Currently I am using silver conducting paint to make the contacts in Liquid Crystal Cells made of ITO coated glass plates and covering it up with Loctite hysol 3425 a&b glue so that the contact remains stable at high temperatures and for a sufficiently long period of time. However after using the cell for a day or two the glue turns black (maybe due to heating) and the contact is spoilt making the whole LC cell useless. Please suggest an way out / any alternative method that I may utilize to do the same(making a stable contact) without spoiling the contact even at temperatures as high as 2000C. Thank you.
We use a metal clip with a hole (for the microscope beam) which is bent slightly to provide a bit of pressure, like a spring, to press the cell onto the heating block. The advantage is that the cell is also heated from above by the hot clip.
Another option (may be not the best one and pricey) but you can use high temperature soldering alloy, like Nickel Clad Copper (~450oC meting point) with again high temperature epoxy glue or various cement solution glues to fix the soldered wires. You might not have good wettability of melted alloy on the ITO surface and probably you would need soldering gun with power more than 60W.
You need this:
http://www.techni-tool.com/237CH204
It is very strong and gives good connectivity.
I used only silver paste to make a wire contact and it worked well at 200C. I did not use any thing to cover silver paste.
Sorry, I misread your question, I thought you were talking about contact between the cell and the heating block, not the wire contact. For the later the best is a high temperature silver glue paste, but you may have to make a new cell every day, or at least when the glue turns brownish. Then again, these are about the temperatures where organic compounds slowly begin to decompose as well, and a new cell once in a while is a good idea anyway.
It is very simple Mr.Sourav!
Purchase LC Cell holder from INSTEC. It will completely get rid of your problem and will help you to study all various dielectric properties at any time upto high temperatures.
Good Luck
Thank you everyone for your valuable suggestions. As suggested by Prof. Dierking I might need to change the LC cell every time the glue turns brown. Therefore I would like to check with high temperature soldering alloy or conductive epoxy according to the suggestion by Mr. Turiv and Mr. Salili. I hope this will help me solve my problem. Thank you.
Can anyone please tell me which type of wires will be preferable for making such contacts that will sustain till very high temperatures providing a very good connection.
Thank you.
Perhaps, try metal particle epoxy. Such epoxy can survive for long time even at high temperatures. Please find suitable metal epoxy for your temperature needs.
@Venkata sir, Can you please suggest such conducting epoxy product (e.g. Product name, company etc.) that may serve our purpose at temperatures as high as 2000C .
Thank you.
Dear Sourav, there are lot of options in the market. Mostly all high temperature metal particle dispersion epoxies are produced for mechanical parts. For e.g., Pattex is one such product. You have to check out for desired withstanding temperature and viscosity to use as electrode contacts. Please google it for best suitable epoxy for your experiment.
Try with this: http://www.ebay.com/itm/Conductive-Electric-Paint-Glue-Pen-Electrical-Circuit-PCB-Repair-Craft-/331889897052?hash=item4d462dee5c:g:7XkAAOSwqu9VUnQ8
if you ask him technical question he will block you, be aware!
If you want to use lower temperatures, I'd suggest Indium solder. It adheres very well to the ITO.
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