Hi all,
I’m creating a high power stabilized power supply.
I need to create wide routes but I would like them to be naked (unpainted) and then add tin on top.
How are naked tracks created?
for kicad v7 and an exact reproduction of the track-shape:
- select one segment of the track in question
- hotkey “U” (expand connection) until the complete wanted track-length is selected
- active layer FMask on appearance panel
- RMB-click–>context menu → create from selection → create polygone from selection
- choose “create bounding hull” checkbox
- disable “delete source” checkbox
- click OK
- new polygone on F.Mask is generated. Select this polygone, set fill-style to “filled”
- note: this mask is independant from the track, so if you afterwards change the track the mask remains in the original shape
If the exact shape is not important: just draw a thick line/rectangle on the F.Mask layer.
remark I: please add your kicad-version to your questions, as the answers depend on the possibilities of the kicad-versions.
remark II: instead of creating a polygone you could also create a filled zone on F-Mask layer.
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Hi,
Naked tracks exposed to cover with solder. Just draw solder mask opening over the tracks. That is how it works, everything what you paint on solder mask layer will erase solder mask in PCB production process. Take the line tool, swich to solder mask then draw what you wish.
From my point of wiew is a pointless to add solder (tin alloy, it have much higher resistivity than cooper). Adding tin doesn improve realy much.
Is better to order PCB with thicker cooper. Cooper thicker than standard 1oz (2oz, 3oz…) REALLY improve the track current capacity, reduce track joule heating, it also increase the cooling. Beware that soldering by iron is much harder. You need to design thermal reliefs for THT pads. Or solder in reflow machine or use hotplate.
What maximum current do you want to pass through the track? Maybe make cooper fill e.g 10mm wide, or wider if you can sacrifice the PCB area.
After all everything in engineering is kind of compromise. Better try to figure out how will be track temperature rise, maybe is not so high? There are simple online calculators that help to figure out track temperature rise.
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Together with tin the 1mm diameter wire can be placed on track.
I’m using release 6.0.11
Route lenght is about 20cm
Current 10Amp
Tension 30Volt
Using DgKey tool to calulate route I haver this:
But I’m not expert, to calculate it I’ve insert rise temp 10° and temp ambient 25° can be realistics value?
Yeah i forgot, one can reinforce the track, by soldering more cooper.
Delta T 10°C is quite safe assumption that work for me as far. Ambient temperature it means ambient temperature of cooper trace on PCB. Long story short. Ta is wrong. You have to assume worst operating conditions. This is a big task for expert to do it acurately. From rule of thumb assume 100°C (ambient T of the trace). Why not? Correct the number if you wish. Long story short. Not huge impact at all, take a big design margin.
If you have the board space, why not add through hole pads so that it is easier to solder the copper wires as short bare jumpers? The copper wires may be worth much more (to reduce DC resistance) than flooding a wide track with solder. I am suggesting a wide track + bare jumpers soldered into through hole pads, and maybe you can forget about omitting the solder mask or flooding with solder.
Copper bus bars for high current are also commercially available.
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