Proper documentation can identify risk associated with particular COTS parts.

A commercial systems manufacturer working on a major defense program experienced failed parts during reliability testing. It was attempting to incorporate commercial off-the-shelf (COTS) computer-related hardware into a battlefield system and was experiencing reliability issues. The parts were labeled by the vendor as “compliant to military (or MIL) standards,” but not clearly identified as SnPb or Pb-free.

Immediate support was provided in the form of an analysis of COTS components using x-ray fluorescence (XRF) and scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS) techniques for chemical identification of Pb-containing parts. The Pb-free components were clearly identified and assessed on the associated failure risk based on its intended application environment. This risk analysis permitted a cost trade-off consideration to determine whether to refinish the parts with SnPb or with a modified process for mixed lead and Pb-free components. This minimized program delay and resulted in improved reliability testing performance.

The recommended longer-term solution was a more proactive approach in development of a Pb-free control plan both internally and through their vendors, so that risk associated with particular COTS components is more clearly identified in the future. A prohibited material flow chart was created (Figure 1) to ensure proper implementation of components throughout the process – from receiving to final assembly. It was recommended that a Pb-free control plan be developed in advance of the upcoming Department of Defense requirement in accordance to guidelines provided by the AIA and the Pb-free Electronics Risk Management consortium (per GEIA-STD-0005-1 and GEIA-HB-0005-1).

It is important to note that many COTS parts supposed to be compliant to SnPb manufacturing applications may in fact result in a high failure risk. The best way to prevent unanticipated risk is through thorough parts identification and tracking, internally and externally, throughout the supply chain. Also, ensure that each vendor is aware that implementation of the Pb-Free Control Plan will soon be a requirement for parts associated with DoD programs in order to simultaneously support supply chain transition and improve program reliability. 

ACI Technologies Inc. (www.aciusa.org) is the National Center of Excellence in Electronics Manufacturing, specializing in manufacturing services, IPC standards and manufacturing training, failure analysis and other analytical services. This column appears monthly.