CLOSED LOOP BACKDRILLING SYSTEM

摘要

A multilayer circuit board (16) is provided with at least one signasl layer (20), at least one feedback layer (22), ans at least one dielectric layer (24) positioned between the signal layer (20) and the feedback layer (22). The signal layer (20) is connected to at least one plated hole (12). The feedback layer (22) has a contact pad (26), which is positioned adjacent to the plated hole (12), but is electrically isolated from the plated hole (12). The contact pad (26) is connected to a measurement unit (48). The dielectric layer (22) is positioned between the signal layer (20) and the contact pad (26) of the feedback layer (22). A portion of the plated hole (12) forms a stub portion (18), which extends a distance away from the signal layer (20) and typically extends a distance away from the contact pad (26) of the feedback layer (22). To remove the stub portion (18), a hole is bored or routed into the multilayer circuit board (16) until electrical feedback is received by the measurement unit (48) upon contact of a portion of the boring device (40) with the contact pad (26) Upon receipt of the electrical feedback by the measurement unit (48), theboring device (40) is retracted from the hole, and the hole formed by the borijng device (40) is filled with an epoxy, or other filler material.