About that white goop in power supplies

[The House of Moth]

I've been removing it for years but have never put any of it back. Some of it is positioned in a way to it could be for thermal transfer, and some of it has no thermal advantages the way it's located, so it's just there to keep stuff in place/insulated.

I'd like to buy some as I have a few projects coming up where *so much* of it has to be removed, I *have* to put some back, even if it's just to make myself feel better. My problems:

1. Is it a glue to keep stuff in place or is it a thermal compound of some sort?
If I put thermal compound where there should not be any and heat starts transferring to places it shouldn't, that could be a problem. Then again if I put an insulating compound down where there should be thermal compound, heat might not get away fast enough...

2. Official names for this stuff.
Plenty of guesses out there, but no clear and decisive "this is what it's called and what it's for". So I don't know what to buy.

3. Which brand is good?
hundreds of results when searching around but without a name to search for it's the wild west with options.

Any experts around here that can help me find what I'm looking for?

 

[This Does Not Compute]

Can you post a photo of what you're referring to specifically?

There's generally two kinds of "goop" that ends up in power supplies. One is thermal paste, which is usually between transistors and heatsinks. There's nothing special about it, and normal computer thermal paste is fine.

The other kind is usually silicone adhesive and is found between components, often larger capacitors. This is for support and shock mitigation, such as during shipping, as large parts rattling around can put stress on their leads. Sometimes hot glue is used instead, which works fine as a replacement (such as after recapping).

 

[Elemenoh]

The glue is silastic and the purpose is what @This Does Not Compute noted above. If you replace it, use something labeled 'electronics grade' or just be sure what you buy doesn't have acetic acid in it.

 

[The House of Moth]

This is the stuff I was referring to @This Does Not Compute. Rock solid but comes off easy after heating it up a little. @Elemenoh I've ordered this, should be alright?
Thanks for the replies!

 

[Elemenoh]

It’s made by Chipquick and says noncorrosive and non conductive. It should be fine, but that’s a tiny tube that won’t go very far.

 

[Crutch]

@Elemenoh what is the particular issue with acetic acid? Maybe related but, @This Does Not Compute I have observed that ordinarily hobbyist hot glue can prevent logic boards from working properly. (Easily repaired by scraping the stuff off.)

 

[This Does Not Compute]

@Elemenoh what is the particular issue with acetic acid? Maybe related but, @This Does Not Compute I have observed that ordinarily hobbyist hot glue can prevent logic boards from working properly. (Easily repaired by scraping the stuff off.)

When I've seen hot glue used to secure components, it's just been between the components themselves, i.e. sticking two tall caps together. I wouldn't use it to glue parts to a PCB, though I'm also not a fan of gluing parts to PCBs to begin with.

 

[Elemenoh]

@Elemenoh what is the particular issue with acetic acid?

Acid is corrosive. it could cause damage to the board over a (probably long) period of time.

 

[Crutch]

When I've seen hot glue used to secure components, it's just been between the components themselves, i.e. sticking two tall caps together. I wouldn't use it to glue parts to a PCB, though I'm also not a fan of gluing parts to PCBs to begin with.

My specific experience was attempting to use hot glue to prevent a coil-shaped, springy wire used to install a Radius Accelerator 16 from bouncing around and making noise when moving the Mac. The wire was, I believe, used to transmit some sort of signal between the accelerator and the logic board. If any hot glue was touching it when I powered up the Mac, the accelerator would fail. I don’t know if the glue was conductive or capacitative or what, but the HF signals in that wire didn’t like it.

 

[ClassicHasClass]

Sure beats the epoxy old power supplies (notoriously Commodore 8-bit ones) were potted with.

 

[The House of Moth]

To whomever may fix this power supply next, I apologize