If you are desperate, you can put a fan inside just blowing air around the enclosure without any holes to outside to keep it water-tight. That should equalize temps nicely. Smallest fans on digikey catalog are 10x10x3mm that is TINY. Put one blowing on that inductor...
That's a proper bodge. Having a nice solid state solution and then introducing moving parts that will inevitably fail. What happens when they do?
Well then there is also the possibility to fill the whole device with fine sand. That solution avoids any moving part.
Is there any possibility of using a copper heat spreader between the active device(s) and the heatsink? Radio hams who build their own power amplifiers use this technique with aluminum heatsinks on a regular basis.
Active cooling as in a fan? This is an external power supply. Looks like a laptop power brick essentially. It does not have a permanent mounting location. It can be placed wherever the user wants...on the ground, in a corner, on a table, etc. I like your idea about using the PCB area as additional heatsinking. Maybe some fine tuning can be done there, though I think the thermal resistance from the inductor to the board is pretty high.
If it is an external power brick, then most of what I said will be useless 
regarding the thermal resistance, it's actually pretty low since the inductor is just a piece of copper which has really good thermal conductivity to the copper layers on the PCB. if you look at GPU designs, most of them use a thermal pad on the other side of the PCB (under the inductor) which transfers heat to the back plate of the GPU. the backplate gets quite warm and acts like a heat sink (i.e: helps cool the inductors if a fan blows on it). that is an insane amount of thermal resistance (1.6mm of FR4 material, 1 or 2mm of thermal pad and then the back plate itself not to mention the 3 different interfaces (boundaries between these layers)), but it still helps to a large degree. I think using copper foil tape as others suggested would be your best bet if you're running out of space. just make sure to use plenty of thermal vias (you can use vias in pad method if you're really out of space) and have the piece of copper foil tape directly under those vias.
The inductor is a big through-hole type. Looks like the below. Direct conduction from the copper wire is probably
okay but it all has to go through essentially two 0.8mm pins. I know our factory does not like to put adhesive underneath the magnetic parts because of the heat during wave soldering. But I could see how getting heat from the
bottom of the inductor to the top-sound ground plane could be helpful.
Thanks.
Is there any possibility of using a copper heat spreader between the active device(s) and the heatsink? Radio hams who build their own power amplifiers use this technique with aluminum heatsinks on a regular basis.
Can you show an example of this?
Thanks.
If you are desperate, you can put a fan inside just blowing air around the enclosure without any holes to outside to keep it water-tight. That should equalize temps nicely. Smallest fans on digikey catalog are 10x10x3mm that is TINY. Put one blowing on that inductor...
That's a proper bodge. Having a nice solid state solution and then introducing moving parts that will inevitably fail. What happens when they do?
Well then there is also the possibility to fill the whole device with fine sand. That solution avoids any moving part.
Hmm, interesting. This also raises the possibility of potting the unit, which could act as a giant heat-spreader. I think potting is not really preferred from a production standpoint since it's time and labor intensive. I know (good) potting compound doesn't cause an issue but I wonder if sand has any safety issues related to it, specifically for creepage paths.
Thanks.
Can you perhaps elaborate how you ended up in this situation with all kinds of parts tooled but before finalising the design? Perhaps we can learn from the situation.
Can you perhaps elaborate how you ended up in this situation with all kinds of parts tooled but before finalising the design? Perhaps we can learn from the situation.
Ah, I thought I explained this earlier, but looks like not.
We have an existing product line (in production for about 2 years) which uses this housing and metal hardware. For this customer, we estimated that re-using the existing tooled hardware would be sufficient, since the power level is similar. However, it turns out that
this power supply runs a little hotter on top of our customer being much more stringent (than most) on this specification
It was a gamble. Half the reason the customer chose us is because we hardly had any tooling costs in our quote. Unfortunately, did not have a say in that process. And now we are struggling to make this work.
It sounds like you are frustratingly close to making it work...
Can power consumption be lowered somewhere else in the system to bring you over the goal line? Usually you can always find a watt or two...
It sounds like you are frustratingly close to making it work...
Can power consumption be lowered somewhere else in the system to bring you over the goal line? Usually you can always find a watt or two...
The opening post states efficiency has been maxed out for a while which suggests they've been looking.