Copper heat sink

[Ross365]

Everyone is saying the interface is crucial, so what's the plan? Does a gentle polishing do anything good? Is there much difference between RS standard thermal paste and "Super Dooper" paste? And... is it true that thermal paste has a short shelf life? What else can be done at the interface?

 

[stuvy]

Everyone is saying the interface is crucial, so what's the plan? Does a gentle polishing do anything good? Is there much difference between RS standard thermal paste and "Super Dooper" paste? And... is it true that thermal paste has a short shelf life? What else can be done at the interface?

No idea, I haven’t got that much experience with it

 

[Misterg]

I can’t share the full details but it’s a camera and bolts to x5 M3 CSK screws

Look at a thin indium "gasket" between the camera and the heatsink if you haven't already done so. It offers extremely good thermal transfer (it's used on cryo-pumps). It must be annealed and fitted between very clean, flat mating surfaces.

 

[sako243]

Keep the number of interfaces down (i.e. @stuvy's idea of bolting together flats to make a wide heatsink isn't the best idea). Where you have an interface then surface area is king but it must be thermally conductive surface area.

Crucial point to remember is that heat will only transfer from a hotter place to a cooler place (remember Flanders and Swan) so maintaining a temperature differential is key.

 

[sako243]

Thermal paste does tend to dry out over time (key reason why laptops etc die over time is the paste dries out and then the chips overheat).

All (decent) pastes should provide a figure for thermal conductivity or resistance so just try and find the best and follow the instructions. We did have a good one in my old job that tended to last (important for systems that are deployed for decades).

There are quite a lot of online heatsink calculators so it's worth having a play with them because sometimes the same area of heat sink but with different variations on fin spacing and spacing makes a massive difference.

 

[sako243]

@stuvy can you provide any details because we might be able to help you a bit more then.

I'm in no way an expert but we had a heating issue (or rather lack of cooling) on a system and unfortunately due to restrictions imposed the two of us (myself and the technical head of the group) had to become expert enough as no one else could be read in. We went from out radio lasting 10 minutes before it shutdown because of overheating to actually having to get the radio team to rewrite their calibration software because my unit ran cooler than the standard units simply by eliminating as many interfaces as possible and reducing the thickness of paste required. A key point to bear in mind is that the thermal paste should ideally be as thin as possible (it's not as good as the metal conductors) and as even as possible (otherwise you develop hot spots which can make the system less efficient overall).

 

[stuvy]

The camera I need to cool is 40 C ambient

It’s a welding camera(made for the job) so obviously there is heat radiance and convection due to the way it’s mounted

It sits approximately 350mm away from the weld area

I can’t say any more as we have dozens of NDA’s at work and this is a public forum

 

[stuvy]

The temp gets upto 86 before it drops out

 

[sako243]

So the camera can run to 40°C ambient but is overheating and shutting down?

Thinking outside the box but wouldn't you be better off trying to reflect a load of the heat away (think tin foil) since there's a fair amount of radiant heat from welding.

As an experiment can you just wrap everything bar the lense in tin foil (literally) and see if it makes a difference. My suspicion is it will.

If you've got somewhere to attach a heatsink I'd then look at possibly a heat pipe (they are phenomenally good) to move the heat away from the camera to somewhere else you can cool it? Water cooler?

 

[Ross365]

What about a Peltier cooler; this is the biggest that RS has but I'm sure there are biggers ones https://uk.rs-online.com/web/p/peltier-modules/1743123

The guidance notes pdf on that page is really interesting.

 

[mike os]

That size block won’t dissipate that much heat once it is up to temperature… I assume you will fin it in some way? Or is the heat input relatively small ?

 

[Maker]

It’s a welding camera(made for the job) so obviously there is heat radiance and convection due to the way it’s mounted

It sits approximately 350mm away from the weld area

I suppose that rules out adding a fan to force some air over the heatsink?

 

[Robotstar5]

Dow Corning was always my go to for heat sink paste.

 

[Red'n'Black]

The camera I need to cool is 40 C ambient

It’s a welding camera(made for the job) so obviously there is heat radiance and convection due to the way it’s mounted

It sits approximately 350mm away from the weld area

I can’t say any more as we have dozens of NDA’s at work and this is a public forum

Can you put a thermocouple on the part that's shutting down, log the temp and see how hot it gets before/after the welding starts?

I.e. is it mostly self-heating, or infrared from the welding that's the problem? The answer to this will determine the best way to attack it.

As mentioned earlier, at normal heatsink temps convection dominates over radiation. But if there is strong external IR from a welding arc or similar, a highly reflective coating on the heatsink might help. Gold (even a fraction of a micron of plating will work) is one of the best IR reflectors you can get. The usual black heatsink finish will make things a lot worse in this case.

 

[PhillipM]

Everyone is saying the interface is crucial, so what's the plan? Does a gentle polishing do anything good? Is there much difference between RS standard thermal paste and "Super Dooper" paste? And... is it true that thermal paste has a short shelf life? What else can be done at the interface?

it being flat is most important, polishing not past like a 400 grit finish - it generally makes it worse after that.
Yes, big difference on thermal compounds.

If the interface is small is it possible to incorporate heatpipes instead?

 

[eLuSiVeMiTe]

How critical is the size of the heatsink.

https://www.overclockers.co.uk/raij...T4IQybmNYMfHSHh3m5X_Utle7n935GcxoCursQAvD_BwE

 

[Beeezer]

where are you roughly?

 

[MetalMonkey]

Might be an obvious question, but have you looked at CPU and GPU heatsinks?
They are available in a range of different shapes and sizes and they are pretty efficient and well optimised.

Might be a lot easier to find one that is close and adapt it rather than reinvent the wheel.

 

[R Kraft]

Maybe a heat pipe type cooler and a fan.

 

[Onoff]

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