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I had been attempting to desolder some SMD ceramic capacitors off a PCB to measure their capacitance. Unfortunately I am quite new to soldering and have managed to screw up.

The below picture shows one side of a removed capacitor, with the base plate which is typically attached to the PCB attached to the capacitor instead. I am very concerned about how I would attach this capacitor back in place, as it is important that the board works after I examine it. Simply sliding it back in place and testing continuity with a multi meter does not show connection, and I am doubtful soldering the capacitor to the still good side would change that.

I had desoldered the cap by heating both sides, then laying the tip to the side of the cap to heat both sides at once, then give it some force to push it off. I had also managed to break off a part off another capacitor with a similar method and it appears that cap might not be working anymore. I am using a very cheap soldering iron for what its worth.

In short I am asking what options I might have to reattach this cap and have the circuit working.

enter image description here

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  • \$\begingroup\$ Solder the capacitor down one side. Use a small wire to go between the other side of the capacitor and the IC pin, could always use a dap of epoxy to hold it in place underneath \$\endgroup\$
    – user103993
    Apr 9, 2016 at 22:19
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    \$\begingroup\$ For surface-mount parts, get a "hot air" iron. These can heat up both sides simultaneously, making removal much easier. \$\endgroup\$
    – rdtsc
    Apr 9, 2016 at 23:05

2 Answers 2

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Yeah, you lifted the pad- it's missing entirely now (well, actually I see it on one end of the cap). It can be fixed by soldering the capacitor down to the remaining pad and jumpering the free end of the cap to the led of the SOIC chip package where it is supposed to go. You can use a very fine bare wire. If you don't have any, strip some stranded wire and use a single strand. Remove that stray pad first.

enter image description here

Next time try practicing on a board where it doesn't matter if it works or not, and try to get better tools. You can actually remove such a cap with just an iron if you don't use pressure and melt each side but it takes a bit of practice. Ideally, one would use special heated tweezers, which work wonderfully, but are not cheap.

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  • \$\begingroup\$ Would using gel flux (as seen in many Loius Rossmann videos) help to avoid over-heating the pad? \$\endgroup\$ Apr 9, 2016 at 22:27
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    \$\begingroup\$ No, using a soldering iron that is temperature-controlled will help, but you also have to avoid scraping it against the board. For some parts a good flux-filled solder wick helps, but for removing SMT parts with just the iron you want to add solder, not subtract it. \$\endgroup\$ Apr 9, 2016 at 23:18
  • \$\begingroup\$ If you don't have soldering tweezers, you can use two soldering irons at the same time. Works just as well. \$\endgroup\$
    – Eli Iser
    Apr 10, 2016 at 5:37
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Scratch solder mask from trace connecting it to the IC (on the picture). Only few millimeters are needed. That way you can use solder bridge to attach to (now free) copper trace. Be very careful when doing this, probably you have applied to much heat in first place.

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