MCPCB Mounting/ adhesive help

pavithra_uk · Jan 8, 2012

I need to mount following LEDS (With Star MCPCB) to Aluminum Heat sink.

INDUS STAR (3 XP-G planing to drive @ 700mA)
XML 1 LED
P7

I have following mounting options:

1. Screw MCPCB to heat sink and use generic thermal paste
2. Use Adhesive thermal pad (Thermal conductivity = 2 w/mk)
3. Use Thermally conductive RTV Siliconne adhesive (Thermal conductivity = 2 w/mk)

Is it enough to use thermal pad or siliconne adhesive for mounting above LEDs ? or should I use first method ?

P.S
I already have Adhesive thermal pads and siliconne adhesive.

Microa · Jan 8, 2012

You should use the first method, many branded thermal paste has the thermal conductivity >3.8W/MK.

MikeAusC · Jan 8, 2012

The best thermal compounds have conductivity one-twentieth that of aluminium - so you should maximise metal-to-metal contact.

Lap the star and heatsink to mate perfectly using 200 then 800 emery paper.

Then the difference in temperature-drop between the best and the worst compound will be trivial.

pavithra_uk · Jan 8, 2012

USe adhesive or pad not enough ?

AnAppleSnail · Jan 8, 2012

pavithra_uk said:
USe adhesive or pad not enough ?

The thermal conductive pads are mainly for rough parts or surfaces with voltage differences. They aren't as good conductors as thermal paste. Neither are nearly as good as touching metal.

kuksul08 · Jan 8, 2012

I would definitely suggest using thermal paste with screws. Computer parts are often held together this way, and the screws are spring loaded.

That being said, I've used the Fujik (DX) thermal glue for a long time as the sole method of attachment without any issues.

MCPCB Mounting/ adhesive help

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