How Do You Remove Conformal Coating?

You may be required to remove a conformal coating from the PCB to replace damaged components or other types of rework. The basic methods as cited by IPC are:

• Solvent Removal – While most conformal coatings can be dissolved in solvent, you should make sure the solvent won’t damage parts or components. Acrylic  is the fastest and easiest coating to remove with solvent. Silicone and urethane coatings will take more soak-time and will probably require brushing to fully remove the coating. Chemtronics offer Electro-Wash Two Step [https://www.chemtronics.com/electro-wash-two-step], which when heated, quickly removes acrylic, silicone and urethane coatings. CircuitWorks Conformal Coating Remover Pen [https://www.chemtronics.com/circuitworks-conformal-coating-remover-pen] is available to dissolve small areas of coating.
• Peeling – Some conformal coatings can be peeled from the circuit board. This is mainly a characteristic of some silicone conformal coatings and some flexible conformal coatings.
• Thermal/Burn‐through – A common technique of coating removal is to simply burn through the coating with a soldering iron as the board is reworked. This method works well with most forms of conformal coatings.
• Microblasting – Micro blasting removes the conformal coating by using a concentrated mix of soft abrasive and compressed air to abrade the coating. The process can be used to remove small areas of the conformal coating. It is most commonly used when removing Parylene and epoxy coatings.
• Grinding/Scraping – In this method, the conformal coating is removed by abrading the circuit board. This method is more effective with harder conformal coatings, such as parylene, epoxy and polyurethane. This method is
  only used as a method of last resort, as serious damage can be incurred.