Thin-Profile MCM-D Packaging for Small Form Factor Applications

MCM-D interconnect is most often pictured as deposited thin-film layers on one side of a supporting substrate. Overall package thickness is limited by the thickness of this supporting structure. Often the substrate is more than an order of magnitude thicker than the thin-film layers deposited on its surface. If this substrate can be removed, much thinner multichip packages are possible. A packaging technique using free-standing copper/polyimide films will be presented. This MCM-D package has devices attached to both sides of the film to achieve not only good silicon density but an overall thin package profile. This paper will discuss an implementation of this technology for an EIAJ-standard 14mm by 20mm body size with a 2.75 mm thickness. Design and assembly of the package will be highlighted.