US 6,388,199 B1 · Selectively adjusting surface tension of soldermask material

Abstract

A method of selectively adjusting surface tension of a soldermask material. Specifically, a method of selectively adjusting the surface tension of a soldermask material to promote adhesion of a molding compound in a ball grid array package while maintaining a low surface tension on the ball attach area to prevent bridging between the solder balls. Solder balls require a low surface tension soldermask to minimize bridging, while the molding compound requires a high surface tension to provide adequate adhesion to the surface of the soldermask. By exposing selected portions of the soldermask to an activation method, such as ultra-violet radiation, the surface tension of the soldermask can be varied such that different areas of the package exhibit different surface tensions.

Claims18

Dependent claims

A system comprising:

a processor;
and
an integrated circuit package operatively coupled to the processor, the integrated circuit package comprising:
a substrate having a first surface and a second surface, the second surface configured to receive a plurality of solder balls thereon;
an integrated circuit die coupled to the first surface of the substrate;
a solder resist disposed on the second surface of the substrate, the solder resist having a first portion having a first surface tension and a second portion having a second surface tension, the first surface tension being higher than the second surface tension;
and
a molding compound disposed on the first portion of the solder resist.

5 more elements

Dependencies are inferred from the claim text.

Selectively adjusting surface tension of soldermask material

Life of this patent

Selectively adjusting surface tension of soldermask material

Life of this patent

Abstract

Claims18