BGA Thermal Cycle Solder Joint Integrity Using a Nonconcentric Microvia in Pad Structure
Authors: Dave Hillman, Dave Adams, Tim Pearson, and Ross Wilcoxon Company: Rockwell Collins Date Published: 10/14/2012
Abstract: The impact of voiding on the solder joint integrity of ball grid arrays (BGAs) can be a topic of lengthy and energetic discussion. Detailed industry investigations have shown that voids have little effect on solder joint integrity unless they fall into specific location/geometry configurations. This paper documents an investigative effort to understand how the solder joint integrity of BGAs is influenced if the microvia location in the pad is preferentially skewed to one edge. It was hypothesized that a BGA void could form at the side of the solder joint and therefore degrade the solder joint integrity compared to BGA voids located in the central region of the solder joint. Thermal cycle testing (-55°C to +125°C) was conducted in accordance with the IPC-9701 specification for both tin/lead and lead-free solder alloys. The investigation test results showed the skewed microvia in pad structure did not have an impact on BGA solder joint integrity.
BGA, solder joint integrity, voids, microvia in pad