Hello Roger, Hitachi is a licensee of the Tessera microBGA (tm) package and is developing their capability for volume manufacture at this time. One unique ability of the Tessera technology is to decouple the mismatch in coeffiecients of thermal exapansion between the silicon and the FR-4 by means of a patented compliant interposer. Recently completed finite element modelling performed by Tessera shows a near 20x reduction in stress in the solder ball joints using this technology. Should you desire more information please feel free to contact me and I will provide you with contacts in Japan working the project. Regards, J. Fjelstad