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This paper describes the fine-pitch interconnection capabilities of the ultra-thin chip packaging (UTCP) technology, a technology under development for embedding thin chips in a flexible polyimide (PI) substrate. It allows for fully flexible electronics, as the rigid chips are thinned down to 20-30 μm, at which point they become truly flexible themselves. This way, instead of just a flexible substrate with rigid components assembled on top, the entire circuitry can be incorporated inside a 30-40 μm thin chip package. The paper briefly introduces the technology's background with a short description of the fabrication process. Building on the developments already achieved, some further optimizations are discussed, and the technology is tested for its fine-pitch interconnection capabilities using test chips with four-point probe and daisy chain patterns, with a pitch down to 40 μm. The possibility to package several chips in the same substrate is investigated, as well, and finally an outlook on future experiments is briefly discussed. [ABSTRACT FROM AUTHOR]

The increasing number of biomedical applications for electronic systems have led to the need for stretchable electronics in order to significantly enhance the comfort of the user. This paper describes the design and manufacturing process of new stretchable high-frequency interconnects with meander-shaped conductors in a coplanar waveguide topology. The novel interconnects are produced based on laser-ablation of a copper foil, which is then embedded in a highly stretchable bio-compatible silicone material. Measurements on prototypes of the designed stretchable high-frequency interconnects revealed a maximal magnitude of -14 dB for the reflection coefficient and a minimal magnitude of -4 dB for the transmission coefficient in the frequency band up to 3 GHz. The influence of stretch on the performance of the high-frequency interconnects was analyzed using a stretch testing machine. The results showed that nor the magnitude, neither the phase of the transmission coefficient was influenced by elongations up to 20%. [ABSTRACT FROM AUTHOR]