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July 2017 • SMT Magazine 23 COUNTERFEIT ELECTRONIC COMPONENTS IDENTIFICATION: A CASE STUDY • They are not easy to identify, even with sophisticated analytical methods • They are in the supply chain, even with authorized distributors • They are more of an issue with obsolete parts Background on Case Study During functional test of control module boards used in a multiple sub-array of a testable antenna, two boards failed. The root cause for the failures was identified as "unable to write specific addresses at system speeds." When di- agnosing the issue, it was narrowed down to an SRAM that was supplied by an electronics part broker. The parts in question were procured from the broker, an approved diminishing ma- terial supply (DMS) supplier, due to unavailabil- ity from a franchised distributor of the origi- nal components manufacturer (OCM). When reviewed by the internal Failure Review Board, it was determined that a comparison of SRAM parts supplied by the broker should be com- pared with parts from the distributor to deter- mine if there were any observable differences in the parts. Analysis Approaches and Techniques A total of seven different methods which ranged from nondestructive to destructive were used to make a determination about the SRAM parts being suspect counterfeit. Any individual analysis does not make a clear case on its own merits. However, to make a legal case for sus- pect counterfeit, enough due diligence is neces- sary. The following outlines the seven analyses used to make the case: 1. Visual inspection by optical microscopy 2. X-ray 3. De-capsulation 4. Scanning acoustic microscopy 5. FTIR 6. Electrical test 7. Discussions with OCM Visual Inspection by Optical Microscopy Once the failure occurs on a component or subsystem, typically there is an optical in- spection to determine if there was any physical damage to the part either before or during test- ing. Damage can occur from a variety of sources including handling, testing conditions and set- up, foreign object damage or debris (FOD), fix- turing, etc. Figure 1 shows a comparison of an SRAM received by an authorized distributor and the broker in question. It was noted that the lot number of the broker part was not in the OCM database. In and of itself, this does not constitute a smoking gun, but it does inspire one to con- tinue the investigation. Upon further visual in- spection, it appeared the workmanship, or qual- ity of the part around the leads suggested a dif- ference in mold processing (Figure 2). Because visual inspection is subjective and directed by any given customer requirements, incoming in- spection (5-10X at AQL) easily can miss the in- Figure 1: Comparison of two SRAM parts with different lot numbers.