Collaboration Between OEM and EMS to Combat Head on Pillowing Defects: Part 2 - Warpage Acceptance Proposal
Authors: Alex Chan, Paul Brown, Richard Coyle, Lars Bruno, Anne-Kathrine Knoph, Thilo Sack, David Geiger, David Mendez, Ron Kulterman, Mulugeta Abtew, Iulia Muntele, and Kirk VanDreel Company: Alcatel-Lucent, Ericsson, Celestica Inc., Flextronics International, Sanmina Corp., and Plexus Corp. Date Published: 7/31/2013
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. These include inspection effectiveness as covered in Part 1 of this two paper set. This second paper addresses the root cause of the HoP defect; specifically the link between HoP defects and component warpage. Multiple case studies contributed by the participating companies are presented to support the proposal that the current industry warpage standard needs to be revised and to demonstrate that further work is needed by the industry to understand the root cause of this defect better. Based on the data from the case studies, the authors propose revised acceptance criteria that set the maximum warpage at 0.090mm (3.5mil) for BGA of 0.8mm pitch and above.