0 Members and 1 Guest are viewing this topic.


Philip

Circuit board protection
« on: Sep 25, 2018, 10:16 pm »
I was to protect some circuit boards on my thermocouple displays, whats best to paint/cover them with?

John Robertson

Re: Circuit board protection
« Reply #1 on: Sep 26, 2018, 10:08 am »
Care is needed in selection as some coatings are partially conductive.  Servisol Plastic Seal 60 is good high-voltage lacquer (don't get it near switches, display panels, etc - it'll wick into any small gap).  For temporary use.  CorrosionX oil-based is also compatible with electronics.  Engine marinisation guide is HERE

Philip

Re: Circuit board protection
« Reply #2 on: Sep 26, 2018, 1:17 pm »
Thanks, the Servisol is exactly what I'm looking for.

Gaz

Re: Circuit board protection
« Reply #3 on: Sep 26, 2018, 3:13 pm »
If you want to go the whole hog and pot your board then this stuff is pretty good.

It doesn't have a shelf life and you can easily dig your circuit board out should the need arise. I dare say it's a little shock absorbing too as its quite soft when set.
National Sarcasm Society - like we need your support
http://www.patsure.com

Philip

Re: Circuit board protection
« Reply #4 on: Sep 26, 2018, 6:40 pm »
If you want to go the whole hog and pot your board then this stuff is pretty good.

It doesn't have a shelf life and you can easily dig your circuit board out should the need arise. I dare say it's a little shock absorbing too as its quite soft when set.
Interesting stuff, must check to see if it's available locally.

Gaz

Re: Circuit board protection
« Reply #5 on: Sep 27, 2018, 11:42 am »
Interesting stuff, must check to see if it's available locally.

Also known as Ray-Gel
National Sarcasm Society - like we need your support
http://www.patsure.com

Philip

Re: Circuit board protection
« Reply #6 on: Nov 06, 2018, 2:48 pm »
The gel arrived today, I hope to get a chance to try it out later on some small parts.

Philip

Re: Circuit board protection
« Reply #7 on: Nov 25, 2018, 5:53 pm »
The RayTech gel does what it says on the tin :) . Produces a clear soft jelly seal, flows into any gap and is easy to use.

Al

Re: Circuit board protection
« Reply #8 on: Nov 25, 2018, 6:37 pm »
What's it like with heat?  Just wondering if it would be any good on the coils etc

Philip

Re: Circuit board protection
« Reply #9 on: Nov 25, 2018, 10:27 pm »
What's it like with heat?  Just wondering if it would be any good on the coils etc
It needs to be in a container so no good for flywheel coils. I dipped my last crafts coils in floor varnish (because I've had a tin in the shed for 19 years) and never had a problem. I've done the same on the Kohler I've got now.

Ian Brooks

Re: Circuit board protection
« Reply #10 on: Nov 26, 2018, 2:13 am »
Tips for making things truly waterproof (to 50,000ft!)

1) Minimise things that pass into the potting, eg wires. Water finds its way down the interfaces between the potting and the wires driven by atmospheric pressure variation. Typically there must obviously be some connections but keep it minimised. Ideally the whole thing is submerged with just a couple of wires coming out.

2) Insulated wires are pipes that transmit water exactly to the most sensitive parts of the circuit! I've seen this many times in failure investigations. Try to avoid insulation passing right to the board.

3) If you can vacuum pot it then so much the better. Put the item in a vacuum chamber, pull a vacuum, hold for a couple of minutes then let the air back whilst before it cures. That'll drive the potting deep into the nooks and crannies.

The main thing I've learned over the years is its really hard to keep moisture out forever. You must either form a chemical bond, form a high pressure seal (O ring) or welded joint to keep it out permanently. But anything you can do is better than nothing!

Dunking coils in varnish is good, better if you gently heat the coil first (70 C is safe, I've done Briggs coils at 90C). Coils would really benefit from vacuum dipping, that will drive the varnish right into the laminations.

Ian

Ian Brooks
Gloucester, UK