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So I haven't soldered in years and only have experience with through hole soldering and large components. Today I attempted a repair with a HTC Vive controller. I know where to solder and managed to do one side but the others points where I had to solder I think I've screwed up. So my question is how do I fix this? (If it's even possible) And was it the result of too much heat?

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I know how to repair trace points and pads that lead to obvious places but these pads I think which are test pads I don't have a schematic, any ideas?

EDIT

For reference this is what I intended to do to fix my broken power cable. https://www.ifixit.com/Guide/How+to+fix+broken+power+button+ribbon/119514?permalink=1#comment-694934

I know they are test points. I need to solder to them because the ribbon cable connection on the main board on the other side was damaged, this bypasses that. If I have lifted the pads is it possible to fix ?

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  • \$\begingroup\$ use a microscope to find the broken end of the trace and connect to that. \$\endgroup\$
    – Jasen
    Nov 7, 2020 at 3:56
  • \$\begingroup\$ If you don't know where they go or what they do, why are you soldering to them? Why do you need to repair it? \$\endgroup\$
    – Ron Beyer
    Nov 7, 2020 at 5:05
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    \$\begingroup\$ Looks to me like you lifted the pads off those test points? If so, they're just test points using during manufacture, you don't need to repair them. \$\endgroup\$
    – user1850479
    Nov 7, 2020 at 15:57
  • \$\begingroup\$ I know they are test points. I need to solder to them because the ribbon cable connection on the main board on the other side was damaged, this bypasses that. Someone I know has created a fix using the two test points. Is it possible to fix the test pads? \$\endgroup\$
    – Z.Davey
    Nov 8, 2020 at 4:19
  • \$\begingroup\$ Look at the place where the pad was. There should be some copper going somewhere that it was connected to. You may have to scrape off solder resist to find it. Once you find it, solder to that. If you completely ripped the pad and trace out off of the board and there is nothing left, then you'd need to figure out where that test point connected and solder to the other end. \$\endgroup\$
    – user1850479
    Nov 8, 2020 at 4:38

2 Answers 2

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I'm a pretty new electrical engineer, but I do a decent amount of soldering at work (I work as a test engineer and I have to layout PCBs for testing a myriad of electronics).

Depending on the frequency of the trace, lifting a pad can mean a new board for me. But if these are just test points (which I agree I think they are) and you don't know where they lead to, then you couldn't get any use out of them anyway... so I wouldn't sweat it.

As far as fixing lifted pads, I think the best bet is to try and flow solder into the pad area. Make sure the solder is also connected to the incoming trace. You should scratch some of the soldermask away from the trace to ensure a good connection. It's not nearly as nice, and you will burn the dielectric doing it. And if its a trace carrying a +100MHz signal I would be very wary.

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  • \$\begingroup\$ Also, I'd clean the flux off from your solder job. Isopropyl and a brush is one way, but if you can rinse it and then bake the board at ~100C that would be optimal . . . unless you have some low-temp solder or something. Don't heat it up too much or you're parts will slide off their footprints! \$\endgroup\$
    – male_wondertwin
    Nov 7, 2020 at 4:29
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First of all, hold the board up against a light and see if you can see the copper traces through the blue solder mask. This is most often possible. From there on, you might be able to figure out where the broken pad connected to and then attach a wire to that component instead of the pad.

If you can't manage this, then use a scalpel to carefully remove the solder mask around the damaged pad. You'll end up exposing copper, it is most often quite possible to solder directly onto that copper using a very thin wire. Or alternatively, use an Ohm meter and try to figure out where the exposed copper connects to, using trial & error.

Note that the pads don't necessarily go anywhere, they could have just been added there to make things symmetric. If they aren't connected anywhere, those pads would come off very easy when heated. But in that case, you don't need to even repair the board since the pad did nothing.

Needless to say, clean up the board with isopropyl before doing anything else.

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