Thermally conductive adhesive

I forgot, you can also solder down a bit of sheet copper on the top side.

It is also worth, filling the holes. Nearly any material is a better thermal conductor than air.

I bought some conductive epoxy from Tri_Con to embed a number of LM35 sensors in a system. While it was a better conductor than most epoxies; it was later clear that that was better than air; it wasn't near what metal-to-metal provided.

I seem to recall that the epoxy was about the same conductive characteristics as heat sink paste.

I think they put a weight on it.

If I had to do this one again, I'd use spring clips and silicone grease maybe.

John

There is an LM35 in a TO220 package, which can be handy.

John

What was between the metal to metal in the micro-spaces that are there?

Paste? Silver filled epoxy squeezes down just as flat, and FILLS all the gaps. Way better than non-bonded metal-to-metal interfaces.

Even paste would be better than a 'dry' mating, unless you are polishing the surfaces to a micro-inch finish and a very flat face.

Doesn't help in our application I'm afraid. It is the combination of small spot and parallel light that we need. The target is only an inch away.

Not until "Ecnerwal" (Lawrence?") posted the same one :)

I hadn't seen it before. Yes, might have been a way to go.

Thanks,

I'll ask them for more information on this.

That's not a problem. The whole thing is in good thermal contact with a metal block with fluid running through it!

Not sure what you mean by "cladding"?

Could do - we have a lot of vias already, and I think those combined with the Aluminium plate should be more than sufficient!

We have used lasers for this on other versions.

They do have other problems. Amplitude noise from mode jumps, speckle and etalon fringes, limited temperature range, ESD sensitivity, external collimator).

As well as many admirable characteristics of course.

We did that too! Had a big dense grid of vias then ran it through the wave solder machine. Unfortunately you then often get little bumps that interfere with the aluminium plate the board is bolted against... I decided we needed good thermal contact with that plate more than the filled vias.

We can spend forever tinkering with this sort of thing... what if we tent solder resist over the holes on one side, what if we put the plate on before wave soldering, etc. But it's all overkill, all we really need do it get the heat away from the immediate vicinity of the led base, which just requires good thermal contact with the groundplane.

Like a shield or ground plane. COPPER.

In other words, an entire area of copper between an array of smaller plated thru holes that surround the one, large, plated thru mounting hole

We use the same idea for cooling SMT transistors. I'll hunt up a pic of a 15kV miniature supply (you could fit 6 in a pack of cigs) that has a real nice heat management around an SMT transistor package. I have to hunt up the pic tho.

I would have done an extra hand step before the HAND attached plate goes on where the face is made flat with solder braid wiping or the like.

OK, we do have actual ground planes (both sides) with lots of vias surrounding the led area, as described in another post.

"cool".

But as I recall; all the metal packages were non-isolated. I didn't need fast response so I just tolerated the resistance. (I was measuring water pipe temps in a home hydronic floor system.)

Perhaps tightly clamped deformable metal foil. There is nothing wrong with solder really, especially controlled (often lowered) melting temperture types.

Gosh, i have seen lots of stuff like that. Many with more fins / fin area.

Sure, I've seen the finned springy ones, but not that specific type.

It looked like I could have used it in conjuction with our aluminium plate.