JPH061961A - Adhesive composition - Google Patents

Abstract

PURPOSE:To provide an adhesive composition good in electrically insulating property and adhesivity, excellent in flame retardancy, and suitable for printed circuit boards. CONSTITUTION:The adhesive composition comprises (A) a brominated phenol novolak epoxy resin, (B) a bisphenol A epoxy resin, (C) a carboxy-modified acrylonitrile-butadiene rubber, and (D) a curing agent, the content of the bromine being >=13% per 100 pts.wt. of (A)+(B), and the amount of (C) being 1-20 pts.wt. per 100 pts.wt. of (A)+(B).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive composition suitable for a printed wiring board, which has excellent electric insulation and adhesiveness and excellent flame retardancy.

[0002]

2. Description of the Related Art Rigid printed wiring boards and flexible printed wiring boards are formed into films by impregnating a single sheet or fiber with an adhesive composition containing a resin alone or a mixture of an elastomer component and a resin and drying. It is generally manufactured by a method in which a metal foil such as copper or aluminum and an insulating film such as polyimide are sandwiched and laminated, and integrated by thermocompression bonding.

Further, the similarities between the rigid type and the flexible type adhesive compositions for printed wiring boards are that an epoxy resin is used as a resin in many cases, and the difference is that in the case of the flexible type, The feature is that the amount of rubber or the like used as an elastomer component is mixed more than twice that of the rigid type. Regarding the effect on the physical properties due to the difference in the component ratio of this resin and the elastomer, when the amount of resin is large, the cross-linking density of the system is high, so the electrical insulation is high, and the heat resistance to solder, etc. Is good because it is on the high temperature side. However, it becomes a film with a brittle property because it lacks elastic components typified by rubber, and there are defects such as cracks in workability as well. Further, adhesion to copper and polyimide, folding resistance,
The circuit embedding property when stacking is poor, and the life during storage is short. On the other hand, when the amount of the elastomer component is large, the above is reversed. Furthermore, in the case of a rigid type, when using a prepreg made by impregnating a blended resin into a non-combustible reinforcing material such as glass cloth, a circuit pattern due to thermal strain or pressure strain, which is a drawback of the high-pressure molding method, is used. We have to think about defects.

In recent years, the demand for safety of electric equipment has increased,
In particular, a printed wiring board (printed wiring board) having flame retardancy has been required. UL94 is generally used as a standard for the flame retardancy of the adhesive composition used for this, but the evaluation sample thereof is an adhesive sheet alone or an integrated polyimide sheet, and further a laminated plate. There is one. That is, in the case of the latter configuration, even if the flame retardancy of the adhesive composition itself is low, there are cases where the standard (V-0) can be cleared by other non-combustible components. When the adhesive composition itself has flame retardancy, a halogen is added to the resin used (eg, JP-A-56-81382) and a flame retardant aid such as metal oxide or metal hydroxide. Additions of these compounds (eg, JP-A No. 3-25468) and combinations of these (eg, JP-A No. 62-60290) are being studied.

Regarding the difference depending on the field of use, there are many examples in the case of a flexible wiring board (JP-A-3-28285, etc.), but in the case of a rigid type adhesive composition for a printed wiring board, Flame retardancy has never been realized. This is because it was not necessary to consider the flame retardancy in the resin itself, because the flame retardancy was evaluated by impregnating the blended resin into a non-combustible reinforcing material such as glass cloth.
(Example: JP-A-3-86545).

Therefore, the present inventors proposed an insulating film for a printed wiring board, which is a glass prepreg substitute containing an epoxy resin and a carboxy-modified acrylonitrile-butadiene rubber as main components, and has electrical insulation, workability and heat resistance. It was shown to be excellent (Japanese Patent Application No. 3-260732). However,
This film had a problem of flame retardancy because it did not contain any nonflammable reinforcing material such as glass cloth and flame retardant at all. When imparting flame retardancy to the system, it is customary to carry out the above treatment, but it is difficult to maintain other properties by imparting flame retardancy to the adhesive composition, It has never been possible. It is noted that when additives such as brominated compounds, aluminum hydroxide, antimony oxide, etc. are added, flame retardancy is increased, but extreme deterioration in performance is observed in terms of electrical characteristics, adhesion to metal foil, solder heat resistance, etc. It can be explained from what is done.

[0007]

DISCLOSURE OF THE INVENTION The present invention provides a flame-retardant property without impairing the physical properties of conventional adhesive compositions for printed wiring boards containing an epoxy resin and a carboxy-modified acrylonitrile-butadiene rubber as main components. It is intended to provide an added adhesive composition. This adhesive composition is suitable for a rigid printed wiring board.

[0008]

The adhesive composition of the present invention is a brominated phenol novolac type epoxy resin.
(A), bisphenol A type epoxy resin (B), carboxy-modified acrylonitrile butadiene rubber (C) and curing agent (D). When 100 parts by weight of (A) + (B) has a bromine content of 13% or more. Yes, (A) + (B)
It is characterized in that (C) is blended in the range of 1 to 20 parts by weight with respect to 100 parts by weight.

This adhesive composition is composed of (A) + (B)
It is possible to further improve the adhesiveness by further mixing 40 parts by weight or less of antimony oxide with respect to 00 parts by weight. Hereinafter, the configuration of the present invention will be described in detail. (A) Brominated phenol novolac type epoxy resin By reacting a brominated phenol novolac resin with epihalohydrin in the presence of a basic compound,
A brominated phenol / novolak type epoxy resin is obtained.
It has the formula:

[0010]

Specific examples of the brominated phenol novolac type epoxy resin include BREN series manufactured by Nippon Kayaku Co., Ltd. BREN-S (Epoxy equivalent 280g
/ eq, Br content: 35% by weight, softening point 84 ° C), low viscosity type BREN-105 (epoxy equivalent 275g / eq, Br content: 35% by weight, softening point 68 ° C), high brominated type BRE
N-304 (epoxy equivalent 310 g / eq, Br content; 45% by weight, softening point 70 ° C.) and the like can be used. Moreover, you may use these individually or in mixture. (B) Bisphenol A type epoxy resin having the following formula.

[0012]

Among glycidyl ether type epoxy resins, epoxy resins having two or more epoxy groups in one molecule, such as bisphenol A epichlorohydrin type, and high molecular weight type epoxy resins include Dainippon Ink and Chemicals
Epicron 1050 (epoxy equivalent 500g / eq),
As a low molecular weight type, E manufactured by Sumitomo Chemical Co., Ltd.
LA128 (epoxy equivalent 187 g / eq) can be mentioned as a representative, but there is no problem even if a commercially available product is used. However, for electronic materials, the chlorine ion content is
It is preferable that the content of hydrolyzable chlorine at 10 ppm or less is 0.1% or less.

(C) Carboxy-modified acrylonitrile-butadiene rubber As the carboxy-modified acrylonitrile-butadiene rubber, a methyl acrylate is three-dimensionally copolymerized with acrylonitrile and butadiene, and a carboxyl group is present in the molecular side chain. This makes it possible to increase the crosslinkability with the epoxy resin as compared with NBR having no functional group. Specific examples include Nippon Pol 1072J manufactured by Zeon Corporation and PNR-1H manufactured by Nippon Synthetic Rubber Co., Ltd. The nitrile group content is not particularly limited, but is preferably 25 to 40% by weight.

(D) Curing Agent The epoxy resin curing agent is preferably a latent curing agent such as a guanidine compound represented by dicyanamide or an imidazole compound. For example, 2-phenylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-benzyl-5.
A one-liquid type such as -hydroxymethylimidazole is preferable. In addition, Lewis acid salts represented by boron trifluoride ethylamine complex, organic acid hydrazides such as adipic acid hydrazide, diaminomaleonitrile and its derivatives, melamine and its derivatives, thermally decomposable amine imide, and further curing A substance obtained by adsorbing the agent on a porous body such as a molecular sieve or a substance containing a microcapsule curing agent may be used. These hardeners are
The amount used may be appropriately selected depending on the type of curing agent and the type and amount of each resin, but generally it is 0 per 100 parts by weight of epoxy resin (100 parts by weight of (A) + (B)).
It can be added in the range of 5 to 60 parts by weight.

(E) Antimony Oxide As antimony oxide, there are antimony trioxide, antimony pentaoxide, and the like, but any one may be used. However, the particle size is preferably 0.02 to 1.5 μm, and the finer the particle size is, the better the dispersibility is, and the better the flame retardancy is. (F) Additive If a filler is further used, inorganic ones such as calcined clay, calcium carbonate, silica, mica and calcium hydroxide are preferable. In addition, inorganic flame retardants such as tin oxide, molybdenum oxide, zirconium oxide and magnesium hydroxide may be added.

In the present invention, by admixing the components (A) to (F) in a predetermined composition range, the adhesive strength
Each physical property value such as electric characteristics and flame retardancy can be achieved, and the following inconvenience occurs when the value is out of the above range.
That is, when the bromine content is less than 13% in 100 parts by weight of the total of 100 parts by weight of the brominated phenol novolac type epoxy resin (A) and the bisphenol A type epoxy resin (B), the amount of bound halogen is relatively small. The amount of liberated halogen is small and the production of antimony halide is small, so the flame retardancy is low. The bromine content is preferably 13% to 45%. 100 parts by weight of epoxy resin ((A) + (B))
If the amount of the carboxy-modified acrylonitrile butadiene rubber (C) is less than 1 part by weight, the film forming property as a film is poor, and in the range of more than 20 parts by weight, the electrical properties of the composition are low and the electrical properties are low. Get lower. The antimony oxide (E) may be used if necessary, but when it is used, the compounding amount is 100 parts by weight of (A) + (B).
It is 40 parts by weight or less, preferably 10 to 40 parts by weight. (E)
With respect to the antimony oxide (1), if the bromine content in the total 100 parts by weight of the resin is 13% or more, the flame retardant effect is remarkably increased by the combined use with the brominated phenol novolac resin (A). Further, in the range where (E) exceeds 40 parts by weight, the rank of flame retardancy is the highest (V-0), but the impurity amount (Fe, Pb) increases, and the electrical characteristics deteriorate.

[0018]

【Example】

Examples 1-6, Comparative Examples 1-5 Brominated phenol novolac type epoxy resin (BREN
-S, 35 parts by weight of Nippon Kayaku Co., Ltd., to a high molecular weight bisphenol A type epoxy resin (Epiclone 1050,
50 parts by weight of Dainippon Ink and Chemicals Co., Ltd., and low molecular weight bisphenol A type epoxy resin (ELA128,
Sumitomo Chemical Co., Ltd.) 15 parts by weight were mixed to make the total amount of epoxy resin 100 parts by weight, and carboxy group-containing NBR1 was added to this.
Parts by weight, 2-phenylimidazole (2P
Z, manufactured by Shikoku Kasei Kogyo Co., Ltd.) was added, and the whole was placed in methyl ethyl ketone and dissolved with stirring at room temperature, and then uniformly dispersed by a sand mill to obtain a varnish. This varnish is coated on a release-treated 40 μm thick polyethylene terephthalate film,
It was dried at ℃ for 30 minutes to obtain a resin film having a thickness of about 100 μm. The two resin films were stacked on each other with a roll laminator to obtain a resin film with a thickness of 200 μm.
(Example 1). In addition, the conditions of superposition are temperature 40 ℃,
The laminator pressure is 2 kgf / cm ² .

The varnish was adjusted according to the formulation contents (parts by weight) shown in Table 1, and the insulating layer was 200 μm in the same manner as in Example 1.
m resin films were obtained (Examples 2 to 6, Comparative Examples 1 to 1)
5). Copper foil peel strength (adhesiveness), electrical insulation (electrolytic corrosion resistance), flame retardancy (UL)
94) was measured by the following method. The results are shown in Table 1.

Copper foil peel strength : With copper foil on one side treated with oxidation
Laminate the above insulation film on 1.6mm FR-4 substrate
(Condition: roll temperature 120 ° C.), then 18 μm copper foil was laminated and cured by a press (conditions: press pressure: 20 kg / cm ² , press temperature: 170 ° C., press time: 1 hour). The evaluation was performed according to JIS-C6481. That is, a copper foil having a width of 10 mm was cut out and peeled off in the 90 ° direction to measure its strength.

Electrical insulation : Vacuum lamination of an insulating film on a laminated board designed with a comb-shaped circuit (line / space = 0.2 mm / 0.2 mm) (condition; laminating temperature 120 ° C.,
A vacuum degree of 40 Torr and a flow rate of 2 m / min) were applied to cure at 170 ° C. for 1 hour. 1000 hours environmental test (85 ℃
/ 85% RH, applied voltage 50V (DC)), then 500V
The insulation resistance value between lines was measured after the voltage was applied for 60 seconds. As a result, a value of 1 × 10 ¹¹ [Ω] or higher is regarded as good and 1 × 10 ^{11
A value of 10} [Ω] or less was regarded as defective.

Flame-retardant property (UL94) : Measured according to UL-94. As the rank, the state is shown by FIRE showing three combustions of V-0, V-1, and V-2. Note that V-
0 is the most flame-retardant grade. Furthermore, V-
0 and V-1 were evaluated as good, and V-2 and FIRE were evaluated as bad.

[0023]

Note) * 1: Phenol novolac type, epoxy equivalent 28
0, bromine content 35%, BREN-S, manufactured by Nippon Kayaku Co., Ltd.

* 2: Phenol novolac type, epoxy equivalent 310, bromine content 45%, BREN-301, manufactured by Nippon Kayaku Co., Ltd. * 3: Bisphenol A type, epoxy equivalent of about 400g / e
q, bromine content 50%, ESB400T, Sumitomo Chemical Co., Ltd.
Made by Co., Ltd. * 4: Bisphenol A type, epoxy equivalent of about 500g / e
q, Epicron 1050, Dainippon Ink and Chemicals, Inc.
Made.

* 5: Bisphenol A type, epoxy equivalent of about 187 g / eq, ELA128, manufactured by Sumitomo Chemical Co., Ltd. * 6: Carboxy NBR, COOH; 4 mol%. * 7: Nipol 1041, made by Nippon Zeon, AN; 41%. * 8; 2-phenylimidazole (2PZ) Shikoku Chemicals
Made by Co., Ltd. * 9; line / space = 0.2 mm / 0.2 mm, 85 ° C / 85%
RH, 50V (DC) applied, insulation resistance between lines after 1000 hours, unit: [Ω].

From Table 1 above, the adhesive composition of the present invention shows that the copper foil has peeling strength, electrical insulation (electrolytic corrosion resistance), and flame retardancy.
It is found that (UL94) is excellent (Examples 1 to 6). On the other hand, in Comparative Example 1, the amount of antimony oxide was 50 parts by weight, which was out of the regular range, and thus there was a sufficient flame retardant effect (UL94V-0) and the peel strength of the copper foil was also sufficient. However, since the amount of impurities (Fe, Pb) associated with antimony oxide in the epoxy resin increases, the electrical characteristics deteriorate. In Comparative Example 2, the amount of the brominated phenol novolac type epoxy resin in 100 parts by weight of the epoxy resin is small, that is, the bromination rate is low. Has not reached. In Comparative Example 3, when NBR was used instead of the carboxy group-containing NBR, the electrical properties were low and the peeling strength of the copper foil was slightly low because the system did not have a functional group and the crosslink density of the system was low. In Comparative Example 4, the compounding amount of rubber is large, but the physical properties of the rubber appear on the surface rather than the physical properties of the epoxy resin, so the crosslink density is low, and therefore the peel strength of the copper foil is high. However, the electrical characteristics are inferior to those of the examples. Comparative Example 5
When the brominated epoxy resin is changed from the phenol novolac type to the bisphenol A type, the flame retardancy is inferior due to the difference in heat resistance due to the structure of the resin, and the ignited material sags or curls.

[0028]

As described above, the adhesive composition of the present invention is excellent in flame retardancy and can be maintained without impairing the electric insulation characteristics, heat resistance and adhesiveness which the conventional adhesive compositions have. Therefore, it is optimal for printed wiring boards.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05K 3/38 E 7011-4E

Claims (2)

[Claims] 1. A brominated phenol novolac type epoxy resin (A), a bisphenol A type epoxy resin (B),
Carboxy modified acrylonitrile butadiene rubber (C)
A curing agent (D), a bromine content of 13% or more in 100 parts by weight of (A) + (B), and (A) +
An adhesive composition containing (C) in an amount of 1 to 20 parts by weight based on 100 parts by weight of (B). 2. A brominated phenol novolac type epoxy resin (A), a bisphenol A type epoxy resin (B),
Carboxy modified acrylonitrile butadiene rubber (C)
, Hardener (D), antimony oxide (E),
The bromine content is 13% or more in 100 parts by weight of (A) + (B), and relative to 100 parts by weight of (A) + (B).
An adhesive composition containing 1 to 20 parts by weight of (C) and 40 parts by weight or less of (E).