Epoxy resins (ER), just like any other conformal coating provides a thin protective film. If the coating is too thick, problems could include shrinkage, cracking, bubbling or trapped solvent. Here at Diamond MT, we are the experts at applying conformal coatings from handling your invaluable piece of technology, to application to quality control and standards. Epoxy is available as a single part or two part compound. Single part compounds are cured thermally or by UV exposure. Two part compounds begin to cure as soon as they are mixed together.
Both systems provide the same benefits. They have good moisture and dielectric resistance. They also have excellent temperature and chemical resistance. Epoxy also has good resistance to abrasion and is rigid.
Epoxy is nearly impossible to rework. Any solvents that can remove Epoxy conformal coating can also remove the epoxy adhering components to Printed Circuit Boards. The solvents also have an affect on the PCB epoxy based laminates. The only possibilities for rework are to either spot remove with a very minimal amount of solvent or burn through the coating with a knife. Heat cure causes the coating to shrink and a low temperature cure or another method is recommended if shrinkage is an issue.
As with Acrylic, Polyurethane and Silicone, Epoxy can be applied by brush, spray or dipping. Spray and machine dipping are most efficient for large batches. Brushing is recommended for prototypes and assemblies requiring a lot of masking. A buffer should be considered for use with more delicate components.
While epoxies are very good at protection from humidity, chemical and abrasion, they are as stated above very difficult to remove. Below is a brief description of some methods in removing this robust coating:
Use extreme caution when burning through epoxy. Though no known gas is emitted, check with the manufacturer before you use this technique.
Because epoxy is so hard, this technique is not recommended. Damage to the board most likely will occur.
Complete coating removal for repair is nearly impossible by chemical means (except in the case of hermetically sealed hybrids), as the solvent can’t discriminate between the epoxy coating, the epoxy-glass printed circuit board, and any epoxy-coated or potted components. However, if done carefully, spot removal of the coating may be accomplished by the application with a cotton-tipped swab of a solvent with a methylene chloride base and acid activator.
There are many different industries that conformal coating plays a critical role in.