Heatsinking a 105C Driver

I love these copper mule sinks. I have been using larger head - Z32 / KL3 to enable a reflector. With LED on copper sinkpad, on large copper heatsink, thermal management is so good.
So what about the poor old 7135 chips?
I made a 3mm thick copper disc with cutout for positive, ran the negative wire through the centre. Took 4 separate mixes of arctic silver to complete the bottom section. Happy with the result, looks neat and now chips not only have a heatsink, the heatsink has good thermal path to mule sink.
So what about the poor old chips on the top?
This is where I knew it was going to get ugly. I needed a thin copper sheet to extend the heatsink around the driver and then epoxied thin copper sheet to top of chips.I went around the edge and pushed the edges together and section where no sheet on top got bent down onto negative ring of pcb.
Then soldered the copper side and top together.
Not pretty now, but all chips have thermal path for heat and whole thing is potted.
The driver sits proud of the resess in bottom of mule sink (therefore need for copper to extend) but it still goes all the way down in the FM 6P host.
Just put a Z44 bezel on to test function,temporary mule. It will be getting a reflector. Wires to lEDS have a bend for bit of spare for future LED replacemnet if I want. LED is screwed down with thermal compound, not epoxy so easy maintenance.
Surprised how much room there is to spare, I might try similar mod but with 3mm copper disc on top too...

Great idea with the copper sheets..
I'm gonna try with the left over copper tapes on the battery spring side.

Btw, what will happen if the chips heat up?
So far I've not experienced any form of chips burn-out due to prolonged usage.

- JonK

they don't burn out, they have internal thermal control, they just shut off if gets too hot.
in my camp light, i used such driver, but i glued video cards heatsinks on both sides, making sure the soldered connections are not touching heatsinks. after 5 min running on 6v sla, both heatsinks got pretty hot.

great job TC. are you running on 2 cr123? cuz i never head heat issues using 1 18650, they usually don't put out more than 2A, at that current chips are not heating up. the only time i had short run on full power from 18650, when i used 8amc drivers, with no mode MC. and fresh panasonic capable of 10A. but never with multimode 8x amc drivers

Thermal control (by the chips) is what I don't want. Just using single 18650 but Samsung ICR2000.
High drain cell, they don't sag much. So this driver was typical of 4 I put together recently - 3.04A spec and I measure 2.97A at tail on high.
They've all been very close to that. Weird thing is I connected 4th star, should be 2 level but it's 4 level.
It seems to be around 0.15% / 2.5% / 30% / 100% - I measured 5mA, 80mA , 840mA , 2.97A.
Cool, I'll try something different. I still have access to stars so can change if I want.

man that front shot showing the black button head screws is legit

So am I right to say that during prolonged usage, the chips will heat up & it will cause the current to drop when it does..
And when current drops, light output drops as well...

- JonK

DellSuperman said:

So am I right to say that during prolonged usage, the chips will heat up & it will cause the current to drop when it does..
And when current drops, light output drops as well...

- JonK

Click to expand...

They heat up, that's a fact. Whether they heat up enough to reduce current will depend on many factors.
It's a linear driver so voltage overhead will cause more heat. Actual drive current will cause heat.
I've got a big copper heatsink with good contact with body so it's the best thermal management I've ever had in a P60 host.
As I believe LED will therefore manage max or close to max output, I want to make sure my driver is not a weak link.

Thermal contact through the case is better than nothing, but the heat sinking of the 7135's junction is through the mounting tab.