Photocurable and thermosetting resin composition and printed circuit boards made by using the same

Abstract

A photocurable and thermosetting composition comprises (A) a carboxyl group-containing resin having at least one carboxyl group in its molecule, (B) a photopolymerization initiator having an oxime linkage represented by the following general formula (I), (C) a reactive diluent, and (D) an epoxy compound having two or more epoxy groups in its molecule. The above-mentioned photopolymerization initiator (B) is incorporated into a formulation which is different from at least a formulation into which the above-mentioned carboxyl group-containing resin (A) and the above-mentioned reactive diluent (C) are incorporated to formulate a system comprising at least two parts.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a divisional of application Ser. No. 11 / 137,641 filed on May 26, 2005, which is a continuation of Application PCT / JP03 / 15187, filed Nov. 27, 2003, which was published under PCT Article 21(2).BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]This invention relates to a photocurable and thermosetting resin composition and a printed circuit board made by using the same, and more particularly relates to a photocurable and thermosetting resin composition which excels in tack-free dryness, adhesiveness, and resolving properties, scarcely produces mist during the thermal curing thereof, enjoys high sensitivity, and excels in storage stability, and to a printed circuit board having a solder resist layer and / or a resin insulating layer excelling in resistance to PCT (pressure cooker test), electrical insulating properties, etc., which are produced by using the composition mentioned above and which reduce the gener...

AI Technical Summary

Benefits of technology

[0018]Another object of the present invention is to provide a photocurable and thermosetting resin composition which exhibits high sensitivity, enjoys high workability, is capable of coping with a solder resist to be used in the laser direct imaging technique, and excels in storage stability.

[0022]Since the photocurable and thermosetting resin composition according to the present invention uses the photopolymerization initiator having an oxime linkage as a photopolymerization initiator, it exhibits high sensitivity and high curing properties in deep portions of a coating film and is capable of stably forming a cured film which excels in such properties as heat resistance and PCT resistance.

[0023]Further, since the composition exhibits high sensitivity, it enjoys high workability, allows preparation at a low cost, and is capable of coping with the laser direct imaging technique. By incorporating the photopolymerization initiator having the oxime linkage which exhibits high sensitivity into a formulation separated from a formulation into which a carboxyl group-containing photosensitive resin and a reactive diluent having at least one unsaturated double bond in its molecule are incorporated, it will be easy to prepare a composition using the oxime-based photopolymerization initiator which generates radicals by the irradiation of visible light. Further, by incorporating the photopolymerization initiator having the oxime linkage into a formulation separated from a formulation into which the carboxyl group-containing resin is incorporated, the oxime-based photopolymerization initiator is prevented from being deteriorated, thereby providing the stable photocurable and thermosetting resin composition. Moreover, there is obtained another effect of reducing the contamination of the working environment because any mist originated from a photopolymerization initiator will not generate in an exposure process, a thermal curing process accompanied with heating, and a soldering process.

Problems solved by technology

However, in the case of the solder resist composition which has been heretofore used, since the photo-curing of the depths of a coating film at the time of exposure is inadequate in the image formation, the coating film may exfoliate during the development thereof, which forms a big factor of preventing formation of the image with high resolving properties.

Among these steps, particularly the exposure step is the very cumbersome process which comprises exchanging a negative film according to the kind of the printed circuit board, carrying out the position alignment thereof, then drawing a vacuum and subjecting it to exposure to light.

However, if the polyfunctional (meth)acrylate compound of a low molecular weight is added to the composition in a large amount, though the sensitivity will be improved, there is a problem that tack-free dryness (tack-free properties) required for the contact exposure decreases remarkably, and the properties of the cured coating film also decrease.

Furthermore, in the formation of a solder resist layer using such a photolithographic developing type solder resist composition, a volatile component (mist) generated from a resist composition adheres to a hot air circulation type drying oven or to an exposure device in a preliminary drying process accompanied with heating, an exposure process, a thermal curing process, and a soldering process, which becomes the cause of the abnormalities in mounting the parts in the following soldering process and a subsequent gold plating process.

The lamination pressing method, however, necessitates use of production facilities which are very voluminous and highly expensive and incurs difficulty in forming fine patterns because the plating is carried out on the outer layer during the plating step of through-holes and the thickness of copper deposit increases.

Further, in the heating step performed after formation of a conductor layer as by electroless plating or electroplating, the volatile component generated from the interlaminar resin insulating layer becomes the cause of inferior adhesiveness of the conductor layer thereto.

However, the material which may fully solving such problems is not found out till now.

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