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

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Conductor width tolerances


Conductor width tolerances | 9 November, 1999

Hi all, our problem we face is the mismatch of conductor width on the delivered PCB and the nominal width given by CAD-data. With CAD we are improving pads and conductors to match the specific needs for soldering and the board houses counteract our improvements by reducing the width to their desire again. Up to now we couldn�t come to any agreeable arrangement with board houses concerning the tolerances of the conductor width.

Our desire is to get what we design.

What are the tolerances we have to consider when doing the layout.

Any recommendations welcome Wolfgang

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Re: Conductor width tolerances | 9 November, 1999

Wolfgang: "Our desire is to get what we design" ... Wanting to get what you ask for ... ummm sounds like a risky proposition!!! ;-)

Two things:

1 Go to the Hadco site and get their "boiler-plate." Use it and some of the Earl Moon specs in the SMTnet archives as the basis for your board spec. 2 For features try: * Dimensions And Tolerances. Dimensions and tolerances shall be as indicated or �0.005". * Conductor Pattern Tolerances. Conductor pattern tolerances shall be � 20%, and nicks, cuts, or other anomalies shall not reduce overall conductor width and thickness by more than 10%.

Good luck

Dave F

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Re: Conductor width tolerances | 10 November, 1999

That�s what we consider to be practical if the 20% were the worst case we see but the reality looks different. By chance we get a -20%, sometimes worse, sometimes a "good" 10%, rarely does it hit the nominal value and never it�s a +%. In short: It looks like it differs around these -20% and not around the nominal value and lately in germany many other customers are complaining about the same thing. Are there different or same experiences out there ?

Stay tuned Wolfgang

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