Electronic assembly with copper pillar attach substrate

An electronic assembly comprising:

• a copper pillar attach substrate comprising:
• a dielectric layer;
• a solder resist layer overlying said dielectric layer, said solder resist layer having a plurality of openings therein and having a solder resist layer thickness;
• and
• a plurality of parallel traces formed on said dielectric layer, each trace having a first end portion, a second end portion and an intermediate portion, said first and second end portions being covered by said solder resist layer, said intermediate portions being positioned in said openings in said solder resist layer, said plurality of parallel traces being positioned in an area defined by a first line perpendicular to said traces and intersecting an outermost one of said trace first end portions and a second line perpendicular to said traces and intersecting an outermost one of said trace second end portions and wherein said plurality of traces each has a length less than the distance between said first line and said second line.

A method of forming a copper pillar attach substrate comprising:

• providing a substrate with a dielectric layer;
• forming a plurality of parallel traces on the dielectric layer;
• applying a solder resist layer over the plurality of parallel traces,
• forming openings in the solder resist layer that exposes an intermediate portion of each trace;
• and
• coating the exposed intermediate portion of each of the traces with conductive material that extends to a height above the height of the solder resist layer.