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Water proofing electronic components

Posted: Tue Jun 23, 2015 3:57 am
by abishur
Hi all, I'm working with some thermistors and wanted to make them safe for permanent water submersion up to 10 feet. I was going to use some adhesive shrink tubing rated for marine use on the leads, and use either direct burial ethernet or direct burial sprinkler wire to connect to them. I am going to put two of them right next to each other in a Wheatstone Bridge and measure doing differential voltages, but since I want to keep everything very close together I wanted to really make sure I was protected from water penetration by coating it in a thin epoxy layer (to be precise I was going to seal off a McDonald's straw, get all my wires in there and fill it with the epoxy compound and then remove the straw when done).

Does anyone have any experience doing things like this so they could point me towards a good epoxy? I know that this will cause my response times to increase as I'm adding a layer of insulation on top of the already epoxied thermistor and am open to suggestions on alternatives like affixing them inside a copper pipe and sealing just the ends instead of the whole thing?

Re: Water proofing electronic components

Posted: Tue Jun 23, 2015 5:02 am
by fruit-uk
Search for 'potting compound', used to protect electrical devices and connections

Re: Water proofing electronic components

Posted: Tue Jun 23, 2015 4:54 pm
by abishur
fruit-uk wrote:Search for 'potting compound', used to protect electrical devices and connections
er... quite so? As I said I plan on putting on a thin layer of epoxy (potting compound if you prefer) but am looking for specific epoxies people have use and am especially interested with any thoughts on tackling the issue of how to encapsulate all this so as to minimize any loss of temperature reading accuracy in the thermistor.

Re: Water proofing electronic components

Posted: Tue Jun 23, 2015 5:20 pm
by fruit-uk
Mm...

searching for
thin "potting compound"
shows mouser as one of the first results. I believe they are US based and perhaps have a tech support line

searching for
sensor "potting compound"
shows http://www.epicresins.com/ElectronicsPo ... ransducers as one of the first results and would seem to suit, again US

Re: Water proofing electronic components

Posted: Wed Sep 12, 2018 4:26 pm
by mahjongg
Araldite is an epoxy based two component glue, used to glue die's (chips) to die-carriers, but can also be used as an air/water tight cover. It has good thermal conductivity properties.

Farnell sells a whole range of potting epoxies. https://nl.farnell.com/w/c/chemicals-ad ... st=potting