Extended Evaluations of Commercial Off-the-Shelf (COTS) Plastic Encapsulated Microcircuits (PEMs) in Simulated SMT Soldering Processes, Temperature Cycling, THB, and High-Temperature Storage

摘要

Dr. William Perry, former Secretary of Defense and now a member of the Boeing board of directors, in 1994 dictated policy for the use of plastic-encapsulated microcircuits (PEMs) in military applications. Since that time, engineering and manufacturing productivity projects have been conducted to establish a literature base and reliability baseline for transfer-molded PEMs. Commercial off-the-shelf (COTS) parts are proposed for use in military systems. The use of single-chip COTS parts in programs such as the AGM-130, anti-satellite (ASAT), Teledesic, and Advanced Technology Programs at Boeing Communications and Information Management Systems, is cost driven. Experimental work in 1997 was initiated to (1) conduct environmental (THB and HAST), high-temperature storage (bias/no bias) on PEMs, (2) perform high-temperature operating life (HTOL) tests, (3) evaluate selected memory devices for upscreening, and (4) determine the performance variations of COTS parts after radiation testing. Initial results were reported at the IMAPS 1997 conference. Finally, experiments were performed on commodity plastic parts that showed excellent thermal cycling characteristics up to 500 cycles of -50° to +125 °C, and simulated vapor-phase and solder reflow tests. Testing in 85/85 conditions and highly accelerated stress testing showed excellent environmental performance. Radiation testing showed susceptibility beginning at 10 kRad total dose that becomes significant at 20 kRad and higher, and a case-by-case analysis of parts may be required. Extended reliability evaluations are complete. Results of this work were incorporated into a supplier qualification, PEM procurement and use specification titled "Selection, Qualification, Reliability Evaluation, Storage, and Handling Procedures for Plastic-Encapsulated Microcircuit (PEM) Components."