Manufacturing and reliability of flexible integrated module boards

In this communication a fabrication process for flexible integrated module boards (IMB) is presented The IMB-technique being developed enables very high density integration of active and passive components into organic substrates. Thinned active components, 50 μm in thickness, were embedded into flexible substrate using elastic molding polymer. Electrical interconnections were fabricated with the solderless fully additive build-up process, where the photoimagible polymer was used as a dielectric layer and high density wirings and interconnections were produced using electroless copper deposition. Since the module consists of flexible elements the resulting structure gives increased operational reliability. In addition to extensive electrical testing the results of finite-element modelling of the IMB interconnections were compared with those of the corresponding flip chip interconnections. Flexible modules and their interconnection structures were also characterized in detail by using the optical and scanning electron microscopy.