Creep Corrosion of OSP and ImAg PWB Finishes

With increasing adoption of lead-free PWB surface finishes, along with increasing product deployments in more corrosive environments, the electronics industry is observing increased occurrances of corrosion-induced product failures. Particularly, creep corrosion on immersion silver has been observed to cause failures after very short service periods in G2 and worse environments, in some cases less than one year. In our previous work (APEX 2009) [1], we demonstrated that creep corrosion of ImAg can be correlated to the presence of certain types of surface contamination (for instance residues left behind by organic acid fluxes). In this work, creep corrosion observed on OSP finished circuit boards will be reported. The effect of post-reflow cleaning process on creep corrosion will be discussed. A Laboratory MFG test will also be discussed that replicates field creep corrosion. Comparison of creep corrosion susceptibility between OSP and ImAg PWB surface finishes will also be made.