This invention relates to the removal of encapsulants from the integrated circuits.
Many integrated circuits are coated with an elastomeric encapsulant to protect the circuit components against condensed moisture, particulate matter, damage during assembly, and in some cases, light. After completion of the encapsulation process, it is often found that one or more components are defective. Since many of the circuits are quite complex and expensive, it is often economically feasible to repair a defective circuit rather than discard it. Repair can only be achieved after the encapsulant has been removed from the area containing the defective component.
Removal of encapsulating materials where the cohesive strength is greater than the adhesive strength does not present a problem. The area to be removed is outlined by cutting and the coating to be removed simply gripped at one edge with a tweezer and peeled off. It was found that other encapsulating materials where the cohesive strength is less than the adhesive strength cannot be as easily removed by this method because the encapsulant breaks apart when peeling is attempted. Furthermore, attempts to pry or lift the latter encapsulants often resulted in destruction or damage of many of the circuit components.
It is therefore a primary objective of this invention to provide a means that would enable non-peelable elastomeric encapsulants to be peeled from integrated circuits without damaging sensitive circuit components.
USPTO Backgrounds
USPTO Backgrounds