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I have some cheap device with a small color TFT display conncted to the board with some tapelike conductor -- which has broken 1 or maybe even 2 conducting lines (I can actually see the tiny gap with a lense I use).

(By the way: they've got broken because a control button is strangely close to the conductor -- so it was pressing it and slowly damaging it over time... figure that design error...)

Now the question -- how to repair it?
(if there is not some known (adequate) procedure, consider it a philosophical question -- just for the cause of wisdom) :)

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Dani AI

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A few practical points and a safe, repeatable repair workflow that build on the thread so far (especially the observations from and ).

First, what matters most is locating the open conductor and deciding whether you can access copper on either side. Do the diagnostics with power removed (or a current-limited supply if you must power it): use a multimeter in continuity/diode mode from the board pads to points along the flex until the trace goes open. A stereo microscope or strong magnification makes this trivial.

Tools and a simple repair sequence that works for hobbyists:

  1. Gather: stereo microscope, fine enamelled copper wire (about 36–40 AWG), fine flux, a temperature-controlled iron with a very fine tip, a fiberglass pen or abrasive pencil, Kapton tape, and a small quantity of silver/conductive epoxy as an alternative.
  2. Find and clean: remove the protective film only at the tiny gap using a fiberglass pen until copper shows. Do not gouge with a knife.
  3. Re-establish conductivity: either
    • bridge with a hair-fine enameled wire soldered to tinned copper on both sides (burnish enamel off the wire ends, use flux, solder quickly), or
    • apply a tiny bead of conductive silver epoxy across the gap and cure per instructions.
  4. Insulate and secure: cover the repair with Kapton tape and a drop of epoxy for strain relief so the button won’t flex the repair.
  5. Test carefully with current limit before full restore.

Notes and cautions: many flex traces have a protective lacquer and oxidize, so solder won’t stick until properly prepared. Avoid strong solvents or excessive heat — both can delaminate the flex or ruin the display drivers. If the display is glued or has no accessible pads on the glass end, a module replacement is often quicker and more reliable than high‑risk microscopic rework. After repair, add a small foam spacer or reroute the button to prevent recurrence.

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Member Avatar for SAZAR

Come on people...

What's that material tape is made of? Maybe I can find some solvent to expose conducting lines...

Member Avatar for SAZAR

Um... I'm talking about this thing:

Picture:

So I ask: how to expose conducting lines? How to repair brooken lines? Is there some solvent? What is that tape made of? What disolves it?

PS: how do I make this forum post actually show the picture?

Member Avatar for Kegtapper

The tape is usually made of MYLAR.
Can you disolve it - NO

And depends on how steady your hands are, and skilled with a low wattage soldering iron and exacto knife can you fix it.

If you could strip back 1/16" of the mylar and had a conductive ink pen, that may fix it. (then re-cover with SCOTCH brand tape)

But those are only possible solutions. The easiest way is to find a broken unit- same model on eBay, and replace the wire.

Questions:
Did you do a continuity check from the test points on the board to the other end of the connector?

Is the other end of the connector directly connected to the TFT?


Also that site doesn't allow external image linking

Member Avatar for SAZAR

(thanks for reply)

So THAT orange transparent stuff from the picture is mylar! ...

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The TFT LCD is soldered to the board (20 pins or something), and I can't figure how to reach the other end of the tape conductor (on the LCD) without damaging it. So I can't even test the lines end-to-end.

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I will try to scratch that stuff from the conducting line, although it's to glossy, to traction at all...

...What about melting it?

--------------------------------
I don't have a conducting ink marker.

I soldered a tiny wire to a component on the tape (resistor or something) which originaly led to the severed line, but when I tried to solder the other end of that tiny wire to the severed line leading to LCD the drop couldn't stick to it... How to tackle this problem?

Member Avatar for Kegtapper

Use the conductive ink pen. You may cause irrepairable damage doing it your way.

I gave the solution and I cannot tell you how to do it wrong. I only know the right way.

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