A new approach for system integrated packaging

As the number of applications for flexible assemblies is growing there is also a larger variation of requirements for such packages. Therefore, different technologies from CSPs to smart cards have been developed. This paper describes the results of the development of a new approach to wafer-level redistribution as well as packaging concepts for CSPs and embedding of ultra-thin ICs into laminated substrates. The electrical interconnection is made by fully-additive deposition of Cu lines. The technology is based on wet-chemical treatments which enable the avoidance of expensive vacuum processes and electroplating. A photo-sensitive epoxy material, commonly used in printed circuit board manufacturing, was chosen as dielectric. Furthermore, the process implements electroless Ni deposition to protect the Al bond pads and to act as a solder diffusion barrier on the Cu lines. The technologies are presented together with the important parameters and typical results achieved. In order to evaluate the applicability of the processes developed, the reliability data of the obtained assemblies is presented and compared.