High Temp Glue

[thefast1]

Hi All, new here and wanted to ask what Glue of sorts  I could use to cover some resistors that get very hot.
Just to explain what it is i  need to do, I have some High power resistors (3) that are going to be used  in conjunction with some after market rear LED car lights, so I want to house the resistors in a small plastic box but want to fill the box with some heat resisting glue or compound of some sort to stop the box melting as well as protecting the components, I have seen various electronics in plastic boxes covered with some sort of Black hard glue, what is this called and where may I get some, I did a search on here but not sure what to call the glue, thanks for your help,

[orbiter]

It's called potting compound. A type of epoxy. I'm not sure if it's ALL high temperature resistant though so you may have to look for
a specific high temp potting compound.

Here's a link to the available compounds at Farnell.. Check the datasheets for specifics.

http://uk.farnell.com/webapp/wcs/stores/servlet/Search?catalogId=15001&langId=44&storeId=10151&categoryId=700000004395&sort=P_PRICE&pageSize=25&beginIndex=1&showResults=true

[thefast1]

Thanks for your speedy reply

[Ian.M]

If they already get very hot, they'll get even hotter in a sealed box and unless you keep the epoxy coating very thin, will probably overheat.  If they are already getting hot enough to melt the box, they will be a fire risk if buried in potting compound.

[SeanB]

You probably will be better off using a small diecast box, and using some aluminium cased resistors inside the box, attached to the case to heatsink them. Then you can simply use a waterproof cable gland and thermal compound between the resistors and the box, and if you want use some silicone grease on the lid to seal it.

I take it you are retrofitting LED lamps to a vehicle with lamp failure detection, so you have to handle the power of the original lamps, around 30W per side. You probably will need to use 50W metal cased resistors to handle the power.

[T3sl4co1l]

What are the dimensions of the box, and what power rating are the resistors?

Tim