Gapless rework and reliability of lead-free BGA assemblies

摘要

In lead-free rework, it is almost impossible not to affect other adjacent parts when applying an existing hot-gas rework to the removal/exchange of parts as they are packed together. The fine pitch BGA components might be heat-damaged by the hot-gas or distorted, while smaller, passive components might experience a distortion of the parts due to melting of soldered joints. In such cases, it would be difficult to guarantee the reliability of the parts. This study focuses on reworked BGA components using flux-only application method. It is important to note that this study did not rework the initial BGA components to evaluate their reliability. As the results indicate, the reworked BGA components show an approximate 36% reduction in life expectancy over the non-reworked BGA components. The adjacent BGA component was also degraded in the drop shock test after the rework process was completed. This adjacent BGA component showed an approximate 38% reduction in drop reliability.