The failure of an electronic product maybe the result of substandard components produced by counterfeiters. The UK-based deisgn and testing company Cobham Technical Services, helped a client find the monkey in the mess of products that that were failing in production. In a case study, Cobham tells the story of a company that found junk parts in its products.
The client needed part that had recently gone obsolete. Procurement personnel turned to the open market to buy excess lots of the obsolete component - a fairly common practice when a part goes obsolete. Problem is, those parts were not produced by the original component manufacturer. When the franchised distributor runs out of the part, company will turn to the “gray” market of independent distributors until the product can be redesigned with a new part. While many independent distributors word hard to inspect components and weed out counterfeits, not all independents are so careful.
While these components were identical on the outside, closer inspection revealed several different designs. Variants 1 to 4 show some of these variants, all at the same magnification.
Variant 1 - the earliest design. No circuitry between the bond pads
Variant 2. Some protective circuitry between the pads
The early design in variant 1 had no parts of the circuit or tracks between the bond pads, as the “real estate” was not deemed so valuable. The different design in variant 2 has some of the protective circuitry between the pads. The chip in variant 3 is similar but has undergone a slight shrink. There were also a few variants like the square chip in variant 4.
|Variant 3. The chip is slightly smaller
Variant 4. Redesign into square form factor
One group of four devices with the same date code (about 6 years ago) had three different types of chip inside. Some of these worked, some passed functional tests of the complete board and some failed automatic testing of components on the board (ATE)
Even with components of known provenance, further potential problems arise when using old components. These include:
moisture absorption - unless the components have been stored very carefully they may have absorbed moisture with the possibility of “popcorn damage”, where the water boils during soldering and splits the package.
solderability - it is often recommended that components are used within 6 months as the terminals may tarnish if left longer and become more difficult to solder.
Counterfeiting of components increase the uncertainty regarding component performance and so compounds the problem. As the above example shows, even the same date code on the outside of a device provides no guarantee that what is inside is the same.