For Layers 2 and 3 I used the “Add filled zones” dialog, selecting the appropriate layer and then drawing my boards outline.
Working on layer 1 and wanting to connect my barrel jack up I did the following:
1/Added a track from the 5v pad to a via using the “Select layer and place through via” and selected Layer 3.
2/Added a track from the GND pads to a via using the “Select layer and place through via” and selected Layer 2.
The bit I am unsure about, is that when I select the next layer I can then draw a trace on Layer 3 or Layer 2 respectively, so I draw a small trace. Is that correct? Please see my pictures to help give some pictorial references for what I am describing:
I am looking for a general check here? I am just a little unsure when doing a via to the vcc or ground layer, the trace on the target layer just seems to be ‘floating’, but I assume thats what it should do?!
Any and all advice greatly appreciated. I have seen some Via tutorials but they always do 2 layer boards, where it is obvious you would have a trace on the under side of the board which isn’t answering my question.
Vias connect to zones with the same net automatically, you don’t need an extra trace on that layer. If the zone pulls back from the via, then the net for the via isn’t assigned properly.
The easiest way to do this is to start the trace on the pad, then place the via while still drawing the trace (just press V, and then click again on the via to end the trace on the bottom layer that you don’t need).
The via rings exist on all layers (also for mechanical reasons), and the zone then connects to the ring when they belong to the same network, or stays away by the zone clearance if they don’t.
Sure you’re using nets: the pads in your schematic are labeled “+5V” and “GND”, these are the net names. The zones need to use the same net names, so they connect.
Pcbnew does not update the zone boundaries automatically (which would be very slow). If you have drawn tracks on a layer, you have to press “b” to recalculate the zone boundaries to see your results properly.
To get an ever better view of what you are doing on the PCB you can start the 3D viewer [Alt + 3] and then turn off both the “board body” and the “Solder mask”
Did you start with a schematic in EESchema? If so, even if you didn’t name nets you are using them. Nets are how the schematic describes to the layout program which pins are connected to which other pins. The term net is short for “network of connections”. See the wikipedia entry for Netlist.
Any plated through hole (both THT pads and vias) will connect to any copper on any layer that is part of the same net. This includes zones and traces. You don’t need to draw traces and drop a via off your connector to get the pins connected to the proper zones. They are already automatically connected, see the thermal relief connections on your screenshots.
Vias are used to move to another layer while laying copper traces for a net. This can be to get past traces of a different net, to connect to a SMT pad on a different layer, or to follow layout guidelines if they exist. (It used to be a common guideline to have vertical traces on one layer and horizontal traces on another layer, especially on fully THT boards.) This includes non-named nets like, for example, the Net-(C2-Pad1) net in my screenshot, above.
If there is a net for each connected component, then my Layer 1 will have lots of nets on it…so I suppose this particular technique is only useful for the GND and VCC layers in my board.
If I draw a trace with a net of “5V” and drop a via, will PCBnew automatically get the via to the right layer based upon the net (assuming that a layer “5V” exists? I will still however need to perform the trace and via placement though?
I also ask again — Does anything look wrong with what I have done so far in my original post? Or is all of this general advice building on my correct starting position?
How can I look at the properties of a via — to see what layer it connects to?
vias are on all layers by definition (they are simple plated through holes that can be connected on any layer)
If you want vias that are only between specific layers then you need to use blind or buried vias. But these will not come cheap in manufacturing. And it might not be the case that you can place them between any layer pair.
That’s very true. Basically you have to decide in advance which manufacturer you will use and know exactly what they can do. Many cheap manufacturers don’t do blind/buried vias at all. I’m not 100% sure, but if in KiCad you can choose the start and end layers for a via you are using blind/buried vias and will pay 5x or 10x price compared to through vias. Do it only if you have extreme size restrictions for the board.
So to confirm, if I want a normal via (not buried / hidden), does that mean that I can’t have my Ground layer directly on top of the same shape as my 5V layer - as that would create a short?
That means that my Layer 2, Ground, would be the only plane on that area of the board…and likewise with the power, as per this:
@Rene_Poschl – are you saying the diagram in my previous post is not correct? i.e I CAN have Layer 2 directly on top of Layer 3(overlapping in positional terms) and the Vias will still route correctly to the Layer 3 somehow without shorting through Layer 2?
Ok – and this relies on having Nets associated with specific wires in the schematic, with the correct Label, and that way Kicad will automatically add the clearance to other layers?!
It behaves exactly like THT pads with 2 layer designs. You can have THT pads inside zones with different nets and there’s no problem. With a 4 layer design you just add more layers.
Okay - so the net must be named according to the pin name, which is how Kicad’s ‘magic’ works.
The nets between signal pads are less important for me to name when dealing with VCC and Ground planes I assume, as I will be drawing traces by hand for these on one layer only.
