Interconnection Reliability of Interposer and Reballing Options For Ball Grid Array Backward Compatibility
Authors: Richard Coyle, Michael Meilunas, Richard Popowich, Martin Anselm, Peter Read, Mike Oswald, and Debra Fleming Company: Alcatel-Lucent, Universal Instruments, Inc., and Interconnect Systems, Inc. Date Published: 10/14/2012
Abstract: High reliability electronic equipment producers that continue to manufacture and support tin-lead (SnPb) electronic products are faced with an increasing number of availability issues with SnPb ball grid array (BGA) components. These supply chain constraints are driving development of backward compatible assembly solutions, which requires integrating a Pb-free BGA component into a printed circuit board assembly (PCBA) being manufactured with SnPb solder processing. This paper addresses two backward compatible assembly solutions: 1) SnPb assembly using an interposer card to mount the Pb-free BGA and 2) SnPb assembly using a SnPb component created by reballing the original Pb-free component. The primary objective of the study was to determine if the interposer or reballing assembly processes degraded the board level attachment reliability of a 676 I/O plastic ball grid array. The intermetallic solder attachments and microstructures were characterized before and after board level assembly using optical metallography and scanning electron microscopy. The reliability was characterized using a 0 to 100 ?C accelerated temperature cycle with 10 minute ramp and 10 minute dwell times. The reliability of the backward compatible assembly solutions is discussed relative to that of the basic SnPb and Pb-free assembly processes.