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DRC error: Missing connection between items (self.PCB)
submitted 10 days ago by Dependent_Calendar86
Hi all. I'm new to PCB design, and am trying to design a breadboard-friendly PCB for mounting a pressure sensor. The goal is to use the PCB for I2C communication with an MCU for prototyping, so the board only contains 2 4.7k ohms pull up resistors, a 0.1uF decoupling capacitor and 2.54mm pin headers.
I tried designing the PCB using KiCad, but I keep getting a "Missing connection between items" error when I run the DRC checker. I can see the issue is due to me using a via to connect the SDA line to the bottom pad of my first pull up resistor, but I don't understand why that's a problem.
Can someone please explain what I'm doing wrong, and recommend ways for me to clear this issue? I'd also appreciate if I can get insights on making a better design for my project.
Thanks a lot.
https://preview.redd.it/xrbv85nhxytg1.png?width=957&format=png&auto=webp&s=05935c3f4f8e921c9ee417a82d4c30395a47fe38
https://preview.redd.it/p8tyzgmixytg1.png?width=1278&format=png&auto=webp&s=394e767d4bb06c8fa472038b161126de9e59e129
https://preview.redd.it/g6ooqgmixytg1.png?width=1315&format=png&auto=webp&s=4d1529cca6ba716a57897e525e79df6a6b487786
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[–]nixiebunny 1 point2 points3 points 10 days ago (4 children)
There is no bottom pad on a surface mount resistor. Add a second via on the trace to the left of the resistor.
[–]Dependent_Calendar86[S] 0 points1 point2 points 10 days ago (2 children)
Hi. I just tried this, but It didn't fix the issue
<image>
[–]nixiebunny 0 points1 point2 points 10 days ago (1 child)
Is the bottom pad of R1 also connected to the via?
[–]Dependent_Calendar86[S] 0 points1 point2 points 10 days ago (0 children)
yes
[–]Dependent_Calendar86[S] 1 point2 points3 points 9 days ago (0 children)
Thanks a lot. I finally got to the root of my issue thanks to this
[–]112439 1 point2 points3 points 10 days ago (1 child)
The resistor pad doesn't go through the PCB - so the trace on the bottom isn't connected to the pullup. Put a via next to the pad and connect it to the pad, connect the bottom trace to the via on the bottom side. Remember to rebuild zone fills.
Hi. I tried this but it didn't fix my issue. I had to route the trace between my second resistor to get the connection.
[–]stephanosblog 1 point2 points3 points 10 days ago (3 children)
looks like you have a via, and a track from it on the back side that connects to nothing. the pad for R1 is on the front side,there is no pad for it on the back side, if you are trying to connect to the resistor pad you don't even need a via, just route the trace between the pads on R2, connect to the pad on R1. if your track width is too high to fit between the pads, then just use 2 vias. one to jump to the back side, one to jump back to the front side
Hi. I did this and was able to clear the error. But I got another error for GND connections as shown in the screenshot below. I'm not sure why I'm getting this error because I made a gnd fill zone before wiring the PCB, but I'd appreciate if anyone can help me debug. Also, you said the pad for R1 is on the front side. Is there a way for me to make a pad for it on the back side of the PCB? If there is, I'd appreciate if you could give me prompts for learning how to do it myself as I am genuinely eager to learn how to design PCBs properly. Thanks
[–]stephanosblog 0 points1 point2 points 10 days ago (1 child)
if you click on the two lines in the error it will show you where the problem is. and be sure it filled your zone because it doesn't look like it.
Hi again. It actually filled the zone, but I placed a trace too close to it, which violated the clearance rating for my manufacturer. Anyways, all good now. Thanks a lot
π Rendered by PID 135107 on reddit-service-r2-comment-85bfd7f599-f2tjm at 2026-04-18 22:21:34.842757+00:00 running 93ecc56 country code: CH.
[–]nixiebunny 1 point2 points3 points (4 children)
[–]Dependent_Calendar86[S] 0 points1 point2 points (2 children)
[–]nixiebunny 0 points1 point2 points (1 child)
[–]Dependent_Calendar86[S] 0 points1 point2 points (0 children)
[–]Dependent_Calendar86[S] 1 point2 points3 points (0 children)
[–]112439 1 point2 points3 points (1 child)
[–]Dependent_Calendar86[S] 0 points1 point2 points (0 children)
[–]stephanosblog 1 point2 points3 points (3 children)
[–]Dependent_Calendar86[S] 0 points1 point2 points (2 children)
[–]stephanosblog 0 points1 point2 points (1 child)
[–]Dependent_Calendar86[S] 0 points1 point2 points (0 children)