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wax and EVA ratio information

This message is in response to Mr. Horton, who wanted to know a while back how much of the EVA glue sticks were needed to make paraffin properties more suitable for electronics potting. I have the answer as I have now done it about ten times: 5%. Simply determine how much weight or volume of paraffin you will use, then calculate 5% of that and add your sticks. I use the low temperature sticks. You can pick these up at Michael's art stores or even some Walmarts have them.

Three years ago, I was in a similar situation to yours and not sure whether I should use wax or a wax mix to pot something that was going to be in environmental extremes of temperature even greater than yours. I did some trials first and determined the 5% suitability, then did the final paraffin-EVA mix. The potted circuit board and transformer have been in temperatures from 0-98 F since that time and no cracks or distortions of any kind. There is evidence of slight, very slight, shrinkage, but far less so than using paraffin by itself. Therefore, I highly recommend the paraffin-EVA mix at 5%.

Hope that helps you out! You can save quite a few dollars potting this way versus actual potting compounds and such and now you have the trials and proof go go along with it. Good luck!

Reply to
Jon I
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Thanks for this information. Although I am past this now and have simply been testing the paraffin blocks by themselves, should I decide to try the EVA additive again, I will mix the way you describe.

Reply to
Jim Horton

I have heard that incompletely crosslinked EVA can decompose to acetic acid (vinegar), and that this can be a problem in solar panels that have not been manufactured with due care and proper materials.

Reply to
Chris Jones

The author replying to me did not indicate this with his potting of electronics, but if it does happen it could be a major problem. I've already gone through this with bathroom type silicone corroding copper wiring, but thankfully doesn't bother stainless which is what I usually use as feedthrough (or recently I just swapped silicone for JB Weld two part epoxy).

Reply to
Jim Horton

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Is the EVA crosslinked by UV light by any chance? I didn't find anything a bout this when I looked.

I did find that a water proofing product, Nicwax, is made by mixing EVA and "mineral wax". They claim to alter the mineral wax by changing it molecul ar structure... whatever that means. I guess they changed it chemically so mewhat. They wanted to make it less brittle. So maybe mixing the two is n ot a terrible idea.

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  Rick C. 

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Reply to
Rick C

Normally it comes in flexible sheets and is melted and then cured (crosslinked) by heating it. If properly made it is stable under UV, or at least those wavelengths of the UV that aren't stopped by the glass.

Reply to
Chris Jones

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