Patent ID: 6326559
Filing Date: 2001-12-04
Classification: H05K,Y10T

Abstract:
A multilayer printed wiring board in which a plurality of conductor layers are laminated as a whole with insulating layers interposed, a non-penetrating via hole is provided by means of an irradiated laser in the respective insulating layers from an opening made in one of the conductor layers on one surface of the insulating layer to a surface of another conductor layer on the other surface of the insulating layer, and a plated conductor layer is provided on an inner periphery of the via hole for electric connection between the conductor layers on both surfaces of the respective insulating layers, wherein the via hole is formed with the irradiated laser of a pulse width from 1 to 100 .mu.s and of a frequency in a range from 100 Hz to 10 kHz to have, at least at a continuing zone of the inner periphery to a bottom surface which is said surface of said another conductor layer, a concave curved surface of a radius in a range from 20 to 100 .mu.m in axially sectioned view of via hole.