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I am designing a PCB with ESP32 module. It has a Top paste mask layer (Gray color region). When I rute or perform DRC, this region is not considered as a conductor. I am worried if it will make a short circuit. I am not sure if Top Paste mask is a conductive material or not. If it is conductive material, the pads 23, 24, 25 and GND of the following pic are short-circuited with the track below it. In that case DRC test results are wrong. Am I right?

Track touching several top paste masking layers

Update:

All the available layers are given below. Note that Top paste mask layer is different from Top Solder mask layer.

All the layers in my design

SKGadi
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  • `Top Paste mask` I never heard this term. Could it be `Top Solder Mask`?. Anyway, it is nothing without a copper pad in it. Assuming the red layer is top or bottom copper layer, I can say that the grey areas are just electrically empty because there are no copper inside them. So it's quite normal to have a DRC test with no errors and/or warnings. When the PCB is manufactured, there'll be no green (or what colour you select) mask paint there. – Rohat Kılıç Nov 08 '21 at 14:48
  • @RohatKılıç TopPasteMask is the layer that defines the paste apertures (used typically for stencil fabrication) – tobalt Nov 08 '21 at 15:01
  • @RohatKılıç, The Solder mask extension is given in purple color. Top layer is red, bottom layer is Blue. Once I make Solder mask extension bigger and DRC didn't notice. When I received PCB, it made the whole bord short circuited because the GND and 12V were short circuited because of the Solder mask extension. I am worried if it happens again with this Top Paste mask layer. I am updating the question with all the available layers – SKGadi Nov 08 '21 at 15:02
  • @tobalt I know the paste layer is used for stencil fabrication. What I knew is that its name was Solder Paste layer, not Solder Paste Mask layer. Interesting. – Rohat Kılıç Nov 08 '21 at 15:05
  • @RohatKılıç Might be an EasyEDA specificity. – tobalt Nov 08 '21 at 15:06
  • Solder paste should just cover the bare copper SMT pads, give or take a bit around the outside. If you put paste on top of anything other than bare copper (or so close to the edge of the copper that it will be drawn in by surface tension) it will make little solder balls in the reflow oven that could fall off and short something. So you want an opening in the mask that is similar size to the pad (give or take a bit around the outside) and solder paste over the exposed copper. – Spehro Pefhany Nov 08 '21 at 16:57

2 Answers2

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If I ignore why you put paste over an area that contains no apparent pad or solder mask opening...

DRC ignores paste altogether as far as I am aware of.

In your case, after you reflow the paste it would stay either as balls on top of the solder mask or it flow to the large rectangular pads and wet them. In either case, it wouldn't lead to any shorts between existing copper patterns.

tobalt
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I think those paste areas are an error in the design of the footprint.

Solder paste would normally be placed on the pad, not off the end of the pad as shown. Are there paste areas shown for other pads of that component?

If you will not be using a paste stencil, you don't need to worry about it, but if you will be using a solder paste stencil, this must be corrected, or thre won't be sufficient solder paste for those pins.

Peter Bennett
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