JPH06268357A - Manufacture of mounting circuit board to which treatment for moisture-proof and insulation is applied - Google Patents

Abstract

PURPOSE:To provide a mounting circuit board in which a moisure-proofed and insulated protective layer of excellent moisture resistance and adhesiveness is formed and to which treatment for high-reliability moisture proof and insulation is applied. CONSTITUTION:This manufacture of a mounting circuit board to which treatment for moisture-proof and insulation is applied comprises the steps of (A) coating, drying and hardening the polymer or the copolymer of alkyl ester of acrylic acid having a transition point of 0 to 80 deg.C and/or alkyl ester of methacrylic acid and then (B) injecting into a molding die and hardening a polyurethane resin composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a mounted circuit board that has been subjected to a moisture-proof insulation treatment.

[0002]

2. Description of the Related Art Conventionally, a printed circuit board on which a wiring diagram is printed on a laminated board of glass-epoxy resin, paper-phenol resin, etc., and various electronic parts such as a microcomputer, a resistor and a capacitor are mounted is not Insulation treatment is performed to protect it from damage. As the insulation treatment method, a method of protective coating with a moisture-proof insulating paint in which an acrylic resin, a silicone resin or the like is dissolved, or a casting method with a polyurethane resin, an epoxy resin or an unsaturated polyester resin is widely adopted. Such a mounting circuit board is used in a harsh environment, especially under high humidity, and is mounted and used in equipment such as an automobile and a washing machine.

However, in the conventional moisture-proof insulation treatment method, for example, the moisture-proof insulation paint cannot completely protect the tips of the leads of various electronic components mounted on the mounting circuit board, and if used for a long time under high humidity, Moisture causes corrosion on the tip of the lead and reduces reliability. In addition, the casting process with the polyurethane resin composition can completely protect the tip of the lead, but if it is used for a long time in high humidity, the resin will peel off at the adhesive interface between the circuit board and the polyurethane resin due to moisture absorption of the resin. The reliability of the circuit board may decrease.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a highly reliable packaging circuit board having excellent insulation and humidity resistance under high humidity. The present invention provides a method for manufacturing an insulating-processed mounted circuit board.

[0005]

SUMMARY OF THE INVENTION The present invention provides a mounting circuit board having (A) a polymer or copolymer of an alkyl ester of acrylic acid and / or an alkyl ester of methacrylic acid having a glass transition point of 0 to 80 ° C. The present invention relates to a method for producing a moisture-proof insulating-processed mounted circuit board, which comprises coating, drying, or curing, followed by casting and curing with (B) a polyurethane resin composition.

The above-mentioned polymer or copolymer having a glass transition point (Tg) of the component (A) used in the present invention is 0 to 80 ° C. is known, and is produced by a known method. .

Examples of the alkyl ester of acrylic acid and the alkyl ester of methacrylic acid include, but are not limited to, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate. Not something.
A copolymer of an alkyl ester of acrylic acid and an alkyl ester of methacrylic acid is also used. If the glass transition point of a polymer of an alkyl ester of acrylic acid or an alkyl ester of methacrylic acid or a copolymer thereof is less than 0 ° C, stickiness remains after drying, and if it exceeds 80 ° C, the coating film becomes hard and peels off. And cracks are likely to occur.
The preferred glass transition point is in the range of 5 to 50 ° C.

The polyurethane resin composition of the component (B) of the present invention is a known resin composition and is produced by reacting an organic compound having a hydroxyl group in the molecule with an organic compound having an isocyanate group in the molecule. It is something.

Examples of the organic compound having a hydroxyl group in the molecule include, but are not limited to, castor oil, castor oil exchange ester compound, polybutadiene-based polyol, polyether-based polyol, polyester-based polyol and the like.

Examples of the organic compound having an isocyanate group in the molecule include tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, xylylene diisocyanate, diphenyl sulfone diisocyanate, triphenylmethane diisocyanate, hexamethylene diisocyanate, 3-isocyanate methyl-3, 5,5-trimethylcyclohexyl isocyanate, 3-isocyanate ethyl-3,
5,5-trimethylcyclohexyl isocyanate, 3
-Isocyanate Ethyl-3,5,5-triethylcyclohexyl isocyanate, diphenylpropane diisocyanate, phenylene diisocyanate, cyclohexylylene diisocyanate, 3,3'-diisocyanate dipropyl ether, triphenylmethane triisocyanate, diphenyl ether-4,4'-diisocyanate, etc. Polyisocyanate of, those isocyanates blocked with phenols, oximes, imides, mercaptans, alcohols, ε-caprolactane, ethyleneimine, α-pyrrolidone, diethyl malonate, sodium bisulfite, boric acid, etc. , Carbodiimide-modified diphenylmethane diisocyanate, and other prepolymers having terminal isocyanate groups derived from these isocyanates Examples include limers. These may be used alone or in combination.

From the viewpoint of obtaining curability and excellent physical properties, the amount of the polyisocyanate compound blended is 0.8 to 1.3 equivalents relative to the hydroxyl group in the organic compound having an isocyanate group in the polyisocyanate compound. It is preferably used in the range of ratio.

Further, the polyurethane resin composition includes flame retardants such as phosphorus compounds and halogen compounds, plasticizers such as phthalates and sebacates, fillers, pigments,
You may mix | blend various additives, such as a dye, as needed.

The method for producing the moisture-proof insulating-processed mounting circuit board according to the present invention includes a brushing method, a dipping method (dipping method), a spray method, etc., of the polymer or copolymer of the component (A) on the mounting circuit board. After coating with, the composition is dried and cured, and then the polyurethane resin composition of the component (B) is cast and cured.

[0014]

EXAMPLES Example 1 and Comparative Examples 1 to 2 Hereinafter, the present invention will be described with reference to Examples and Comparative Examples.
The invention is not limited to these examples. In addition,
Parts in Examples and Comparative Examples mean parts by weight. 1) Synthesis of Acrylic Copolymer 214 parts of butyl methacrylate, 25 parts of butyl acrylate and 150 parts of toluene are charged into a 4-liter separable flask having a capacity of 1 liter, and the temperature is raised to 90 ° C. while keeping the temperature while passing nitrogen gas. 200 parts of butyl methacrylate, 21 parts of butyl acrylate, and 3 parts of azobisisobutyrotolyl were mixed and dissolved in this, and the solution was added dropwise over 2 hours to proceed with polymerization. After that, the temperature was raised to 110 ° C., the temperature was kept for 2 hours, the polymerization was completed and then cooled. When the temperature reached 50 ° C., 200 parts of toluene was charged and stirred for 10 minutes to obtain a uniform solution. 25 using this solution
A film having a thickness of μ was prepared, and the glass transition point (Tg) was 12 ° C. as measured by the Ventration method of TMS (Thermal Physical Tester).

2) Synthesis of polyurethane resin 100 parts of 1,4-polybutadiene polyol (manufactured by Idemitsu Petrochemical Co., Ltd., trade name: Polybd R-45HT),
40 parts of dioctyl phthalate and 13 parts of carbodiimide-modified diphenylmethane diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., trade name: Millionate MTL) were mixed to obtain a polyurethane resin composition.

The acrylic copolymer and the polyurethane resin composition obtained above were combined in the combinations shown in Table 1 to print wiring on a glass epoxy copper clad laminate, respectively, and dip it on a mounting circuit board on which an IC and a resistor were mounted. Was coated with, dried at 60 ° C. for 2 hours, then cast by pouring, cured at 80 ° C. for 2 hours to prepare a water resistance evaluation test piece, and tested for water resistance. Further, the glass epoxy copper clad laminates each coated with the solder resist in the combinations shown in Table 1 were coated with a bar coater to a coating thickness of 40 μm and cured at 80 ° C. for 2 hours to evaluate the adhesion. Test pieces were prepared and tested for adhesion.

[0017]

[Table 1] * 1 Water resistance The soldering surface on the back surface of the mounted circuit board that had been subjected to moisture-proof insulation was immersed in water, a voltage of 100 V was applied, and the corrosion state of the lead tips of each electronic component was observed. ◯: No corrosion on lead tip ×: Corrosion on lead tip * 2 A goose eye test was performed by a goose eye tape peeling test. * 3 The test piece shown in FIGS. 1 (A) and 1 (B) was prepared and measured with an autograph tester (manufactured by Shimadzu Corporation) at a pulling speed of 20 mm / min in the pulling direction indicated by the arrow in FIG. .

[0018]

According to the method of manufacturing a mounting circuit board of the present invention,
By forming the moisture-proof insulating protective layer having excellent moisture resistance and adhesion, it is possible to obtain a highly reliable moisture-proof insulating-treated mounted circuit board.

[Brief description of drawings]

FIG. 1 is a schematic view of a test piece for adhesion test used in Examples and Comparative Examples.

[Explanation of symbols]

 1 Solder Resist Coated Laminate 2 Acrylic Copolymer or Polyurethane Resin Composition 3 Mylar Film

Claims (1)

[Claims] 1. A (A) glass transition point is 0 on a mounting circuit board.
Characterized by coating, drying or curing a polymer or copolymer of an alkyl ester of acrylic acid and / or an alkyl ester of methacrylic acid at -80 ° C, and then casting and curing with the (B) polyurethane resin composition. And a method for manufacturing a moisture-proof insulated circuit board.