Low cost method of testing a cavity-up BGA substrate
 A new method is provided for the testing of complex, high density flip chip packages. A temporary electrical short is provided by a layer of metal for all the interconnect metal lines of the package, vias are created in a surface of the package for the connection of the flip chips to the package. These vias are plated using either copper or copper followed by nickel and gold. The process of plating requires uninterrupted electrical paths between the vias that are being plated and the layer of metal that provides a temporary electrical short. Where this uninterrupted electrical paths is not present, due to problems of poor via creation or problems of opens in the interconnect lines of the package, the vias will be improperly plated and can as a result be readily identified. The metal layer that has provided the common short between all interconnect lines of the package is now patterned and probed for problems of shorts or opens. 
Thin Film Module, Inc.
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Chung W.
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