JPS6211002B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to photopolymerizable resin compositions for coating hybrid integrated circuits, including printed circuit boards.

In hybrid integrated circuits including printed circuit boards,
The use of resin coatings on elements such as conductors, resistors, and capacitors to protect them from external atmosphere such as moisture and dust is increasing year by year.

Conventionally, thermosetting resins such as silicone resins, epoxy resins, polybutadiene resins, urethane resins, and polyimide resins have often been used as resins for this type of purpose. Methods for applying the resin include screen printing as with other parts, dipping the entire hybrid integrated circuit, brushing, and spraying. However, when heating and curing the above-mentioned resin, there are drawbacks such as changes in the characteristics of internal elements due to heating, curing failure of the resin due to variations in curing temperature, and long curing time, which reduces productivity. They were often inferior in points.

Therefore, in order to meet these demands, UV-curable resins and electron beam-curable resins have been studied in recent years, and UV-curable resins have been actively researched in particular because of their rationalization of production and low capital investment costs. ing. Epoxy acrylate, polyester acrylate, or urethane acrylate are the mainstream base resins for UV curable resins, but the electrical properties of the cured products of these UV curable resins are extremely poor, and the temperature at which they can be used continuously is relatively low. At present, it cannot be used at all for electrically insulating coatings on hybrid integrated circuits, and is only used slightly for silver marks. On the other hand, the cured product of an ultraviolet curable resin using 1,2-polybutadiene acrylate as a base resin has extremely excellent electrical properties, and exhibits satisfactory properties for use as an electrically insulating coating for hybrid integrated circuits. However, when 1,2-polybutadiene resin is left in a high-temperature atmosphere, it undergoes an autooxidation reaction and its electrical properties deteriorate, resulting in poor heat resistance. Silicone acrylate resins are UV-curable resins that have excellent electrical properties and heat resistance when cured, and have recently been studied. However, silicone resins have the disadvantages of poor thixotropy, poor workability such as printability, and poor solvent resistance and mechanical properties of cured products.

The purpose of the present invention is to eliminate the drawbacks of the prior art described above, and to provide a cured resin product with extremely excellent electrical properties, especially dielectric properties, frequency characteristics and temperature characteristics, high continuous use temperature, heat resistance, and workability such as printability. It is an object of the present invention to provide a photopolymerizable resin composition for coating hybrid integrated circuits in a broad sense, including printed circuit boards, which have excellent solvent resistance and mechanical properties as a cured product.

In order to achieve the above object, the inventors investigated various resin compositions, and found that the main components are at least one type of organopolysiloxane having an axoloyl group or a methacryloyl group at the molecular end, and an acryloyl group or a methacryloyl group at the end of the molecule. and at least one type of 1,2-polybutadiene resin or epoxy acrylate resin, and an addition polymerizable monomer having at least one CH ₂ =C group and having a boiling point at normal pressure of 100°C or higher. It has been found that a paste made by kneading a photosensitizer, a thermal polymerization initiator, and a filler is good.

That is, the photopolymerizable resin composition for coating a hybrid integrated circuit of the present invention contains 100 parts by weight of at least one type of organopolysiloxane having an acryloyl group or a methacryloyl group at the molecular end, and an acryloyl group or a methacryloyl group at the molecular end. 5 to 100 parts by weight of 1,2-polybutadiene resin or epoxy acrylate resin,
5 to 100 parts by weight of an addition-polymerizable monomer having at least one CH ₂ =C group and having a boiling point of 100°C or higher at normal pressure, 0.05 to 5 parts by weight of a photosensitizer, and thermal polymerization. 0.01 to 3 parts by weight of initiator and particle size of 5 μm
It consists of 10 to 200 parts by weight of the following fillers, including a thixotropic agent, a coloring agent, an adhesion imparting agent, an antioxidant,
It is a mixture of surface hardening accelerators, etc., and the resulting resin composition has excellent workability such as printability, and the resulting cured resin has excellent electrical properties, especially dielectric properties. It has excellent heat resistance and can be used continuously at temperatures up to 150℃.
℃ or higher, it has excellent solvent resistance and mechanical properties, and since the cured coating film has no pinholes, it has good moisture resistance, making it convenient for coating hybrid integrated circuits in a broad sense, including printed circuit boards.

Next, materials used in the present invention will be explained.
As the organopolysiloxane, a silicone compound having an acryloyl group or a methacryloyl group at the molecular end is desirable, and the molecular weight is preferably
500-10000 organopolysiloxane is good. If the molecular weight is less than 500, the mechanical properties of the cured resin will be poor, and if the molecular weight is more than 10,000, the photopolymerizable resin composition will become too viscous and have poor workability, making it impossible to put it into practical use. .

The molecular weight of 1,2-polybutadiene resin or epoxy acrylate resin that has an acryloyl group or methacryloyl group at the molecular end
A molecular weight of 500 to 5000 is preferable, and if the molecular weight is less than 500, the mechanical properties of the cured resin will be poor, and the molecular weight will be lower than 500.
If it is larger than 5,000, the photopolymerizable resin composition becomes too viscous liquid, resulting in poor workability and impractical use. One or a mixture of two or more of these resins may be used, and it is effective to use them in an amount of 5 to 100 parts by weight per 100 parts by weight of the organopolysiloxane. When it is less than 5 parts by weight, the photopolymerizable resin composition has low thixotropy and printability and other workability is undesirable, and when it is more than 100 parts by weight, it is not preferable because the heat resistance of the cured coating film decreases. In either case, it is difficult to put it into practical use.

As the addition polymerizable monomer, at least one
Contains CH ₂ =C group and has a boiling point of 100℃ at normal pressure
The above is desirable, and addition polymerizable monomers with a boiling point lower than 100°C may increase the viscosity of the resin during work or volatilize during photocuring, which is not preferable from the viewpoint of safety. Examples of the addition polymerizable monomer include styrene, styrene derivatives such as vinyltoluene, acrylic acid, acrylic acid compounds such as butyl acrylate, methacrylic acid,
Methacrylic acid compounds such as ethyl methacrylate, 1,6-hexanediol diacrylate,
Polyfunctional acrylic ester compounds or polyfunctional methacrylic ester compounds having two or more unsaturated groups such as ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate, and other polyfunctional vinyl monomers such as divinylbenzene and diallyl phthalate. Polyester-based addition-polymerizable oligomers having an acryloyl group or a methacryloyl group such as Aronix 6300 (manufactured by Toagosei Kagaku Kogyo Co., Ltd.) and the like can be mentioned, and one kind or a mixture of two or more of these monomers can be used. It is effective to use these monomers in an amount of 5 to 100 parts by weight per 100 parts by weight of the organopolysiloxane. If it is less than 5 parts by weight, the mechanical strength of the cured coating film will be low and the photopolymerizable resin composition will become too viscous and liquid, resulting in poor workability and impractical use. Moreover, if the amount is more than 100 parts by weight, the electrical properties, mechanical properties and heat resistance of the cured coating film will deteriorate, which is undesirable and difficult to put to practical use in either case. Photosensitizers include benzoin and its derivatives, benzoin ethers such as benzoin methyl ether, benzyl and its derivatives, anthraquinone and its derivatives, aryldiazonium salts, acetophenone and its derivatives, sulfur compounds such as diphenyl disulfide, and benzophenone. and its derivatives,
Examples include sulfur compounds such as diphenyl disulfide, benzophenone and its derivatives, and one or a mixture of two or more of these photosensitizers may be used. It is effective to use these photosensitizers in an amount of 0.05 to 5 parts by weight per 100 parts by weight of the organopolysiloxane. If the amount is less than 0.05 part by weight, the photocuring speed of the photopolymerizable resin composition is slow and a cured coating film with excellent electrical and mechanical properties cannot be obtained from the cured resin, which is undesirable.
If the amount is more than 1 part by weight, a cured resin product with a high molecular weight cannot be obtained, and the electrical properties are significantly deteriorated, which is not preferable, and in either case, it is difficult to put it into practical use.

Note that it is particularly effective to add the photosensitizer in an amount of 0.5 to 2 parts by weight.

As a thermal polymerization initiator, benzoyl peroxide, lauryl peroxide, dicumyl peroxide, cumene hydroperoxide, di-t-butyl peroxide, 1,1-
Common radical polymerization initiators such as bis(t-butylperoxy)3,3,5-trimethylcyclohexane and azobisisobutylontolyl are used, and these thermal polymerization initiators are It is effective to use it in a range of 0.01 to 3 parts by weight. The thermal polymerization initiator is added to promote curing of the resin composition by the heat generated during ultraviolet irradiation, and particularly to improve internal curing properties. If it is less than 0.01 part by weight, the curing of the resin composition will be slow, which is undesirable. If it is more than 3 parts by weight, it will not be possible to obtain a cured resin product with a high molecular weight, and the moisture resistance will be significantly reduced, which is not desirable. In either case, it is difficult to put it into practical use.

As a filler, the particle size is 5 due to workability such as printability.
Preferably, aluminum oxide,
silicon dioxide, calcium carbonate, titanium dioxide,
Barium sulfate, mica powder, etc. can be used, and these fillers are resistant to organopolysiloxanes.
It is effective to use 10 to 200 parts by weight. If it is less than 10 parts by weight, the resin composition will have poor workability such as printability, which is undesirable, and if it is more than 200 parts by weight, the viscosity of the resin composition will become too high, which is undesirable in terms of workability. It is difficult to put it into practical use.

As the thixotropic agent, fine silicon dioxide powder having a specific surface area of 100 to 450 m ² /g and/or additives such as dioctyl phthalate are suitable. As coloring agents, ordinary pigments and dyes such as phthalocyanine green and phthalocyanine blue can be used, and as adhesion agents, γ-methacryloxypropyltrimethoxysilane, vinyl tris (β
- Silane coupling agents such as (methoxyethoxy) silane are good. Usual thermal polymerization inhibitors such as hydroquinone, hydroquinone methyl ether, catechol, and 2,6-di-t-butyl-4-methylphenol are effective as antioxidants, and cobalt naphthenate, cobalt naphthenate, and surface hardening accelerators are effective. Organic acid metal salts such as manganese octylate are good.

Light sources used in the present invention include high-pressure mercury lamps, ultra-high pressure mercury lamps, metal halide lamps, carbon arc lamps, and xenon lamps.

Note that the viscosity of the resin composition is 30,000 when the spindle rotation speed of a rotational viscometer at room temperature is 10γpm, considering that it is applied by screen printing.
~200000 centipoise is desirable. If the viscosity is lower than 30,000 centipoise or higher than 200,000 centipoise, good coverage cannot be obtained.

Hereinafter, the present invention will be explained using specific examples.

Example Molecular weight is approximately 5000 with a methacryloyl group at the end
100 parts by weight of organopolysiloxane with a molecular weight of approximately 2600 and a methacryloyl group at the end.
25 parts by weight of polybutadiene resin, 15 parts by weight of ethylene glycol dimethacrylate, Aronix
6300 35 parts by weight, 4-methoxybenzophenone 0.6
parts by weight, 0.6 parts by weight of 2-methylanthraquinone,
1,1-bis(t-butylperoxy)3,3,
1.2 parts by weight of 5-trimethylcyclohexane, 65 parts by weight of α-alumina powder with a particle size of 1 μm, 9 parts by weight of fine silicon dioxide powder with a specific surface area of 380 m ² /g, 0.6 parts by weight of dioctyl phthalate, γ-methacryloxypropyltri After mixing 4 parts by weight of methoxysilane and 2 parts by weight of phthalocyanine green, the mixture was homogenized by roll kneading to obtain a paste-like resin composition.
The above resin composition was printed to a thickness of approximately 50 μm to match the shape of the internal elements on the substrate using a regular screen printer, and a 120 W/cm metal halide lamp was printed at 30 μm.
A cured coating film was obtained by irradiation from a distance of 15 cm per second.
This cured coating had no pinholes, was not swollen by solder flux during or after assembly of the hybrid integrated circuit, and was not swollen by chlorocene used for cleaning the flux, and no change in properties was observed. In addition, it has good adhesion to the substrate, excellent electrical insulation, and temperature cycle (+150℃ to -
The crack resistance and moisture resistance at 30°C were also good.

Comparative Example 1, 2- from among the resin compositions shown in Examples
About a resin composition excluding polybutadiene resin and 1,1-bis(t-butylperoxy)3,3,5-trimethylcyclohexane was printed on a substrate using an ordinary screen printing machine in the same manner as in the above example.
It was printed to a thickness of 50 μm. This resin composition has a relatively low thixotropy, so its printability is slightly inferior, and a 120W/cm metal halide lamp is used.
The cured coating obtained by irradiating the film from a distance of 150 cm for 30 seconds had excellent electrical properties, heat resistance, moisture resistance, etc., similar to the cured coating obtained in the example, but it had poor solvent resistance and solder flux resistance. It was slightly inferior in terms of , and slight swelling was observed.

As described above, the resin composition according to the present invention has extremely excellent electrical properties, heat resistance, solvent resistance, and mechanical properties of the cured product, and has excellent workability such as printability, and also has pinholes in the cured coating film. Since there is no moisture, it has good moisture resistance, making it convenient for covering hybrid integrated circuits.

Claims (1)

[Claims] 1 100 parts by weight of organopolysiloxane having an acryloyl group or methacryloyl group at the molecular end as a main component, 5 to 100 parts by weight of 1,2-polybutadiene resin or epoxy acrylate resin having an acryloyl group or methacryloyl group at the molecular end, At least one CH ₂ =
5 to 100 parts by weight of an addition polymerizable monomer having a C group and having a boiling point of 100°C or higher at normal pressure, 0.05 to 5 parts by weight of a photosensitizer, and a thermal polymerization initiator.
0.01 to 3 parts by weight and 10 to 3 parts of filler with a particle size of 5 μm or less
1. A photopolymerizable resin composition for coating a hybrid integrated circuit, characterized in that 200 parts by weight are kneaded into a paste.