Urmi Ray

First demonstration of drop-test reliability of ultra-thin glass BGA packages directly assembled on boards for smartphone applications

This paper reports the first demonstration of the drop-test reliability performance of large, ultra-thin glass BGA packages that are directly mounted onto the system board, unlike the current approach of flip-chip assembly of interposers, involving additional organic packages which are then SMT assembled onto boards. The packages, 18.4mm × 18.4mm in size made of 100μm-thick glass, were also successfully assembled, for the first time, in a SMT line. The effect on drop reliability of the glass BGAs with circumferential polymer collars was studied extensively. While the glass BGA packages met the reliability requirements, both with and without polymer collars, the polymer collars were found to further enhance the drop performance, as well as the fatigue life of solders. Finite element modeling was used to understand strain-relief mechanisms and provide design guidelines for reliability. The glass substrates fabrication process along with the formation of polymer collars by spin coating is detailed. The glass package-to-PCB assemblies were formed using SMT-compatible processes with standard equipment, followed by reliability testing through thermal cycling and drop tests. The compiled failure data from drop testing was fitted into a Weibull distribution plot. Comprehensive failure analysis was performed to assess the structural integrity of the glass substrates and identify the predominant failure mechanisms in drop test.

3D TSV integration technology challenges for high volume production from fabless supply chain aspect

Limited battery power for wireless devices demands improvement in power efficiency while enhancing system performance. Traditional semiconductor scaling faces challenges to meet this requirement. 3D integration of multiple chips using through silicon via (TSV) is one of the technologies that can extend the performance scaling trend. However, the semiconductor industry will need to overcome many technology hurdles before 3D TSV integration can be implemented in high volume manufacturing, particularlyfor the fabless supply chain. This paper will review the integration challenges and recent progress in process integration, reliability, yield and cost.