Doug, You could attach a process tag that goes with the board and have the inspectors and testers stamp that instead. I'm sure you could make your manufacturing processes accommodate the change and still maintain traceability. The product at the customer's site does not need the stamps on the PCB, you just need to maintain traceability during your manufacturing process.
Just one low-tech option I'm sure. Dan -----Original Message----- From: POWELL, DOUG [mailto:doug.pow...@aei.com] Sent: Friday, December 06, 2002 6:03 PM To: EMC-PSTC (E-mail) Subject: PCBA Inspection Stamps Hello group, I have a request for information on stamping methods of PCBAs. I would normally post this question on one of the discussion forums for PCB design, but this question really does pertain to product safety. But first, please indulge me while I provide a little background information... My company uses a very large number of PCB assemblies with wide variety of technologies. Many of these boards have safety considerations and receive routine hipot testing during manufacture. As is normally the case, in-house and outsource assembly of the boards requires various kinds of inspection and test with stamps for validation. Traditionally these are rubber stamps or some form of an adhesive label with printing. Many of our boards have high voltage separation from SELV circuits and as it turns out the most convenient place to put a stamp is in a safety keepout zone. There have been a number of hipot failures that track right through this stamp. In our standard practices manual, we specify the use of only white epoxy based inks, but some of these are conductive as well. In addition, with the ever shrinking geometries of high density boards, placing a nonconductive stamp on a low voltage circuit interferes by insulating test points for "bed of nails" testing. Since inspection marks are usually placed by hand, the faults we see are fairly random. So, on the one hand conductive inks are bad and on the other hand nonconductive inks are bad. In an effort to solve this problem, we've considered providing a silk-screened area of the board that is safe to stamp, but real estate is now at a premium and solder-side silk costs on average about 10% more. Plus, it won't be long until computerized component ID and location eliminates the need for silk-screen entirely. My question is this: Has anyone discovered a technology or process of any sort, for marking of ultra-high density or high voltage PCBAs and is easy to implement in most board houses? I have to think that with all the technological advances the old rubber stamp or adhesive label could be replaced somehow. Who knows, maybe some form of UV identification? I am very interested to hear any success stories that you may have. Best regards to all, -doug Douglas E. Powell Compliance Engineer Advanced Energy Industries, Inc. Fort Collins, CO 80535 USA _______________________________________________________________ This message, including any attachments, may contain information that is confidential and proprietary information of Advanced Energy Industries, Inc. The dissemination, distribution, use or copying of this message or any of its attachments is strictly prohibited without the express written consent of Advanced Energy Industries, Inc. ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list" ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"