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Printed Circuit Board Assembly & PCB Design Forum

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Plating crack

Ashok Dhawan

#2891

Plating crack | 27 September, 2000

What could be possible resons for " Plating Crack on Barrel (tented via)" This tented via is in proximity to parts being hand soldered. The crack in barrel was detected on failure analysis - micro-section of via where barrel is having crack ( circular crack)where inter layer is connected to barrel. The PCB is 6 layers board, HASL finish and pass through 2 reflow soldering cycles and hand soldering. The vias are tented. Any clue where to look for reasons ?

Ashok

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#2892

Re: Plating crack | 27 September, 2000

Ashok: Plating thickness and ductility of the copper are things to look for. If it�s a crack where two layers are pressed together one possible cause could be bad process parameters while pressing these layers together at the PCB shop with the result that during soldering the expension is higher than expected with a given possibility of cracks. You should make sure that your soldering processes including the handsoldering are within the standart limits and - sorry to say that- do some more microsectioning - best through a row of vias in line - to see if the cracks always occur at the same layer. If so talk to the board house, it�s a tough game - we are in it for more than half a year now and it still goes on. And don�t think that�s only the boards you found out by know, it�s most probably the whole batch and early failures in the field are to be expected. We traced our whole batch and changed the suspected boards in the field.

I feel with you

Wolfgang

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#2893

Re: Plating crack | 27 September, 2000

Wolfgang is correct. Copper plating thickness of the via barrel walls is a key question you need to answer to troubleshoot this.

Tenting is a red herring.

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