Evaluation of Polymer Core Solderballs for Wafer Level Reliability Improvements

摘要

Wafer Level Chip Scale Packaging (WLCSP) began with very small packages having solderball counts of 2-6 I/Os. Over the years, the I/O count has grown, but much of the industry perception has remained that WLCSPs are limited to low I/O count, low power applications. But within the last few years, there have been growing demands for WLCSP packages to expand into applications with higher levels of complexity. With the ever increasing density and performance requirements for components in mobile electronic systems, the need has developed for an expansion of applicability for Wafer Level Package (WLP) technology. Wafer Level packaging has demonstrated a higher level of component density and functionality than has been traditionally available using standard packaging. This has led to the development of WLCSPs with larger die and increasing solderball connectivity counts. With the majority of the WLCSP applications being for mobile devices, there also have been strong incentives to reduce the packaging costs of these devices. For a typical 4-mask WLCSP design with a plated redistribution structure, the opportunities for manufacturing cost reductions are limited. With the customer drive for a lower cost solution, WLCSPs with 3-mask process flows have been introduced into the marketplace. These structures eliminate the Under Bump Metallization (UBM), and instead bond the solderball directly to the Redistribution Metal Layer (RDL). The elimination of the UBM changes the stress distribution, and has been shown to have lower levels of Board Level Reliability (BLR) performance. The work referenced in this presentation had two objectives. One was to increase the size and I/O count of WLCSPs and the second was to improve the reliability performance of the 3-mask WLCSPs. A Zinc Oxide Nanowire-Based Sensing Platform for Carbon Dioxide Detection Bruce Kim, Dept. of Electrical Engineering, City University of New York Anurag Gupta, The University of Alabama Trace detection of hazardous nitroaromatic gases is a rapidly emerging field. The prospective utility of these compounds by extremists for developing improvised explosive devices (IEDs) pose a grave threat to human lives. Traditional detection methods such as, gas chromatography, standoff Raman, fluorescence spectroscopy, and X-ray suffer from implicit limitations of portability and sensitivity. To mitigate this challenge, ultra-sensitive unmanned platforms are needed that can remotely identify hazardous nitroaromatic vapors while being compact in terms of real estate. The advancing frontiers of nanotechnology have provided a viable alternative in terms of nanostructured materials with morphology- and surface-dependent physicochemical properties, which can be tuned for specific applications.