Packaging requirements and solutions for CMOS imaging sensors

Image sensors place additional demands on packaging technology, beyond those for conventional ICs, including (1) an optical quality window, (2) precision mechanical die alignment, and (3) protection of die imaging attributes from environmental and manufacturing effects. In our development of CMOS sensors, we chose a commercially available package, the windowed QFP, as the basis for the CMOS sensor package. A pre-molded epoxy cavity package provides moisture protection similar to that for ceramic packages. Control of the tip and tilt components of die/package alignment and the tolerance stack-up between die and lens enables simple lens system alignment. The ceramic/glass lid maintains moisture protection while providing superior thermomechanical performance. This packaging technology gives customers a major advantage in board assembly with a mass reflow capable package that is unique in the industry