Electronic hardware can be susceptible to corrosion and electrochemical migration-related failures in geographies with high concentrations of gaseous and particulate contamination. In these environments, conformal coating may be necessary to prevent corrosion of PCBs and the components mounted on them.
Conformal coatings are presently tested by determining the time to failure of conformally coated surface-mounted resistors. This test methodology does have disadvantages. For example, the testing environment is not representative of operating conditions — it is done at a very high temperature that may cause reliable parts to be rejected, plus the test environment has no humidity and no gas other than sulfur. Another disadvantage is the time required to test. Tests can take months to complete, which is too long to be practical.
This iNEMI project was organized to evaluate and develop a more efficient and effective conformal coating screening test that will be able to determine whether a conformal coating material — and the process used to apply it — will be able to provide the required protection from harsh environment stressors. Having a better qualification process will speed the introduction of new coatings and improved application processes.
The project plans to leverage iNEMI’s flower-of-sulfur (FoS) chamber, which proved to be very successful in predicting the occurrence of creep corrosion in similar environments. The test will be based on quantitative measurement of diffusion of corrosive gases and moisture through the conformal coatings as a function of temperature and humidity in an environment containing sulfur and chlorines gases.
Today, it takes many months to evaluate and qualify a conformal coating, and test conditions do not accurately represent operating conditions. The ability to evaluate and qualify conformal coatings by a test of less than one-week duration, under environmental conditions approximating the operating conditions, will greatly aid the industry by reducing the qualification test time. Quantitative measurement can help optimize the conformal coating parameters (e.g. thickness, type) to ensure product reliability.
Presentation: End-of-Project Webinar (December 16, 2020, and January 5, 2021)
Call-for-Participation Webinar Presentation: Conformal Coating Evaluation for Improved Environmental Protection (March 25 & 27, 2019)
Haley Fu (firstname.lastname@example.org)