Understanding Smart Sensors - Nomads.usp

Packaging, Testing, and Reliability Implications of Smarter Sensors 237Figure 10.7 Surface-mount packaging in Oncore GPS. (Courtesy of Motorola, Inc.)(Oncore is a trademark of Motorola, Inc.)packaging. High-volume manufacturing cost for a 0.5-in 2 version of the circuitin Figure 10.8 is estimated to be about $1.10.4.3 Flip-ChipFlip-chip packaging technology, commonly used in ICs, is starting to receiveattention in sensors [11]. Flip-chip technology will allow the electronics to befabricated on one chip, which can be attached to the MEMS chip througheither a fluxless process or flux-assisted solder reflow process. This is anMCM-Si approach to combining different silicon processing technologiesinstead of increasing masking layers and die size to achieve a monolithic siliconsolution.Figure 10.9(a) is an example of flip-chip technology in a standard ICprocess [12]. The technology has been used in automotive and computer applicationsfor several years. The solder bump is formed over plated copper atthe wafer level. Several steps precede the actual formation of the bump. A