BGA with Controllable Warpage Used to Confirm the Need For a Lower Warpage Specification
Authors: Alex Chan, Paul Brown, Rich Wensel, Kim Hartnett, Nancy Renfro, David Geiger, David Mendez, Ron Kulterman, Brent Selin Company: Nokia, Micron Technology Inc, Flex Ltd., Milpitas Date Published: 9/17/2017
Abstract: There have been many publications, industry workshops, and symposia that describe process mitigation techniques for minimizing the occurrence of Head-on-Pillow (HoP) defects during surface mount assembly. This paper addresses the root cause of the HoP defect; specifically, the link between HoP defects and component warpage. Through the support and collaboration of a component supplier, a controlled study was performed to further pinpoint the onset of HoP based on multiple versions of the same package that were engineered to produce low, middle and high warpage. Based on the data from this study, the authors propose a revised acceptance criteria that sets the maximum acceptable warpage at 0.090mm (3.5mil) for BGAs with 0.8mm and 1mm pitch.