I just repaired a 12 years old telephone base station where the LCD display meanwhile turned blank completely. That display does not have pressure contacts but a plastic foil with printed conducting paths which is glued/laminated to the LCD’s base glass and the LCD’s printed circuit board. After quite some time I found out that this foil somehow lost electrical contact, though on visual inspection and mechanically it seemed totally right.
After further experimenting I realized that applying heat of 180°C and pressure reinstalled electrical contact. I used a digitally controlled solder iron with a screwdriver type of tip.
After quite some delicate work with a head loupe I succeeded in getting nearly all pixels work again. Only at three contacts I spoiled it as the tip used was slightly wider than the contact zone, and and at these three contacts I seemingly cut the printed conducting paths of the foil at the point where the foil runs over the edge of glass base plate. So it seems a good idea to chose a tip a little less wide than the contact zone, but not too small (no pencil tip) in order to spread pressure evenly.
I’m curious for how long my repair will last…
After further experimenting I realized that applying heat of 180°C and pressure reinstalled electrical contact. I used a digitally controlled solder iron with a screwdriver type of tip.
After quite some delicate work with a head loupe I succeeded in getting nearly all pixels work again. Only at three contacts I spoiled it as the tip used was slightly wider than the contact zone, and and at these three contacts I seemingly cut the printed conducting paths of the foil at the point where the foil runs over the edge of glass base plate. So it seems a good idea to chose a tip a little less wide than the contact zone, but not too small (no pencil tip) in order to spread pressure evenly.
I’m curious for how long my repair will last…