MULTILAYER PRINTED WIRING BOARD HAVING FILLED-VIA STRUCTURE

摘要

The invention provides a multilayer printed wiring board having a filled viahole structure for forming a fine circuit pattern, providing excellent resistance against cracking under a thermal shock. The multilayer printed wiring board is comprised of conductor circuitry layers and interlaminar insulative resin layers having formed through them holes filled with a plating layer to form a viahole. The surface of the plating layer exposed out of the hole for the viahole is formed substantially flat and lies at a substantially same level as the surface of the conductor circuit disposed in the interlaminar insulative resin layer. The thickness of the conductor circuitry layer is less than a half of the viahole diameter and less than 25 mu m. The inner wall of the hole formed in the interlaminar insulative resin layer is roughened and an electroless plating layer is deposited on the roughened surface. An electroplating layer is filled in the hole including the electroless plating layer to form the viahole.