A thin chip package for off-the-shelf ICs is developed which enables the embedding of these chips into a flexible circuit board. The package consists of a copper fan-out on a polyimide substrate, in which the thinned IC (30μm) is embedded. These packages are subsequently integrated in a standard flexible circuit board (FCB). A microcontroller and a proprietary DSP processor are embedded using this technology. The yield of the Ultra-Thin Chip package (UTCP) was measured before embedding in the circuit board, and reaches up to 87% for the packaged microcontrollers (MSP430 family, known-good dies). The yield on the DSP processor was measured to be 62%. After embedding in the FCB, 95% of the functional UTCP-packaged dies are still functional.

Autonomous systems for healthcare and sports applications benefit largely from a small form factor, as minute dimensions result in maximal mobility and comfort. By embedding a commercially available IC in a flexible circuit board (FCB), the overall size of a system can be reduced. This work presents the process of thinning and packaging an IC in a flexible interposer, and the embedding thereof in a FCB. To illustrate the potential of this technology towards miniaturization, a commercially available RF transceiver ZL70102 was packaged and embedded, thus realizing a volume reduction of 60%. I ntroductionResearch in the field of healthcare and sport monitoring tends to focus on the development of smart devices, where the output of multiple sensors is combined with the functionality of a microcontroller, memory and an RF transceiver for wireless communication to a base station or other nodes in the Body Area Network (BAN). The picture is often completed with a battery or energy harvester, thus providing an autonomous solution which enables the user or patient to monitor his/her health with a higher effectiveness and precision. Conventional technology often results in bulky solutions, and miniaturization of these systems only seems to be possible at the expense of functionality, autonomy and comfort.This paper reports on the development of a versatile packaging technology which allows integrating commercially available ICs into a miniature package by embedding the chip into a flexible circuit board (FCB). This action then allows rerouting the passives on top of the IC, which results in a system with a smaller form factor, breaking the boundaries imposed by SMD technology and fine pitch packages.