I forgot a resistor on my PCB prototype – how do I add one in?

I need to add a resistor into a data line on my project. The data line is a trace and carries low speed data. A through-hole resistor will be fine. The pins for both ends of the trace are exposed, but how do I add the resistor and remove the trace?

If your PCB has a solder mask, you can fix this with an SMT resistor even when traces are close together. Cut the trace and scrape the solder mask away on both sides of the cut, over a few mm. Solder an 0603 or 0402 over the cut. If I patch like that, I actually make two cuts a mm apart, and remove the trace by dental pick between both cuts to make sure there’s a decent interruption of the trace.
Alternatively, you can do the same and solder a PTH resistor, whose wires you first bent so that they lay flat on the trace. Won’t probably work as well on narrow traces, like 0.5mm.

Read More: A Brief Guide to Prototype PCB Assembly

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Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.
Picture of Oliver Smith

Oliver Smith

Oliver is an experienced electronics engineer skilled in PCB design, analog circuits, embedded systems, and prototyping. His deep knowledge spans schematic capture, firmware coding, simulation, layout, testing, and troubleshooting. Oliver excels at taking projects from concept to mass production using his electrical design talents and mechanical aptitude.

What Others Are Asking

How can I fix the PCB to the mechanical structure?

I designed a PCB with an imaging sensor that is mechanically coupled to a lens assembly using four 2-56 screws. I’m noticing that even though the screws are holding the board tightly against the mechanical structure if I flick or lightly knock the the assembly the image “moves”.  I’m hoping to get a few suggestions for ways to fix the PCB to the mechanical structure. Any suggestions for adhesives or the like? Something else?

Why are there no BGA chips with triangular tessellation of circular pads?

A triangular tiling would allow π⁄√12 or 90.69% of the footprint to be reserved for the solder balls and the surrounding clearance, while the ubiquitous square tiling only allows π/4 or 78.54% of the footprint to be used. Why are there no BGA chips with triangular tessellation?

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