Defeating the Golden Sample Syndrome: Crede Sed Proba!

Since my early days as a process engineer in the printed circuit board (PCB) industry, I’ve been witness to the “Golden Sample Syndrome.” Back then, it was difficult to have multilayer PCBs consistently pass UL flammability and delamination and blister testing. As the testing was lengthy and expensive, PCB fabricators were motivated to pass on the first try.

What did some of them do? They’d purchase (or doctor themselves) “juice” materials that contained an additional amount of “tetrabrom” the flame retardant agent popular then. These doctored samples would pass delamination and D&B testing even if you took a flame thrower to them.

In the modern era, the fabrication of Golden Samples continues, and the perpetrators have become alternately more sophisticated players and sloppy amateurs. What unifies them is the desire to wring cost out of the products they manufacture. In our work we see frequent examples of component and material substitution, the application of lower manufacturing and QA standards for volume production and the use of unapproved and unaudited sub contractors.

How does the smart buyer defeat this ploy? It’s basically a set of common sense disciplines and tactics applied diligently. Our check list is below:

  • Audit your vendor and keep detailed records. Revisit at least once a year and determine what’s changed in their processes and systems. Hold the vendor to the original standard.
  • Pull your own samples. Visit yourself or have an independent agent drop in unannounced to pull representative samples.
  • Utilize well written bilingual supply agreements and product specifications. Pin down exact performance criteria. Require that the vendor allow random and unannounced audits and inspections.
  • Test and retest. Require that the vendor submit samples of components, materials and finished products to a laboratory that you select. Submit the samples that you pull for referee testing in another laboratory.
  • Zero tolerance. When you find inferior workmanship or a substituted component, reject the lot and demand compensation.

To use my wife’s adage that’s often applied in her kindergarten class, “you get what you get and don’t get upset.” Stated another way as I learned in high school Latin class “Creda sed proba” or “Trust but Verify.”


Jack Daniels

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