KR19980068274A - Adhesive composition - Google Patents

Abstract

The present invention relates to an adhesive composition used in the manufacture of a flexible printed circuit board or coverlay film having excellent physical properties such as adhesiveness, heat resistance, chemical resistance, solvent resistance, water resistance, flame retardancy, and electrical insulation.

The present invention specifically relates to an adhesive composition composed of an acrylic resin, an epoxy resin, an amine curing agent and other additives, such as acrylonitrile, an acrylic resin having an alkyl group having 2 to 10 carbon atoms, acrylic acid or methacrylic acid, and hydroxyethyl acrylic. A bisphenol-based epoxy brominated with epoxy resin and a cresol novolac epoxy are mixed and used with a monomer made of a monomer composed of acrylate or hydroxyethyl methacrylate. An acrylic resin having the composition described above is used. It has excellent adhesive properties such as flexibility, chemical resistance, adhesive strength, and is particularly suitable for manufacturing a flexible printed circuit board or coverlay film.

Description

Adhesive composition

The present invention relates to an adhesive composition having excellent general properties such as adhesiveness used in the manufacture of a flexible printed circuit board or a coverlay film.

Recently, the trend of miniaturization, high integration, simplification, high performance, etc. has been prominent in the electric and electronic industries. To satisfy these demands, it is absolutely necessary to develop flexible printed circuit boards having good flexibility and integrating circuits. The flexible printed circuit board is flexible and can be folded according to the internal structure of the product. The flexible printed circuit board is made of a very thin material, and has a merit that it can sufficiently perform a role as a circuit board while occupying little space.

In general, a flexible printed circuit board is a copper base or an aluminum foil attached to a film such as a polyimide resin, a polyester resin, a polyamideimide resin, a polyetherimide resin, or the like as a basic substrate. Since these films are used as substrates because of their excellent thermal, mechanical, and electrical properties, an adhesive is applied to these substrates, and a conductor such as copper or aluminum is adhered to, and screen printing and dry film photo on the surface of the metal conductor are performed. Print the circuit using a resistor and etch the metal foil. In order to protect the printed circuit, the coverlay film is coated with an adhesive on a film of the same material as the original and then semi-cured, and then a film or paper having a releasability is used as a protective sheet on the adhesive surface. And protect the printed circuit surface by covering it on the flexible printed circuit board.

Adhesives used in the manufacture of flexible printed circuit boards and coverlays are excellent in heat resistance, chemical resistance, solvent resistance, electrical insulation, flame retardancy, water resistance and flexibility.In the case of coverlays, the adhesive flows out of the film during lamination processing. It should be small and fill the gaps between circuits well and have long life span in semi-cured state. At this time, the preservation life should be about 3 months at room temperature and 6 months at 5 ℃.

Adhesives used in flexible printed circuit boards include acrylonitrile-butadiene rubber / epoxy resins (JP 60-79079, JP 63-186787), polyester / epoxy watches (JP 63-297438, JP 62-275178, JP 1- 170091), butyral resins, nylon / epoxy resins (JP 57-64997), acrylic resins / phenolic resins (JP 61-261307), acrylic resins (EP 0201102, JP 57-59973) and the like.

The present invention has been made to provide a new adhesive composition that satisfies the above-described characteristics, specifically used in the manufacture of flexible printed circuit boards or coverlay films, adhesive strength, heat resistance, flame retardancy, chemical resistance, insulation, contents It is an object of the present invention to provide an adhesive composition having excellent properties such as formulation and flexibility.

The present invention provides an adhesive composition composed of a high molecular weight acrylic resin, a flame retardant epoxy resin, a cresol novolac epoxy resin, an amine hardener and other additives in order to achieve the above object.

Hereinafter, the present invention will be described in detail.

The acrylic resin used in the present invention has a high molecular weight having a weight average molecular weight in the range of 500,000 to 1,500,000, wherein the monomer composition of the acrylic resin used for the polymerization is 25 to 45% by weight of acrylonitrile and 2 to carbon atoms. 50 to 70% by weight of acrylate having 10 alkyl groups, 1 to 10% by weight of acrylic acid or methacrylic acid, and 1 to 10% by weight of hydroxyethyl acrylate or hydroxyethyl methacrylate. Acrylonitrile has excellent chemical resistance and heat resistance, acrylate having an alkyl group having 2 to 10 carbon atoms gives flexibility, acrylic acid or methacrylic acid has a crosslinkable reactor by reacting with epoxy, hydroxyethyl acrylate or Hydroxyethyl methacrylate gives excellent adhesion.

Epoxy resin used in the present invention is mixed with bisphenol-based epoxy containing 18 to 50% bromine and cresol novolac-epoxy for heat resistance, and the use ratio is 100 parts by weight of brominated bisphenol-based epoxy It is preferable that the cresol novolac epoxy is in the range of 10 to 100 parts by weight.

In the present invention, an amine curing agent having excellent heat resistance such as diaminophenylmethane is mainly used as the curing agent, and antimony oxide or the like is used as an additive for improving flame retardant properties.

The mixing ratio of acrylic resin, epoxy resin, curing agent and other additives used as described above is 25 to 100 parts by weight of acrylic resin, 1 to 100 parts by weight of curing agent, and 1 to 15 parts by weight of other additives based on 100 parts by weight of epoxy resin. Good characteristics can be expected.

At this time, the acrylic resin to be used includes a carboxyl group, which can be combined with epoxy and impart flexibility and adhesiveness to the adhesive. When used in excess of the above ranges, heat resistance or flame retardancy may be reduced. Brominated bisphenol epoxy in epoxy resins impart flame retardant properties and increase adhesion, but excessive use reduces heat resistance. Cresol novolac epoxy serves to impart heat resistance, but when used excessively, adhesion and flexibility are degraded. If the curing agent is insufficient or excessive in the above limited range with respect to the epoxy content, solvent resistance, heat resistance, electrical resistance, etc. are lowered.

As described above, the adhesive prepared according to the present invention is generally used in the adhesive tape manufacturing process to have a viscosity of 100 to 200 cps. That is, the adhesive is applied on a heat resistant film so that the thickness after drying is 20 to 50 μ and 80 to 120 After drying for 1 to 20 minutes at a thickness of 5 ~ 80μ rolled copper foil, electrolytic copper foil, aluminum foil, etc. are laminated and pressure of 3 ~ 50kg / ㎠ using a metal roll or a heat resistant rubber roll heated to 100 ~ 150 ℃ It is bonded by pressing and cured at 80 to 200 ℃ for 3 to 48 hours to obtain a flexible copper clad laminate.In the case of coverlay film, instead of attaching copper plate, attach a release film or paper and apply it at 80 to 120 ℃. The coverlay film is subjected to a semi-curing process for ˜30 minutes. The coverlay film is printed on a flexible copper clad laminate and then laminated thereon, and the pressure of 10 to 60 kg / ㎠ at 160 to 180 ° C. It is adhered to the press for 30-90 minutes to.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, and the physical property evaluation performed at this time was performed by the following method.

Adhesive strength

Adhesion strength between copper foil and heat resistant film is measured according to ICP-FC-240B. Measurement conditions were measured for 180 ° peeling strength after standing for 48 hours at a temperature of 20 ℃, 65% relative humidity.

Solder Heat Resistance

The wiring surface was floated for 60 seconds on the lead melt at 260 ° C, and the appearance was observed.

Flame retardant

The adhesive layer was applied on a polyimide film at 30 mu, then dried at 100 ° C. for 5 minutes, and then tested for flame retardancy according to the UL94 standard with a sample having a width of 1 cm and a length of 12.7 cm.

Chemical resistance

According to JISC 6181, the test piece is immersed in acetone and methylene chloride at room temperature for 15 minutes, and then taken out to observe the appearance.

Long-term heat resistance

Adhesion is measured after storing the specimen at 150 ° C for 120 hours.

Water resistance

After immersing the specimen in boiling water for 1 hour, it is allowed to stand at room temperature for 1 hour and the adhesion is measured.

Insulation Resistance

According to JISC 6471, the insulation resistance is measured after being left for 96 hours at a temperature of 40 DEG C and a relative humidity of 90%.

Example 1

30 parts by weight of acrylonitrile, 60 parts by weight of butyl acrylate, 5 parts by weight of methacrylic acid, and 5 parts by weight of hydroxyethyl acrylate were mixed together with distilled water and an emulsifier to prepare a monomer mixture. KPS was dissolved in distilled water and used as a polymerization initiator, and the monomer mixture prepared in advance was added dropwise for 3.5 hours while stirring the aqueous solution of which the temperature was raised to 70 ° C. Then, the aging reaction was further performed at 70 ° C for 4.5 hours. After the reaction was completed, the temperature was cooled to room temperature, and 10% NaOH solution was added to precipitate the resin. The precipitated resin was washed with water four times after filtration and dried at 60 ° C. in a vacuum oven, and the weight average molecular weight of the resulting acrylic resin was 1,200,000.

80 parts by weight of bromobisphenol epoxy (45% bromine), 20 parts by weight of cresol novolac epoxy, 65 parts by weight of the acrylic resin obtained above, 20 parts by weight of diaminodiphenylmethane and 5 parts by weight of antimony oxide particles with an amine curing agent The viscosity of the solution was adjusted to 1,000 CPS using methyl ethyl ketone and toluene solvent.

Using this adhesive, it was applied on a polyimide film (trade name: KAPON, DUPONT) having a thickness of 25μ and dried (120 ° C, 5 minutes), followed by laminating an electrolytic copper foil having a thickness of 35μ and using a rubber roll at 140 ° C, 15 After lamination under the conditions of temperature and pressure of kg / cm 2, postcure was performed at 130 ° C. for 15 hours to completely cure the adhesive layer. A coverlay film sheet was obtained by applying onto a 25 μm-thick polyimide film using an adhesive of the same composition, drying (120 ° C., 10 minutes), and attaching a release-treated polyester film to an adhesive surface. After printing the circuit on the flexible copper-clad laminate, the coverlay film from which the release film was removed was pasted onto the printed circuit, and then bonded to the printed circuit by using a press at a temperature and pressure of 160 ° C. and 30 kg / cm 2.

The characteristics of the flexible printed circuit board manufactured as described above were evaluated and the results are shown in Table 1.

Example 2

Bromobisphenol epoxy 65 parts by weight (bromine content 45%), cresol novolac epoxy 35 parts by weight, 60 parts by weight of the acrylic resin synthesized as in Example 1, 20 parts by weight of diaminodiphenylmethane with an amine curing agent, antimony 5 A flexible printed circuit board was obtained in the same manner as in Example 1 except for mixing the parts by weight and adjusting the viscosity of the solution to 1,000 CPS using methyl ethyl ketone and toluene solvent, and the physical property evaluation results are shown in Table 1 below.

Example 3

40 parts by weight of acrylonitrile, 55 parts by weight of butyl acrylate, 2.5 parts by weight of methacrylic acid, and 2.5 parts by weight of hydroxyethyl acrylate were mixed together with distilled water and an emulsifier to prepare a monomer mixture. Then, KPS was dissolved in distilled water and used as a polymerization initiator, and the previously prepared monomer mixture was added dropwise for 3.5 hours while stirring the aqueous solution of which the temperature was raised to 70 ° C. Then, the aging reaction was further performed at 70 ° C for 4.5 hours. After the reaction was completed, the temperature was cooled to room temperature, and 10% NaOH solution was added to precipitate the resin. The precipitated resin was washed with water four times after filtration and dried at 60 ° C. in a vacuum oven, and the weight average molecular weight of the resulting acrylic resin was 900,000.

80 parts by weight of bromobisphenol epoxy (45% bromine), 20 parts by weight of cresol novolac epoxy, 65 parts by weight of the acryl resin obtained above, 20 parts by weight of diaminodiphenylmethane and 5 parts by weight of antimony oxide with an amine curing agent The viscosity of the solution was adjusted to 1,000 CPS using methyl ethyl ketone and toluene solvent.

Using this adhesive, a flexible printed circuit board was obtained in the same manner as in Example 1, and physical properties were evaluated and the results are shown in Table 1.

Example 4

60 parts by weight of bromobisphenol epoxy (bromine content 45%), 40 parts by weight of cresol novolac epoxy, 60 parts by weight of acrylic resin synthesized as in Example 3, 20 parts by weight of diaminodiphenylmethane and 5 parts by weight of antimony oxide A flexible printed circuit board was obtained in the same manner as in Example 1, except that the viscosity of the solution was adjusted to 1,000 CPS using methyl ethyl ketone and toluene solvent. The results of the evaluation are shown in Table 1 below.

Comparative Example 1

50 parts by weight of bromobisphenol epoxy (bromine content 45%), 50 parts by weight of cresol novolac epoxy, 50 parts by weight of acrylic resin prepared as in Example 1, 20 parts by weight of diaminodiphenylmethane as an amine curing agent and antimony oxide 5 A flexible printed circuit board was obtained in the same manner as in Example 1 except for mixing the weight parts and adjusting the viscosity of the solution to 1,000 CPS using methyl ethyl ketone and toluene solvent. The results of the evaluation are shown in Table 1 below. .

Comparative Example 2

100 parts by weight of bromobisphenol epoxy (45% bromine), 50 parts by weight of the acrylic resin synthesized as in Example 1, 20 parts by weight of diaminodiphenylmethane and 5 parts by weight of antimony oxide were mixed, and a methyl ethyl ketone and a toluene solvent were mixed. A flexible printed circuit board was obtained in the same manner as in Example 1 except that the viscosity of the solution was adjusted to 1,000 CPS. The physical properties were evaluated and the results are shown in Table 1.

Comparative Example 3

35 weight part of acrylonitrile, 60 weight part of butyl acrylate, and 5.0 weight part of methacrylic acid were mixed with distilled water and an emulsifier, and the monomer liquid mixture was prepared. Then, KPS was dissolved in distilled water and used as a polymerization initiator, and the previously prepared monomer mixture was added dropwise for 3.5 hours while stirring the aqueous solution of which the temperature was raised to 70 ° C. Then, the aging reaction was further performed at 70 ° C for 4.5 hours. After the reaction was completed, the temperature was cooled to room temperature, and 10% NaOH solution was added to precipitate the resin. The precipitated resin was washed with water four times after filtration and dried at 60 ° C. in a vacuum oven, and the weight average molecular weight of the resulting acrylic resin was 1,200,000.

80 parts by weight of bromobisphenol epoxy (bromine content 45%), 20 parts by weight of cresol novolac epoxy, 65 parts by weight of acrylic resin, 20 parts by weight of diaminodiphenylmethane and 5 parts by weight of antimony oxide, methyl ethyl ketone and toluene solvent Was used to adjust the viscosity of the solution to 1,000 CPS.

Using this adhesive, a flexible printed circuit board was obtained in the same manner as in Example 1, and physical properties were evaluated and the results are shown in Table 1.

[Comparative Example 4]

50 parts by weight of acrylonitrile, 45 parts by weight of butyl acrylate and 5 parts by weight of hydroxyethyl acrylate were mixed together with distilled water and an emulsifier to prepare a monomer mixture. As the polymerization initiator, KPS was dissolved in distilled water, and the aqueous monomer mixture was heated to 70 ° C. while stirring. The monomer mixture prepared in advance was added dropwise for 3.5 hours, and then aged at 4.5 ° C. for 4.5 hours. After the reaction was completed, the temperature was cooled to room temperature, and 10% NaOH solution was added to precipitate the resin. The precipitated resin was washed three to four times after filtration and dried at 60 ° C. in a vacuum oven, and the weight average molecular weight of the resulting acrylic resin was 600,000.

80 parts by weight of bromobisphenol epoxy (45% bromine), 20 parts by weight of cresol novolac epoxy, 65 parts by weight of the acrylic resin obtained above, 20 parts by weight of diaminodiphenylmethane and 5 parts by weight of antimony oxide, and methyl ethyl ketone And toluene solvent were used to adjust the viscosity of the solution to 1,000 CPS.

Using this adhesive, a flexible printed circuit board was obtained in the same manner as in Example 1, and physical properties were evaluated and the results are shown in Table 1.

[Comparative Example 5]

50 parts by weight of bromobisphenol epoxy (45% bromine), 40 parts by weight of cresol novolac epoxy, 50 parts by weight of acrylic resin prepared in Example 1, 20 parts by weight of diaminodiphenylmethane, and methyl ethyl ketone and toluene A flexible printed circuit board was obtained in the same manner as in Example 1 except that the viscosity of the solution was adjusted to 1,000 CPS by using a solvent, and the physical properties thereof were shown in Table 1 below.

TABLE 1

As can be seen from the above examples and comparative examples, the adhesive composition according to the present invention has excellent performance in various properties such as adhesive strength, heat resistance, chemical resistance, flame retardancy, and insulation when used in the manufacture of a flexible printed circuit board or coverlay film. Indicates.

Claims (4)

100 parts by weight of an epoxy resin containing 18-50% bromine bisphenol epoxy and cresol novolac epoxy, 25-45% by weight acrylonitrile and 50-70% by weight acrylate having an alkyl group having 2-10 carbon atoms. Adhesive composition, characterized in that consisting of 25 to 100 parts by weight of acrylic resin, 1 to 100 parts by weight of heat-resistant amine hardener, and 1 to 15 parts by weight of other additives, which are made of% and monomers composed of 1 to 10% by weight of acrylic acid or methacrylic acid. The adhesive composition according to claim 1, wherein the epoxy resin is mixed with 10 to 100 parts by weight of cresol novolac epoxy based on 100 parts by weight of the brominated bisphenol epoxy. The adhesive composition of claim 1 wherein the amine curing agent is diaminodiphenylmethane. The adhesive composition according to claim 1, wherein antimony oxide is used to improve flame retardancy as other additives.