Electrically, mechanically, and thermally enhanced ball grid array (BGA) packages are described. An IC die is mounted in a centrally located cavity of a substantially planar first surface of a stiffener. The first surface of a substrate is attached to a substantially planar second surface of the stiffener....http://www.google.de/patents/US6906414?utm_source=gb-gplus-sharePatent US6906414 - Ball grid array package with patterned stiffener layer
