Effects of solder joint shape on joint reliability under drop impact loadings

The purpose of this paper is to compare the ability of solder joint with different shape (hourglass-shaped, barrel-shaped and cylinder-shaped) to resist destruction under drop impact loadings. Three 3D finite element models of VFBGA (very-thin-profile fine-pitch BGA) packages, including different shape of solder joints, are established respectively. According to the condition B in the drop test standard of JEDEC, the stress-strain responses of the whole packages under drop impact loadings are calculated by ANAYA/LS-DYNA. The results showed that the stress on the solder joint reaches its peak at about 1 ms and the maximum peeling stress on the critical solder joint which is located at the most outer corner of the BGA package. The hourglass-shaped solder joints which show the minimum peeling stress at the critical moment, have the strongest ability to resist destruction among three shaped solder joints under drop impact loadings.