Solderless interconnection and packaging technique for embedded active components

In the present study a solderless interconnection and packaging technique for active components is presented. It is based on electroless copper deposition directly onto photodefined wiring tracks connecting the (I/O) pads of embedded active components. In this manner better electrical conductivity, higher reliability and accuracy of ultra fine-pitch interconnections in a low-cost multichip module are achieved. This non-vacuum and solderless copper/polymer process which makes use of a photosensitive epoxy resin, has been used for interconnecting successfully the pads as small as 30×30 μm². It is emphasized that this solderless process enables the production of reliable electrical connections at ambient temperature without difficulties related to mechanical and thermal stability of very small solder joints. Detailed microstructural observations of interconnected test chips each containing 376 contact pads revealed good chemically bonded interfaces. The electrical performance of the embedded active components is also briefly discussed