David,

Currently I am designing a new product which will use surface mount
components. Some of the linear voltage regulators used in this product
must supply a high current, and due to the large voltage drop across
them, it is necessary to heat sink them

We will be using the conductive surface of the PCB to provide this
heatsinking ability. By using the specified junction-case thermal
resistance of the voltage regulator and the specified case-ambient
thermal resistance of the PCB copper area, we will be sure our design is
robust.

Specifically, what I need to know is how to calculate the thermal
resistance of a certain PCB copper area, which I expect will be
dependant on the copper surface area, copper thickness, shape, whether
there is solder resist placed over the copper surface (where the surface
doesn't touch the metal of the voltage regulator), etc.

Any ideas as to what other specifications or reference books I can point
him at.


Regards,

David Taylor.
Chief Engineer
East Coast Printed Circuits
Dee Why N.S.W. Australia.

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