Oracle International Corporation

Stephanie Moran

Michael C Freda

Karl Sauter

A method and apparatus for determining misregistration of internal layers of a PCB using resistance measurements is disclosed. In one embodiment, a method includes measuring a first resistance between a first center terminal and a first peripheral terminal of a first registration coupon on a printed circuit board (PCB) panel including at least one PCB. The method further includes measuring a second resistance between the first center terminal and a second peripheral terminal of the first registration coupon, wherein the first and second peripheral terminals are associated with a first internal layer of the PCB. A difference between the first and second resistances is then calculated. Then, based on this difference, a determination is made of a distance of misregistration of the first internal layer, if any, along a first axis.

Layer-layer registration coupon for printed circuit boards

A step drill test structure for a PCB and method for using the same is disclosed. In one embodiment, a test structure includes a drill path and a connection via. The drill path may include sensing pads on selected ones of a plurality of layers of the PCB (e.g., the non-surface layers). The sensing pads of a given drill path may be electrically conductive, while the remaining portion of the drill path is non-conductive. The sensing pads of each drill path may be electrically coupled to the connection via. The depth of a given layer at a particular drill path may be determined by drilling, using an electrically conductive drill bit, into the drill path and determining when an electrical connection is made between the drill bit and the connection via.

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San Francisco, CA, United States of America

Stephanie Moran