Abstract: A photopolymerizing cross-linking hardenable resin composition is disclosed which is comprised of a binder resin, cross-linking monomer and photopolymerization initiator. The composition of each of the above mentioned components is such that dry film resist incorporating the resin composition of the present invention and used in processes for selective etching and plating of printed circuit boards can be developed in weak aqueous alkaline solution after selective exposure to light. In this way, the efficient and economical manufacture of high definition printed circuit boards is made possible. Additionally, dry film resist incorporating the photopolymerizing cross-linking hardenable resin composition of the present invention lends to easy handling and storage characteristics.

Abstract: A crosslinking-curable resin composition suitable for use in dry film resists, consisting essentially of(a) 40 to 70 parts by weight of a thermoplastic polymer binder obtained by copolymerizing four specific polymerizable substances in specific proportions;(b) 20 to 50 parts by weight of a crosslinkable monomer having one or more ethylenically unsaturated groups in the molecule and containing 51 to 100% by weight of a compound of the general formula ##STR1## where R.sub.2 is an alkylene group of 3 to 6 carbon atoms, R.sub.3 and R.sub.4 are hydrogen or methyl, and n is a positive whole number of 5 to 9; and(c) 0 to 10 parts by weight of a photopolymerization initiator;the combined amount of components (a) to (c) being 100 parts by weight.

Abstract: An electronic part mounting construction, such as a transistor package or a substrate for a resin mold device, has a substrate for mounting an electronic part on a principal surface, at least one metallized layer deposited on the principal surface and soldered to the electronic part thereon, another metallized layer continuously extended from the at least one metallized layer in a direction perpendicular thereto, and an insulator layer deposited on the other metallized layer. The other metallized layer is provided on a side surface of a wall member or the substrate. The other metallized layer and the insulator layer may be formed by steps of forming a hole in an insulator sheet, depositing a metallized layer and an insulator layer successively on the surface of the hole, and leaving the metallized layer and the insulator layer at predetermined region(s) by punching the insulator sheet.