Finding Fault: Accelerated Testing of Coated Lead-Free Circuit Boards

Cleaning electronic circuit boards after reflow remains a critical problem, especially before boards are subjected to conformal coating or embedded in a potting compound.

Cleaning electronic circuit boards after reflow remains a critical problem, especially before boards are subjected to conformal coating or embedded in a potting compound. But not all cleaning processes are equal; there is a variety of materials that are created during the soldering steps significantly impair the cross linkage needed for good adhesion. These unwanted byproducts can be safely removed by using the appropriate cleaning processes. Specific analyses for so-called cross linking “toxins” are therefore highly recommended in addition to standardized cleanliness testing procedures, such as ionic contamination measurements. A fully integrated and optimized cleaning process increases the long-term product reliability, which ultimately translates into process related cost savings – especially when compared to production methods that skip the cleaning process. Because of this, there has been an increase in the need to clean No Clean products, especially lead-free. Products that have not been cleaned, even though manufacturing with No Clean technology, have been increasingly at the root of observed infield service failures, particularly with coated assemblies. We recently completed an extensive failure analysis study commissioned by a major railway manufacturer to establish the climatic reliability of a key electronic assembly, the “DSTPCB”. Specifications for the electronic assemblies called for them to be fully functional over a period of 30 years – including an average daily operating span of 16 hours (180,000 total hours of operation), within a given temperature range of -40°F to +185°F, and full exposure to the operating environment.

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ZESTRON Article

Accelerated Testing of Coated Lead-Free Circuit Boards