BOTTOM TERMINATED COMPONENT (BTC) VOID CONCERNS: REAL AND IMAGINED

摘要

The introduction of X-ray inspection/analysis technology into the printed circuit assembly process has enabled the observation of voids in solder joints. The impact of voiding on the solder joint integrity of ball grid arrays (BGAs) was resolved in 2010-2012 after significant industry investigation was completed and the IPC-JSTD-001 specification criteria was revised. Solder joint void discussions continue to cause debate as the industry implements bottom terminated components (BTCs). The observation of BTC solder voids has resulted in extended, energetic industry discussions concerning their possible impact on reliability. This paper documents an investigation to assess the impact of voiding on the reliability of Quad Flatpack No-lead (QFN - a type of BTC) components, subjected to thermal cycle testing (-55°C to +125°C) in accordance with the IPC-9701 specification, for both tin/lead solder and lead-free solder alloys. A recommended BTC void requirement for the IPC-JSTD-001 specification was extracted from the analysis of the experiment results.