# High power LED on aluminium core PCB

I'm working with a high power LED(40W heat dissipation) on a single layer aluminium core PCB.To calculate the required heatsink it did the following:

$P = 40W$

$Rjc = 0.6K/W$ (datasheet)

$Rcpcb = 0.77K/W$ case to PCB. This is the thermal resistance of the isolation layer(MSC TC-Lam 1.3, 100µm)

$dT = (Rjc + Rcpcb) * P = ~55K$

In summer $(Ta = 45°C)$ this would require a heatsink with $(Tjmax - dT - Ta)/P = (110 - 55 - 45) / 40 = 0,25K/W$ which is hard to achieve without forced air flow(not allowed in the environment) The only parameter I can change is Rcpcb.

Question: The manufacturer can mill through the isolation layer, but is there a way to connect(solder) the thermal pad directly to the aluminium core? Are there any other ways to get the heat away?

• Edit: VERY low volume production! Maybe only a single prototype. – 1uk3 Sep 15 '17 at 7:40
• Copper core PCB? – Brian Drummond Sep 15 '17 at 8:47
• Can you give the LED datasheet? I'd like to see the mechanical dimensions... – peufeu Sep 15 '17 at 14:25
• Datasheet: ledengin.com/files/products/LZP/LZP-00UB00.pdf (I can't use the provided star MCPCB because of shape/size) Copper core is quite expensive for low volume – 1uk3 Sep 16 '17 at 20:11