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Specifications are consensus documents agreed upon by a panel of interested industry participants composed of suppliers, manufacturers, assembly houses, and end users. The IPC Plating Sub-committee 4-14 is no exception. If there is consensus then the committee documents it in a specification. In cases where no consensus is readily arrived at, the committee undergoes its own testing in what is commonly referred to as a round robin (RR) study.
In an RR study, an agreed-upon test vehicle (TV) is designed and manufactured. The TVs are then sent to the different suppliers who deposit the agreed-upon thicknesses to be investigated. The TVs are collected and the deposit thicknesses are verified and documented. The TVs are then coded. The coding is done to conceal the identity of the specific supplier, to keep the evaluation objective and to ensure it is not a comparative study between different suppliers. This is followed by again sending the TVs to the different testing sites that test for the desired attribute like soldering, contacting and wire bonding capabilities of the different finish thicknesses. The data is then collected sorted out and documented. At this point a new attempt at consensus is made and upon arrival, the thickness specification is set.
Specifications are reference documents called out by designers and OEMs. Designers may take exception to one or more items in the specification to ensure that the product meets the requirements of its intended use. The term “AAUBUS,” as agreed upon between user and supplier, is part of any specification.
Editor's Note: This column originally appeared in the September 2013 issue of The PCB magazine.