Circuit board insulation

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DarkenReaper57

2[H]4U
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Oct 2, 2003
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I build a fan controller on a hobby board for an external watercooling box. The external system's housing is metal, so I would like to make sure the metal doesn't short the fan controller on the backside, as this is where all of the solder connections are.

My idea is to use some sort of adhesive nonconducting pad, similar to that which is found on a critcool powerplant for the eheim 1250. What would something like this be called, where would I get it, and roughly how much would they cost?

I would like to not build an enclosure for the circuit since there are heatsinks for the LM317 chips, and these need airflow.

Any ideas or suggestions? Thanks.

Oh, on another note, is it ok to paint heatsinks that don't need to dissipate a ton of heat?
 
dunno anything about an adhiesive pad but a cut up old mouse pad or any other similar material would work well to insulate. as far as painting heat sinks it would work fine, just use a few thin coats enough to lay color without soaking the thing in paint.
 
you don't need a special pad - any paper, cardboard, plastic from a milk crate, even electrical tape will work. if you buy the anti static pad from radio shack (what I think you are thinking of), that will actually cause more problems because it is actually conductive.

I would advise against painting heat sinks with regular paint, however high temp paint would be fine. regular paint will start to bubble when it gets hot, and you would be surprised the amount of heat a TO-92 can dissipate.
 
theshadow27 said:
you don't need a special pad - any paper, cardboard, plastic from a milk crate, even electrical tape will work. if you buy the anti static pad from radio shack (what I think you are thinking of), that will actually cause more problems because it is actually conductive.

I would advise against painting heat sinks with regular paint, however high temp paint would be fine. regular paint will start to bubble when it gets hot, and you would be surprised the amount of heat a TO-92 can dissipate.
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Well the paint that I have just so happens to be high performance paint and can withstand higher temperatures :).

Oh, is paint a good conductor of electricity? I was rather dumb when I designed the chip and I have two heatsinks close to eachother (1mm apart or so). Each heatsink is part of a separate circuit, so if they touch, there is actually a short and it causes all of the fans to run at the same voltage. I've been trying to figure out a good way (that looks half decent) to insulate the narrow gap between them. If paint will do this for me then that is great.

If all else fails, I suppose I could take a dremel to the heatsink and chop off 2mm or so.

As for the backside...I didn't even think of electrical tape, although I would prefer a better solution as this tends to get sticky over time.

I was initially thinking of a sort of insulated backing as seen here http://www.criticool.com/Powerplant.html.
 
If you could find a small scap of the asphalt sound dampening material (i.e. DynaMat or some off brand) maybe this would work for what you would want? Just a suggestion.
 
PedroDaGr8 said:
If you could find a small scap of the asphalt sound dampening material (i.e. DynaMat or some off brand) maybe this would work for what you would want? Just a suggestion.
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Hmm, that is an idea. I'll keep an eye out for something like that. In the meantime, I'll just use some electrical tape. If I am satisfied with that, then I may stick with it. My only concern is that it will fall off and get really sticky over time.

Perhaps liquid electrical tape would work...
 
I put a layer of silicone to the back of my projects/boards if there's a danger of them shorting out on something. Then, if I"m feeling really paranoid, i'll put a small piece of cardboard, or the broken-off top of a cd jewel case on the silicone. Electrical tape works, too.
 
hignaki said:
I put a layer of silicone to the back of my projects/boards if there's a danger of them shorting out on something. Then, if I"m feeling really paranoid, i'll put a small piece of cardboard, or the broken-off top of a cd jewel case on the silicone. Electrical tape works, too.
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Do you use a silicone pad or something that comes in a tube? Where do you get something like this?

Really good idea with the cd jewel case though, I may need to do that.
 
The industry standard for mounting PCBs when proper mounting has been ignored for some reason, is to use double sided foam tape. The normal 2mm thick stuff you get form a stationary store. Paint and electrical tape are not very good as the sharp component legs will poke through after a while. Anther one is to use some plastic sheet from a blister pack to go underneath the board.

Painting the heatsinks is fine if they are not getting too hot. Once again, not suitable for insulation as it scrapes off with time.
 
chopsuwe said:
The industry standard for mounting PCBs when proper mounting has been ignored for some reason, is to use double sided foam tape. The normal 2mm thick stuff you get form a stationary store. Paint and electrical tape are not very good as the sharp component legs will poke through after a while. Anther one is to use some plastic sheet from a blister pack to go underneath the board.

Painting the heatsinks is fine if they are not getting too hot. Once again, not suitable for insulation as it scrapes off with time.
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Thanks for the advice. I may need to get some double sided foam tape...
 
MD_Willington said:
pot it with RTV silicone or epoxy...
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NOOOOoooooooooooooooooooooooooo!!!!!!!!



At least not if you want to ever work on it again!
 
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