When designing a PCB I would dearly love the ability to place a zero-ohm resistor to ‘jump’ over a track… but not have to cross-probe the net to the schematic, insert a resistor (0 ohms), update the PCB, go back to the PCB and put the new resistor in place. Then I might find that I need two, or more. And then I might find a better solution by “jumping” another track somewhere else and wanting to rip up the existing “jumps”.
Is there a facility to allow PCBnew to dump jump resistors into a net, and back-propagate them to the schematic later?
Perhaps the “WireIt” plugin could help here?
I went through a ‘0Ω resistor’ and ‘wire jumper’ phase when I was trying to etch single-sided boards at home.
My advice is, quite simply, “avoid that”. It can be an easy way out of tricky ‘corners’, but I, personally, would think you’d be better served by either looking for different, perhaps unconventional, ways to route your single sided board, or just make the jump to a two sided board.
I don’t know exactly what you’re making, but if you’re going single-sided because you’re self-etching? In several forums I’ve been told over and over, ‘you’re just kicking yourself in the balls over and over by trying to etch at home, just use a fab house!’ I held out for a couple of months trying to do my own boards because of quicker turnaround, but eventually I threw in the towel, ordered from a fab house (JLC), and it has been bliss. Is the turnaround time worse? Sure. But it’s actually cheaper than home-etching! And I get to have multiple layers! And I won’t keep accumulating noxious chemicals that I’ll have to pay to get rid of.
Regardless, is adding resistors to the schematic and then updating the PCB from the schematic that onerous? If so, why? Or are you just trying to use a different workflow?
I mostly agree with ipmcc123’s remarks about home etching, when ordering from a fab, you get dual sided PCB’s, drilled pads and via’s and metallization two soldermask and two silkscreen layers. And likely also in a higher resolution then you can make at home (0.25mm tracks or narrower is standard from ordered PCB’s) but sometimes the quick turnaround or other factor are more important. (Some countries have shipping problems for example).
One option is to enable more layers in the board setup. You can then use via’s and an extra layer as “wire bridges”, and then after the PCB is fully routed replace these with your 0 ohm resistors. This way it’s less switching between the schematic and PCB editors.
I see a basic problem in back-propagating 0Rs from PCB to schematic. There can be no wire directly corresponding to the track you break at PCB with 0R to break that wire and place there a resistor. And total rearranging a net at schematic is enough complicated task in my opinion just to left user to do it.
I am using 0Rs to avoid breaking my GND layer at 2 layer PCBs. At this PCB there are 2 0Rs at VCC net (other that can be supposed as 0Rs are ferryte beads):
To be a little more specific in what I was doing, I have a 6 layer board. So far I’ve avoided doing ViP (via-in-pad) simply because it gives me more options as to where I can get it made.
Stackup is track/gnd/track/power/gnd/track. Power is actually 7 different supplies (24dirty/24clean/24analog/5digital/5digital/3.3digital/1.8digital). I am using the second gnd for ‘emergency’ tracks when I simply can’t get them anywhere else. It’s a damn tight board, but not ‘mobile phone’ level tight!
There was a couple of tracks where I simply could not rout the things. Ended up using the ‘pwr’ layer to sneak a couple of tracks through… not fantastic for EMI, but hey, at least the ‘bottom’ gnd layer was mostly continuous (only broken/peppered with holes for via clearance)!
I was going to throw a couple of 0R in there, but it turned out I didn’t have the space for vias as well as the resistors.
I could have gone 8 layers, but I view PCB layout as a challenge and adding layers is for babies!
Home etching? Gave that away in the mid-nineties and just paid through the nose. Now with JLC & PCBway I think you’d be mad (or really want fast turnaround) to home etch.
