No abstract

For 2.5 D package integration interposers based on silicon have widely been investigated. However, their high cost adder to the package is a major drawback. An alternative interposer based on polymer- nanoparticle compound material is introduced. It can be manufactured in large volume by low cost processes. Depending on polymer layer structure a CTE varying between 0 to 8 ppm/ °C can be adjusted. A polymer system which has a CTE close to Si of 2.6 ppm/ °C is used for a thermally matched interposer. The material is less fragile than silicon or glass. Copper vias through the polymer substrate have been manufactured with a diameter of 2 um by laser drill. The manufactured thickness of the interposer varies between 200 um and as low as 85 um. In addition, by choice of appropriate nano particles the interposer can act as overvoltage protection element where regions between wires become conductive under high voltage conditions. This enables an intrinsic ESD protection implemented into the interposer protecting the stacked dies against ESD discharges as high as 15 kV IEC.