Patent ID: 6323436
Filing Date: 2001-11-27
Classification: H01L,H05K

Abstract:
A high,density PWB having increased circuit density and improved electrical and mechanical properties at locations in which electrical/mechanical connection is made between said PWB and a surface mounted device comprising:a substrate comprising a thermoset resin selected from the group consisting of epoxy, bismaleimide, and cyanate resins, and combinations thereof, impregnated with an organic reinforcement material selected from the group consisting of a random oriented mat of chopped p-aramid fibers which are transversely isotropic and have an axial CTE of about -3 to about -6 ppm/.degree. C. below the glass transition temperature and a thermoplastic liquid crystalline polymer paper.said impregnated substrate having a first major surface and a second major surface;a plurality of electrically conductive through-holes extending between and electrically interconnecting said first and second surfaces;and at least one of said first and second surfaces including a thin film redistribution layer affixed thereto;said organic reinforcement material having a dielectric of at least 3.25, and possessing in combination with said thermoset resin, a low overall CTE which is adjusted to match the CTE of a solder mounted silicon semiconductor chip in the range of about 3 to 10 ppm/.degree. C.