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PCB Markings – Missing Silk Screening

Question: We have some panels of 6 PCBs each, double sided, which were built on our pick and place machine. After the panels were built, it was discovered that a couple panels do not have the silk screening for the component locations on one side of the board. Per IPC 10.5.3, it appears these are a defect(scrap), but it does not affect our end use form, fit, or function and we hate to scrap product without a good reason. Is this possible?

Answer: Markings are used for a variety of reasons and according to IPC-A-610 Section 10.5, they must be required by contract agreement between the fabricator and the customer.

If the markings are missing, we need to define which markings are missing; for example board information data, such as part numbers, revision, serial number or date of manufacture. If these are missing then the product is defective and rejectable. Whereas other markings could be for component orientation and/or component identification. Either way if the contract demands that they be there and they are not, the product is not acceptable and has to be dispositioned.

Overall if the marking is missing on certain circuits on a panel, the reason should be defined as to why, as these panels may have failed electrical test at the board level and this is sign that these circuits are no good.

If you are a subcontractor, then you need permission from your customer to use these boards. If you are an OEM and these are your boards going into your products, then the disposition is through your Material Review Board and if the product is functional, then the disposition would be to use as is.

Either way they are reject-able, but whether to use or not has to be made by engineering.