I'm replacing the SMD LEDs on my instrument gauge cluster in my truck with a new color LED. While attempting to remove one of the original LEDs, the solder pads came off from both the positive and negative contact points. One of the pads is salvageable (still attached to the light I removed), but the other is not. Please advise. It is neither visually appealing, nor safe to be traveling at night without an illuminated speedometer.

I visited a computer repair shop in town and they said if a solder pad is gone, there is no way to repair it. They advised me to buy a new instrument cluster at a cost of $150-$200.

Online I found a suggestion to fix. Buy silver based conductive epoxy. Place where pad was. Make sure it is touching an exposed lead. Either attach light to epoxy while curing, or let cure, then solder the light to the cured epoxy.

Also I saw a suggestion of using copper wire to make a bridge. With the method, I didn’t know where to scrape the green area to expose copper below. Nor what, nor where to connect that wire to beyond the LED. Also I had questions of how and where to create the new contact points, being that there is a positive and negative side. I’m sure the created new contact points wouldn’t be created too far away, but placement of the light is important because they are designed to be in the original place for a reason.

I am also open to any and all ideas I have not mentioned above.

photo of the PCB

  • One side goes to the test point above it, the bottom side goes to a blind via under that black section? Which pad is actually damaged? The top or bottom one? If it's the top that's easier. – cde Oct 22 '18 at 23:51
  • 2
    Easily fixed. But this requires good soldering skills. You may want to bring the board and replacement LED to a shop that has great skill with rework soldering. – Dwayne Reid Oct 23 '18 at 0:24
  • This is doable under high power stereo scope of 30x. – soosai steven Oct 23 '18 at 2:19

[This is to expand on Dwayne's comment that this desoldering mishap is easy to fix for someone with good SMT soldering skills, right tools and supplies.]

  1. Trace the connection of this LED.
    (The anode connects to a test point nearby. Cathode may take some figuring out.)

  2. Glue the LED to the PCB. Epoxy would be a good adhesive for this. Make sure that epoxy doesn't cover the electrical contacts of the LED (don't use too much epoxy). Make sure that the orientation is the same as the original, because LEDs are polarized.

  3. Tin the contacts of the LED.

  4. Solder thin insulated wire between the LED and the place where it should connect.
    Typically, this is done with 30AWG solid wire.
    For the Anode, you could solder to the test point.
    For the cathode, you could scrape the lacquer (solder mask) from the trace that goes East, and solder wire to the bare trace.

further reading: Tutorial, More tutorial

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