Miniaturized camera system using advanced packaging techniques

Recent years have shown the tremendous need for visual recording in consumer, telecom and security. Especially mobile phones have driven that trend to today´s ultra-small cameras embedded into the handset. While the image capture IC features ever-decreasing pixel geometries and surging megapixel numbers, the readout circuitry and optical systems are now challenged to follow-up with this trend. This paper describes a miniaturization approach using advanced packaging techniques for the electronic system (bare die assembly in stack-wirebond and flip chip) onto a high density circuit board and leveraging a MEMS based optical system providing the possibility for a variable focus lens and aperture concept. This can give rise to a camera including the optical system with just ~3 mm times 10 mm times 10 mm total dimensions. For prototypes, some electronic bare dice are mimicked by de-capsulating the IC from the plastic housing and re- bumping it for use as flip chip. This prototype procedure is also described. Operation of the MEMS device challenges the assembly technique for particulate free manufacturing of all back end processes. Bare die assembly with wirebond and flip chip provides ultimate miniaturization onto a rigid-flex multi layer PCB. The process flow for MOEMS assembly, electronic components assembly and final housing is designed to be generically applicable to current and future needs of ultraminiaturized cameras.