SUBSTRATE AND METHOD FOR PRODUCING THE SAME

摘要

A both−sided circuit substrate having metallic via holes and used suitably as a submount for mounting a semiconductor element,and a method for efficiently producing a substrate ensuring good electrical contact between the metallic via holes and a circuit pattern and facilitating positioning of an element being bonded.The ceramic substrate having via holes internally filled with a conductive material has surface roughness Ra≤0.8μm at the ceramic part on at least one side of the ceramic substrate.A substrate where the conductive material filling the via holes existing on at least one side is projecting by 0.3−5.0μm from the surface is employed as a material substrate and after a conductive layer is formed on the surface thereof,the conductive layer is patterned or a solder film for mounting an element is formed based on the position of protruding parts of the conductive layer resulting from the via holes existing beneath the conductive layer.