Building a Reliable UV LED Process for Electronics Substrate Curing
It's not as easy as just putting a PCB under the brightest UV source to cure the electronics substrate. The process must produce the proper wavelength and UV energy without overheating the substrate or causing unneeded stress around sensitive components, or leaving material uncured in shaded areas. The goal is to create a reproducible curing window for the process engineer that correlates the photosensitive material, the substrate configuration, the UV processing equipment and the rate of production. Therefore, the quality and consistency of the final electronic assembly should be used as an evaluation criterion for a well-designed industrial UV LED curing system, instead of the irradiance output. Start with the Substrate and Photosensitive Material The material specification should be the first point to consider when starting the curing process. These are some of the typical electronics applications of conformal coatings, component adhesives, encapsulants, solder mask coatings and protective coatings. They can be used on rigid PCBs, flexible circuits, ceramic boards, glass, and metal-backed boards and thermally sensitive polymer films. UV and temperature are different for each substrate/material combination. Find out the recommended wavelength, minimum UV dose, range of acceptable irradiance and maximum temperature from the material supplier. The thickness of ...