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40 PCB007 MAGAZINE I SEPTEMBER 2019 New technologies are emerging each day with more stringent requirements than the past. Also, reversals in obsolescence programs bring products back to the market for which the original documentation and/or require - ments are ancient compared to today's stan- dards; in some cases, this documentation is even lost. Further, it is not uncommon to find that original artwork isn't available or that the part must be recreated from a finished circuit board sample. This involves learning a netlist profile and then scanning layer by layer to recreate the actual film layers, but that is a whole different subject that I'll discuss in a future column. Specifications and Drawings With specifications and drawings, it gets complicated very quickly. When printed cir- cuits are procured, the purchase order (PO) is sent along with the master drawing and other deliverable requirements. In most cases, this is a straight forward process. The PO states what is being purchased, and the mas- ter drawing outlines the specifics and in- structions on what is required for the build. Usually, the master draw- ing will specify industry specifications and require- ments, which may include a special OEM specification. This is where it can get tricky, especially for historic or obsolete re- builds. These old specifications may not be available. Now what? For the fabrication house, this often requires consulting with the OEM and either obtaining the lost document or acquiring a deviation or waiver for the lost document. Even though the product may be a new build, there's a chance that the master drawing calls out for an older specification. Diligence is re- quired by the fabrication house to make sure that the proper specifica- tion is used. It can- not be assumed that the latest specification and/ or methods are to be used. This be - comes increasing- ly important when processing military products. One can- not assume the Understanding the Fine Print Testing Todd Feature Column by Todd Kolmodin, GARDIEN SERVICES USA

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