Greg Marszalek, 3M
Ultra-Thin Coatings to Mitigate Damage of LEDs and Associated Printed Circuit Boards Due to Environmental Exposure Greg Marszalek, Molly Smith, Erik Olson 3M Company, St. Paul, Minnesota
Electronic devices and components’ can have their performance and lifetimes decreased by corrosion and contaminates from the environment. To protect from these elements, printed circuit boards, light emitting diodes (LEDs) and other internal electronic components often use thin coatings to cover the sensitive areas. Ultra-thin fluoropolymer coatings make an excellent choice for this as they are hydrophobic (repel water) and oleophobic (repel oil). To demonstrate the effectiveness of these ultra-thin coatings, a number of tests were completed.
Fluoropolymer coatings were tested on a portfolio of LEDs to determine chemical compatibility. The data showed there was no effect on light transmission, brightness or visible color shift after 1000 hours. They were also subjected to 2,000 hours of UV light exposure (per ASTM-G154-12a) to demonstrate stability and showed no discoloration or degradation of the coating.
LEDs and electronics may also need to be protected against environmental sulfur, water or salt water. In the Flowers-of-Sulfur (FOS) test (ASTM B809) the coatings were shown to mitigate creep corrosion. In the water immersion test, boards were powered and immersed in 1-meter of water for up to 1 hour, showing significantly less corrosion growth on the coated verse uncoated boards.
The conclusion is that easy-to-apply, ultra-thin protective fluoropolymer coatings can help protect electronics and components from moisture, chemicals and environmental elements that can reduce performance, shorten useable lifetimes and cause expensive losses in time and materials.