Degradation studies of epoxy coatings on printed circuit boards after pressure cooker test

The present work focuses on the investigation of the degradation of screen-printed epoxy coatings on printed circuit boards under multiple corrosion loads realized by the pressure cooker test (PCT). Since methods like the common mechanical shear strength tests are destructive and limited in information, the authors' approach used electrochemical impedance spectroscopy to study the change of their electrochemical behavior and the state of degradation. Complementarily, the Fourier-transformed infrared spectroscopy was used to investigate the possible molecular change of the polymer due to the exposition. The experiments were carried out after different times of load. It could be shown that the complex conditions of the PCT initiate a controversial mechanism. The harsh corrosion load already results in a degradation of the polymer after 8 h but simultaneously the enhanced test temperature leads to ongoing curing processes consuming the remaining parts of resin and curing agents. As a result, the degradation kinetic seems to be delayed and after the test time of 96 h, the epoxy is less degraded than it was expected based on the results after a shorter time exposition.

Automated summary

This study focused on investigating the degradation of screen-printed epoxy coatings on printed circuit boards under multiple corrosion loads using the pressure cooker test. The approach utilized electrochemical impedance spectroscopy and Fourier-transformed infrared spectroscopy to study the change in electrochemical behavior and molecular structure of the polymer. The results showed that the complex conditions of the PCT initiated a controversial mechanism, leading to delayed degradation kinetics of the epoxy resin.