JPH05179173A - Photocurable moistureproofing insulating coating material and production of moistureproof insulated electronic component - Google Patents

Abstract

PURPOSE:To obtain the title material which can give a coating film excellent in moistureproofness and heat resistance by mixing a plurality of specified (meth)acryloxy-terminated polybutadienes with a wax and a photopolymerization initiator. CONSTITUTION:The title material comprises a photocurable (meth)acryloxy- terminated polybutadiene of a number-average molecular weight of 300-10000 and a degree of hydrogenation of 90% or above (e.g. TEAI-1000, a product of Nippon Soda Ltd.), a photocurable (meth)acryloxy-terminated polybutadiene of a number-average molecular weight of 300-10000 (e.g. TE-2000, a product of Nippon Soda Ltd.), a wax (e.g. microcrystalline wax) and a photopolymerization initiator (e.g. benzil dimethyl ketal).

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
Electronic components such as C (integrated circuit) are printed with a wiring diagram 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 on them. 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 under a harsh environment, especially 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 period of time, for example, in a few seconds to a few minutes has been developed, but one 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 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%.
The above-mentioned photo-curable terminal acryloxy polybutadiene or terminal methacryloxy polybutadiene, (B) photo-curable terminal acryloxy polybutadiene or terminal methacryloxy polybutadiene having a number average molecular weight of 300 to 10,000, (C) wax and ( D) A photocurable moisture-proof insulating coating material containing a photopolymerization initiator, and a method for producing a moisture-proof insulated electronic component by applying the coating composition to an electronic component and curing it.

The photocurable terminal acryloxypolybutadiene or methacryloxypolybutadiene (A) having a hydrogenation rate of 90% or more used in the present invention is a terminal hydroxypolybutadiene having a hydrogenation rate of 90% or more.
The number average molecular weight obtained by reacting with polyisocyanate and then with hydroxyethyl acrylate or hydroxyethyl methacrylate is 300 to 10,
000 acrylic modified hydrogenated polybutadiene resin. The number average molecular weight of this resin is 300 to 10,000,
The hydrogenation rate is preferably 500 to 5,000, and the hydrogenation rate is 90% or more, preferably 95% or more. Number average molecular weight is 3
When it is less than 00, the film-forming property is poor, and when it exceeds 10,000, the viscosity is high and the workability is poor. The hydrogenation rate is 90%
If it is less than 4, the flexibility of the resulting coating film after heat deterioration is lowered, and the heat resistance is poor. Commercially available products of this acryl-modified hydrogenated polybutadiene resin are trade name T manufactured by Nippon Soda
EAI-1000, TEAI-3000, etc. are mentioned.

The photocurable terminal acryloxypolybutadiene or terminal methacryloxypolybutadiene (B) used in the present invention is a terminal hydroxypolybutadiene,
The number average molecular weight obtained by reacting with polyisocyanate and then with hydroxyethyl acrylate or hydroxyethyl methacrylate is 300 to 10,
000 acrylic modified polybutadiene resin. The number average molecular weight of this resin is 300 to 10,000, preferably 500 to 5,000. Number average molecular weight is 300
If it is less than 100%, the film-forming property is poor, and if it exceeds 10,000, the viscosity is high and the workability is poor. A commercially available product of this acrylic-modified polybutadiene resin is TE manufactured by Nippon Soda Co., Ltd.
-2000 etc. are mentioned. The blending ratio of the acrylic modified polybutadiene resin (B) is preferably 5 to 150 parts by weight, more preferably 10 to 100 parts by weight based on 100 parts by weight of the component (A) in view of flexibility of the coating film. 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 are solid at room temperature and have extremely low volatility when melted. is there. These can be used alone or in combination of two or more. The blending ratio of the wax (C) is preferably 5 to 100 parts by weight, more preferably 10 to 50 parts by weight, based on 100 parts by weight of the component (A), from the viewpoint of preventing stickiness and flexibility of the coating film. preferable.

Photopolymerization initiator (D) used in the present invention
Is benzoin ether such as benzyl dimethyl ketal, benzoin, benzoin ethyl ether, benzoin propyl ether, benzoin phenyl ether,
Examples thereof include benzoin thioethers, benzophenone, acetophenone, 2-ethylanthraquinone furoine, benzoin ether Michler's ketone, decylnothioxanthone chloride, etc. These can be used alone or in combination of two or more. These photopolymerization initiators (D)
From the viewpoint of curing speed and film-forming property, the blending ratio is preferably 0.01 to 20 parts by weight, and more preferably 0.1 to 15 parts by weight with respect to 100 parts by weight of the component (A).

The photocurable moisture-proof insulating coating material of the present invention can be obtained by blending the components (A), (B), (C) and (D), and heating and dissolving. (A),
The components (B), (C) and (D) may be used in combination of two or more kinds. 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-tert-butylstyrene, 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, 1,6-hexanediol dimethacrylate, trifunctional methacrylic acid esters such as trimethylolpropane trimethacrylate, methyl acrylate, ethyl acrylate, lauryl acrylate , 2-
Hydroxyethyl acrylate, 2-hydroxypropyl acrylate, acrylic acid and Cardura E-10
Reaction products such as monofunctional acrylic acid ester, ethylene glycol diacrylate, diethylene glycol diacrylate, difunctional acrylic acid ester 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. Can be mentioned.
These can 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, which are moisture-proof insulated using the photocurable moisture-proof insulating coating material of 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 irradiation with ultraviolet rays.

[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 rate: 97%) 100 parts, TE-200
0 (manufactured by Nippon Soda Co., Ltd., acrylic modified polybutadiene resin, number average molecular weight: about 2,000) 25 parts, Hi-M
40 parts of ic-1080 (manufactured by Nippon Seiro Co., Ltd., microcrystalline wax, melting point: 84 ° C.) and 3.5 parts of benzyl dimethyl ketal were mixed and stirred at a temperature of 120 ° C. to obtain a paint A.

Comparative Example 1 TE-2000 (manufactured by Nippon Soda Co., Ltd., acrylic modified polybutadiene resin, number average molecular weight: about 2,000) 10
0 part, benzyl dimethyl ketal 2 parts and toluene 1
A coating material B was obtained by mixing and stirring 00 parts at a temperature of 50 ° 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 2 parts of benzyl dimethyl ketal were mixed and stirred at a temperature of 100 ° C. to obtain coating C.

The paints A to C obtained 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 to test the curability. Further, these paints were applied to a comb-shaped electrode made of an alumina ceramic substrate (electrode spacing 0.3 mm, made of electrode AgPd) by a dipping method and cured under the above curing conditions to prepare a test piece for a moisture resistance test, Moisture resistance was tested. Further, with respect to these test pieces, test pieces for bending test were prepared according to JIS C2103 and cured under the above-mentioned curing conditions, and the test piece was heated at 125 ° C. for 1 hour.
It was left for 00 hours and tested for flexibility. The results are shown in Table 1. When the coating materials A and C were applied by the dipping method, the coating materials A and C were heated to 120 ° C. before use. Also, the humidity resistance is 6 while applying DC15V to the humidity resistance test piece.
It is left in a constant temperature and humidity chamber at 0 ° C and 95% RH, and taken out from the constant temperature and humidity chamber at each standing time shown in Table 1, and 2 hours later at 23 ° C.
Then, DC50V was applied and the insulation resistance was measured and evaluated.

[0017]

[Table 1] * 1 Curability ◯: No tack on the surface of the coating film. X: There is tack and string on the surface of the coating film. * 2 UV irradiation part: The surface of the coating film that is irradiated with UV light. * 3 UV non-irradiated area: The surface of the coating film that is not exposed to UV light (for example, the bottom of mounted parts such as IC and resistors)

[0018]

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 in which flexibility is hardly deteriorated even when deteriorated by heating. It is an excellent paint, and it is possible to manufacture electronic parts with improved reliability.

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) a number average molecular weight of 300 to 10,
000 photocurable terminal acryloxypolybutadiene or terminal methacryloxypolybutadiene, (C) wax and (D) 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.