Hello,
Right now every time I have Vcc pin or Ground pin, I draw a trace from that pin into via that connects to that Vcc or GND.
But is this necessary? If I double click on that pin, and assign the proper Net in the pad properties, then why waste space on the board drawing traces and vias !
As an experiment, in my last layout I added test point for 5V, GND, and 3.3V, and I did not draw any traces or vias. I just assigned the proper net to them. Then when the board came in, I measured the correct voltages on all of them.
Right now, I am not sure if the factory detected this as mistake on my part, and they fixed it, or if what I did was correct, and normal. If you know, please let me know.
Thanks.
If you had zones at your PCB they automatically connect to pads of the same net provided they are able to do so (zone at bottom will not connect to SMD pad at top).
You are speaking about pin or pad?
Pin is at schematic and you not need to assign net. You just connect it with other pins with wires.
Pad is at PCB and you not need to assign net as it is assigned when you update PCB from schematic.
I am talking about IC pin in the layout (so yes pad).
I do not have zones.
In general it’s not good to design PCB’s without a GND zone. There is an 2h and some minutes long video about GND zones, their use and importance on youtube from Rick Hartley. It’s well worth watching. (And yes, GND zones are important enough to watch a 2 hour video for. The first time I noticed the video was over 2 hours long I thought, meh, I’ll skip some parts if I get bored. In the end it turns out I watched the whole video twice.
For the other 5% of the PCB’s… It depends, and your description is too short to get a good idea of what you are doing. Adding test points just to use as via’s seems cumbersome. Why would that be less work them placing tracks and via’s? And where do (did) your via’s go to if it is not to a (GND) zone?
Maybe I misunderstood you. If you mean by “zone” a “fill zone”, then I do not have any. However, I do have one full Ground layer in the board of 6 layers.
The test point I added was for experimentation purpose. I wanted to see if I can do away with trace/via combo.
You didn’t told if test points you use are THT or SMD.
THT having right net should be automatically connected to right zone if it is at the region you place this point.
How have you done full ground layer having no zones?
Have you draw a filled rectangle at that layer?
If you have no zones than I don’t know which way 5V and 3.3V test points were automagically connected.
To tell you truth. I don’t believe you. I suppose you have 3.3V and 5V zones at some layers and THT test point placed at right position is simply connected to the zone with the same net.
That is the same for KiCad. KiCad does not have dedicated “copper plane” layers as some other programs do. In KiCad you just draw a zone on any of the copper layers.
You are correct.
I just remembered, when I created the layers I did draw rectangles and filled them. So, yes they are filled zones. Sorry about my confusion as I do not frequently make PCB boards. I made this board last January.
Also, yes, the test point was through hole.
So, basically you say if the pad (or IC pin) is through hole, then I do not need to draw trace from the pad then connect through via to the Net. Instead, I just assign the proper Net to this pad in the pad properties, and KiCad will connect it directly to that Net.
Yes. When you use THT footprints, they go though all layers, and when the net name of a pin matches that with the net name of a zone, then they connect. (Unless you explicitly set the Pad Connections in the Zone Properties to None). A THT pin of a test point is just a pad. The only difference with other THT footprints, is that those other footprints have more pads, but the pads themselves behave the same.
You can also easily verify this:
- Depress the b shortcut key to re-calculate internal geometry of all zones.
- Right click on the Properties manager and then select Hide all layers from the popup menu.
- Now enable (only) the copper layer you are interested in.
- Observe the result.
For a definitive review you should check the gerber files with a gerber viewer, but during PCB design, doing this in the PCB editor is more convenient.
1 Like
Ok. Thank you very much.
1 Like
This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.