PCB exhibit internal short - x-section find cu residue

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We have filed returned (approx. 5%) of the boards that exhib... - Jul 10, 2007 by 5why

We doubt that entrapped process chemicals cause under-etch. ... - Jul 16, 2007 by davef

5why

#50977

PCB exhibit internal short - x-section find cu residue | 10 July, 2007

We have filed returned (approx. 5%) of the boards that exhibit inner layer short @ a particular connector locations. X-section revealed there exhibit Cu residue, but aside from that, we also suspect there could be organic contaminant, what test should be done to confirm there is organic contaminantn in the INNER layers??

2nd thing, the board house told us the Cu resiude is due to under-etch problem, so what normally cause under-etch? and what check&balance they should so that to ensure no more defect escape?? AOI is not going to help, correct? because we are talking about Cu particles... any inputs are greatly appreciated. Thanks a lot !!!

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davef

#51061

PCB exhibit internal short - x-section find cu residue | 16 July, 2007

We doubt that entrapped process chemicals cause under-etch. Over-etch maybe, but not under-etch

Under-etch is an indicator of improper process control/improper chemistry during etching. Under-etch can result in bridging between traces, resulting in short circuits. [NASA Workmanship Standards]

AOI should help. Look here: http://www.camtek.co.il/php/component/option,com_docman/task,doc_view/gid,7/Itemid,148/

An ol' friend wrote a paper than may help you appreciate the board fab business better. Look here: "PRINTED CIRCUIT BOARD FABRICATION BASICS AN OUTLINE" E Moon http://www.smtnet.com/express/199907/pcbfabbasics/

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