does glue transmit heat??

I'm going to be making a block type heatsink for my open can laser to fit in to, by glueing together several layers of aluminum flat bar. My question is, what type of glue should I use to glue the layers together to best transmit heat?? Obviously I could use thermal compound but I'd rather use regular glues if it's possible.

thebucketmouse said:

I'm going to be making a block type heatsink for my open can laser to fit in to, by glueing together several layers of aluminum flat bar. My question is, what type of glue should I use to glue the layers together to best transmit heat?? Obviously I could use thermal compound but I'd rather use regular glues if it's possible.

Click to expand...

No...
Glue is an insulator, not a conducter.
Use Arctic Silver thermal epoxy.

Most glues insulate heat pretty well... They make "thermal adhesive" for gluing heatsinks onto video cards etc, though it's expensive and hard to come by.

I've been meaning to try adding copper filings to j-b weld epoxy to see if I can DIY something that transfers heat at least reasonably well.

http://www.google.com/products?q=arctic+silver+5&btnG=Search+Products

if you know someone with a high frequency tig welder they could lay down
a nice bead across the strips to connect them  

or you could drill a hole and connect them with all thread or a bolt

it matters what glue this is good stuff
http://www.dealextreme.com/details.dx/sku.4579

man that pisses me off
i ordered three tubes of that stuff in oct
two months went by so i contacted dx  they would'nt reply so i got with pay pal
and filed a complaint well then dx replies hi so sorry but we have order ready to ship could you remove pay-pal complaint so we can proceed with your order
like a dumb a$$ i removed it .now my order says completed and they tell me it was shipped out two months ago i should have %$#@@ no i dont have it you never shipped it or its been lost -- I go back to pay-pal they said sorry once you release the complaint you cannot do anything else

so I'm burned 25 bucks thanks DX you rock


WOW sorry i went off its like the third time dx has burned me but i keep going back shame on me!!!!!!!!!!!

pseudolobster said:

[highlight]Most glues insulate heat pretty well...[/highlight] They make "thermal adhesive" for gluing heatsinks onto video cards etc, though it's expensive and hard to come by.

I've been meaning to try adding copper filings to j-b weld epoxy to see if I can DIY something that transfers heat at least reasonably well.

Click to expand...

He wants to transmit it, not insulate it.

john_lawson said:

or you could drill a hole and connect them with all thread or a bolt

Click to expand...

ahh good idea. ill probably do that

The problem with layering aluminum to use as a heatsink, is that as aluminum oxidizes from exposure to air, it develops a hard, semi-conductive coating of Alumina on any of its exposed surfaces (this characteristic is what makes Aluminum stand up well to harsh weather environments).

This coating of Alumina is practically invisible (unless the Alumina is dyed in a process called Anodizing), but it's enough to create real problems if you try to use layered aluminum parts as a heatsink or even when used as an electrical conductor.

One contigenous block of aluminum can make an excellent heatsink, whereas stacked, individual aluminum plates of the same volume, will have a much lower efficiency, due to the insulating coatings of alumina.

-My advice, if aluminum is your only choice and you can't use copper or bronze plates, is to sand the aluminum plates, just before assembly and then spread a thin coating of thermal paste on the mating side of the aluminum plates right before bolting them all together. The sanding will remove the insulating oxidation from the aluminum and the thermal paste, regular or silver, will help keep oxygen away from the exposed area, preventing the oxidation from quickly building up again.

You can always get nice, solid pieces of copper (and bronze) from the hardware store. Look in the Electrical section and ask for "Grounding Rods" -you can use to make round stock and "Grounding Straps" -you can use to make flat stock.

hmm ok, i forgot about the oxidation. i'll try the grounding straps then when i get to the hardware store

I don't see why you need to transmit the heat between the plates. The object is to sap the heat from the center, and multiple plates should do that quite nicely even though the temp in each plate won't be identical.

Spyderz20x6 said:

[quote author=pseudolobster link=1229137511/0#2 date=1229138901][highlight]Most glues insulate heat pretty well...[/highlight] They make "thermal adhesive" for gluing heatsinks onto video cards etc, though it's expensive and hard to come by.

I've been meaning to try adding copper filings to j-b weld epoxy to see if I can DIY something that transfers heat at least reasonably well.

Click to expand...

He wants to transmit it, not insulate it.[/quote]

Precisely. Mr. Lobster is stating regular glue is insufficient.

Cyparagon said:

I don't see why you need to transmit the heat between the plates. The object is to sap the heat from the center, and multiple plates should do that quite nicely even though the temp in each plate won't be identical.

Click to expand...

Thats what I was thinking, don't people use aluminum washers as a heatsink all the time? Seems like the same concept.

mix 2 parts thermal paste(arctic silver, grease like thermal paste) to 5 parts regular epoxy. the better the thermal paste you use the better your results will be. you could even go so far as to add diamond dust in the mix for extra heat transfer.

thebucketmouse said:

[quote author=Cyparagon link=1229137511/0#11 date=1229157907]I don't see why you need to transmit the heat between the plates. The object is to sap the heat from the center, and multiple plates should do that quite nicely even though the temp in each plate won't be identical.

Click to expand...

Thats what I was thinking, don't people use aluminum washers as a heatsink all the time? Seems like the same concept.[/quote]

It depends if you want something that can do some kind of heatsinking or something that will do the best job of heatsinking.
Back when I used to play around with CPU overclocking, the ability to sap the most heat as quickly as possible from the chip was the biggest part of the challenge (unless you went with esoteric cooling, like water or peltiers).

A single, contigenous block of metal is always going to be better than a multi-part assembly. If you do have to go with an assembly, bolting or gluing pieces of rusty steel together, isn't the best way to do it -oxidized aluminum being, analogically, the same thing.

A good (not perfect, but good) rule of thumb, when trying to judge if something would be good medium for heat transfer, is to look at it's ability to conduct electricity. If it's a good conductor of electricity, it will usually be a good conductor of heat (both being forms of excited electrons).

If Arctic Silver or Thermal Grease is hard to find or too expensive, look in your medicine cabinet for a tube of zinc oxide (people put it on their nose to block sunburn and on their face to dry up pimples) and scrounge up a couple of #2 pencils. Split the pencils, remove and grind up the graphite "lead" into a fine powder and mix it with half a teaspoon of zinc oxide. This will make a quite serviceable thermal transfer paste. -And yes, it conducts electricity quite nicely. Check it with a meter if you like.

~SK

Is it really worth your time over-doing a heatsink for a $10 diode? It sounds like you all want him to put $50 of work into it. Yes, you could obtain a 3 pound block of copper and drill a hole in that and cool it with peltiers... but why? It's a $10 diode that will operate sufficiently with layered aluminum.