JPH08134376A - Photosetting moistureproof insulation coating and production of moistureproof insulated electronic part - Google Patents

Abstract

PURPOSE: To provide a photosetting coating material containing a photo-setting polybutadiene, a cross-linkable monomer and a photopolymerization initiator, having excellent curability and moisture resistance, exhibiting high heat- resistance to substantially keep the flexibility even after thermal deterioration and capable of providing an electronic part having high reliability. CONSTITUTION: This coating material is produced by compounding (A) 100 pts.wt. of a photo-setting polybutadiene having a number-average molecular weight of 300-10,000 (preferably 500-5,000) and a hydrogenation ratio of >=90% (preferably >=95%) and containing 1-5% (preferably 2-3%) isocyanate groups in the terminal functional groups and the remaining part of (meth)acryloyloxy groups with (B) preferably 10-200 pts.wt. (especially 50-100 pts.wt.) of a cross- linkable monomer consisting of a mono to trifunctional (meth)acrylic acid ester, etc., and (C) preferably 0.01-10 pts.wt. (especially 0.1-5 pts.wt.) of a photopolymerization initiator such as benzyl dimethyl ketal, benzoin (thio)ethers and benzophenone.

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. Insulation is performed to protect it from dust. For this 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 is the above and contains 1-5% of the terminal functional groups is an isocyanate group and the rest is a photocurable polybutadiene having an acryloxy group or a methacryloxy group, (B) a crosslinkable monomer and (C) a photopolymerization initiator. The present invention relates to a photo-curable moisture-proof insulating coating material and a method for producing a moisture-proof insulated electronic component in which the coating material is applied to an electronic component and cured.

The photocurable polybutadiene (A) used in the present invention is obtained by reacting terminal hydroxypolybutadiene having a hydrogenation rate of 90% or more with polyisocyanate, and then reacting with hydroxyethyl acrylate or hydroxyethyl methacrylate. It is an acrylic modified hydrogenated polybutadiene resin having a number average molecular weight of 300 to 10,000. In order to make 1 to 5% of the terminal functional groups an isocyanate group, the above-mentioned terminal hydroxypolybutadiene and polyisocyanate are reacted in an amount to react all hydroxyl groups with an isocyanate group, and then the isocyanate group is 1 to 5%. Hydroxyethyl acrylate or hydroxyethyl methacrylate is reacted as the remaining amount. The number average molecular weight of this resin is 300-
The hydrogenation rate is 10,000, preferably 500 to 5,000, and the hydrogenation rate is 90% or more, preferably 95% or more. The proportion of isocyanate groups in the terminal functional groups is 1 to 5%,
Preferably it is 2-3%. 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. Further, if the proportion of isocyanate groups in the terminal functional groups is less than 1%, the portion not irradiated with ultraviolet rays will not be cured and the moisture resistance will be poor, and if it exceeds 5%, the thermal stability of the resin itself will be poor.

Examples of the crosslinkable monomer (B) used in the present invention include styrene, vinyltoluene, α-methylstyrene, p-tert-butylstyrene, chlorostyrene, divinylbenzene, diallylphthalate and 2-hydroxyethyl. Monofunctional methacryl such as methacrylate, 2-hydroxypropylmethacrylate, methylmethacrylate, ethylmethacrylate, laurylmethacrylate, methacrylic acid and a reaction product of Cardura E-10 (trade name of glycidyl ester of higher fatty acid, manufactured by Shell Chemical Co.). Acid ester, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate,
Bifunctional methacrylic acid ester such as 1,6-hexanediol dimethacrylate, trifunctional methacrylic acid ester such as trimethylolpropane trimethacrylate, methyl acrylate, ethyl acrylate, lauryl acrylate, 2-hydroxyethyl acrylate, 2 -Hydroxypropyl acrylate, monofunctional acrylic acid esters such as the reaction product of acrylic acid and Cardura E-10, ethylene glycol diacrylate,
Bifunctional acrylic acid esters such as diethylene glycol diacrylate and 1,6-hexanediol diacrylate, and trifunctional acrylic acid esters such as trimethylolpropane triacrylate are used, and these are used alone or in combination of two or more kinds. Can be used.
The mixing ratio of these monomers (B) is 10 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 composition.
To 200 parts by weight is preferable, and 50 to 100 parts by weight is more preferable.

The photopolymerization initiator (C) used in the present invention includes benzyl dimethyl ketal, benzoin, benzoin ethyl ether, benzoin propyl ether,
Examples 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, A range of 5 parts by weight is more preferable.

The photocurable moisture-proof insulating coating material of the present invention is obtained by blending the above-mentioned components (A), (B) and (C) and heating and dissolving them. 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 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 photo-curable 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.

[0012]

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 GI-1000 (manufactured by Nippon Soda Co., Ltd., hydrogenated polybutadiene resin, number average molecular weight: about 1500, hydrogenation rate: 97%) 100 parts, tolylene diisocyanate 40
0 part and 500 parts of butyl acetate were placed in a four-necked flask, stirred under a nitrogen gas atmosphere, and reacted at 80 ° C. for 2 hours.
Then, 670 parts of 2-hydroxyethyl methacrylate was added and reacted at 80 ° C. for 2 hours to obtain a varnish A (isocyate group 2.3%). This varnish A in a metal beaker
60 parts, 1,6-hexanediol dimethacrylate 4
Paint A was obtained by mixing and dissolving 0 part and 5 parts of benzyl dimethyl ketal at room temperature.

Example 2 A coating material B was obtained by mixing and dissolving 80 parts of the varnish A obtained in Example 1, 20 parts of trimethylolpropane triacrylate and 5 parts of benzophenone in a metal beaker at room temperature.

Comparative Example 1 100 parts of TE-2000 (manufactured by Nippon Soda Co., Ltd., terminal methacryloyl group polybutadiene resin, number average molecular weight: about 2,000), 5 parts of benzyl dimethyl ketal and 100 parts of toluene in a metal beaker at a temperature of 50. Coating C was obtained by mixing and stirring under the condition of ° C.

Comparative Example 2 TEAI-1000 (Nippon Soda Co., Ltd., acrylic modified hydrogenated polybutadiene resin, number average molecular weight: about 1,000, hydrogenation rate: 97%) in a metal beaker 100
Parts and 5 parts of benzyl dimethyl ketal at a temperature of 100 ° C.
Coating D was obtained by mixing and stirring under the conditions of.

The paints A to D 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. With a mercury lamp of 50 W / cm for an irradiation distance of 1
Ultraviolet irradiation from 0 cm for 120 seconds was performed to prepare a test piece for evaluation of curability, and the curability was tested. In addition, these paints were used as comb-shaped electrodes made of glass epoxy copper clad laminate (electrode spacing: 0.
3 mm, made of AgPd electrode) 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. Furthermore, regarding these test pieces, J
A test piece for bending test was prepared according to IS C 2103, cured under the above curing conditions, and allowed to stand at 80 ° C. for 100 hours to test the flexibility. Table 1 shows the results. When the coating materials A, B and D were applied by the dipping method, the coating materials A, B and D were heated to 80 ° C. before use. In addition, the humidity resistance is 8 while applying DC14V to the humidity resistance test piece.
It is left in a thermo-hygrostat at 5 ° C and 85% RH, and taken out from the thermo-hygrostat at the time shown in Table 1 after 2 hours at 23 ℃.
Then, DC500V was applied and the insulation resistance was measured and evaluated.

[0017]

[Table 1]

[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 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, the hydrogenation rate is 90% or more, 1 to 5% of the terminal functional groups are isocyanate groups, and the rest are acryloxy groups or methacryloxy groups, photocurable polybutadiene, (B) a crosslinkable monomer and (C) 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.