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

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SMT electronics assembly manufacturing forum.

via in pad



via in pad | 12 October, 2002

Hello All,

I am having issued with insufficient solder due to via in pad. It is a 10 mils via and PCB is 70 mil thick. Six mils stencils was used since there are some 20 mils (No clean process). Any recommendation?

Thank you.

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via in pad | 12 October, 2002

Alternatives to consider are: * Opening-up your stencil aperture put-down more paste to compensate for the amount that is being used to fill the via. * Relaying-out the board to plug and plate over the via. * Relaying-out the board to move the via from the pad.

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Abelardo Rodriguez Santana


via in pad | 15 October, 2002

We run into that issue all the time. If a corrective action must be done right away. Place Kapton tape on the bottom side of the board to cap off the via. If you have room to place tape if not use pink lady or something to plug the via. And weather or not you have sufficient solder on the component termination to meet your requirements run, if not try adding height to your print. Long term go with gentlemen's suggestion.

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via in pad | 15 October, 2002


In your response on this thread you mention "pink lady". Please help us understand "pink lady" better. Is that a temporary solder mask?

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Brian W.


via in pad | 16 October, 2002

Pink Lady refers to solder stop, or temporary solder mask. There are a couple of types. Peelable, which you must peel off after processing, before wash, and of course before you ship. There is also a water soluble version, which dissolves in the wassh. However, you must evaluate your eash system before using it. When I used the water soluble, we had an extra set of filters up front to keep the sediment from getting into the main filters.

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via in pad | 18 October, 2002

If you have room try putting a small piece of tape on the bottom of the stencil right next the aperture that is giving you the problem. The added height of the tape (Kapton tape is usually about 3 mils thick) will likely give you a heavy enough deposit to make up for what the via erodes away. If you try this and it gets better but not perfect try adding tape to the other side of the aperture.

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