A major telecoms company performed HALT on one of their very complex and expensive products which consisted of several large plug-in cards secured to a large backplane. Prior to the HALT, extensive Design Verification testing was performed to qualify and validate the product.
No problems or failures were found during this test process. Further to the testing mentioned above, several complete units were sent to external sites such as universities and customers for alpha/Beta testing. This type of evaluation lasted for several months and again no problems were found.
The next stage was the final qualification where the product was subjected to HALT at the Anecto test laboratory. During the fast ramp temperature excursions from the Upper Operating Limit (UOL) to the Lower Operating Limit (LOL) failures started to occur causing major functional errors.
Failure analysis found that an inner layer etch was defective, opening and closing like an electronic switch. This failure was induced by a manufacturing error in the backplane and exposed by HALT during the High to Low temperature fast ramp rates causing the inner layer etch to expand and contract. When the product was brought back to ambient temperature it performed correctly.
Arrows point to breaks on inner layer PCB etch due to insufficient solder caused during manufacturing process. These flaws were exposed by Anecto’s HALT testing.
The result was a major Engineering change on several hundred backplanes. If the product had not been exposed to a HALT it would have been shipped with the problem resulting in field failures in a short period of time and probably a total recall. The company in question informed Anecto that the testing saved millions of dollars.
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Case Study – Emerson Network Power
How Anecto developed a number of innovative solutions for the leading multinational Emerson Network Power.