What you see on the photo is
a ceramic tile, poled on one side with a blob of solder in the centre
a ceramic tile, the other side
a rectangular piece of 0.5mm polystyrene
a similar piece of polystyrene, cut with indentations and 9 of these tiles glued on
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The polystyrene is there to hold the ceramic tiles together
We have cut indentations to allow some movement and flex
We solder leads on the solder blobs sticking out through the holes cut into the polystyrene
The ceramic tiles are glued on with epoxy glue. The glue serves to (a) glue the tile on and (b) insulate the poled side
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This works beautifully, except, and the reason for this post:
Regular flexing and/or vibrations unstick the tiles creating tiny gaps between ceramic tile and polystyrene. Liquid then sips into the gap and there are shortages. The idea is to minimise the shortages.
I have tried other plastic materials, polypropylene, PetG, PVC - nothing sticks really well and the polystyrene is the least worst.
I have tried some other glues, nothing I have tried works equally well on both surfaces.
The inherent problem is that polystyrene flexes but ceramic tiles do not. Trying to bind two such different materials and then exposing them to vibrations and flexes ...
I was trying to think out of the box. What if I do not use glue at all, but simply varnish the poled side. I would also have to varnish the solder blob and the lead soldered on to it. But how then to secure the tile onto the polystyrene template ? By the lead itself maybe? So the tiles are allowed to flop around but are held in place by the lead, similar to how we stitch shirt buttons on ? If the epoxy/nail varnish/yacht varnish is applied on the poled side, it will never go because nothing would be pulling on it. But if we glue the tile on to the plastic substrate then when it snaps off it also peels away the layer of glue and then the poled side remains exposed.