JP2002088332A - Adhesive composition and adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an adhesive composition and to prepare an adhesive sheet that manifest a strong adhesiveness after a low-pressure and shortened-time adhesion treatment, has high heat resistance causing no reflow crack even at a high temperature of >=200 deg.C in solder reflow with no protrusion of the adhesive and additionally that can be stored at room temperature with high storage stability. SOLUTION: The objective adhesive composition comprises (a) a carboxylic acid-modified block copolymer prepared by adding a carboxylic acid or its derivative to a block copolymer including (a1) an aromatic vinyl polymer block and (a2) a conjugated diene polymer block, (b) an epoxy compound bearing a glycidylamino group and at least >=3 epoxy groups in the molecule and (c) an epoxy resin bearing >=2 epoxy groups in the molecule.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an adhesive composition and an adhesive sheet. INDUSTRIAL APPLICABILITY The adhesive composition and the adhesive sheet of the present invention are advantageously used for fixing electronic parts and the like, particularly for bonding a metal reinforcing material used in electronic parts such as an IC package and a heat-resistant film such as a polyimide film. Can be.

[0002]

2. Description of the Related Art Various adhesives are used for fixing electronic parts and the like for the purpose of improving reliability. In particular,
In the manufacturing process such as fixing flexible printed wiring boards and reinforcing materials, fixing circuit boards used in semiconductor devices such as ball grid arrays and reinforcing boards or heat sinks, and temporary fixing when transporting parts. Adhesives have come to be used in many applications.

In such applications, a polyimide film is used for a flexible circuit board, and a metal material or a glass epoxy plate is used for a reinforcing material. Good adhesiveness is required. In addition, in such applications, it has high heat resistance to withstand high temperatures of 200 ° C or more, which is the condition of solder reflow during component mounting, and it is possible to perform bonding at low pressure and in a short time for the purpose of improving productivity. Required. In addition, as the size of electronic devices has been reduced, the bonding area has tended to be reduced. Due to the problem of external appearance and the deterioration of the function of electronic components, the flow of the adhesive has to be controlled (glue). Is very important. Further, the adhesive is required to have good storage stability.

Conventionally, for example, epoxy adhesives and polyimide adhesives have been studied as adhesives used for bonding electronic parts and the like.

An adhesive sheet using an epoxy-based adhesive is
Adhesion treatment at low pressure and in a short time is possible, and the adhesive strength is excellent. However, the epoxy adhesive has a large water absorption rate of the adhesive itself, and causes peeling / floating or the like, that is, reflow crack, due to vapor pressure generated by rapid vaporization of moisture absorbed at a temperature of 200 ° C. or more during solder reflow. There was a problem of causing high heat resistance. Further, there is a problem that unreacted low-molecular-weight epoxy resin flows out (glue runs out) at the time of press bonding or the like, causing problems such as abnormal appearance. Further, there is a problem that the storage stability is poor and the process management becomes complicated, such as the time of exposure to room temperature during the bonding process of the adhesive sheet. Further, an adhesive sheet using a polyimide-based adhesive is excellent in adhesive strength and storage stability, but it is difficult to perform an adhesive treatment in a low pressure and in a short time. In addition, there is a problem that high heat resistance cannot be satisfied.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional adhesive composition and adhesive sheet for fixing electronic parts, and provides a low-pressure, short-time adhesive treatment. And exhibit strong adhesive strength, and can be used during solder reflow.
It is an object of the present invention to provide the adhesive composition and the adhesive sheet which have high heat resistance without reflow crack even at a high temperature of 00 ° C. or more, and which does not cause paste to overflow. Still another object is to provide an adhesive composition and an adhesive sheet which can be stored at room temperature and have good storage stability.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above problems, and as a result, have found that the above objects can be achieved by the following adhesive composition, and have completed the present invention. Was.

That is, the present invention provides a carboxylic acid having a structure in which a carboxylic acid or a derivative thereof is added to a block copolymer comprising an aromatic vinyl compound polymer block (a1) and a conjugated diene compound polymer block (a2). Acid-modified block copolymer (a), epoxy compound having a glycidylamino group in the molecule and at least three epoxy groups (b), and epoxy resin having two or more epoxy groups in the molecule An adhesive composition containing (c).

In the above adhesive composition, since the carboxylic acid-modified block copolymer (a) having hydrophobicity is used as a base polymer, peeling / foaming due to vapor pressure generated by vaporization of moisture absorbed during solder reflow. And high heat resistance. Further, the carboxylic acid-modified block copolymer (a) has a reactive functional group that becomes a reaction starting point with the epoxy compound (b) as a cross-linking agent and the epoxy resin (c) as a curing agent. -Strong adhesion can be achieved by a short-time adhesion treatment. Particularly, the epoxy compound (b) has a high reaction rate with a carboxylic acid, and when a varnish obtained by dissolving an adhesive composition in a solvent is applied to a substrate and dried, a carboxylic acid-modified block copolymer which is a main component is used. The coalescing (a) is crosslinked, thereby suppressing the paste from overflowing. On the other hand, when the epoxy resin (c) is coated with a varnish obtained by dissolving an adhesive composition in a solvent and then dried, the reaction does not proceed, and after bonding the produced adhesive sheet to the adherend, A curing reaction is caused by heating, and strong adhesiveness is obtained.

In the adhesive composition, 0.05 to 5 parts by weight of an epoxy compound (b) and 1 to 20 parts by weight of an epoxy resin (c) are used based on 100 parts by weight of the carboxylic acid-modified block copolymer (a). Is preferable.

When the proportion of the epoxy compound (b) used is small, the crosslinking of the carboxylic acid-modified block copolymer (a) does not proceed sufficiently, and it may flow due to heat at the time of bonding and cause abnormal appearance such as glue protrusion. . Therefore, the use ratio of the epoxy compound (b) is preferably at least 0.05 part by weight, more preferably at least 0.1 part by weight. On the other hand, if the proportion of the epoxy compound (b) used is too large, the crosslinking becomes too dense, it is difficult to perform the bonding treatment at low pressure and in a short time, and the adhesiveness may be reduced. Is preferably not more than 5 parts by weight, more preferably not more than 1 part by weight. If the proportion of the epoxy resin (c) is small, the curing reaction does not proceed sufficiently and the heat resistance may be insufficient. Therefore, the proportion of the epoxy resin (c) used is 1 part by weight or more, and further 3 parts by weight. Parts or more. On the other hand, if the proportion of the epoxy compound (c) used is large, the initial adhesiveness is good, but if the adhesive is left at a high temperature (100 ° C. or more) continuously after the adhesive, the adhesive strength may be extremely reduced. From the viewpoint of the reliability of long-term high-temperature bonding, the proportion of the epoxy resin (c) used is preferably 20 parts by weight or less, more preferably 10 parts by weight or less. When the amounts of the epoxy compound (b) and the epoxy resin (c) are within the above ranges, the storage stability can be maintained well, and the storage can be performed at room temperature.

In the adhesive composition, the aromatic vinyl compound polymer block (a1) and the conjugated diene compound polymer block (a2) of the block copolymer serving as the raw materials of the carboxylic acid-modified block copolymer (a) are used. Weight ratio of (a
It is preferable that 1) / (a2) = 10/90 to 40/60.

The aromatic vinyl compound polymer block (a
When the proportion of 1) is low, the solubility of the carboxylic acid-modified block copolymer (a) in the solvent is low, and the solution viscosity of the adhesive composition becomes high, making it difficult to apply. The ratio of the polymer block (a1) is 10
% By weight or more, more preferably 20% by weight or more. On the other hand, aromatic vinyl compound polymer block (a1)
When the ratio is large, the solubility in a solvent is increased, and the solvent resistance of the adhesive sheet tends to be deteriorated. Therefore, the ratio of the aromatic vinyl compound polymer block (a1) is 40% by weight or less, and more preferably 30% by weight or less. % By weight or less.

The adhesive composition may contain a filler. Fluidity control by containing filler,
This is preferable because it has the effects of improving heat resistance and moisture resistance. The filler is a carboxylic acid-modified block copolymer (a) 1
It is preferable to contain 10 to 30 parts by weight with respect to 00 parts by weight. In this range, the above-mentioned effect is favorably exhibited.

Further, the present invention relates to an adhesive sheet having an adhesive layer formed from the adhesive composition on one or both sides of a base film. The adhesive sheet for fixing an electronic component using the adhesive composition of the present invention as an adhesive layer exhibits strong adhesive strength by a low-pressure, short-time adhesive treatment, and reflows even at a high temperature of 200 ° C. or more during solder reflow. It has high heat resistance without cracks, and no glue sticks out.
Good storage stability.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The carboxylic acid-modified block copolymer (a) used as a base polymer in the adhesive composition of the present invention comprises an aromatic vinyl compound polymer block (a1) and a conjugated diene compound polymer block. (A2)
And a structure obtained by adding a carboxylic acid or a derivative thereof to a block copolymer consisting of

The aromatic vinyl compound polymer block (a
1) includes a styrene polymer block, and the conjugated diene compound polymer block (a2) includes a butadiene polymer block or an isoprene polymer block. As the block copolymer, SI
Block copolymers such as S-type, SBS-type, and SIBS-type can be used without particular limitation. Examples of the carboxylic acid or its derivative include maleic acid, acrylic acid and the like, and anhydrides thereof.

As the carboxylic acid-modified block copolymer (a), it is preferable to use a hydride of the carboxylic acid-modified block copolymer (a) because of its good thermal stability. The hydride of the carboxylic acid-modified block copolymer (a) can be obtained, for example, by subjecting the block copolymer to hydrogenation and then to carboxylic acid modification. In this case, the hydrogenation of the block copolymer is performed to such an extent that the olefinically unsaturated double bond is saturated. Hydrogenation also
Hydrogenation is preferably performed on a part of the unsaturated double bond of the block copolymer so that the carboxylic acid or its derivative can be added. An acid or a derivative thereof can be added. The hydride of the carboxylic acid-modified block copolymer (a) can also be obtained by adding a carboxylic acid or a derivative thereof to the block copolymer and then hydrogenating the block copolymer.

Commercially available hydrides of such carboxylic acid-modified block copolymers (a) include, for example, Tuftec M series (trade name, manufactured by Asahi Kasei Kogyo Co., Ltd.),
Clayton FG1901X (trade name, manufactured by Shell Japan KK) and the like.

The epoxy compound (b) is a compound having a glycidylamino group in the molecule and having at least three or more epoxy groups. The glycidylamino group has a structure in which two glycidyl groups are added to an amino group, and the number of the epoxy groups includes the epoxy group in the glycidylamino group. Examples of the epoxy group other than the glycidylamino group include a glycidyl ether group in which a hydroxyl group is glycidylated.

Examples of such compounds include glycidylated diaminodiphenylmethane, glycidylated aminophenol, glycidylated aminocresol, glycidylated xylenediamine, glycidylated diaminocyclohexane, and glycidylated diaminobenzene. These compounds (b) can be used alone or in combination of two or more.

The epoxy resin (c) has two or more epoxy groups in the molecule. As the epoxy resin (c),
For example, bisphenol F type epoxy resin, bisphenol A type epoxy resin, phenol novolak type epoxy resin, cresol novolak type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic type Epoxy resins, spiro ring-containing epoxy resins, halogenated epoxy resins and the like can be mentioned. These can be used alone or in combination of two or more.

Further, a curing catalyst for an epoxy resin can be added to the adhesive composition of the present invention, if necessary. As such a curing catalyst, various types of conventionally known curing catalysts can be selected according to the intended reaction rate, but those which can be used as a latent curing system are preferable from the viewpoint of storage stability. Examples of the curing catalyst include dicyandiamide, imidazole, imidazole derivatives, hydrazine compounds, and the like.
The properties of the cured product are adjusted by using a combination of two or more kinds. In particular, in consideration of storage stability, a curing catalyst that forms a heterogeneous system in the adhesive composition, that is, one that is made insoluble or microencapsulated is preferable.

The adhesive composition of the present invention may contain various known additives such as an inorganic filler, an organic filler, a pigment, an antioxidant, a silane coupling agent and a tackifier as long as the adhesive properties are not deteriorated. Can be added as necessary. In particular, inorganic fillers and organic fillers are preferred because they have the effects of controlling the fluidity of the adhesive, improving heat resistance, and improving moisture resistance. Examples of such an inorganic filler include silica, alumina, aluminum hydroxide, and magnesium hydroxide.
Examples of the organic filler include silicone powder and the like. In particular, those treated with a silane coupling agent are preferable from the viewpoint of improving compatibility with resin and adhesion.

The adhesive sheet of the present invention is produced by forming an adhesive layer of the adhesive composition on a substrate.
The formation of the adhesive layer is performed by dissolving the adhesive composition in a solvent, applying the composition to a substrate, and drying by heating. Here, the solvent is not particularly limited, but aromatic solvents such as toluene and xylene have good solubility and are preferably used.

Examples of the substrate include a release-treated film as a release liner. Examples of the release-treated film include a plastic film such as polyester, polyolefin, polyamide, and polyimide, and a release liner obtained by subjecting a high-quality paper laminated with glassine paper or polyethylene to a release treatment such as silicone or fluorine.

As the substrate, polyimide, polyamide,
Polyetherimide, polyamideimide, polyester, polyphenylene sulfide, polycarbonate, polytetrafluoroethylene, polyetheretherketone and the like plastic film substrate and its porous substrate,
Examples include nonwoven fabric substrates such as cellulose, polyamide, polyester, and aramid; metal film substrates such as aluminum foil and SUS foil; steel wool substrates; and metal mesh substrates. When a release film is used as the substrate, the adhesive layer formed on the release film can be transferred onto the substrate.

In the adhesive sheets, an adhesive layer can be provided on one or both sides of the substrate. The obtained adhesive sheets can be used as a sheet or a tape. The thickness of the adhesive layer of the adhesive sheet is 10 to 20.
It is preferably about 0 μm.

[0029]

The present invention will be described more specifically below with reference to working examples of the present invention. The numerical value of each component in the table means parts by weight.

Examples 1-3, Comparative Examples 1-2 Maleic acid-modified block copolymer (Asahi Kasei Corporation)
(Trade name: Tuftec M1943), glycidylamino group-containing epoxy compound (trade name: TETRAD-C, manufactured by Mitsubishi Gas Chemical Co., Ltd.) and epoxy resin (trade name: Yuko Shell Epoxy Co., Ltd., Epicoat 828 or 100)
4) were blended so as to have the composition ratios shown in Table 1, respectively, and dissolved in a toluene solvent so as to have a concentration of 20% by weight to prepare an adhesive composition solution. However, in Example 3, 4,
4′-Diaminodiphenyl sulfone and silica in Comparative Example 2 were mixed so as to have the composition ratios shown in Table 1, respectively.

The above adhesive composition solution is applied as a release liner on a release film made of a silicone release-treated polyethylene terephthalate film having a thickness of 50 μm, and then dried at 150 ° C. for 3 minutes to form a release liner. A thermosetting adhesive layer having a thickness of 50 μm was formed to obtain a thermosetting adhesive sheet.

The thermosetting adhesive sheets obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were tested for the adhesive strength, adhesive run-out, and solder heat resistance by the following methods. Further, as a storage stability promotion test, a test of the adhesive strength was performed on a sample in which each adhesive sheet was left at 50 ° C. and 120 ° C. for 168 hours. Table 1 shows the results.

<90 ° Peel Adhesive Strength> An adhesive sheet having a width of 10 mm and a length of 50 mm was adhered to a polyimide film having a thickness of 75 μm, and this was adhered to SUS (BA304). This sample was placed at 200 ° C. × 10 kg / cm ² ×
After pressure bonding under a press condition of 10 seconds and curing by heat treatment in a hot air oven at 150 ° C. × 2 hours, a temperature of 23 ° C.
After leaving for 30 minutes in an atmosphere condition of a humidity of 65% RH, the film was pulled in a 90 ° direction at a pulling speed of 50 mm / min under an atmosphere condition of 23 ° C., and the center value was set to 90 ° peel adhesive strength (N / c).
m).

<Glue Extrusion> A 2 cm diameter hole was made at the center of the adhesive sheet cut into a 10 cm square, and the temperature was 200 ° C.
After pressure bonding under a pressure of 0.98 MPa and a press time of 10 seconds, the maximum value of the length of the glue protruding into the hole was measured.

<Solder heat resistance> SU
S (BA304) and polyimide film (75 μm) were bonded together so that no air bubbles entered between them. A sample cut into a 30 mm square was placed at 200 ° C. × 0.9
Crimping under the press conditions of 8 MPa × 10 seconds, 150 ° C. × 2
After curing by heat treatment for 35 hours, 35 ° C / 80% R
After leaving for 168 hours in the humidifying condition of H, SUS (BA3
04) with the solder bath melted at 260 ° C. floating for 60 seconds. The bonded state of the sheet after the treatment was visually observed, and it was determined whether or not the foaming of the adhesive and abnormal bonding (floating, wrinkling, peeling, displacement) occurred. ：: No change / abnormal, ×: Change / abnormal.

[0036]

[Table 1] Note 1: Tuftec M1943 (manufactured by Asahi Kasei Corporation) Note 2: TETRAD-C (manufactured by Mitsubishi Gas Chemical Co., Ltd.) Note 3: Epicoat 828 (manufactured by Yuka Shell Co., Ltd.) Note 4: Epicoat 1004 (Manufactured by Yuka Shell Co., Ltd.), Note 5: Admafine S0-E5 (manufactured by Admatex Corporation).

As is clear from Table 1 above, each of the thermosetting adhesive sheets of Examples 1 to 3 of the present invention is excellent in adhesive extruding property at the time of bonding, and is excellent in adhesive strength, heat resistance and storage stability. You can see that it is. In contrast, in Comparative Example 1,
Since it does not contain the epoxy compound (b), the base polymer (a) does not undergo a cross-linking reaction at the time of bonding, and the glue sticks out. In the case of the epoxy / rubber adhesive of Comparative Example 2, the epoxy resin increases the water absorption of the adhesive, and the solder heat resistance after absorbing moisture is inferior. In addition, storage stability is poor.

Continuation of the front page (72) Inventor Toshimitsu Okuno 1-2-1 Shimohozumi, Ibaraki-shi, Osaka F-term in Nitto Denko Corporation (reference) 4J004 AA02 AA05 AA11 AA13 AA18 AB05 CA02 CA04 CA06 CA08 CB01 CB02 CD02 CD05 CD06 DA02 DA04 DB02 EA05 FA05 GA01 4J040 DM011 EC062 EC072 EC082 EC122 EC152 EC262 EC282 EK032 GA07 HA136 HA156 HA306 JA02 JA09 JB02 KA03 KA07 KA42 LA05 LA06 LA08 MA02 MA10 NA20

Claims (6)

[Claims] 1. An aromatic vinyl compound polymer block (a)
A carboxylic acid-modified block copolymer (a) having a structure in which a carboxylic acid or a derivative thereof is added to a block copolymer composed of 1) and a conjugated diene-based compound polymer block (a2); and a glycidylamino group in the molecule. An adhesive composition comprising: an epoxy compound (b) having at least three epoxy groups; and an epoxy resin (c) having two or more epoxy groups in a molecule. 2. A carboxylic acid-modified block copolymer (a)
Epoxy compound (b) 0.05 to 100 parts by weight
The adhesive composition according to claim 1, comprising 5 parts by weight and 1 to 20 parts by weight of the epoxy resin (c). 3. A carboxylic acid-modified block copolymer (a)
The weight ratio of the aromatic vinyl compound polymer block (a1) and the conjugated diene compound polymer block (a2) of the block copolymer as the raw material for (a1) / (a2) = 10/9
The adhesive composition according to claim 1, wherein the adhesive composition has a ratio of 0 to 40/60. 4. The adhesive composition according to claim 1, further comprising a filler. 5. A carboxylic acid-modified block copolymer (a)
The adhesive composition according to claim 4, wherein the filler is contained in an amount of 10 to 30 parts by weight based on 100 parts by weight. 6. An adhesive sheet having an adhesive layer formed from the adhesive composition according to claim 1 on one or both sides of a substrate film.