JPH07286117A - Photo-setting moistureproof insulating coating and production of moistureproof insulated electronic part - Google Patents

Abstract

PURPOSE:To provide a coating capable of providing electronic parts excellent in curability and moisture resistance, hardly deteriorating the flexibility even when thermally degraded and improved in reliability. CONSTITUTION:This photo-setting moistureproof insulating coating contains (A) a photo-setting terminal acryloyloxypolybutadiene or a terminal methacryloyloxypolybutadiene having 300-10,000 number-average molecular weight and >=90% hydrogenation ratio, (B) an acrylic or a methacrylic monomer having a cyclic structure, (C) a wax and (D) a photopolymerization initiator. Furthermore, this method for producing moistureproof insulated electronic parts is to coat the electronic parts with the resultant coating and curing the coating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photocurable moisture-proof insulating coating suitable for moisture-proofing and insulating electronic parts and a method for producing electronic parts treated with the same.

[0002]

2. Description of the Related Art Conventionally, a mounting circuit board and a hybrid I
For electronic components such as C (integrated circuit), a wiring diagram is printed on a substrate such as glass epoxy, paper phenol, and alumina ceramic, and various components such as a microcomputer, a resistor, and a capacitor are mounted. Insulation is performed to protect it from dust. As the insulation treatment method, a protective coating treatment using a paint such as acrylic resin, silicone resin, phenol resin, or epoxy resin is widely adopted. Such a mounting circuit board and a hybrid IC are used in a harsh environment, particularly under high humidity, and are mounted and used in equipment such as an automobile and a washing machine.

[0003]

However, since the coating material is heat-curable, high temperature treatment and long-time treatment are required to completely cure the coating material and obtain an insulating effect. On the other hand, an ultraviolet curable resin coating composition that can be cured in a short time, for example, in a few seconds to a few minutes has been developed, but a coating material having sufficient flexibility and moisture resistance has not yet been obtained. In addition, a portion such as a lower portion of the mounted component which is not irradiated with ultraviolet rays is in a liquid state and is in an uncured state, and there is a possibility that reliability of the electronic component is deteriorated. The present invention solves the above-mentioned problems of the prior art, can be treated for a short time, and produces a coating film excellent in flexibility and moisture resistance. It is an object of the present invention to provide a method of manufacturing a moisture-proof insulated electronic component.

[0004]

The present invention provides (A) a number average molecular weight of 300 to 10,000 and a hydrogenation rate of 90%.
It contains the above-mentioned photo-curable terminal acryloxy polybutadiene or terminal methacryloxy polybutadiene, (B) an acrylic monomer or methacrylic monomer having a cyclic structure, (C) wax and (D) a photopolymerization initiator. The present invention relates to a photocurable moisture-proof insulating coating material and a method for producing a moisture-proof insulating electronic component, which comprises applying and curing the coating material on an electronic component.

The photocurable terminal acryloxypolybutadiene or terminal methacryloxypolybutadiene (A) used in the present invention is obtained by reacting a terminal hydroxypolybutadiene having a hydrogenation rate of 90% or more with a polyisocyanate, followed by hydroxyethyl. It is an acryl-modified hydrogenated polybutadiene resin having a number average molecular weight of 300 to 10,000 obtained by reacting acrylate or hydroxyethyl methacrylate. The number average molecular weight of this resin is 300 to 10,000, preferably 500 to 5,0.
00, the hydrogenation rate is 90% or more, preferably 95% or more. When the number average molecular weight is less than 300, the film-forming property is poor, and when it exceeds 10,000, the viscosity is high and the workability is poor. On the other hand, if the hydrogenation rate is less than 90%, the flexibility of the obtained coating film after heat deterioration is lowered and the heat resistance is deteriorated. Commercially available products of this acrylic modified hydrogenated polybutadiene resin are trade names TEAI-1000 and TEA manufactured by Nippon Soda Co., Ltd.
I-3000 and the like can be mentioned, and these can be used alone or in combination of two or more kinds.

As the acrylic monomer or methacrylic monomer (B) having a cyclic structure used in the present invention,
Benzyl acrylate, cyclohexyl acrylate,
Phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, dicyclopentenyl acrylate, isobornyl acrylate, benzyl methacrylate, cyclohexyl methacrylate, phenoxyethyl methacrylate, tetrahydrofurfuryl methacrylate, isobornyl methacrylate and the like, which may be used alone or in combination. The above can be used in combination. The mixing ratio of these monomers (B) is 10 to 20 with respect to 100 parts by weight of the above-mentioned component (A) from the viewpoint of the curing speed and the viscosity of the coating material.
The range of 0 parts by weight is preferable, and the range of 50 to 100 parts by weight is more preferable.

The wax (C) used in the present invention is a natural wax or a synthetic wax such as carnauba wax, rice wax, beeswax, paraffin wax and microcrystalline wax which is solid at room temperature and has extremely low volatility when melted. is there. These can be used alone or in combination of two or more. The mixing ratio of the wax (C) is preferably 5 to 100 parts by weight, and more preferably 10 to 50 parts by weight with respect to 100 parts by weight of the component (A) in view of prevention of stickiness and flexibility of the coating film. More preferable.

The photopolymerization initiator (D) used in the present invention includes benzyl dimethyl ketal, benzoin, benzoin ethyl ether, benzoin propyl ether,
Examples thereof include benzoin ethers such as benzoin phenyl ether, benzoin thioethers, benzophenone, acetophenone, 2-ethylanthraquinone furoine, benzoin ether Michler's ketone, decylnothioxanthone chloride, etc. These may be used alone or in combination of two or more. Can be used. The mixing ratio of these photopolymerization initiators (C) is preferably in the range of 0.01 to 10 parts by weight with respect to 100 parts by weight of the above-mentioned component (A) from the viewpoint of curing rate and film-forming property, and is 0.1 to 10. A range of 5 parts by weight is more preferable.

The photocurable moisture-proof insulating coating material of the present invention can be obtained by blending the above-mentioned components (A), (B), (C) and (D) and heating and dissolving them. In addition, a crosslinkable monomer, a silane coupling agent, a polymerization inhibitor, etc. can be added to the photocurable moisture-proof insulating coating material of the present invention, if necessary.

Examples of the crosslinkable monomer include styrene, vinyltoluene, α-methylstyrene, p-tertiarybutylstyrene, chlorostyrene, divinylbenzene, diallylphthalate, 2-hydrooxyethyl methacrylate and 2-hydrooxypropyl methacrylate. , A monofunctional methacrylic acid ester such as a reaction product of methyl methacrylate, ethyl methacrylate, lauryl methacrylate, methacrylic acid and Cardura E-10 (trade name of glycidyl ester of higher fatty acid, manufactured by Shell Chemical Co., Ltd.),
Bifunctional methacrylic acid esters such as ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, and 1,6-hexanediol dimethacrylate, trifunctional methacrylic acid esters such as trimethylolpropane trimethacrylate, methyl acrylate, ethyl acrylate, and lauryl acrylate. , 2-
Hydroxyethyl acrylate, 2-hydroxypropyl acrylate, acrylic acid and Cardura E-10
Reaction products such as monofunctional acrylic acid esters, ethylene glycol diacrylate, diethylene glycol diacrylate, difunctional acrylic acid esters such as 1,6-hexanediol diacrylate, and trifunctional trimethylolpropane triacrylate. Acrylic acid esters and the like are used, and these can be used alone or in combination of two or more kinds.

Examples of the silane coupling agent include γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, vinyltrimethoxysilane and vinyltriethoxysilane. These may be used alone or in combination of two or more.

As the polymerization inhibitor, quinones such as hydroquinone, paratertiary butyl catechol and pyrogallol, and other commonly used ones can be used.

Electronic components such as mounted circuit boards and hybrid ICs that are moisture-proof insulated using the photocurable moisture-proof insulating coating material according to the present invention are manufactured by a generally known brush coating method. The coating material may be applied to the electronic component and cured by a dipping method (dip method), a spray method, or the like. Curing of the coating film after coating is performed by ultraviolet irradiation.

[0014]

EXAMPLES The present invention will now be described with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. Those expressed as "parts" indicate parts by weight. Example 1 TEAI-1000 (manufactured by Nippon Soda Co., Ltd., acrylic modified hydrogenated polybutadiene resin, number average molecular weight: about 1,
000, hydrogenation ratio: 97%) 60 parts, benzyl acrylate 40 parts, carnauba wax (manufactured by Nikka Seiko Co., Ltd., trade name purified carnauba wax No. 2) 30 parts and benzyl dimethyl ketal 5 parts at a temperature of 80 ° C. Paint A was obtained by mixing and stirring under the conditions.

Example 2 TEAI-1000 (manufactured by Nippon Soda Co., Ltd., acrylic modified hydrogenated polybutadiene resin, number average molecular weight: about 1,
000, hydrogenation rate: 97%) 60 parts, isobornyl methacrylate 40 parts, carnauba wax (manufactured by Nikka Seiko Co., Ltd., trade name purified carnauba wax No. 2) 30 parts and benzophenone 5 parts at a temperature of 80 ° C. A paint B was obtained by mixing and stirring under the conditions.

Comparative Example 1 TE-2000 (manufactured by Nippon Soda Co., Ltd., terminal methacryloyl group polybutadiene resin, number average molecular weight: about 2,000)
0) 100 parts, benzyl dimethyl ketal 5 parts and toluene 100 parts were mixed and stirred at a temperature of 50 ° C. to obtain coating C.

Comparative Example 2 TEAI-1000 (manufactured by Nippon Soda Co., Ltd., acrylic modified hydrogenated polybutadiene resin, number average molecular weight: about 1,
000, hydrogenation rate: 97%) and 5 parts of benzyl dimethyl ketal were mixed and stirred at a temperature of 100 ° C. to obtain a coating D.

The paints A to D obtained as described above are applied by dipping onto a mounting circuit board on which wiring is printed on a glass epoxy copper clad laminate and ICs and resistors are mounted. Irradiation output manufactured by USHIO INC. Was irradiated with ultraviolet rays from a mercury lamp of 50 W / cm for an irradiation distance of 10 cm for 120 seconds to prepare a test piece for evaluation of curability, and the curability was tested. Also, these paints were applied by a dipping method to a comb-shaped electrode made of glass epoxy copper clad laminate (electrode gap 0.3 mm, made of electrode AgPd),
It was cured under the above-mentioned curing conditions to prepare a test piece for a moisture resistance test, and the moisture resistance was tested. Further, with respect to these test pieces, test pieces for bending test were prepared in accordance with JIS C2103 and cured under the above-mentioned curing conditions, and the temperature was raised to 100 at 80 ° C.
It was left for a period of time and tested for flexibility. The results are shown in Table 1. When applying the coating materials A, B and D by the dipping method,
Paints A, B and D were used after being heated to 80 ° C. Also,
Moisture resistance was measured by leaving the test piece for a humidity resistance test at 14 ° C and 85% RH in a constant temperature and humidity chamber while applying DC14V, and taking out from the constant temperature and humidity chamber at each standing time shown in Table 1 and after 2 hours 2
DC500V was applied at 3 degreeC, and insulation resistance was measured and evaluated.

[0019]

[Table 1]

[0020]

As shown in Table 1, the photocurable moisture-proof insulating coating material according to the present invention is excellent in curability and moisture resistance, and has heat resistance that hardly deteriorates flexibility even when deteriorated by heating. It is an excellent paint, and it is possible to manufacture electronic parts with improved reliability.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Eiji Omori 4-13-1, Higashimachi, Hitachi City, Ibaraki Prefecture Hitachi Chemical Co., Ltd. Yamazaki Factory

Claims (2)

[Claims] 1. (A) Number average molecular weight of 300 to 10,0
00, a photocurable terminal acryloxypolybutadiene or terminal methacryloxypolybutadiene having a hydrogenation rate of 90% or more, (B) an acrylic monomer or methacrylic monomer having a cyclic structure, (C) a wax and ( D) A photocurable moisture-proof insulating coating material containing a photopolymerization initiator. 2. A method for producing a moisture-proof insulated electronic component, which comprises applying the photocurable moisture-proof insulating coating composition according to claim 1 to an electronic component and curing it.