The present invention describes an interposer which improves the thermal performance of a semiconductor device. The interposer may be situated between a substrate and a board. The interposer is attached to two layers of solder balls. The first layer of solder balls electrically and mechanically connects...http://www.google.de/patents/US6335491?utm_source=gb-gplus-sharePatent US6335491 - Interposer for semiconductor package assembly
