KR19990019014A - Adhesive composition for flexible printed circuit board - 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 high molecular weight water-soluble acrylic resin, epoxy resin, tertiary amine hardener, flame retardant and other additives and water, wherein the adhesive having such a composition has heat resistance, flame retardancy, flexibility, chemical resistance, and adhesive strength. Various physical properties such as such have excellent characteristics, and are particularly suitable for manufacturing a flexible printed circuit board or coverlay film.

Description

Adhesive composition for flexible printed circuit board

BACKGROUND OF THE INVENTION 1. Field of the Invention 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 coverlay film.

Recently, the trend of miniaturization, high integration, simplification, and high performance has been prominent in the electric and electronic industries. To satisfy these demands, it is absolutely necessary to develop a flexible printed circuit board having flexibility and integration of circuits. . The flexible printed circuit board can be folded according to the internal structure of the product because the substrate itself is flexible, and it is made of a very thin material, which takes up a small space and has a merit of sufficiently serving as a circuit board.

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, they have excellent thermal, mechanical, and electrical properties, so that an adhesive is applied to these substrates, and a conductor such as copper or aluminum is adhered to, and screen printing and dry film photoresist are applied on the surface of the metal conductor. The circuit is printed using and the metal foil is etched. In order to protect the printed circuit, coverlay film is coated with an adhesive on a film of the same material as the original and semi-cured, and then a film or paper having a release property is used as a protective sheet on the adhesive surface, and when used, peel off the release film or the release paper. It is protected by covering the printed circuit surface 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, and in the case of coverlays, the adhesive flows out of the film during lamination processing. It should be small and fill gaps between circuits well and have long life span in semi-cured state. The shelf life should be approximately three months at room temperature and six months at 5 ° C.

Adhesives used in flexible printed circuit boards include acrylonitrile-butadiene rubber / epoxy resins (Japanese Patent Application No. 0-79079, Japanese Patent Application No. 3-186787), and polyester / epoxy watches (Japanese Patent Application No. 63-297438, Japan). Japanese Patent Application Laid-Open No.63-275178, Japanese Patent Application Laid-Open No. 1-170091), Butyral Resin System, Nylon / Epoxy Resin System (Japan Open Small 7-64997), Acrylic Resin / Phenol Resin System (Japanese Patent Application Laid-Open No. 61-261307), Acrylic Resin System (EP 0201102) Japanese Patent Laid-Open No. 57-59973).

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

The present invention provides an adhesive composition composed of a high molecular weight water-soluble acrylic resin and a polyfunctional water-soluble epoxy resin having three or more epoxy groups, an amine curing agent, other additives and water 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 methylacrylic acid, and 1 to 10% by weight of hydroxyethyl acrylate or hydroxyethyl metal acrylate. Acrylonitrile is excellent in 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, hardoxyethyl acrylate or Hydroxyethyl methacrylate gives excellent adhesion.

In the present invention, as the epoxy resin, a water-soluble epoxy resin having three or more epoxy groups and excellent heat resistance and adhesive strength is used. The amount of the epoxy resin is 5-50 parts by weight based on 100 parts by weight of the acrylic resin. At this time, if the amount is less than 5 parts by weight, the heat resistance or adhesion is insignificant, and if it exceeds 50 parts by weight, the flexibility is lowered.

In the present invention, a tertiary amine-based curing agent such as triethanolamine and dimethylethanolamine is mainly used as a curing agent, and a compound containing a halogen or a phosphorus component as an additive for improving flame retardant properties or oxidized into particles Antimony is used. At this time, the amount of the curing agent is used in the range of 0.001-5 parts by weight with respect to 100 parts by weight of the acrylic resin, if insufficient or excessive solvent resistance, heat resistance and the like is lowered. In addition, it is preferable to use 5-50 parts by weight of the flame retardant containing halogen and phosphorus component and 1-30 parts by weight of antimony oxide.

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 μm and 80 to 80 After drying for 1 to 20 minutes at 120 ° C., rolled copper foil, electrolytic copper foil, aluminum foil, etc., each having a thickness of 5 to 80 μm, laminated, and a pressure of 3 to 50 kg / cm 2 using a metal roll or a heat resistant rubber roll heated to 100 to 150 ° C. 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 / cm 2 at 160 to 180 ° C. It is adhered to the press for 30-90 minutes.

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 ° peel 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 is 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 immersion in water for 1 hour to break the specimen, leave for 1 hour at room temperature and measure the adhesion.

Insulation Resistance

Insulation resistance is measured after leaving for 96 hours at the temperature of 40 degreeC and 90% of a relative humidity based on JISC 6181.

(Example 1)

30 parts by weight of acrylonitrile, 60 parts by weight of butyl acrylate, 5 parts by weight of glycidyl methacrylate, and 5 parts by weight of hydroxy ethyl 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 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 to obtain an acrylic resin having a solid content of 40% by weight, wherein the weight average molecular weight of the acrylic resin was 1,200,000. 100 parts by weight of the acrylic resin and 35 parts by weight of the polyfunctional water-soluble epoxy resin (trade name: EX-614, NAGASE), 0.35 parts by weight of dimethylethanolamine as an amine curing agent, 2 parts by weight of antimony oxide particles, and a flame retardant (brand name: HP-36 , GREAT LAKES) 40 parts by weight of the solution was adjusted to 1,000 CPS.

Using this adhesive, apply on 25μ thick polyimide film (trade name: KAPTON, DUPONT), dry (120 ℃, 5 minutes), laminate 35μ thick electrolytic copper foil, and use rubber roll to 140 ℃, 15Kg / ㎠ After lamination under the condition of the temperature and pressure of postcure at 130 ℃ 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 a circuit on a flexible copper clad laminate, a flexible printed circuit board was manufactured by attaching a coverlay film from which a release film was removed and pasting the printed circuit onto a printed circuit at a temperature and pressure of 160 ° C. and 30 kg / cm 2 using a press.

The characteristics of the flexible printed circuit board thus manufactured were evaluated, and the results are shown in Table 1.

(Example 2)

40 parts by weight of acrylonitrile, 50 parts by weight of butyl acrylate, 5 parts by weight of glycidyl methacrylate, and 5 parts by weight of hydroxyethyl acrylate were mixed together with distilled water and an emulsifier to prepare a monomer mixture. KPS was distilled water as a polymerization initiator. The monomer mixture prepared in advance was stirred for 3.5 hours while stirring the aqueous solution heated to 70 ° C., and then aged at 4.5 ° C. for 4.5 hours. After the reaction was completed, the temperature was cooled to room temperature to obtain an acrylic resin having a solid content of 40% and a weight average molecular weight of 1,000,000.

Using the acrylic resin obtained above, an adhesive was prepared in the same manner as in Example 1, and a flexible printed circuit board was manufactured. The characteristics thereof were evaluated, and the results are shown in Table 1 below.

(Comparative Example 1)

35 parts by weight of acrylonitrile, 60 parts by weight of butyl acrylate and 5 parts by weight of glycidyl methacrylate were mixed with distilled water and an emulsifier to prepare a monomer mixture. As the polymerization initiator, KPS was dissolved in distilled water, and the prepared monomer mixture was added dropwise for 3.5 hours while stirring the aqueous solution heated to 70 ° C, and then aged at 4.5 ° C for 4.5 hours. After the reaction was completed, the temperature was cooled to room temperature to obtain an acrylic resin having a solid content of 40% and a weight average molecular weight of 1,000,000.

Using the acrylic resin obtained above, an adhesive was prepared in the same manner as in Example 1, and a flexible printed circuit board was manufactured. The results of the evaluation are shown in Table 1 below.

(Comparative Example 2)

35 parts by weight of acrylonitrile, 60 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 solution was heated to 70 ° C., and the prepared monomer mixture 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 to obtain an acrylic resin having a solid content of 40% and a weight average molecular weight of 1,000,000.

Using the acrylic resin obtained above, an adhesive was prepared in the same manner as in Example 1, and a flexible printed circuit board was manufactured. The results of the evaluation are shown in Table 1 below.

(Comparative Example 3)

30 parts by weight of acrylonitrile, 60 parts by weight of butyl acrylate, 5 parts by weight of glycidyl methacrylate, 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 prepared monomer mixture was added dropwise for 3.5 hours while stirring the aqueous solution heated to 70 ° C, and then aged at 4.5 ° C for 4.5 hours. After the reaction was completed, the temperature was cooled to room temperature to obtain an acrylic resin having a solid content of 40% and a weight average molecular weight of 1,200,000.

100 parts by weight of the acrylic resin obtained above, 35 parts by weight of a polyfunctional water-soluble epoxy resin (trade name: EX-614, NAGASE Co., Ltd.), and 0.35 parts by weight of dimethylethanolamine were added, and the viscosity of the solution was 800-1000 CPS using distilled water. Set to.

Using the adhesive obtained above, a flexible printed circuit board was manufactured in the same manner as in Example 1, and the results thereof are shown in Table 1 below.

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

Claims (4)

100 parts by weight of water-soluble acrylic resin, 5-50 parts by weight of water-soluble epoxy resin having three or more epoxy groups, 0.01-5 parts by weight of tertiary amine, 5-50 parts by weight of flame retardant compound containing halogen or phosphorus and antimony oxide 1- Adhesive composition for flexible printed circuit board, characterized in that consisting of 30 parts by weight, other additives and water The adhesive composition for a flexible printed circuit board according to claim 1, wherein a water-soluble acrylic resin has a high molecular weight having a weight average molecular weight of 500,000-1,500,000. The adhesive composition according to claim 1, wherein the tertiary amine as a curing agent is selected from triethanol amine or dimethylethanol amine. The adhesive composition for a flexible printed circuit board according to claim 1, wherein the adhesive is used with a viscosity of 100-200 CPS.