dispersion solvent is removed by evaporation, followed by firing. The method includes a step of forming a release layer having a thickness of 20 μm and a step of forming a heat conductive rubber layer having a thickness of 30 to 200 μm on the other surface side of the metal foil.

  According to the production method of the present invention, it is possible to produce a thermocompression-bonding composite sheet that has good cushioning properties, thermal conductivity, and releasability as described above, and that hardly undergoes thermal deformation or delamination. In particular, since the release layer and the rubber layer are formed on the surface of the metal foil by the method as described above, the adhesion between the layers can be further improved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the thermocompression bonding composite sheet of the present invention. Moreover, FIG. 2 is a schematic block diagram which shows an example of the apparatus used for manufacture of the composite sheet for thermocompression bonding of this invention.

  As shown in FIG. 1, the thermocompression bonding composite sheet of the present invention has a metal foil 12, a release layer 11 provided on one surface side thereof, and a heat provided on the other surface side of the metal foil 12. And a conductive rubber layer 13.

  The release layer 11 contains a fluorine resin. Examples of the fluororesin include polytetrafluoroethylene (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer (PFA), and polyvinylidene fluoride. Can be mentioned.

  The fluororesin may be a resin having an antistatic function by adding a conductive material such as carbon black or metal powder. In that case, the addition amount of the conductive substance is preferably 5 to 20% by weight in the release layer 11. As carbon black, furnace black, channel black, thermal black, acetylene black, etc. can be used.

  The thickness of the release layer 11 is 3 to 20 μm, and preferably 5 to 10 μm. When the thickness is less than 3 μm, the release layer does not have the mechanical strength, so that defective portions such as pinholes and scratches are likely to occur, and the release effect may not be sufficiently exhibited. On the other hand, if it exceeds 20 μm, the thermal conductivity is lowered, which is not preferable for practical use.

  For the rubber layer 13, silicone rubber, fluorine rubber, acrylic rubber, or the like is used. The rubber layer 13 is thermally conductive and contains a thermally conductive substance. Examples of the thermally conductive substance include metal compound particles, metal powder, and glasses. Examples of the metal compound particles include metal nitrides such as boron nitride and aluminum nitride, metal oxides such as magnesium oxide, and metal carbides such as silicon carbide. The content of the heat conductive material is preferably 90 to 95% by weight in the rubber layer 13.

  Therefore, in order to form the rubber layer 13, a commercially available silicone rubber heat curing type elastomer for heat radiation (KE1867 made by Shin-Etsu silicone, X32-2020, X32-2152, SE4450 made by Toray Dow Corning, GE It is preferable to use TSE3281-G) manufactured by Toshiba Silicone.

  The thickness of the rubber layer 13 is 30 to 200 μm, and preferably 50 to 200 μm. When the thickness is less than 30 μm, the cushioning effect is not sufficient, and in the case of a large-sized electronic device, there is a problem that the contact is not uniform. On the other hand, if it exceeds 200 μm, the thermal conductivity deteriorates, which is not preferable.

  As the metal foil 12, commercially available stainless steel, aluminum, copper, or the like can be used. 10-50 micrometers is preferable and, as for the thickness of the metal foil 12, 20-30 micrometers is more preferable. If the thickness is less than 10 μm, the workability is deteriorated and wrinkles tend to enter and lack in adhesion, and if it is thicker than 50 μm, the necessary thermal conductivity tends not to be ensured.

  If necessary, the metal foil 12 may be subjected to an adhesion improving process such as a roughening process or a primer process.

  The composite sheet for thermocompression bonding of the present invention is manufactured by the manufacturing method of the present invention, that is, a dispersion containing a fluororesin is applied to one surface side of a metal foil, the dispersion solvent is removed by evaporation, and then fired. It is preferably manufactured by a manufacturing method including a step of forming a release layer having a thickness of 3 to 20 μm and a step of forming a heat conductive rubber layer having a thickness of 30 to 200 μm on the other surface side of the metal foil. be able to. Hereinafter, the production method of the present invention will be described.

  The dispersion used in the step of forming the release layer preferably contains an aqueous dispersion solvent. The removal of the dispersion solvent by evaporation is preferably performed at a temperature near the boiling point of the dispersion solvent. The firing is preferably performed at a temperature equal to or higher than the melting point of the fluororesin.

  Any of the step of forming the release layer and the step of forming the rubber layer may be performed first, but it is preferable to form the release layer first from the viewpoint of the firing temperature. In the case of applying by dipping (immersion), there is a method of using two stacked metal foils and peeling them after application.

  The step of forming the rubber layer includes, for example, a method in which a rubber component dissolved in a solvent is applied to one side of a metal foil and then heated to scatter the solvent. If necessary, crosslinking (vulcanization) is performed in this heating step.

  As a method of forming a rubber layer, instead of applying a rubber component dissolved in a solvent as described above, a rubber layer that has been finished in the form of a film (sheet) is heat-pressed with an adhesive and bonded to an aluminum foil. May be. Examples of the adhesive used in this case include an epoxy system, a silicone system, and a rubber system.

  For the formation of each layer, a coating / heating device using various coaters can be used. For example, when forming a rubber layer, the continuous type apparatus shown in FIG. 2 can be used. In this apparatus, the rubber component is applied by the comma roll coater 33 via the guide roll R while feeding the metal foil 12 (or the laminate of the metal foil 12 and the release layer 11) from the feeding roll 31, and the drying zone. After heating and drying at 34, the product is sent out while being sandwiched by the nip roll 35, and the product is taken up by the take-up roll 36.

  The composite sheet for thermocompression bonding thus obtained can be suitably used for a process of joining electronic / electronic device parts, particularly a liquid crystal display, a plasma display, etc. by thermocompression bonding using ACF.

  Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, the evaluation item in an Example etc. measured as follows.

(1) Thermal conductivity Using the thermocompression bonding apparatus shown in FIG. 1 (manufactured by Nikka Equipment Engineering Co., Ltd., Anisolum thermocompression bonding machine AC-S50), the flexible wiring board 5, the ACF2, and the glass plate 6 are laminated, Thermocompression bonding was performed through the thermocompression bonding composite sheet S disposed on the upper surface. At that time, the setting temperature is 300 ° C., the setting pressure is 3.0 MPa, the setting time is 20 seconds, the size of the composite sheet S is 25 mm × 100 mm, and the temperature on the lower surface side of the ACF 2 is a digital thermometer (Rika Kogyo Co., Ltd., DP-500). The thermal conductivity was evaluated by the reached temperature at a set temperature of 300 ° C.

(2) Cushioning property In the thermocompression bonding test of (1) above, evaluation was performed by observing deformation of conductive particles in the ACF from the back side of the glass plate with a microscope. ○ is when the conductive particles in the ACF are uniformly deformed, and × is when the conductive particles in the ACF are not uniformly deformed.

(3) Thermal deformability In the thermocompression bonding test of (1) above, the degree of deformation of the composite sheet S was evaluated visually. A circle indicates no thermal deformation, and a circle indicates a case where thermal deformation occurs.

(4) Releasability In the thermocompression bonding of (1) above, it was visually evaluated whether the composite sheet S adhered to the thermocompression bonding plate or not when the thermocompression bonding plate was opened after heating. ○ indicates that the composite sheet S does not adhere to the thermocompression bonding plate, and x indicates that the composite sheet S adheres to the thermocompression bonding plate.

[Example 1]
An aqueous dispersion of fluororesin PTFE (Asahi Glass Co., Ltd., Fullon AD-938) was applied by dipping (immersion) on two aluminum foils (thickness 25 μm) and heated at 100 ° C. for 4 minutes to evaporate and remove moisture. did. Then, it heated at about 400 degreeC, the aluminum foil which piled up two sheets was peeled, and the mold release layer of the fluororesin with a thickness of 5 micrometers was formed in the aluminum foil single side | surface. Apply a rubber component containing solvent (toluene) and metal compound particles (heat-dissipating silicone rubber, heat-curing type elastomer, Shin-Etsu Silicone KE1867, dilution base concentration 90% by weight) on one side of this aluminum foil with a comma coater. The mixture was heated at 150 ° C. for 5 minutes to disperse and crosslink the solvent to form a heat conductive rubber layer having a thickness of 200 μm, thereby producing a thermocompression bonding composite sheet. The rubber layer and the release layer were adhered to the metal foil with sufficient strength, and it was difficult to delaminate (the same applies to Examples 2 to 5).

[Examples 2 to 5]
In Example 1, a composite sheet for thermocompression bonding was produced in the same manner as in Example 1 except that the thickness of each layer was set to the values shown in Table 1. When the fluororesin release layer had a thickness of 10 μm, coating, drying and firing were repeated twice.

[Comparative Examples 1-4]
In Example 1, a composite sheet for thermocompression bonding was produced in the same manner as in Example 1 except that the thickness of each layer was set to the values shown in Table 1. When the fluororesin release layer had a thickness of 30 μm, coating, drying, and firing were repeated four times.

  Said evaluation was implemented using the composite sheet for thermocompression bonding obtained in these Examples 1-6 and Comparative Examples 1-4. These results are shown in Table 1 below.

表１の結果が示すように、実施例１〜６は何れも熱伝導性、クッション性、耐熱性、離型性ともに良好な値を示している事が判る。これに対し、比較例１、３はＰＴＦＥ層の厚さが３μｍの為離型性がない。比較例１、４はシリコーンゴム層が２０μｍの為、クッション性がない。比較例２、３はシリコーンゴム層が２２０μｍの為、熱伝導性がないことがわかる。

As shown in the results of Table 1, it can be seen that Examples 1 to 6 all show good values for thermal conductivity, cushioning properties, heat resistance, and releasability. On the other hand, Comparative Examples 1 and 3 have no releasability because the thickness of the PTFE layer is 3 μm. Comparative Examples 1 and 4 do not have cushioning properties because the silicone rubber layer is 20 μm. It can be seen that Comparative Examples 2 and 3 have no thermal conductivity because the silicone rubber layer is 220 μm.

Sectional drawing which shows an example of the composite sheet for thermocompression bonding of this invention The schematic block diagram which shows an example of the apparatus used for manufacture of the composite sheet for thermocompression bonding of this invention Process diagram showing an example of a manufacturing process using a conventional ACF The perspective view which shows an example of the thermocompression bonding process of the manufacturing process using the conventional ACF The perspective view which shows an example of the thermocompression bonding process of the manufacturing process using the conventional ACF The perspective view which shows an example of the thermocompression bonding process of the manufacturing process using the conventional ACF The perspective view which shows an example of the thermocompression bonding process of the manufacturing process using the conventional ACF Schematic configuration diagram showing an example of a thermocompression bonding apparatus used in the evaluation of Examples etc.

Explanation of symbols

11 Release layer 12 Metal foil 13 Rubber layer S Composite sheet for thermocompression bonding

Claims (4)

  Metal foil, a release layer having a thickness of 3 to 20 μm provided on one surface side and containing a fluorine-based resin, and a thermal conductivity of 30 to 200 μm in thickness provided on the other surface side of the metal foil. A composite sheet for thermocompression bonding comprising a rubber layer.   The composite sheet for thermocompression bonding according to claim 1, wherein the rubber layer contains silicone rubber and metal compound particles.   The composite sheet for thermocompression bonding according to claim 1 or 2, wherein the release layer is provided with an antistatic function by adding carbon black. Applying a dispersion containing a fluorine-based resin on one surface side of the metal foil, evaporating and removing the dispersion solvent, and firing to form a release layer having a thickness of 3 to 20 μm; And a step of forming a thermally conductive rubber layer having a thickness of 30 to 200 μm on the other surface side.

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