NON-DESTRUCTIVE DETERMINATION OF THE MOISTURE CONTENT IN AN ELECTRONIC CIRCUIT BOARD USING COMPARISON OF CAPACITANCE MEASUREMENTS ACQUIRED FROM TEST COUPONS, AND DESIGN STRUCTURE/PROCESS THEREFOR

摘要

Two test coupons are utilized in an apparatus, method and design process/structure for determining the moisture content in an electronic circuit board (e.g., a printed circuit board (PCB) or panel). The first coupon has a laminate stack-up with voltage planes separated from each other by dielectric material. These voltage planes include etched clearances with neither plated through holes (PTHs) nor drilled holes extending therethrough. The second coupon is substantially identical to the first coupon except that each of the voltage planes of the first coupon includes PTHs extending through etched clearances corresponding to the etched clearances of the first coupon. In one embodiment, an alarm indicating unacceptably high moisture content is generated if a delta capacitance calculated as a difference between capacitance measurements acquired from the respective coupons is greater than a threshold. Preferably, the alarm notifies a user that at least one aqueous process related to PTH formation is implicated.