Conformal coating is used on PCBs to protect them in their operating environment from chemicals, moisture, dust and temperature. The coating layer is a few thousands of an inch in thickness. Their makeup falls into a broad variety of categories including but not limited to epoxy, silicone, urethanes and acrylics. Once the board is assembled and tested the coating is applied. If removal and replacement of components is required the conformal coating must first be removed in order to mechanically detach the component from the assembly prior to removal.
Conformal coating removal can be challenging as there are several methods as well as associated risks involved with removing the coating prior to rework. Chemical removal may harm components or board materials. Heat, abrasion or mechanical force applied to the coating may damage components or the physical attributes of the PCB. In addition to the damage caused by the removal of the coating the rework process itself may cause soldering anomalies on the PCB. Areas in and around the rework area, when heated, may cause the solder to “squirt out” from the underside of the leadless devices or BGA packages causing electrical failures.
BEST has a vast amount of experience in working with conformally coated printed circuit boards being able to determine which of several methods are the best-suited for the rework job at hand.