Rigid flex circuits have historically been used in military and high-end performance electronic packaging to improve reliabiltiy, reduce weight and save space. This type of interconnect offers higher reliabiltiy and a tighter form factor when compared to more conventional interconnect techniuqes. improvements in printed circuit fabrication processes and laminate materials have made possible unique opportunities for high density rigid flex circuitry. Recently MCM-L or laminate based multi chip modules have been gaining in popularity as a lower cost packaging alternative to traditional MCM-C or laminate based multi chip modules have been gaining in popularity as a lower cost packaging alternative to traditional MCM-C or ceramic substrate based multi chip modules. This paper describes the steps taken to redesign existing modules from MCM-C technology to MCM-L(F), Several actual products that have been redesigned from ceramic substrate technology to laminate based packaging using rigid flex as the enabling technology are shown. Data is presented on thermal dissipation, mechanical reliabiltiy, electrical performance, and thermal reliabiltiy of the laminate substatre as well as assembly information.
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