Is it safe to use a hot-glue gun to keep LED's in place?

I have seen ugly hot-glue work on cheap boards to hold cables and big components in place and even to insulate mains carrying traces on PCBs, so there doesn't seem to be much conductivity. It is another question if the epoxy surface of the LEDs will stick to it, but worth a try.

I'd build in some kind of strain relief for the LED leads, and smother the assembly in RTV silicone rubber, that you can get at any hardware store, "Home Club"-type store, or auto-parts store.

I wouldn't trust hot glue unless it's the type that dries resilient. (Is there even any such of a thing?) Rigid stuff will crack, although epoxy might have the kind of toughness that you need.

Good Luck! Rich

snipped-for-privacy@mindspring.com wrote in news:1117249160.423650.214750 @z14g2000cwz.googlegroups.com:

When making connections to really small parts of circuit boards (ie soldering a 30awg wire to a via on a motherboard) - I often will put a blob of hot glue on it as a form of very basic strain relief. I've done various tests with hot glue and at least whatever I'm using (from craft store) does not conduct at all.

-Michael

I'd say it's safe, if your question is about whether the glue will hurt the components.

But my experience with hot glue is that it tends to be less permanent, ie it gets too warm or too old and things fall apart. At least, with plastics.

Epoxy, or as someone said RTV silicone whatever, tends to be more permanent. The latter, which can be a real drag to remove if you need to, has the advantage that there's a level of flexibility to cushion those vibrations.

Michael

Thanks all! I guess I will go with the RTV silicone stuff. My only other question is if the silicone will effect the light output... my LED's project their light in about a 60degree angle, and I wonder if the silicone stuff will refocus the light?

What would be the best way to apply the stuff... just at the base of the LEDs, or totally cover the LEDs in a think layer of the RTV silicon stuff?

Lastly, since this will be on my RC car, dirt and other stuff will soon cover parts of my stuff. I use the general parts-cleaners that mechanics etc. use... spray can. Will that eat away at the RTV silicone stuff, or cause harm to the resistors and LED's? Would just using soapy warm water be better...and just let it dry thoroughly overnight?

Thanks again,

--Farrell F.

Not if you don't slop it all over the top of the LED. :-)

Put it between the LED and the board, with just enough excess to bring its level up to the rim around the LED base, maybe a teeny tiny bit more:

top of LED _ / \\ / \\ | | | | | |

--------------_| |_---- cover parts of my stuff. I use the general parts-cleaners that mechanics

There's almost nothing that will attack RTV silicone. Acetone might attack the plastic LED surface, although they should be epoxy, which is also pretty impervious. Resistors are also inert, although there's a possibility it could wash the paint stripes off, which won't harm the actual resistor.

But be sure and use a cleaner spray that leaves no residue. Do NOT use WD-40 for cleaning - that just gums stuff up.

Hope This Helps! Rich

Be careful with RTV. There are two types and one corrodes wire. It is marked, Not for electronic use.

I see a lot of LEDs mounted in consumer electronics with a little dab of hot melt glue.

There is hot-melt and there is hot-melt. We use a polyamide stick (Tec-bond