What is the most effective method to do so? I have enameled wire, which seems safer to me due to the insulation. My plan is to cover them with solder mask. However, I have a question: Would it be better for me to do this on an existing plane of the board? Is it possible to do so without interfering with normal operation? Additionally, is it safe to implement this in a circuit with balanced lines and differential signals? Can a small new plane be added to the ground plane? The circuit is very small, so space isn't a major concern. What would you recommend I do? I apologize if these questions seem obvious; I am still learning. Also, I apologize for any grammatical errors in my English; I am also learning the language. Thank you in advance.
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1\$\begingroup\$ Possible at all, absolutely; possible in any given context -- no idea. Is this a one-off or prototype? Production design change? What skills and tools are available, is there a budget to meet? \$\endgroup\$– Tim WilliamsCommented May 9 at 19:21
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\$\begingroup\$ Can you add some photos/images for clarification? I guess, for getting useful answers, we need to know at least what type of components are to be added and how the existing PCB looks like. And if this is volume production or a one-off prototype. \$\endgroup\$– feynmanCommented May 9 at 19:24
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\$\begingroup\$ If this is for development, then go for it. Superglue is your friend. If this is for production, you need to draw up what you want produced, as accurately as for the original PCB. Our production department used to hate 'hand mods' with a passion, and never let us forget it every time we introduced a new one. Once we got to more than 3 on a board, we would re-spin the board or they would riot. \$\endgroup\$– Neil_UKCommented May 9 at 19:38
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2\$\begingroup\$ I would make a small PCB for the additional circuitry, wire and glue it to the “motherboard”. Is that an option to you? \$\endgroup\$– winnyCommented May 9 at 19:50
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\$\begingroup\$ Why can't the PCB be modified? \$\endgroup\$– Kuba hasn't forgotten MonicaCommented May 9 at 21:52
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2 Answers
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If you want to hand-wire a circuit change into an existing PCB, gluing the parts into a spare area and wiring them up with solder-through enamel wire is certainly one option. See dead bug assembly.
If you have several of these to do, a slightly better option is to fabricate a small PCB to hold the new circuit (parts on one side only) and glue that down to the main board, leaving just its inputs and outputs to be hand-wired.
You mention differential signals and balanced pairs. Are these for low-noise analog circuits or high-speed digital signals? Obviously, it will be difficult to control the transmission line parameters as tightly with hand wiring, as compared to a PCB design.
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\$\begingroup\$ We use this technique, but only on a prototype or early production board. Eventually, we almost always have to update the artwork and build a new board. \$\endgroup\$– SteveShCommented May 9 at 23:52
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1\$\begingroup\$ @SteveSh: As it happens, I have a board right now on which we had to swap out one voltage regulator for another one with an incompatible footprint. We're hand-wiring an adapter board into a few prototypes so that software development and design verification can continue while a respin is in progress. \$\endgroup\$ Commented May 10 at 0:55
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\$\begingroup\$ That's interesting. Most of the places I've seen those kind of piggy-back boards used has been in power supplies, usually because the chosen/designed in part would not past muster with our supply chain. \$\endgroup\$– SteveShCommented May 10 at 10:48
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\$\begingroup\$ @DaveTweed Hello. Apologies for the delay in responding. Could I cut a custom copper pad from a blank PCB board and glue it onto the board I need? This is only for soldering small SDM resistors and capacitors, it is not power electronics. I have seen that some people use cynoacrylate/loctite/superglue, but my question is if it will resist the heat when soldering it. \$\endgroup\$– condor12Commented May 12 at 15:41
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\$\begingroup\$ Well, we're using these because the chips we're using have leads on 0.05" centers, and we also needed through-hole connections. But you can get similar boards that are just arrays of SMT pads if that's all you need. Just cut a piece to the size you need and glue that down (cyanoacrylate is fine) and then solder your components and wires to it. \$\endgroup\$ Commented May 12 at 18:09
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I don’t know if this is applicable to your situation but here’s something I did some years back: we had a batch of PCBs where some didn’t have an internal ground plane connected properly. Some boards were ok so it wasn’t picked up until a number of PCBs had been populated. I had a thin (0.4mm) single-sided PCB made with a copy of the ground plane on it. Fortunately the vias weren’t tented so we were able to through-pin the extra board onto the back of the existing board.
These days I’d be much more inclined to scrap the boards, but that’s what we did at the time.
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\$\begingroup\$ Hello. Apologies for the delay in responding. Could I cut a custom copper pad from a blank PCB board and glue it onto the board I need? This is only for soldering small SDM resistors and capacitors, it is not power electronics. I have seen that some people use cynoacrylate/loctite/superglue, but my question is if it will resist the heat when soldering it. \$\endgroup\$– condor12Commented May 12 at 15:40
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\$\begingroup\$ I just relied on the through-pins. If you’re hand-soldering the board then cyanoacrylate would probably do, it may break down close to soldered joints but these should be plenty of remaining area. It’s likely to give off toxic fumes when heated though. Otherwise try epoxy resin. \$\endgroup\$– FrogCommented May 12 at 19:41