JP5272866B2 - Silicone rubber sheet for thermocompression bonding - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a silicone rubber sheet for thermocompression bonding used for the purpose of transferring heat and applying uniform pressure in a wiring connection process of electrical / electronic equipment components.

  When manufacturing a liquid crystal panel, an anisotropic conductive adhesive (paste or film) is used to connect the transparent lead electrode of the liquid crystal panel and the lead electrode of the flexible printed circuit board (COF) on which the driving LSI is mounted to drive the liquid crystal. And the like, and thermocompression-bonded via an electrical and mechanical connection. In this case, for the purpose of applying a uniform pressure together with heat, it is common to sandwich a silicone rubber sheet between the pressurizing / heating metal tool and the COF.

  In addition, since a single-layer thermally conductive silicone rubber sheet is not sufficiently releasable from an anisotropic conductive adhesive, a silicone protective layer is laminated on at least one surface of the thermally conductive rubber sheet. Thus, it has been proposed to improve releasability with respect to anisotropic conductive adhesive and improve workability.

  In this case, in the above-described thermocompression bonding step, it is performed to repeatedly feed the sheet a little after being crimped several times using the same location of the silicone rubber sheet. That is, being able to use as much of the same place of the silicone rubber sheet as possible leads to the advantage of manufacturing cost. The silicone rubber sheet gradually deteriorates by repeated contact with the anisotropic conductive adhesive that is not covered with COF or exposed from the COF during pressure bonding. It is very important to improve the releasability of the rubber sheet with respect to the anisotropic conductive adhesive.

  However, with regard to the silicone protective layer provided on the surface of the thermally conductive silicone rubber sheet used in the thermocompression bonding connection process of electrical / electronic equipment parts, the type of thermosetting resin of the anisotropic conductive adhesive that is the subject No case has been developed or evaluated in consideration of the above.

  As a result of previous studies, the present inventors have reduced the amount of inorganic powder (filler) in the silicone protective layer as compared with the thermally conductive silicone rubber sheet base material layer. It has been confirmed that the releasability with respect to an anisotropic conductive adhesive (hereinafter referred to as epoxy conductive adhesive) in which conductive particles are dispersed in can be improved (Patent Document 1: Patent No. 3902558, Patent Document 2: Special No. 2005-297234).

  However, in recent years, anisotropic conductive adhesives (hereinafter referred to as acrylic conductive adhesives) in which conductive particles are dispersed in an acrylic resin, which has been widely used for low-temperature and short-time pressure bonding, have very strong adhesive force, Regardless of the conductive silicone rubber sheet or the multilayer sheet provided with a protective layer on the conductive rubber sheet, sticking or breakage of the sheet occurred with a small number of times of crimping. Therefore, there has been a drawback that the amount of the sheet used is increased as compared with the epoxy conductive adhesive.

Japanese Patent No. 3902558 JP 2005-297234 A

  This invention is made | formed in view of such a situation, and provides the silicone rubber sheet for thermocompression bonding which has the releasability excellent also with respect to not only an epoxy electrically conductive adhesive but an acrylic electrically conductive adhesive. With the goal.

The above object of the present invention is to provide a silicone rubber sheet used in a thermocompression wiring connection process for electrical / electronic equipment parts from a thermally conductive silicone rubber sheet base layer and a silicone protective layer provided on at least one surface thereof. The silicone protective layer comprises a silicone addition cured product as a main component, and the composition is an addition reaction with respect to 100 mol of dimethylsiloxane units ((CH ₃ ) ₂ SiO _1/2 ). It was achieved by a silicone rubber sheet characterized in that it contains 2 mol or more of silethylene group (Si—CH ₂ —CH ₂ —Si) as a part.

That is, as a result of various studies by the present inventors, it has been found that the releasability with respect to the acrylic conductive adhesive correlates with the crosslinking density of the silicone component which is the main component of the protective layer.
However, when the crosslink density of the single-layer thermally conductive silicone rubber sheet is increased, the flexibility is lost, and there is a problem in that a crimping failure occurs in the wiring connection process.
Further, the conventional protective layer has been obtained by diluting a liquid silicone rubber composition containing a small amount of thermally conductive filler with a solvent, and applying and curing the liquid silicone rubber composition. However, the crosslinking density is insufficient with so-called silicone rubbers that can obtain flexibility and elongation even when cured alone. With such a protective layer, the releasability with respect to the epoxy conductive adhesive is remarkably improved, but the releasability with respect to the acrylic conductive adhesive is not improved at all as compared with the base material layer.

  Therefore, as a result of further investigation, the protective layer of the present invention alone increases the cross-linking density until it becomes a film, and it is thinly formed on the thermally conductive silicone rubber sheet base layer and partially soaked. In this way, the sheet was made to function like a surface modifier, thereby obtaining a sheet in which only the crosslink density in the vicinity of the surface was remarkably increased while ensuring the flexibility and thermal conductivity of the entire sheet. is there. As a result, we succeeded in improving the releasability from the acrylic conductive adhesive, which had never been seen in conventional silicone rubber sheets, to more than twice that of conventional products, and completed the present invention. is there.

（式中、ＲはＣＨ ₃ 又はＣＨ＝ＣＨ ₂ であり、ＲがＣＨ＝ＣＨ ₂ の場合、ｘ＝５０〜３００、ｙ＝１〜３０、ｙ／ｘ＝０．０２〜０．０５であり、ＲがＣＨ ₃ の場合、ｘ＝３０〜３００、ｙ＝３〜３０、ｙ／ｘ＝０．０２〜０．０５である。）
で示される側鎖にビニル基を有するジオルガノポリシロキサンと、下記一般式（２）

（式中、Ｒ ² は、メチル基又は水素原子であり、分子鎖側鎖に少なくとも２個の水素原子が結合している。分子鎖末端にも水素原子が結合していてもよい。ｚは、２〜２００の整数である。）
で示される側鎖にＳｉＨ基を有するオルガノハイドロジェンポリシロキサンと、白金系触媒とを含有し、上記オルガノハイドロジェンポリシロキサンのＳｉＨ基が、上記側鎖にビニル基を有するジオルガノポリシロキサンのビニル基１モルに対して０．５〜５．０モルとなる量で用いられているシリコーン組成物を硬化してなるシリコーン付加硬化物からなり、ジメチルシロキサン単位（（ＣＨ₃）₂ＳｉＯ_1/2）１００モルに対して、付加反応部であるシルエチレン基（Ｓｉ−ＣＨ₂−ＣＨ₂−Ｓｉ）を２モル以上含有することを特徴とする熱圧着用シリコーンゴムシート。
請求項２：
上記シリコーン保護層が、厚さ０．１μｍ以上３０μｍ以下であることを特徴とする請求項１記載のシリコーンゴムシート。
請求項３：
上記シリコーン保護層が、金属、金属酸化物、金属窒化物、金属炭化物から選択される少なくとも１種の無機粉末を、０．１質量％以上３０質量％以下含むことを特徴とする請求項１又は２記載のシリコーンゴムシート。
請求項４：
上記無機粉末が、球状微粉末シリカであることを特徴とする請求項３記載のシリコーンゴムシート。
請求項５：
上記微粉末シリカが、平均粒径１μｍ以上３０μｍ以下の球状粉であり、さらに３５μｍ以上の粗粒をメッシュカットしたことを特徴とする請求項４記載のシリコーンゴムシート。
請求項６：
上記熱伝導性シリコーンゴムシート基材層が、熱伝導率０．１Ｗ／ｍＫ以上５Ｗ／ｍＫ以下かつ厚さ０．０５ｍｍ以上１ｍｍ以下を満たすことを特徴とする請求項１乃至５のいずれか１項記載のシリコーンゴムシート。
請求項７：
アクリル導電性接着剤用である請求項１乃至６のいずれか１項記載のシリコーンゴムシート。
Accordingly, the present invention provides the following silicone rubber sheet for thermocompression bonding.
Claim 1:
Silicone rubber sheet used in thermocompression wiring connection process for electrical and electronic equipment parts is for multi-layer thermocompression bonding consisting of a heat conductive silicone rubber sheet base material layer and a silicone protective layer provided on at least one surface thereof A silicone rubber sheet,
The silicone protective layer has a viscosity at 25 ° C. by a rotational viscometer of 50 to 5,000 mPa · s, and the following general formula (1)

(In the formula, R is CH ₃ or CH═CH ₂ , and when R is CH═CH ₂ , x = 50 to 300, y = 1 to 30, y / x = 0.02 to 0.05. When R is CH ₃ , x = 30 to 300, y = 3 to 30, and y / x = 0.02 to 0.05.)
A diorganopolysiloxane having a vinyl group in the side chain represented by the following general formula (2):

(In the formula, R ² is a methyl group or a hydrogen atom, and at least two hydrogen atoms are bonded to the side chain of the molecular chain. A hydrogen atom may be bonded to the terminal of the molecular chain. Z is , An integer from 2 to 200.)
A diorganopolysiloxane vinyl containing an organohydrogenpolysiloxane having a SiH group in the side chain and a platinum catalyst, wherein the SiH group of the organohydrogenpolysiloxane has a vinyl group in the side chain. It consists of a silicone addition cured product obtained by curing a silicone composition used in an amount of 0.5 to 5.0 moles per mole of group, and is composed of dimethylsiloxane units ((CH ₃ ) ₂ SiO _1/2 ) A silicone rubber sheet for thermocompression bonding containing 2 mol or more of silethylene group (Si—CH ₂ —CH ₂ —Si), which is an addition reaction part, per 100 mol.
Claim 2 :
The silicone protective layer is a silicone rubber sheet according to claim 1 Symbol mounting, characterized in that the thickness of 0.1μm or more 30μm or less.
Claim 3 :
The silicone protective layer is a metal, metal oxide, metal nitride, at least one inorganic powder selected from metal carbides, claim 1 or characterized in that it comprises less than 30 wt% 0.1 wt% 2. The silicone rubber sheet according to 2 .
Claim 4 :
The silicone rubber sheet according to claim 3 , wherein the inorganic powder is spherical fine powder silica.
Claim 5 :
The silicone rubber sheet according to claim 4 , wherein the fine powder silica is a spherical powder having an average particle size of 1 µm to 30 µm, and coarse particles of 35 µm or more are mesh-cut.
Claim 6 :
The heat conductive silicone rubber sheet base layer, any one of claims 1 to 5, characterized in that satisfy the following thermal conductivity of 0.1 W / mK or higher 5W / mK or less and a thickness 0.05mm least 1 mm 1 The silicone rubber sheet according to Item.
Claim 7 :
The silicone rubber sheet according to any one of claims 1 to 6 , which is used for an acrylic conductive adhesive.

The silicone rubber sheet for thermocompression bonding of the present invention has an excellent releasability with respect to the acrylic conductive adhesive.
Further, like the conventional multilayer silicone rubber sheet having a protective layer, this sheet also has releasability for epoxy conductive adhesive and releasability for peripheral members such as glass, transparent lead electrodes, and COF. Therefore, it is possible to bring about a great effect on rationalization of the liquid crystal panel manufacturing process and cost reduction.

The silicone rubber sheet for thermocompression bonding of the present invention comprises a thermally conductive silicone rubber sheet substrate layer and a silicone protective layer provided on at least one surface thereof.
In this case, as the heat conductive silicone rubber sheet base material layer, a known heat conductive silicone rubber sheet used for anisotropic conductive adhesive is used, and a known silicone rubber composition containing a heat conductive filler is used. What was obtained by sheet-molding and curing the product can be used. A commercially available product may be used as the silicone rubber composition, for example, a silicone rubber sheet HC-25MS manufactured by Shin-Etsu Chemical Co., Ltd. is used. In addition, as a heat conductive silicone rubber sheet base material layer, the thing whose heat conductivity is 0.1 W / mK or more and 5 W / mK or less, especially 0.5-5 W / mK is preferable. If the thermal conductivity is less than 0.1 W / mK, it is necessary to increase the thermocompression bonding temperature or lengthen the crimping time, which may be disadvantageous in terms of efficiency. Even if it exceeds 5 W / mK, a particularly advantageous effect cannot be expected. The thickness of the heat conductive silicone rubber sheet base material layer is preferably 0.05 mm or more and 1 mm or less, particularly preferably 0.1 to 0.8 mm. If it is thinner than 0.05 mm, the strength may be insufficient, and if it exceeds 1 mm, it may be disadvantageous in terms of heat conduction.

The silicone protective layer in the present invention comprises a silicone addition cured product,
(A) an organopolysiloxane having an alkenyl group,
(B) an organohydrogenpolysiloxane having a hydrogen atom directly bonded to a silicon atom,
(C) platinum-based catalyst: effective amount,
(D) Reaction control agent: effective amount,
(E) It is preferable that it is a hardened | cured material of the silicone composition which has at least 1 sort (s) selected from a metal, a metal oxide, a metal nitride, and a metal carbide as an essential component.

  The component (A) is preferably a diorganopolysiloxane having at least two alkenyl groups, particularly vinyl groups, in one molecule, and is the main component (base polymer) of the silicone composition of the present invention.

  The molecular structure of the alkenyl group-containing organopolysiloxane is not limited as long as it is liquid at room temperature (25 ° C.), and examples thereof include linear, branched, and partially branched linear. Preferably it is linear. Examples of the alkenyl group include alkenyl groups having about 2 to 8 carbon atoms such as allyl group, propenyl group, isopropenyl group, butenyl group, hexenyl group, and cyclohexenyl group. It is preferable to use a vinyl group for ease.

  (A) As a group bonded to a silicon atom other than an alkenyl group in the component, in addition to a methyl group, as an unsubstituted or substituted monovalent hydrocarbon group, for example, an ethyl group, a propyl group, an isopropyl group, a butyl group, Cycloalkyl groups such as isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, dodecyl group, etc., cyclopentyl group, cyclohexyl group, cycloheptyl group, etc. , Aryl groups such as phenyl group, tolyl group, xylyl group, naphthyl group, biphenylyl group, aralkyl groups such as benzyl group, phenylethyl group, phenylpropyl group, methylbenzyl group, and carbon atoms of these groups Some or all of the hydrogen atoms are halogen atoms such as fluorine, chlorine and bromine, cyano groups For example, chloromethyl group, 2-bromoethyl group, 3-chloropropyl group, 3,3,3-trifluoropropyl group, chlorophenyl group, fluorophenyl group, cyanoethyl group, 3,3,4, Examples include 4,5,5,6,6,6-nonafluorohexyl groups having 1 to 10 carbon atoms, particularly 1 to 6 carbon atoms, but the cost, availability, chemical It is preferable to use all methyl groups for reasons such as mechanical stability and environmental load.

The organopolysiloxane of component (A) can be used singly or in combination of two or more having different viscosities and compositions. In this case, the viscosity of the organopolysiloxane is preferably 10 to 10,000 mPa · s, more preferably 50 to 5,000 mPa · s, and more preferably 100 to 1,000 mPa · s at 25 ° C. measured by a rotational viscometer. preferable.
In the present invention, the organopolysiloxane is preferably a dimethylpolysiloxane having two or more vinyl groups, particularly preferably one represented by the following formula (1), particularly those having a vinyl group in the side chain. .

In the above formula (1), R is CH ₃ or CH═CH ₂ . In this case, the ratio of silethylene groups (Si—CH ₂ —CH ₂ —Si) to 100 mol of dimethylsiloxane units [(CH ₃ ) ₂ SiO _1/2 ] (crosslinking) in the silicone addition cured product forming the silicone protective layer. In order to make the point) 2 mol or more, when R is CH = CH ₂ , x = 10 to 1,000, y = 0 to 100, y / x = 0 to 0.1, especially x = 50 to Preferably, 300, y = 1 to 30, and y / x = 0.02 to 0.05. Further, when R is CH ₃ , x = 10 to 1,000, y = 2 to 100, y / x = 0.02 to 0.1, particularly x = 30 to 300, y = 3 to 30, y / x = 0.02 to 0.05 is preferred, but it is preferred that R has a vinyl group in the side chain (that is, y ≠ 0) regardless of whether CH is CH ₂ ═CH or CH _3. it is preferred when R is CH ₂ = CH when y ≧ 1, R is CH ₃ is y ≧ 2.

Further, in order to improve the mechanical strength of the protective layer of the present invention, a silicone resin may be used in combination with the organopolysiloxane component (A). Silicone resins include R ¹ ₃ SiO _0.5 unit (M unit) and SiO ₂ unit (Q unit), or M unit and Q unit, R ¹ SiO _1.5 unit (T unit) and / or R ¹ ₂ SiO unit. There are MQ resin, MTQ resin, MDQ resin or MDTQ resin consisting of (D unit), but as a silicone resin used in this application, (CH ₂ = CH) (CH ₃ ) ₂ SiO _0.5 unit or (CH A vinyl group-containing silicone resin containing ₂ = CH) (CH ₃ ) SiO units is preferred. As the R ^1, 1 monovalent hydrocarbon group having 1 to 8 carbon atoms (alkyl group, an alkenyl group, an aryl group, etc.) can be mentioned, preferably a methyl group.

  It is preferable that content of the silicone resin added to this (A) component is 30 mass% or less with respect to (A) component. A silicone resin usually contains a silanol (SiOH) group and has a property of reacting with a resin component in an anisotropic conductive adhesive. Although the addition amount of the silicone resin is preferably small, particularly when it exceeds 30% by mass, the influence of the reaction with the silanol group becomes large, and the releasability may be lowered.

  The component (B) is an organohydrogenpolysiloxane having at least two hydrogen atoms bonded to silicon atoms (that is, SiH groups) in the side chain of one molecule, and the crosslinking agent of the component (A) It is a component that acts as That is, a hydrogen atom bonded to a silicon atom in the component (B) is added by a hydrosilylation reaction with an alkenyl group such as a vinyl group in the component (A) by the action of the platinum catalyst of the component (C) described later. Thus, a crosslinked cured product having a three-dimensional network structure having a cross-linked bond is obtained.

  As the organic group bonded to the silicon atom in the component (B), an unsubstituted or substituted monovalent hydrocarbon group other than the alkenyl group can be used. To a methyl group.

  The structure of the component (B) is not particularly limited and may be linear, branched or cyclic, but is preferably linear.

（式中、Ｒ²は、メチル基又は水素原子であり、分子鎖側鎖に少なくとも２個の水素原子が結合している。分子鎖末端にも水素原子が結合していてもよい。ｚは、２以上の整数である。）
で表される。この場合、ＳｉＨ基は側鎖に存在しているものであり、側鎖のみにＳｉＨ基を有するものであってもよいが、側鎖に加えて分子鎖末端にもＳｉＨ基が存在してもよい。 Component (B) is, for example, the following general formula (2):

(In the formula, R ² is a methyl group or a hydrogen atom, and at least two hydrogen atoms are bonded to the side chain of the molecular chain. A hydrogen atom may be bonded to the terminal of the molecular chain. Z is It is an integer of 2 or more.)
It is represented by In this case, the SiH group is present in the side chain and may have a SiH group only in the side chain. However, in addition to the side chain, the SiH group may be present at the end of the molecular chain. Good.

  Z is preferably an integer of 2 to 200, more preferably 20 to 200. If z is too small, the amount of dimethylpolysiloxane that volatilizes or penetrates into the thermally conductive rubber sheet as the base material increases until it is cured after coating, and a stable addition reaction cannot be obtained.

In addition, (B) component can be used even if single 1 type also combines 2 or more types.
Component (B) is added in an amount such that the SiH group of component (B) is 0.5 to 5.0 moles per mole of vinyl group in component (A), preferably 0.8 to 3. The amount is 0 mol. If the amount of the Si-H group of the component (B) is less than 0.5 mol relative to 1 mol of the vinyl group in the component (A), the hardness of the cured product cannot be obtained sufficiently. On the other hand, when the amount exceeds 5.0 mol, a large amount of SiH groups remain, and the releasability with respect to the anisotropic conductive adhesive is lowered.

  In this invention, after (A) component and (B) component harden | cure, the silethylene group which is an addition reaction part contains 2 mol or more with respect to 100 mol of dimethylsiloxane units in the hardened | cured material, It is characterized by the above-mentioned. . More preferably, it is 2-10 mol, More preferably, it is 3-5 mol. The addition reaction part is obtained by a hydrosilylation reaction between the vinyl group in the component (A) and the hydrogen atom bonded to the silicon atom in the component (B). Examples include chain bonds and side chain-side chain bonds. The degree of contribution to improving the crosslink density is: side chain-side chain bond> terminal-side chain bond> terminal-terminal bond, but generally the reaction rate is the opposite end-terminal bond> terminal-side chain bond> It becomes a side chain-side chain bond. Increasing the side chain-side chain bond is particularly effective for increasing the crosslink density, that is, improving the releasability of the acrylic conductive adhesive, but in order to stabilize the curability, the end-side chain bond is allowed to coexist. It is preferable to keep it. In addition, if the crosslinking density is increased too much, the hardness of the protective layer increases, and uniform pressure transmission is hindered, and the sheet is liable to tear at the time of pressure bonding.

  The platinum-based catalyst of the component (C) promotes the addition reaction between the vinyl group in the component (A) and the hydrogen atom bonded to the silicon atom in the component (B), and the three-dimensional network structure from the composition of the present invention. It is a component mix | blended in order to give the crosslinked hardened | cured material of.

(C) As a component, all the well-known catalysts used for normal hydrosilylation reaction can be used. Specific examples thereof include platinum group metals such as platinum (including platinum black), rhodium and palladium, H ₂ PtCl ₄ · nH ₂ O, H ₂ PtCl ₆ · nH ₂ O, NaHPtCl ₆ · nH ₂ O. , KHPtCl ₆ · nH ₂ O, Na ₂ PtCl ₆ · nH ₂ O, K ₂ PtCl ₄ · nH ₂ O, PtCl ₄ · nH ₂ O, PtCl ₂ , Na ₂ HPtCl ₄ · nH ₂ O (where, n is an integer of 0 to 6, preferably 0 or 6.), etc.), such as platinum chloride, chloroplatinic acid and chloroplatinate, alcohol-modified chloroplatinic acid, chloroplatinic acid and olefin complex, platinum black , Platinum group metals such as palladium supported on a carrier such as alumina, silica, carbon, rhodium-olefin complex, chlorotris (triphenylphosphine) rhodium (Wilkinso Catalyst), platinum chloride, chloroplatinic acid or chloroplatinate and a vinyl group-containing siloxane. In addition, the platinum-type catalyst of (C) component can be used even if single 1 type also combines 2 or more types.

  (C) The compounding quantity of a component should just be an effective amount required in order to harden the composition of this invention, Although it does not restrict | limit, Usually, it is 0 in conversion of the mass of the platinum group metal element with respect to (A) component. .1 to 1,000 ppm, preferably 0.5 to 500 ppm.

  The (D) component reaction control agent is for adjusting the reaction rate of the (A) component and the (B) component that proceed in the presence of the (C) component.

  As the component (D), all known addition reaction inhibitors used in ordinary addition reaction curable silicone compositions can be used. Specific examples thereof include acetylene compounds such as 1-ethynyl-1-cyclohexanol and 3-butyn-1-ol, nitrogen compounds, organic phosphorus compounds, sulfur compounds, oxime compounds, and organic chloro compounds. In addition, the addition reaction inhibitor of (D) component can be used even if single 1 type also combines 2 or more types.

  The blending amount of component (D) varies depending on the amount of component (C) used, and thus cannot be defined unconditionally. However, it may be any effective amount that can adjust the progress of the hydrosilylation reaction to a desired reaction rate. It is good to set it as about 10-50,000 ppm with respect to the mass of A) component. When the amount of component (D) is too small, sufficient pot life may not be ensured, and when too large, the curability of the composition may be lowered.

  The component (E) is at least one selected from metals, metal oxides, metal nitrides, and metal carbides. The release layer of the present invention has thermal conductivity, surface slip properties, and stable film thickness during coating. It imparts sex. Specific examples of these include silver powder, copper powder, iron powder, nickel powder, aluminum powder, etc. for metal, zinc oxide, metal oxides such as magnesium, aluminum, silicon, iron, boron, aluminum for metal nitride, Examples of nitrides such as silicon and metal carbides include carbides such as silicon and boron.

  Among these, as (E) component, a silica powder is suitable and a spherical thing is especially preferable. By using this powder, particularly excellent surface slipperiness and film thickness stability can be obtained. In addition, since the specific gravity is low, stable coating is possible with little sedimentation over time.

  (E) It is preferable that the average particle diameter of a component is 1 micrometer or more and 30 micrometers or less, and it is especially preferable that it is 5-20 micrometers. When the average particle size is less than 1 μm, it is difficult to obtain surface slipperiness. In addition, if it exceeds 30 μm, it is necessary to increase the thickness of the coating film in order to prevent the filler from falling off, and the thermal conductivity of the entire sheet decreases, so the set temperature of the pressurizing / heating metal tool may be increased. Necessary. In addition, an average particle diameter can be calculated | required with the particle size distribution measuring apparatus by a laser beam diffraction method, and can be obtained as a weight average value.

  (E) The compounding quantity of a component is an quantity used as 0.1 to 30 mass% in a silicone protective layer. It is particularly preferable to use in the range of 5 to 30% by mass. If it is less than 0.1% by mass, it is difficult to obtain effects such as surface slipperiness and film thickness stability. From this point, it is recommended that the content be 5% by mass or more. Moreover, when it exceeds 30 mass%, the mold release property with respect to an anisotropic conductive adhesive will fall.

  However, even when the blending amount of the component (E) is less than 0.1% by mass, a stable coating can be performed by providing an uneven shape on the surface of the heat conductive rubber sheet as a base material and roughening the surface. Is possible.

  As a method for imparting irregularities to the rubber sheet surface, in the case of calendar molding, there is a method in which the silicone rubber composition before curing is dispensed onto a plastic film having an irregular surface to transfer the irregular shape. Moreover, although there exists a method of pressing the roll with an unevenness | corrugation on the sheet | seat surface before hardening, and transferring an unevenness | corrugation, it is not limited to these.

  As a coating method of the protective layer of the present invention, a material for forming a silicone protective layer (the above silicone composition) dissolved in a solvent such as toluene on a thermally conductive silicone rubber sheet substrate and liquefied, knife coating, There are methods such as comma coating, bar coating, dip coating, spray coating, and the like, followed by solvent removal and heat curing in the atmosphere, but the method is not limited thereto. The heat curing is preferably performed at 120 to 180 ° C. for 3 to 10 minutes, but is not limited thereto.

  The conventional protective layer is mainly composed of liquid silicone rubber, and solvent dilution is essential. However, in the present invention, by reducing the viscosity of the components (A) and (B), solvent-free coating is possible. Become. Compared with the solvent dilution coating, the coating line speed can be increased, and the productivity can be remarkably improved.

  The thickness of the protective layer of the present invention is preferably 0.1 μm or more and 30 μm or less. Since it is a highly crosslinked composition, the surface is modified even with a thin film thickness, and high releasability is obtained. However, if it exceeds 30 μm, the thermal conductivity of the entire sheet is lowered, so it is necessary to increase the set temperature of the pressurizing / heating metal tool.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, this invention is not restrict | limited to the following Example.

(Thermal conductive silicone rubber sheet base material layer)
A silicone rubber sheet HC-25MS (thickness 0.25 mm, thermal conductivity 0.85 W / mK) manufactured by Shin-Etsu Chemical Co., Ltd. was used as a base material on which the silicone protective layer was applied.
(Preparation of coating solution)
100 parts by mass of dimethylpolysiloxane having a vinyl group (component (A)), 0.2 part by mass of 1-ethynyl-1-cyclohexanol (component (C)), vinyl siloxane complex of chloroplatinic acid (platinum content 0) 0.5 mass%) after adding 0.2 parts by mass (component (D)) and kneading, dimethylpolysiloxane having hydrogen atoms directly bonded to silicon atoms (component (B)) and an average particle size of 15 μm and 35 μm or more 15 parts by mass (component (E)) of high-purity spherical silica filler obtained by mesh-cutting coarse particles was added.

  In the examples, the composition of the component (A) was variously evaluated. As the component (B), one having an average structure represented by the following formula (3) was used. The amount added was adjusted so that the vinyl groups in the component (A) and the hydrogen atoms bonded to the silicon atoms in the component (B) were equimolar.

(Coating method)
The coating solution was applied by comma coating on a substrate with PET and cured in a heating furnace at 160 ° C. for 5 minutes. Moreover, after peeling PET film, it heat-processed for 4 hours at 200 degreeC, and the sample for evaluation was obtained. The film thickness was adjusted to be about 10 μm.

(Evaluation of pressure bonding test for anisotropic conductive adhesive)
Fix the sheet under pressure / heated metal tool pressure heated to 300 ° C (with the silicone protective layer facing down and stretch the sheet away from the tool and glass except during crimping), and then acrylic underneath The glass substrate to which the system anisotropic conductive adhesive film has been transferred is inserted and pressure bonded at 5 MPa for 10 seconds. The glass substrate with the new anisotropic conductive adhesive film transferred is inserted and pressure-bonded with the sheet as it is. While repeating this, the change of the sticking condition of the sheet and the acrylic anisotropic conductive adhesive film was confirmed.
The evaluation results are shown in Table 1.

[Examples 1 to 3, Comparative Examples 1 to 4]
As the component (A), seven types having a structure represented by the following formula (4) were prepared. In the formula, x and y are values shown in Table 1.

[Comparative Examples 5 and 6]
Comparative Example 1 is an evaluation result of HC-25MS used as a base material. Comparative Example 2 is a silicone rubber sheet HC-25MR3 manufactured by Shin-Etsu Chemical Co., Ltd. provided with a protective layer having a thickness of 0.02 mm.
[Crosslinking point]
It is defined by the number of moles of silethylene group per 100 moles of dimethylsiloxane structure.
The silicone protective layer is hydrolyzed with tetraethoxysilane and potassium hydroxide and calculated from the peak area of ethoxysilane represented by the following formulas (5) to (8) detected when analyzed with a gas chromatograph-FID detector. be able to. The formula (5) is a component derived from a dimethylsiloxane unit, and the formulas (6) to (8) are components derived from a silethylene crosslinking point. Although the detection sensitivities are different from each other, correction is made from the measurement result of the substance having a known composition, and the molar ratio is converted.

Details of the test conditions will be described below.
(Silicon protective layer treatment method)
A silicone protective layer (0.1 g) is scraped into a vial, and 3 g of tetraethoxysilane and 0.01 g of potassium hydroxide are added and sealed. After heating it at 120 ° C. for 1 hour, it was neutralized with carbon dioxide at room temperature, and the supernatant obtained by centrifugation (10,000 rpm / 10 minutes) was obtained from Agilent gas chromatograph HP-6890 (FID detector). ).
(Gas chromatograph measurement conditions)
Model: HP-6890 (FID detector)
Column: J & W DB-5MS (film thickness 1 μm) 0.25 mmI. D. × 30m
Column temperature: 50 ° C .− (10 ° C./min)→300° C. (10 min)
Inlet temperature: 250 ° C
Detector temperature: 300 ° C
Carrier gas: He (5 mL / min)
Sample injection volume: 2 μL

[Number of crimps (1), (2)]
The number of times of pressure bonding (1) is the number of times that the sheet and the acrylic anisotropic conductive film are separated from each other without touching or lightly touching the sheet after pressure bonding, that is, very light releasability is maintained. The number of times of crimping (2) is the number of times until the releasability is lowered and the components of the acrylic anisotropic conductive film are clearly transferred to the sheet.
[result]
Under the conditions of this pressure bonding test, Examples 1 to 3 maintained high releasability of 10 times or more in the item of the number of times of pressure bonding (1). Among them, it was shown that Example 2 having side chain-side chain cross-linking exhibits particularly excellent releasability.
When the cross-linking point was less than 2, the number of times of crimping (1) was particularly reduced, and even when the number of times of crimping was small, sticking between the sheet and the anisotropic conductive film was observed.
As a comparative example, single-layer sheets and multilayer sheets manufactured by Shin-Etsu Chemical Co., Ltd. were placed. Even if various sheets of each company were evaluated in the same manner regardless of whether they were single-layer or multilayer, they were pressed against acrylic conductive adhesive. The test results are side by side, and the present invention greatly contributes to increasing the efficiency of the thermocompression wiring connection process of electrical / electronic equipment components.

Claims (7)

Silicone rubber sheet used in thermocompression wiring connection process for electrical and electronic equipment parts is for multi-layer thermocompression bonding consisting of a heat conductive silicone rubber sheet base material layer and a silicone protective layer provided on at least one surface thereof A silicone rubber sheet,
The silicone protective layer has a viscosity at 25 ° C. by a rotational viscometer of 50 to 5,000 mPa · s, and the following general formula (1)

(In the formula, R is CH ₃ or CH═CH ₂ , and when R is CH═CH ₂ , x = 50 to 300, y = 1 to 30, y / x = 0.02 to 0.05. When R is CH ₃ , x = 30 to 300, y = 3 to 30, and y / x = 0.02 to 0.05.)
A diorganopolysiloxane having a vinyl group in the side chain represented by the following general formula (2):

(In the formula, R ² is a methyl group or a hydrogen atom, and at least two hydrogen atoms are bonded to the side chain of the molecular chain. A hydrogen atom may be bonded to the terminal of the molecular chain. Z is , An integer from 2 to 200.)
A diorganopolysiloxane vinyl containing an organohydrogenpolysiloxane having a SiH group in the side chain and a platinum catalyst, wherein the SiH group of the organohydrogenpolysiloxane has a vinyl group in the side chain. It consists of a silicone addition cured product obtained by curing a silicone composition used in an amount of 0.5 to 5.0 moles per mole of group, and is composed of dimethylsiloxane units ((CH ₃ ) ₂ SiO _1/2 ) A silicone rubber sheet for thermocompression bonding containing 2 mol or more of silethylene group (Si—CH ₂ —CH ₂ —Si), which is an addition reaction part, per 100 mol. The silicone protective layer is a silicone rubber sheet according to claim 1 Symbol mounting, characterized in that the thickness of 0.1μm or more 30μm or less. The silicone protective layer is a metal, metal oxide, metal nitride, at least one inorganic powder selected from metal carbides, claim 1 or characterized in that it comprises less than 30 wt% 0.1 wt% 2. The silicone rubber sheet according to 2 . The silicone rubber sheet according to claim 3 , wherein the inorganic powder is spherical fine powder silica. The silicone rubber sheet according to claim 4 , wherein the fine powder silica is a spherical powder having an average particle size of 1 µm to 30 µm, and coarse particles of 35 µm or more are mesh-cut. The heat conductive silicone rubber sheet base layer, any one of claims 1 to 5, characterized in that satisfy the following thermal conductivity of 0.1 W / mK or higher 5W / mK or less and a thickness 0.05mm least 1 mm 1 The silicone rubber sheet according to Item. The silicone rubber sheet according to any one of claims 1 to 6 , which is used for an acrylic conductive adhesive.