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The display on our Polder thermometer loses most of its crystals. I thought I could open it up and just wipe its “zebra” contacts, but they seem to be taped over and not subject to contamination. Plus, the crystals respond if I press on the sandwiched glass sheets. Do I try separating the sheets to inspect contact points, or is this repair not worth attempting?
I recall something similar cropping up on the community forum a while back.
You can get anisotropic conductive film tape:
https://www.3m.co.uk/3M/en_GB/p/d/v000073742/
if you can manage to separate and clean up the existing connection which usually requires a bit of heat eg:
"Bonds made with 3M
Anisotropic Condustive Film Adhesive 7303 are repairable
by heating the bond-line to above 100°C (e.g. with a hot plate or rework tool) and
peeling the circuits apart. The bond site then requires cleaning with a solvent, after
which the circuit can be re-bonded using a fresh piece of ACF 7303. Solvents such
as 3M
There was a tutorial showing someone doing this type of repair, which might be worth a search for.
You probably want to practise a few times on another disposable device first though as it looks a bit tricky.
Adafruit do 'Z axis' anisotropic tape in smaller quantities:
https://www.adafruit.com/product/1656
I also recall there being flexible splices available with the anisotropic tape pre-attached either end, which allow you to re-terminate the ribbon if the end is damaged.
You can also get T-bar tips for soldering irons that help with such repairs:
https://www.amazon.co.uk/CITALL-Soldering-T-iron-Ribbon-Repair/dp/B07BBMD8DW
in which case a quick reheat followed by some pressure might do the trick, or alternatively help with removal without damage ready for clean-up and new tape.
