Hello, my PCB is done in the PCB editor. I have a cooper filled zone on layer F.Cu which is dedicated to GND while B.Cu is dedicated to audio signal and positive voltages.
Now since I will solder all TH components and that it is advisable to do so I’d like to set all pads to thermal relief but in one operation for all the pads (F.Cu & B.Cu)
How to do that ?
I know I can do it pad by pad but I’m quite sure I can do it with “one click” (but I don’t find the way)
Another point : when I edit the cooper zone the dialog box tells me that all GND pads have a thermal relief (see pict please) but when I edit them one by one they are in the “from parent footprint” mode…
You cannot do that.
Each zone needs to be created independently. You have at least two zones: one for F.Cu and one for B.Cu.
As you show in your above illustration, setting Pad Connections to “Thermal reliefs” will result in your Gnd. zone connecting all the pads on the Gnd. net with Thermal reliefs.
Individual Pads can be set with “Thermal reliefs” in the Pad properties.
I’m not sure of the meaning of the terminology “From parent footprint”, maybe someone will enlighten us.
Well I created one zone only (for GND) and so to shield the circuit… but I did not add a filled zone on B.Cu since this layer mixes voltages and audio signal. B.Cu is only made of different nets and pads.
Should I create a filled zone on B.Cu too ? I guess it makes no sens… ?
I thought there was a way to assign thermal relief to all the pads included in a one PCB (what ever the concerned layers are)
True, mostly.
Thermal reliefs allow hand soldering to be completed quickly. If there are no thermal reliefs, heat dissipation through the zone or very wide track may cause dry or poor joints and possibly damage, or lift, pads. To overcome the heat dissipation the iron temperature may need to be increased thereby increasing the possibility of the pad lifting from the support (dielectric} layer.
Usually I solder very fast (less than 1 sec) but at high T° (~350° C) and silver/tin/lead solder
Since my board does not include so much B.Cu pads should I set them to thermal one by one ? but which “spoke” and which “gap” do you recommend ?
The cooper filled zone is set to 0.508 for both by default…
Regards
Here is a screen capture of the B.Cu side of my board. One can see that tracks are quite spaced.
The power concerned here is +48v@15mA maximum. All nets are set to 0.5mm (voltage & signal). GND is connected straight to the cooper zone and all GND from the diff. boards will be connected together to one and only point (and to chassis).
By default (unless you select a different pad to fill type) all pads that have the same net as the surrounding fill will get a thermal relief. So if you fill both front and back with a GND fill this will automatically happen. Obviously other, non-GND pads should not have a thermal relief to GND as that would be an unwanted connection.
I think before v7, you had to do F.Cu and B.Cu with two fills. Now you can select both in one fill.
I can’t fill the B.Cu layer with a filled zone since this layer shares voltages AND audio signal.
So I will have to set manually all B.Cu pads to thermal relief…
The GND pads (F.Cu filled cooper zone) are indeed thermal relief.
F.Cu is GND with a cooper filled zone so to shield the circuit. Since I didn’t want to do 4 layers (PCB price) then I shared B.Cu with voltages (low current = 15mA) and with audio signal
If the default is Thermal relief.
Copper zone properties > Pad connections offer four alternatives. ie. Solid, Thermal relief, Relief for PTH & None.
I have no idea which was default.
Yes, if the Pad connections is set to Thermal relief.
True, and I think you would be pushing uphill to make other non-gnd pads connect to gnd. If pads were inside a wide track, you might want thermal relief also.
“all pads” had me stumped.
Well spotted No. 9/10 ths. I’d missed that altogether.
Top GND fills are connected with bottom GND with many vias.
If you hand solder it than it is not important if you have one side full of copper and second with little copper, but if PCB will be reflow soldering than you should have as close as possible copper % cover on both sides to avoid bending the PCB when being heat.
But if your idea is to shield than more GND copper at PCB then more shielding applied.
I set both to 0.25, but I generally have small SMD elements.
When designing footprint:
for each pad you can individually decide if it has specific connection to zone or it will use the way specified for the whole footprint.
for footprint itself you can specify how it is (means all its pads except those having individual specification) connected to zone or if it uses zone settings.
I think that most KiCad footprints not define thermal relief making it being taken from zone setting so you need not to do anything else than setting thermal relief connection for zone and you will have all pads connected to zone as you want.
By the way - why you use V6.
People use V5 because since V6 Win10 is required. But there is no such difference between V6, V7 and V8.
I use V8 as is simply better than V6.
I don’t use V9 as some changes made would need me to redefine all my footprints.
I don’t see the utility of setting another filled zone for my voltage & signal layer (but I’m a real beginner in Kicad). I’ve been told to set the upper layer to GND (F.Cu) than the bottom one (for better shielding) but I think now it’s not that important : I could have set it on B.Cu without any issue I’m sure.
As I said I use to solder fast at ~350° C so I guess I won’t damage the pads. The SnPb solder melt very well and fast.
I use version 6 because I’m on MacBook Pro / OS 10.14.06, not on Windows.
Regards
