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How to create TPH pads with copper only on top or bottom?
Hi All, this is my first time at the Forum
As the title says I cannot figure out how to create a TPH pad with copper in only one of the sides: top or bottom but not both
Why copper on one side and an apparently pointless hole?
The developer of AutoTRAX DEX.
Just put a SMD pad and then add a hole where you want.
Hi Iliya, the pass-through components often do not require copper connectivity in one of the sides, so why having a pad in that side. I realize that it is easier to have all the pass-through holes double sided with plated-hole but a single side PCB does not require copper in one of the sides and no plated-holes at all.
While creating a part footprint sometimes could be useful to have one sided TPH pads to make that side less copper populated and more space for tracks.
I realize that even not having copper in one side a track cannot be nearer to the hole than the DRC allows.
I think it could be useful at PCB > Pads to have choices for 'Top TPH' and 'Bottom TPH' pads, which will not create plated hole.
If this proposal creates a mess with currently implemented patterns please discard it, we can live adding vias to SMD pads.
Hi Mick, true, I just finished a board built at PCBWAY where I used SMD pads with added vias for the holes, thanks.
I understand your idea and it does have some merit but I doubt that I would ever want one EXACTLY as you posed the question... however, I might want to REDUCE the size of the pad on one side to allow a bit more clearance though..
Something like a header pin and if I want to pass 12v through the space between two pads on the layer that the header is mounted on, I could reduce the size of that pad to allow that bit more clearance from the lower voltage circuitry..
Not a bad idea, it is up to iliya to decide if he can implement it or not...
Thinking further on this it could allow the passage of TWO tracks between adjacent header pins (which I have seen in professional PCBs but never actually done one before..
I could replicate the above by using SUB-PICK and selecting the pad and reducing the size down to a suitable size and then adding a SMD pad on the solder side.. Of course DRC will report 2 pads breaching the relevant rule but if you are happy with the result you can ignore it..
Hi Mick, in my latest board I reduced some pad sizes to allow tracks between them with the con that in the connected side had a small pad, but still usable .
I do not want to ask Iliya things that represent big changes but having top and bottom TPH pads can help in some specific situations, even new parts creation.
I share your idea that a regular TPH can have both sides size locked but with the option of independently change the size of each side and even setting one to zero. More headache for Iliya
edited December 2019
I agree with bigmik. I don't think I ever would want to have a plated hole with pad
at one side and none on the other.
But I have very often used the feature to REDUCE the size. In fact, for compact multi-layer boards this is even standard for inner layers. It makes a big difference for routing the inner layers.
AutoTRAX has very powerful features but in simple cases like the one I am referring of having the choice for pads for TPH with only top or only bottom copper you need to create these little monsters from scratch instead of being standard selections.
Anyway I am happy placing holes or vias in the middle of SMD pads and cancelling the DRC rules that do not like the trick, so in cases as the one mentioned by Mike I can have a header with tracks easily running between pins and still having a practical pad size
At least in one case the manufacturer of the board (PCBway) did not bother about this approach
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