LAMINATED SUBSTRATE AND INSULATING LAYER THEREOF

PROBLEM TO BE SOLVED: To provide a laminated substrate having an insulating layer reconciling strength as a structure constituting a part of the laminated substrate and easiness to process such as the formation of a viahole. SOLUTION: A single side resin-clad copper foil having an epoxy resin alone as an insulating layer is bonded to a double side copper clad plate having an epoxy prepreg as insulating layers and a single side copper clad foil having an epoxy prepreg as an insulating layer is further bonded to form a laminated substrate 1. In this laminated base plate, the insulating layer constituting the greater part of the vol. thereof has such a structure that a single insulating layer 12 containing no glass fiber is arranged to the central part in a thickness direction and a first composite insulating layer 11 and a second composite insulating layers 13 being glass fiber-containing reinforced layers are arranged on both sides thereof. By this constitution, strength as a stricture and the easiness of viahole boring processing due to laser beam are reconciled.