Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Michael Allen

#16839

Lead Sweep | 22 January, 1998

Is there a standard (JEDEC or other) for "lead sweep" errors on fine pitch (eg, 0.5mm) gull wing leads? Parts from one of my suppliers has a sweep error up to 6 mils; the mechanical drawing does not address lead sweep error, nor is there a true position tolerance on the leads. If there's no standard, then please tell me if you've seen QFP mechanical specs that include a tolerance on lead sweep.

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Chris Fontaine

#16840

Re: Lead Sweep | 28 January, 1998

I have not been able to find a standard which governs component lead sweep. We use an internal standard of 4 mils here at Sanders, and your 6 mil sweep would definitely be unacceptable. I believe the reason there is no standard governing sweep is because the amount of acceptable lead sweep is dependent on the width of the pads in relation to the width of the leads. It is surprising to me that there is no standard governing SMT lead condition. Such a standard is obviously necessary.

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