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SMT on rig-flex and multi-flex boards


SMT on rig-flex and multi-flex boards | 22 October, 2004

Is there anyone who knows the yield rate difference for SMT on multi-flex boards and rig-flex boards ? Basically, I think the yield rate should be higher for rig-flex than multi-flex due to the poor dimensional stability of polyimide, since multi-flex is 100% based on polyimide, while rig-flex is a hybrid of FR4 and polyimide. Can anyone share his comments with me? Thanks.

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C Lampron


SMT on rig-flex and multi-flex boards | 22 October, 2004

Hi Christina,

What would you be basing the yields off of? Is it solder defect, component placement, etc....? I have worked for a flex house for quite a few years. You are right. The Polyimide is very dimentionally unstable. (even more so on humid days) I would imagine that processing very small parts would be a problem especially on a very large flex. Also, we have had some problems printing fine pitch QFP's due to the gross bared insulation around the pads. This caused the stencil not gasketing to the pad. So in answer to your question yes, the yields would not be as high for flex compared to ridgid PCB's especially if design considerations for SMT manufacture are not realized. Extra precautions need to be taken to maximize accuracy and minimize defects. I would be happy to share any of our resolutions for some common problems that we encountered. Please let me know if you are interested and I will get a hold of you.

Good Luck


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SMT on rig-flex and multi-flex boards | 24 October, 2004

Dear Chris

Thank you so much for the prompt reply and it really helps. Do you have any SMT experience for rig-flex boards? Can you share with me about the differences with that of rigid boards? Is there any special precaution needed? When you were doing SMT on flex boards, were the SMT equipments the same with those being used for rigid boards SMT? Looking forward to your further advisement.

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