Hi Roland-

It can vary a bunch, depending on how much metal is in the pcb and how that metal is arranged.  Most designs for thermal transfer depend on thermal vias to do most of the work.  You can get fast ballpark answers with "back of the envelope" thermal transfer coefficients for PCB laminate, or even better, grab a board that's similar and just measure the performance.  If you need answers within a few degrees, then the thermal analysis can get considerably more complex.

Wayne Thayer

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Roland Jaquet
Sent: Tuesday, April 22, 2014 4:06 AM
To: [log in to unmask]
Subject: [TN] Seeking : Thermal Resistance onto PCB surface

Dear Technetters,

 

I am confronted to an unusual challenge I am not able to solve. Can someone help, if you please

 

We are seeking : Thermal Resistance onto PCB surface (14 layers) standard approx.. 1.8 mm thick

 

Between 

 

External Cu of approximately 30 to 35 metric microns covered with ENIG

 

And

 

Aluminum "Alodinized" 1200 or  Anodized in black 

 

Thank you for your help

 

 

Meilleures salutations

Best Regards

Roland

 



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