SilkS or CrtYd & How to do a printed spark gap?


#21

We can not answer these questions. (We do not have your footprint. Nor do we have the detailed specification of your project.)

All we can do is give you the general information. Read my above linked FAQ article.

I try to explain it a bit differently this time. You need to ensure that there is no soldermask where you put paste. So either make the mask cutout large enough to encompass the full copper pad -> in this case you can select the solder paste layer of the pad.
Or if you do not want the full copper pad to be free of soldermask, then you can create a special paste pad that covers only the copper area that will be free of soldermask. -> In this case do not select solder past in the copper pads. (Create a paste only pad exactly as you want it to look like)


#22

Okey I think that I understood it, but, when I place the 2 pads/electrodes and after that, I create a polygon with the area that I don’t want solder mask ( the gap basically), i make it a big bigger than the gap, taking a part of the electrodes and after confirming the operation, the part where is the pad the solder mask layer doesnt appear, so I supposed that automatically the solder paste layer got prefference in front of the solder mask layer. Then, I can just make a square that covers both electrodes and supposing that what I have said is correct, there is nothing more to care about both layers. Am I wrong?


#23

Marc, may I suggest you read up on PCB and Surface Mount Technology to fill up the gaps in your understanding. Perhaps read this:
http://www.pcb.electrosoft-engineering.com/04-articles-custom-system-design-and-pcb/01-printed-circuit-board-concepts/printed-circuit-board-pcb-concepts.html

You are using SMD pads as electrodes, whereas “normally” the SMD pads are used to mount SMD components on to, using solder paste and reflow. Hence the disconnect or “semantic gap” which frustrates the discussion back and forth, I see that. Hope you find this suggestion useful!


#24

Thanks @EL84, I will read it for sure. I know that SMD pads are used to mount SMD components but that’s the only way I found in order to create my electrodes: make them as SMD pads with the specific shape and dimensions, cover the SMD pad with solder paste in order to act as an electrode and then there is our spark gap. Maybe there are better ways but I didn’t find any way to do it.
Also, the dimensions are really small, the spark gap will be of 1,6mm*0,8mm (the dimensions of a 0603 MLCC capacitor).


#25

I am not sure you need to have solder on the pads for it to function as a spark gap. Do you?
You may want to have solder mask covering your copper pad, possibly to protect it from the atmosphere, corrosion etc. Perhaps. Anyway I don’t really understand your application but I do see a ‘semantic gap’ apart from the spark gap :grinning:


#26

No, the electrodes could be done with the copper of the own PCB but people that worked with them before explain that if the electrodes are made of tin the life time and the work performance are way better.