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54 The PCB Magazine • January 2016 Got Class? The PCB industry has documented different performance classes for printed wiring boards. In ET this is very important to know. Testing a board with parameters to match or exceed its class requirement is mandatory. The perfor- mance class is always found on the fab drawing. Many times a reference to IPC-6012 Class I, II or III will be documented. From this information ET knows what parameters and test methodol- ogy are allowed. Spec Check? Above and beyond the IPC manufacturing specification, ET must also be aware of any pro- prietary specification that may be called out. If the proprietary specification has any specifics around ET, it is desirable that this information be on the print notes as well. If those require- ments are not specified it could lead to a non- conformance issue at the customer. Electrical test must also review for a military specification. If the ET department or contractor is granted suitability to test military product by the De- fense Logistics Agency (DLA) they must test ac- cording to the specification and report product tested in the required annual report. Electrical test contractors or the internal ET department can only certify the product conforms to the electrical requirements of the specification un- less the department has the final authority to write the certificate of compliance for the entire manufacturing process. In the scope of today's discussion, ET does not have the authority to certify the product is built to a certain specifica- tion. ET can certify the product was tested in accordance with the given specification. Stamp it? This is a subject that may require ET to re- view other pages of the drawing set other than the notes section. If a board passes ET it will usually receive a stamp or mark that shows it has passed ET. There are cases where the fab drawing states exactly where a stamp should be placed and conversely may also state the area(s) where it cannot be placed. Is ET Special? Another attribute ET should be looking for are special test requirements or parameters. These requirements will override the default specifications in most cases. This could be iden- tification of buried passive components and ca- pacitive attributes that may be present, which ET should know about so as to adjust equip- ment as necessary to avoid false failures and unnecessary delays. Getting it Right! From the receipt of the new order the sales/ tooling department needs to make sure all re- quirements are flowed down to every depart- ment involved. Missing information to any given department can cause delays. This is even more critical when independent contractors are used, whether in-house or external. Missing me- chanical attributes such as layup or image array orientation are just as important to ET as miss- ing electrical attributes. Missing information in these areas can cause costly delays, including wrong fixture tooling, incorrect programming for flying probes and incorrect parameters being used to test product. Diligence in all these areas can mean the difference between successful on- time delivery and costly restarts. PCB Todd Kolmodin is the vice president of quality for gardien services usa, and an expert in electrical test and reliability issues. to read past columns, or to contact the author, click here. testing todd FABRICATION DRAWINGS AND ELECTRICAL TEST—READING THE FINE PRINT " above and beyond the ipc manufacturing specification, et must also be aware of any proprietary specification that may be called out. "