Cree LED XHP70.2 thermal management


I’m an engineering student and I’m currently building my own high power flashlight.
I’m using the Cree XHP70B-00-0000-0D00N40E1which has the following features:

Vf = 12V
If = 1050mA
Pt = 12.6W
θJA = 0.9°C/W

I’ve already made the driver for this LED but I can’t really find any clear information on how to cool the LED.
I’m planning on using a double sided PCB (dimmensions : 20mm X 20mm) but do I need any aditional cooling?
I will also 3D print the case for the flashlight so little to no heat will be disipated trough the case.

With kind regards

Hi sebastien_t

yes, you will need A LOT of additional cooling/thermal mass if you are planning to run the XHP70.2 anywhere close to full power. Enclosing the flashlight in a plastic case (generally a bad idea) means you will have to add thermal monitoring. Check the max junction temp that's allowed for your LED, you want to stay below that or your LED will degrade really fast (and/or outright melt your 3D printed case).

Here is what I did to run a 70.2 in a plastic case.. 1A is not a lot of power so you do not need too much cooling. Use a heat sink and make sure nothing touches the 3D printed plastic with its low softening point. You will need airflow to extract heat out of the plastic if you plan on running the light for a long time since the heat builds with no way to escape.

To run it on full power you will need good direct thermal patch cooper MCPCB (star) and heatsink about 250gr.

The technical data are 6V 5A or 12V 2.5A. The XHP70.2 normally has 30W power. There are dedicated drivers available for it.

It is a quite efficient and bright led but as others already mentioned it needs a big heatsink.

Welcome to BLF sebastien_t :sunglasses:
Can you show us some pics of your driver and all your parts you plan on using ?
This will help us give you suggestions. :wink:

I hope you enjoy your stay, sebastien_t!

You need to use an MCPCB.
If you didn’t buy the LED already, you can avoid having to do an oven reflow by buying one that is pre-mounted, like this:

Then you just screw it onto a large heatsink with some thermal paste.