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74 SMT007 MAGAZINE I JUNE 2020 ures that were shipped with a certificate of conformance. What this tells me is that histor- ical pass/fail criteria imposed by the customer or offered from the suppliers may not be suffi- cient for your product. Segregation of material from standard pro- duction normally falls into one of three buck- ets: releasing, reprocessing/reworking, and rejecting. I mostly think of issues around quar- antine to be related to incoming raw materi- als as they are received and go through the standard paperwork checks. You can certainly use the same word for an assembly during the build process. Most times, the assembly in question will be segregated from the line and put into a spe- cial tray or rack for further review and dispo- sition. When raw materials are received and don't conform to the specs on the drawing or the purchase documents for one reason or another, that material needs to be segregated to a part of your receiving area and tagged so that it is not used in normal production until disposition is decided. This also applies to raw materials used directly for assembly like bare boards, raw components, solder paste, and fluxes, but should also apply to anything that can have an impact on your product. Often, handling materials like gloves, finger cots, pink foam, and ESD bags are overlooked when there isn't a direct measurement for accept or reject con- ditions. All of these materials will most likely come into contact with your product at some point. Any material that contacts your prod- uct will always be a risk for contamination, but that isn't what this column is about, so I digress. Releasing is easily the best of the three buck- ets, as the material will be reviewed by a sup- plier quality engineer (SQE) or someone simi- lar and, if deemed acceptable for use, released into production. With incoming raw materials, the best-case scenario is a typo on the paper- work side where the shipping documents don't match the purchase order. Remember, I don't work in purchasing, which might be why I think that is the better option. When inspect- ing assemblies that have been deemed out of specification for some reason during the build process, it may be a more difficult call to just release it. Testing of some sort like functional or possibly more strenuous environmental exposure might need to be done before a deci- sion can be made. The second bucket—reprocessing/rework—is normally reserved for work in progress assem- blies that fail some sort of ICT, visual inspec- tion, or other end-of-line testing. An assembly that fails some inspection during the build can be sent to a rework and repair area and brought back into spec for use. Issues are caused by conditions like insufficient solder joints or mis- placed components, among others. There are many variables to consider when determining if it is acceptable or not, and many times—especially in the case of high-reliability products—rework and repair may not even be allowable. Form, fit, and function will always be the first criteria, but beyond that, it's impor- tant to see if the customer has imposed any other metrics you need to meet. Bucket number two is normally reserved for assemblies, but it could apply to incoming raw materials too. If bare boards or components need to be cleaned before use due to some issue at the supplier, it would be considered a reprocessing/rework. This is not something I have seen on a regular basis, but we have seen it, so there's a chance. The last bucket is rejecting the material and returning to the supplier for replacement. This is normally the worst of all buckets. Rejecting incoming materials is never fun because that can cause delays in your build schedule while you wait for new conforming material. That is Many companies—too many, if you ask me—rely on the material supplier to include a certificate of conformance with every shipment and never question it.

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