Patent ID: 9684237
Date: 2017-06-20
CPC Classifications: G03F,H05K

Claim:
1. A circuit board, comprising: a conductive pattern formed on a substrate; a first negative resist formed on the substrate and the conductive pattern; the first negative resist having a first via exposure portion formed on the surface of the conductive pattern; a second negative resist formed on the first negative resist having the first via exposure portion; the second negative resist having a second via exposure portion formed on the first via exposure portion, the second via exposure portion larger than the first via exposure portion, the first via exposure portion comprising a first sub-portion that overlaps the second via exposure portion and a second sub-portion that does not overlap the second via exposure portion; a via opening formed corresponding to the location of the first and second via exposure portions defined by concurrent development of the first and second negative resists such that the second via exposure portion is unexposed, and such that the first sub-portion of the first via exposure portion is unexposed, and such that the second sub-portion of the first via exposure portion is exposed, the via opening reaching the conductive pattern; and the via opening filled with a conductive material.