Void on Cap plated via

Design and Layout
1

On our design, we have cap plated vias on the thermal planes. However, during PCB inspection, we noticed small voids are seen at edge of the cap plated via. What is the cause?

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2

Hard to say without knowing exactly what was done but guessing these are cap plated non-conductive filled vias. If so, the wrap plating is probably missing and you are seeing separation between the base copper and the barrel plating. Suggest you get a cross section of the vias to confirm as this condition doesn’t meet IPC specs and can cause internal separation and failure.

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3

Steve,

Thanks for the sharing. I try to include a photo of the observed condition but the system does not allow me to do so.

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4

Hello, you can copy/paste your image within the text. It should work.

5

Lucy,

I have tried to attach the image within the text, it still does not allow me to post it. Anyway, thank you for your assistance.

6

Sorry about that. It might just be because you were at trust level 0. I upgraded your profile to trust level 2 in case you want to try one last time.

7

Lucy,

Picture on the left is cap plated filled via on thermal planes. Almost all of them have the observed condition as shown. Picture on the right indicate the missing cap on cap plated filled via on component solder pad. Hope from the pictures, the root cause can be shared with me.

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8

Can’t be totally sure without seeing the actual board but it looks like the non-conductive fill wasn’t metallized properly and didn’t plate up.

9

Dear All,

If the cap plated resin fill via has the following observed conditions, is it a concern? What is the root cause and possible latent impact on reliability? The PCBs are for Space application.

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10

Can only guess without seeing an actual board but looks like a contamination issues under the mask. Also the copper pad has mask residue on it and don’t know if it’s supposed to be covered or not. They might have stripped the solder mask and re-coated but it didn’t come out very well. Residue on the pads will cause connection problems – can’t solder to it – and contamination under the mask can cause it lift and cause other corrosion related problems. Safe thing to do is reject the boards.

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11

Steve,

Thank you so much for the prompt reply. The information is very helpful for someone like me.

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12

You’re welcome.