Backfill System for PCB Rework
Original Publication Date: 1981-Apr-01
Included in the Prior Art Database: 2005-Feb-11
In this system, a fiber wick is inserted into and fills a hole that has been drilled in a multilayer printed circuit board (PCB) to remove a defect, e.g. a short-circuit. A low viscosity dielectric liquid, e.g., an epoxy-resin, is applied to and absorbed by the wick by capillary action and subsequently cured by an appropriate time/temperature cycle. Thereafter, the excess resin-impregnated wick on the outside of the hole is trimmed by milling or the like. The system prevents trapping of air in the hole and/or run-out of the resin during curing, as well as providing a compatible dimensionally stable backfill for the hole.