Abstract: Multilayer printed wiring boards may be prepared by forming a via hole by laser irradiation in insulating layer formed by a prepreg, comprised of a glass cloth impregnated with a thermosetting resin composition, and subjecting the via hole to a glass etching treatment with a glass etching solution and then to a desmear treatment with an oxidizing agent solution. By such a process, etch back phenomenon and excessive protrusion of glass cloth from the wall surface of a via hole can be sufficiently suppressed, and a highly reliable via can be formed. Particularly, a highly reliable via can be formed in a small via hole having a top diameter of 75 ?m or below.

Abstract: Multilayer printed wiring boards may be prepared by forming a via hole by laser irradiation in insulating layer formed by a prepreg, comprised of a glass cloth impregnated with a thermosetting resin composition, and subjecting the via hole to a glass etching treatment with a glass etching solution and then to a desmear treatment with an oxidizing agent solution. By such a process, etch back phenomenon and excessive protrusion of glass cloth from the wall surface of a via hole can be sufficiently suppressed, and a highly reliable via can be formed. Particularly, a highly reliable via can be formed in a small via hole having a top diameter of 75 ?m or below.

Abstract: Multilayer printed wiring boards may be prepared by forming a via hole by laser irradiation in insulating layer formed by a prepreg, comprised of a glass cloth impregnated with a thermosetting resin composition, and subjecting the via hole to a glass etching treatment with a glass etching solution and then to a desmear treatment with an oxidizing agent solution. By such a process, etch back phenomenon and excessive protrusion of glass cloth from the wall surface of a via hole can be sufficiently suppressed, and a highly reliable via can be formed. Particularly, a highly reliable via can be formed in a small via hole having a top diameter of 75 ?m or below.

Abstract: Multilayer printed wiring boards may be prepared by forming a via hole by laser irradiation in insulating layer formed by a prepreg, comprised of a glass cloth impregnated with a thermosetting resin composition, and subjecting the via hole to a glass etching treatment with a glass etching solution and then to a desmear treatment with an oxidizing agent solution. By such a process, etch back phenomenon and excessive protrusion of glass cloth from the wall surface of a via hole can be sufficiently suppressed, and a highly reliable via can be formed. Particularly, a highly reliable via can be formed in a small via hole having a top diameter of 75 ?m or below.

Abstract: A metal core substrate comprises a core layer (10) consisting of first and second metal plates (11, 12) layered with a third insulating layer (13) interposed therebetween; first and second insulating layers (20, 21) formed on the first and metal plates, respectively; first and second wiring patterns (45, 46) formed on the first and second insulating layers, respectively. A conductive layer (40) formed in a through-hole (22) penetrates the first insulating layer, the first metal plate, the third insulating layer, the second metal plate and the second insulating layer for electrically connecting the first wiring pattern with the second wiring pattern. The first metal plate (11) is electrically connected with the first wiring pattern (45) and the second wiring pattern (46), respectively, by means of a via (44) and by means a via (43).

Abstract: A metal core substrate comprises a core layer (10) consisting of first and second metal plates (11, 12) layered with a third insulating layer (13) interposed therebetween; first and second insulating layers (20, 21) formed on the first and metal plates, respectively; first and second wiring patterns (45, 46) formed on the first and second insulating layers, respectively. A conductive layer (40) formed in a through-hole (22) penetrates the first insulating layer, the first metal plate, the third insulating layer, the second metal plate and the second insulating layer for electrically connecting the first wiring pattern with the second wiring pattern. The first metal plate (11) is electrically connected with the first wiring pattern (45) and the second wiring pattern (46), respectively, by means of a via (44) and by means a via (43).