Need Help On SST-90 (Bare Emitter) and DK-105T Development Kit

zackz

Newly Enlightened
Joined
Sep 7, 2013
Messages
1
Hi all

I am new to setting up LEDs, thus I have bought a development kit, DK-105T for my SST-90. However, I am unsure of how to mount them on the development kit after soldering the leads on the back of the bare LED.
Is there anyone with experience or any idea on how to work on the development kit?
Is it safe if I were to just mount the bare LED with soldered lead using Arctic MX-4 Thermal Compound onto the metal face of the DK-105 development kit?

Thanks in advance.
DK-105T-1.JPG
Pi
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DIWdiver

Flashlight Enthusiast
Joined
Jan 27, 2010
Messages
2,725
Location
Connecticut, USA
No, that's not what you want to do. Firstly, MX-4 is a non-hardening paste, not a glue, so it wouldn't mount the LED well anyway. But the real reason is that the thermal conductivity is way too low. It's 8.5 W/m-K, where aluminum is about 200. Thermal compounds are applied in as thin a layer as possible to displace air, which is around 0.03 W/m-K.

I would try to get the LED onto a star, which could then be mounted to the heatsink. Barring that, maybe you could get a piece of aluminum (or better yet, copper) that would lay on the back of the LED between the wires, and raise it off the heatsink enough that the wires would not touch the heatsink.

Just a rough estimate of 7mm square area, 2mm thick, and 30W of heat, you would have 140 degrees C drop across the MX-4, vs about 6 degrees for aluminum, or about 3 for copper.

Even a fairly thick film of 0.1mm would drop 7 degrees, way better than 0.01mm of air, which would be around 200 degrees.
 
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