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| Complete newcomer to PCB layout - where do I start? |
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| eti:
--- Quote from: tautech on November 24, 2021, 09:07:20 pm ---Generally a Net problem with component pads assigned to different/wrong Nets. In the image above it could also be a Clearance rule issue too with the trace too close to both pads. --- End quote --- Thanks! It won't let me specify traces < 0.2mm... is that why? |
| nctnico:
--- Quote from: eti on November 24, 2021, 09:44:54 pm --- --- Quote from: tautech on November 24, 2021, 09:07:20 pm ---Generally a Net problem with component pads assigned to different/wrong Nets. In the image above it could also be a Clearance rule issue too with the trace too close to both pads. --- End quote --- Thanks! It won't let me specify traces < 0.2mm... is that why? --- End quote --- No, it definitely is a problem in your schematic. For trace widths: You have to setup minimum clearances and trace widths to match the abilities of the PCB manufacturer. But leave those untouched for now; 0.2mm width & clearance is producable by any PCB manufacturer. It is better not to push the limits anyway. When I create a PCB I usually do this for a .15mm width / 0.15mm clearance manufacturing process but the traces I use are often 0.25mm. |
| eti:
--- Quote from: nctnico on November 24, 2021, 09:54:39 pm --- --- Quote from: eti on November 24, 2021, 09:44:54 pm --- --- Quote from: tautech on November 24, 2021, 09:07:20 pm ---Generally a Net problem with component pads assigned to different/wrong Nets. In the image above it could also be a Clearance rule issue too with the trace too close to both pads. --- End quote --- Thanks! It won't let me specify traces < 0.2mm... is that why? --- End quote --- No, it definitely is a problem in your schematic. For trace widths: You have to setup minimum clearances and trace widths to match the abilities of the PCB manufacturer. But leave those untouched for now; 0.2mm width & clearance is producable by any PCB manufacturer. It is better not to push the limits anyway. When I create a PCB I usually do this for a .15mm width / 0.15mm clearance manufacturing process but the traces I use are often 0.25mm. --- End quote --- I think I have worked it out now, and it's pretty obvious when I consider it. Connecting pads between components which are not connected on the schematic, ergo the nets are not connected, won't work, else that would be changing the circuit, wouldn't it... After having sussed this out myself, I saw confirmation of it here, not that it was needed tbh: https://forum.kicad.info/t/how-to-connect-pin-on-pcb-that-was-not-connected-on-the-schematic/23812/4 |
| tautech:
--- Quote from: eti on November 25, 2021, 03:39:19 am --- --- Quote from: nctnico on November 24, 2021, 09:54:39 pm --- --- Quote from: eti on November 24, 2021, 09:44:54 pm --- --- Quote from: tautech on November 24, 2021, 09:07:20 pm ---Generally a Net problem with component pads assigned to different/wrong Nets. In the image above it could also be a Clearance rule issue too with the trace too close to both pads. --- End quote --- Thanks! It won't let me specify traces < 0.2mm... is that why? --- End quote --- No, it definitely is a problem in your schematic. For trace widths: You have to setup minimum clearances and trace widths to match the abilities of the PCB manufacturer. But leave those untouched for now; 0.2mm width & clearance is producable by any PCB manufacturer. It is better not to push the limits anyway. When I create a PCB I usually do this for a .15mm width / 0.15mm clearance manufacturing process but the traces I use are often 0.25mm. --- End quote --- I think I have worked it out now, and it's pretty obvious when I consider it. Connecting pads between components which are not connected on the schematic, ergo the nets are not connected, won't work, else that would be changing the circuit, wouldn't it... After having sussed this out myself, I saw confirmation of it here, not that it was needed tbh: https://forum.kicad.info/t/how-to-connect-pin-on-pcb-that-was-not-connected-on-the-schematic/23812/4 --- End quote --- Yep, exactly. While the ratsnest on the PCB looks like it makes no sense it's the important Net connections to help you with the PCB layout. The trick is to look past the ratsnest and visualize traces instead and where they might be run even though the ratsnest connections are all in straight lines. Once you think you have the layout somewhat sorted use Autoroute to show the the bits that won't work then unroute and improve the layout. Rinse and repeat a few times and it all comes together bit by bit. After a few layouts you will use Autoroute less and less as experience and the skill of trace visualization grows. It's all real fun, enjoy the process. :) |
| MIS42N:
I began my PCB design learning in February, using KiCad. No idea what I was doing for a while, I thought when looking at the bottom layer I was looking from the bottom. Consequently the first one sided board didn't work out too well (but did work). Second board I designed some pads and 2 layers. Better, but forgot to clean up the screen printing and I left out some text. But it also works. Many problems I had are answered by the documentation. Some by the Internet. And some I still haven't worked out. Third board will be better again. I have no regrets about KiCad, it gets more sensible the more I learn. I just made a simple opto coupler circuit, it isn't a PCB but I dumped the circuit into KiCad, shuffled the bits until I liked the layout, then wired it up on a proto board. There's a lot to learn, but as I go it seems easier to grasp that next concept. My message is don't expect to make the perfect board first time up. It will come. People who learn a musical instrument say the first 10,000 hours are the hardest. You'll get good way quicker than that. |
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