A method and apparatus for achieving a three-dimensional high density warp-resistant integrated circuit module is provided. Selected individual integrated circuit packages which comprise the module are mounted with a thin stiffener, or a thin layer of material having a coefficient of thermal...http://www.google.com.tw/patents/US5801437?utm_source=gb-gplus-share專利 US5801437 - Three-dimensional warp-resistant integrated circuit module method and apparatus 
