JP2010053170A - Acrylic resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acrylic rubber composition to produce an adhesive for electronic materials having a high adhesion strength. <P>SOLUTION: This acrylic resin composition is produced by copolymerizing monomeric components containing 60-99 wt.% alkyl acrylate, 1-16 wt.% diglycidyl (meth)acrylate, and 0-39 wt.% monomer polymerizable with the monomers, on the basis of 100 wt.% of the total of the monomer components. The resin composition has a weight average molecular weight (Mw) of ≥200,000, and has a molecular weight distribution (Mw/Mn) of ≤2.0. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an acrylic resin composition suitably used for adhesion of electronic materials.

  In recent years, electronic devices have been used in a wide range of applications such as personal computers, game machines, mobile phones, digital cameras, DVD players / recorders, liquid crystal / plasma flat-screen TVs, and automobiles. Progressing. Accordingly, the density of semiconductor packages mounted on these electronic devices has been increased, and the density of the substrate on which the semiconductor package is mounted is also required. Furthermore, the miniaturization of wiring is further advanced on the substrate side.

  With the recent rapid increase in the density of semiconductor packages and mounting boards and the miniaturization of wiring, stricter reliability is also required for electronic materials such as adhesives for bonding semiconductor elements and mounting boards equipped with various electronic components. It has been. Therefore, an adhesive for electronic materials that bonds a semiconductor chip, a mounting substrate, a wiring board, and the like is required to have a higher adhesive strength than before, and studies for improving the adhesive strength are being promoted.

  As materials for adhesives for electronic materials and mounting substrates on which various electronic components are mounted, compositions in which an elastomer component such as acrylonitrile butadiene rubber or acrylic elastomer is blended with an epoxy resin and a curing agent are widely used (for example, , See Patent Document 1). In order to improve the adhesive strength, various improvements have also been made for these elastomer components. However, sufficient adhesive strength is not obtained with the current adhesive for electronic materials.

JP-A-8-283535

  As described above, conventional acrylic elastomers for electronic materials have not been able to obtain sufficient adhesive strength.

As a result of intensive research aimed at eliminating the above-mentioned drawbacks in the conventional method, the present inventors have found that a monomer component that can be polymerized with an alkyl acrylate ester and glycidyl (meth) acrylate and, optionally, can be obtained. It has been found that an acrylic resin composition for bonding an electronic material having excellent adhesive strength can be obtained by copolymerizing as a monomer component and reducing the molecular weight distribution.
That is, the present invention
(1) 100% by weight of the entire monomer component, 60 to 99% by weight of acrylic acid alkyl ester, 1 to 16% by weight of glycidyl (meth) acrylate, and 0 to 39% by weight of monomer component polymerizable with these An acrylic resin composition having a weight average molecular weight (Mw) of 200,000 or more and a molecular weight distribution (Mw / Mn) of 2.0 or less,
(2) The acrylic resin composition according to (1), wherein the copolymerization is living radical polymerization,
(3) The acrylic resin composition according to (2), wherein the living radical polymerization is RAFT polymerization,
(4) 100% by weight of the whole monomer component, 60 to 99% by weight of acrylic acid alkyl ester, 1 to 16% by weight of glycidyl (meth) acrylate, and 0 to 39% by weight of monomer component polymerizable with these %, And a copolymerization method using a RAFT agent as a chain transfer agent,
(5) Acrylic resin composition obtained by the production method according to (4),
About.

  When the acrylic resin composition of the present invention is used as an acrylic elastomer for electronic materials, an adhesive for electronic materials having excellent adhesive strength can be obtained.

Details of the present invention will be described below.
The acrylic resin composition in the present invention is based on 100% by weight of the entire monomer component, 60 to 99% by weight of acrylic acid alkyl ester, 1 to 16% by weight of glycidyl (meth) acrylate, and a single amount polymerizable with these. It is obtained by copolymerizing 0 to 39% by weight of a body component (hereinafter referred to as a copolymerizable monomer component) as a monomer component.
The amount of the acrylic acid alkyl ester used is 60 to 99% by weight, preferably 65 to 98% by weight, more preferably 75 to 98% by weight, based on 100% by weight of the entire monomer component. If the amount is less than 60% by weight, the adhesion and flexibility tend to be insufficient. If the amount exceeds 99% by weight, the amount of glycidyl (meth) acrylate added is less than 1% by weight, and the adhesion tends to be low. It is in.

 The amount of the glycidyl (meth) acrylate used is 1 to 16% by weight, preferably 2 to 12% by weight, based on 100% by weight of the entire monomer component. If the amount of glycidyl (meth) acrylate used is less than 1% by weight, the adhesive strength is lowered, and if it exceeds 16% by weight, there is a risk of crosslinking during the synthesis of the acrylic resin composition, and storage stability is improved. There is a tendency to decrease.

 Moreover, the usage-amount of the monomer component which can be polymerized with the said acrylic acid alkylester and glycidyl (meth) acrylate is 0 to 39 weight% when the whole monomer component is 100 weight%, Preferably it is 0 to 35 weight%. %, More preferably 0 to 25% by weight. If it exceeds 39% by weight, adhesion and flexibility tend to be insufficient.

Examples of the alkyl acrylate ester include, but are not limited to, methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, acrylic Examples include lauryl acid and stearyl acrylate. Of these, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate are preferable from the viewpoint of characteristics of the obtained resin composition. These may be used in combination of two or more, and Tg and the like can be adjusted by mixing.
Examples of glycidyl (meth) acrylate include, but are not limited to, glycidyl acrylate and glycidyl methacrylate. Among these, glycidyl methacrylate is preferable from the viewpoint of availability.
In addition, monomer components that can be polymerized therewith are not limited to the following examples, but include aromatic vinyl monomers, acrylic acid ester monomers other than alkyl esters, methacrylic acid ester monomers, acrylonitrile, and the like. These vinyl monomers are mentioned.

  The acrylic resin composition of the present invention has a weight average molecular weight (polystyrene conversion by gel permeation chromatography (GPC)) of 200,000 or more. If the weight average molecular weight is less than 200,000, the adhesion and strength tend to be low. Preferably, it is the range of 300,000 to 2,000,000. When it exceeds 2 million, the solubility in a solvent tends to decrease and the workability tends to deteriorate.

  The acrylic resin composition according to the present invention has a molecular weight distribution (Mw / Mn) of 2.0 or less. Even if the average molecular weight is the same, if the molecular weight distribution is widened, the low molecular weight component is increased, so that the adhesive strength tends to be low.

  In order to obtain an acrylic resin composition having a molecular weight distribution (Mw / Mn) of 2.0 or less, it is preferable to use living radical polymerization in the present invention. As a result, a polymer having a narrow molecular weight distribution can be obtained as compared with ordinary radical polymerization. As the living radical polymerization, atom transfer polymerization (ATRP polymerization), reversible addition-fragmentation chain transfer polymerization (RAFT polymerization), and the like are known, and any method can be used, but polymerization can be performed by RAFT polymerization. More preferred.

  RAFT polymerization is characterized by using a polymerization initiator and a reversible addition-fragmentation chain transfer agent (hereinafter referred to as RAFT agent). This polymerization is superior to other living radical polymerizations in terms of (1) applicable to various monomers and (2) applicable to a wide range of reaction conditions. The RAFT agent used for obtaining the acrylic resin composition of the present invention is not limited to the following examples, but includes O-ethyl-S- (1-phenylethyl) dithiocarbonate, O-ethyl-S- (2- Propoxyethyl) dithiocarbonate, dithiocarbonates such as O-ethyl-S- (1-cyano-1-methylethyl) dithiocarbonate, cyanoethyl dithiopropionate, benzyl dithiopropionate, benzyl dithiobenzoate, acetoxyethyl dithiobenzoate Dithioesters such as S-benzyl-N, N-dimethyldithiocarbamate, dithiocarbamates such as benzyl-1-pyrrolecarbodithioate, dibenzyltrithiocarbonate, S-cyanomethyl-S-dodecyltrithiocarbonate, etc. Trithiocarbonates, etc. And the like. The RAFT agent to be used is preferably selected in accordance with the reactivity of the monomer. In particular, dithiocarbamates and dithiocarbonates are suitable for the polymerization of acrylic esters, and for the polymerization of methacrylic esters. Is preferably a dithioester. The RAFT agent is preferably used in an amount of 0.01 to 10 parts by weight, more preferably 0.05 to 3 parts by weight, based on 100 parts by weight of the total amount of monomers. If it is less than 0.01 part by weight, the molecular weight distribution is not sufficiently narrow, and if it exceeds 10 parts by weight, the average molecular weight tends to be low.

  Examples of the polymerization process for obtaining the acrylic resin composition of the present invention include solution polymerization, suspension polymerization, emulsion polymerization and the like, and the method for producing the acrylic resin composition in the present invention includes suspension polymerization or emulsion polymerization. Is preferred. In order to increase the adhesive strength of the adhesive for electronic materials, it is preferable to increase the molecular weight of the acrylic rubber, but in solution polymerization, it is difficult to increase the molecular weight.

  In the present invention, the polymerization initiator used when polymerizing the monomer component can be used without particular limitation as long as it is a generally known radical polymerization initiator. Examples of radical polymerization initiators include, but are not limited to, the following examples: benzoyl peroxide, lauroyl peroxide, di-t-butylperoxyhexahydroterephthalate, t-butylperoxy-2-ethylhexanoate, Organic peroxides such as 1,1-t-butylperoxy-3,3,5-trimethylcyclohexane, t-butylperoxyisopropyl carbonate, azobisisobutyronitrile, azobis-4-methoxy-2,4-dimethyl And azo compounds such as valeronitrile, azobiscyclohexanone-1-carbonitrile, azodibenzoyl, and the like. The polymerization initiator is preferably used in the range of 0.01 to 10 parts by weight, more preferably 0.05 to 5 parts by weight, and 0.1 to 3 parts by weight with respect to 100 parts by weight of the total amount of monomers. Part is more preferred. If it is less than 0.01 part by weight, the polymerization becomes insufficient, and if it exceeds 10 parts by weight, the molecular weight becomes too low, or the decomposition products increase, which may adversely affect the adhesion. .

 The acrylic resin composition of the present invention can be dissolved in a solvent and provided as a solution-like acrylic resin composition (acrylic resin varnish) as an adhesive material for electronic materials such as for semiconductor devices and wiring boards. .

  The solvent is not limited to the following examples, but general organic solvents such as toluene, xylene, methyl ethyl ketone, acetone, methyl isobutyl ketone, cyclohexane, ethyl acetate, butyl acetate, and tetrahydrofuran can be used. The amount used is preferably such that the content (solid content concentration) of the acrylic resin composition is 5 to 40% by weight and the amount of 10 to 30% by weight is the total amount with the acrylic resin composition. More preferred.

  The acrylic resin composition produced by such a method can be suitably used as an adhesive for electronic materials in combination with epoxies, phenol resins and their curing agents. Examples of the form of the adhesive for electronic materials include an adhesive film and a paste.

  The acrylic resin composition of the present invention can be mixed with an epoxy, a phenol resin and a curing agent thereof as necessary to form a polymer alloy, which can be used as an electronic material. These epoxy resins, phenol resins and their curing agents are not particularly limited, and commercially available materials can be used. Moreover, in order to improve reactivity, adhesiveness, and intensity | strength, materials, such as a filler, a hardening accelerator, a silane coupling agent, and various fillers, can be used together. The electronic material may be in the form of a film, paste, or solution.

  There is no restriction | limiting in particular in the mixing ratio of an acrylic resin composition and an epoxy resin, For example, it can be used in the ratio of 10 / 90-90 / 10 by the former / latter (weight ratio).

  The epoxy resin is not particularly limited as long as it cures and exhibits an adhesive action. In general, an epoxy resin having two or more functions (containing two or more epoxy groups in one molecule) can be used. Examples of the bifunctional epoxy resin include bisphenol A type or bisphenol F type epoxy resin. In addition, a polyfunctional epoxy resin having a trifunctional or higher functionality (containing 3 or more epoxy groups in one molecule) may be used. Examples of the trifunctional or higher functional epoxy resin include a phenol novolac type epoxy resin and a cresol novolak type epoxy resin. Resins and the like are exemplified.

  As the curing agent for the epoxy resin, those usually used as a curing agent for the epoxy resin can be used, and two or more amines, polyamides, acid anhydrides, polysulfides, boron trifluoride, and phenolic hydroxyl groups in one molecule. It is possible to use bisphenol A, bisphenol F, bisphenol S, or a phenol resin, which is a compound having the same. From the viewpoint of excellent electric corrosion resistance at the time of moisture absorption, it is preferable to use a phenol novolac resin, a bisphenol novolac resin, a cresol novolac resin, or the like.

  In general, the curing agent is preferably used so that the group that reacts with the epoxy group of the curing agent is 0.6 to 1.4 equivalent to 1 equivalent of the epoxy group of the epoxy resin. It is more preferable to use it so that it may become 2 equivalent. When the amount of the curing agent is too small or too large, the heat resistance tends to decrease.

  Furthermore, a hardening accelerator can also be used with a hardening agent, and various imidazoles etc. are mentioned as a hardening accelerator. When the curing accelerator is used, the blending amount is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 15 parts by weight with respect to 100 parts by weight of the total of the epoxy resin and the curing agent. If it is less than 0.1 parts by weight, the curing rate tends to be slow, and if it exceeds 20 parts by weight, the pot life tends to be short.

  There is no restriction | limiting in particular in the method in the case of making it into a film form, For example, the varnish of the said adhesive agent for electronic materials can be apply | coated and dried using a various coating apparatus on a base film.

  The acrylic resin composition of the present invention is preferably used for an electronic material such as an adhesive for a semiconductor such as a film adhesive, a substrate material for a flexible wiring board, an adhesive used therefor, and an adhesive film for circuit connection.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but these do not limit the scope of the present invention.

Example 1
[Production of acrylic resin composition]
A 4 liter flask constituted by a stirrer, a thermometer, a nitrogen gas introduction tube and a discharge tube, and a heating jacket was used as a reactor. First, nitrogen was passed through the flask at 200 mL / min. Next, the flask was charged with 160% by weight of water and 0.02% by weight of polyvinyl alcohol as a dispersion aid, with the total amount of monomers described below being 100% by weight.
A monomer mixture consisting of 51% by weight of butyl acrylate, 27% by weight of ethyl acrylate, 20% by weight of acrylonitrile, 2% by weight of glycidyl methacrylate, 0.3% by weight of lauroyl peroxide as a polymerization initiator, a chain transfer agent As a solution, 0.08% by weight of O-ethyl-S- (1-phenylethyl) dithiocarbonate, which is a RAFT agent, was dissolved, and nitrogen was bubbled to reduce dissolved oxygen to 1 ppm or less. After supplying this into the flask, it was heated with stirring to maintain the temperature in the reactor at 60 ° C. and reacted for 10 hours (first step). After confirming that the polymerization rate was 80% or more, the temperature was raised to 90 ° C., and the reaction was further continued for 2 hours (second step). Thereafter, the reactor contents were cooled, the produced acrylic resin composition was taken out, and the molecular weight distribution of the resin was measured. The results are shown in Table 1.
The GPC conditions for molecular weight measurement are as follows.
<GPC conditions>
Pump: Hitachi L-7100 [Hitachi, Ltd.]
Column: Gel pack GL-A100M (2 pieces) [trade name, manufactured by Hitachi Chemical Co., Ltd.]
Eluent: Tetrahydrofuran, Measurement temperature: 30 ° C, Flow rate: 1.00ml / min, Detector: Shodex SE-61 [Showa Denko Co., Ltd.]
In addition, the polymerization rate is obtained by collecting a part of the resin during polymerization and heating to volatilize the residual monomer and moisture to obtain a solid content (% by weight). From this value (a), the following formula is obtained. It was.

[Production of adhesive film]
The acrylic resin composition was dissolved in methyl isobutyl ketone so that the heating residue was 25% by weight to prepare an acrylic resin varnish. Next, 200 parts by weight of acrylic resin varnish, 40 parts by weight of bisphenol A type epoxy resin (manufactured by Japan Epoxy Resin Co., Ltd., Epicoat 828), 40 parts by weight of phenol resin (manufactured by Dainippon Ink & Chemicals, Inc., LF2882), As a curing accelerator, a mixed solution consisting of 0.5 parts by weight of 1-cyanoethyl-2-phenylimidazole (manufactured by Shikoku Kasei Kogyo Co., Ltd., Curazole 2PZ-CN) is placed on a polyimide film (UPILEX 50S manufactured by Ube Industries, Ltd.). It was applied, dried at 80 ° C. for 30 minutes, and further dried at 100 ° C. for 30 minutes to produce an adhesive film.

[Evaluation of molecular weight distribution]
The acrylic resin composition was dissolved in THF, and the molecular weight distribution was measured by GPC. As a standard sample for comparison, PS706a (weight average molecular weight 253,000 to 260000) was used.

[Evaluation of adhesive strength]
A polyimide film (Upilex 50S manufactured by Ube Industries Co., Ltd.) is layered on the adhesive layer of the prepared adhesive film, and using a thermocompression bonding machine manufactured by Tester Sangyo Co., Ltd., mold temperature 170 ° C. (both sides), pressure 1.8 MPa. The test piece was thermocompression bonded under the condition of a pressure bonding time of 18 seconds and then left for 1 hour at 170 ° C. to complete the curing reaction.
For the adhesive strength, the peel strength of the polyimide film was measured using a 90-degree peel strength measuring machine manufactured by Tester Sangyo Co., Ltd.

Comparative Example 1
An acrylic rubber was obtained in the same manner as in Example 1 except that the chain transfer agent in Example 1 was changed to n-octyl mercaptan.

  The peel strength evaluation results of Example 1 and Comparative Example 1 are shown in Table 1 together with the acrylic rubber synthesis conditions.

※１ Ｏ−エチル−Ｓ−（１−フェニルエチル）ジチオカーボネート。
※２ ｎ−オクチルメルカプタン。

* 1 O-ethyl-S- (1-phenylethyl) dithiocarbonate.
* 2 n-octyl mercaptan.

As shown in Example 1 of Table 1, as a chain transfer agent added at the time of acrylic rubber production, O-ethyl-S- (1-phenylethyl) dithiocarbonate, which is a RAFT agent, is used, and the molecular weight distribution of the present invention is A narrow acrylic rubber could be obtained. The adhesive film for electronic materials using this acrylic rubber has high adhesive strength. On the other hand, as shown in Comparative Example 1, the molecular weight distribution of acrylic rubber obtained by using n-octyl mercaptan, which is a general thiol, as a chain transfer agent is wide, and for electronic materials using this acrylic rubber. The adhesive strength of the adhesive film was low.
As described above, by using an acrylic rubber having a narrow molecular weight distribution as an electronic material-adhering acrylic rubber, an adhesive for electronic material having a high adhesive strength can be obtained.

Claims (5)

 100% by weight of the whole monomer component, 60 to 99% by weight of acrylic acid alkyl ester, 1 to 16% by weight of glycidyl (meth) acrylate, and 0 to 39% by weight of monomer component polymerizable with these An acrylic resin composition obtained by copolymerization as a monomer component, having a weight average molecular weight (Mw) of 200,000 or more and a molecular weight distribution (Mw / Mn) of 2.0 or less.  The acrylic resin composition according to claim 1, wherein the copolymerization is living radical polymerization.  The acrylic resin composition according to claim 2, wherein the living radical polymerization is RAFT polymerization.  100% by weight of the entire monomer component, 60 to 99% by weight of acrylic acid alkyl ester, 1 to 16% by weight of glycidyl (meth) acrylate, and 0 to 39% by weight of monomer component polymerizable with these And a method for producing an acrylic resin composition, wherein the copolymer is copolymerized using a RAFT agent as a chain transfer agent.  The acrylic resin composition obtained by the manufacturing method of Claim 4.