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I'm talking about an LCD like what is shown in the picture below. Can hot glue applied to its borders damage the liquid crystal molecules or anything else inside it?

enter image description here

I searched on the web and found this (Ref. 1):

Typically, standard LCD character and graphics modules provide a temperature range of 0°C to +50°C. However, several display manufacturers offer extreme temperature models with operating temperatures of -40°C to +80 or +85°C. There also is a wide selection of standard versions that range from -20°C to +70°C

If this is true, it may not be safe to use hot glue for this purpose. However, since hot glue is applied for less than one minute to a small fraction of the area I'm not sure. (I have only one of these. Otherwise, I would just tested it!)

Reference:

  1. https://www.digikey.com/en/articles/selecting-lcd-modules-for-extreme-temperatures
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    \$\begingroup\$ Just to clarify, when you write that you want to 'fix' the LCD, you're wanting to 'affix/attach' the LCD to the panel, not 'repair' it on the panel? \$\endgroup\$
    – brhans
    Commented Sep 7, 2021 at 13:05
  • \$\begingroup\$ Could you use double-sided sticky tape, or double-sided foam tape? Or even make a slot in something for it to fit in? \$\endgroup\$ Commented Sep 7, 2021 at 13:05
  • \$\begingroup\$ @brhans, Yes, I want to attach it. \$\endgroup\$
    – apadana
    Commented Sep 7, 2021 at 13:07
  • \$\begingroup\$ @AndrewMorton, I'm going to first fix the LCD and then its backlight LED (it's a transparent LCD). I'm not sure if I can use tape here. \$\endgroup\$
    – apadana
    Commented Sep 7, 2021 at 13:16
  • \$\begingroup\$ @AndrewMorton, after your suggestion I tried the only double-sided foam tape that I have. The LCD is quite firm now, but I wish the foam was thinner. Thanks anyway. \$\endgroup\$
    – apadana
    Commented Sep 7, 2021 at 13:56

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The link you post talks about temperatures operating conditions. This is not the same as storage temperature, which in turn is not the same as some peak temperature for a short moment (during soldering etc).

Very likely, you don't need to worry about the temperature rating unless you intend to glue the modules while they are powered. Hot glue with the average hot glue gun melts at around 100-120 dgr C somewhere but the temperature when the glue is applied against the module will be lower.

What you should be concerned with however is glue getting inside the LCD module itself in case of low viscosity or capillary action. That might discolor the LCD or form blobs in the view itself. Silicone might be a better option than hot glue. You'll have to do some practical experimentation.

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  • \$\begingroup\$ The important thing to remember if considering using silicone with electronics is to get the neutral cure type which does not release acetic acid while it sets. \$\endgroup\$
    – brhans
    Commented Sep 7, 2021 at 14:58

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