Patent ID: 6270607
Filing Date: 2001-08-07
Classification: H05K,Y10T

Abstract:
A method of manufacturing a multilayer printed wiring board, comprising:forming a through hole in an aramid nonwoven fabric impregnated with a thermosetting resin when the impregnating thermosetting resin is in a semi-setting state;filling the through hole with conductive paste to complete an insulating substrate;bonding a copper foil on both sides of the insulating substrate by thermo-compression to form a copper-clad laminate;forming an internal conductive pattern layer and an internal conductive pattern land made of only the copper foil to complete an inner circuit board, said land covering a portion of said aramid nonwoven fabric where the through hole is formed;forming a photosensitive resin film on a surface of the inner circuit board;forming a photo via communicating with the land or the internal conductive pattern layer in the applied photosensitive resin film by exposing and developing said film;filling the photo via with conductive paste, the viscosity of which is adjusted by adding solvent;reducing the solvent from the conductive paste filled in the photo via; andforming an external conductive pattern layer on the photosensitive resin film and a land just above the photo via by plating on a surface of the photosensitive resin film said surface including a portion lust above the photo via,wherein a diameter of the photo via is smaller than the diameter of the through hole, and a diameter of the land on the photo via is smaller than a diameter of the internal conductive pattern land.