For FR4 - resin/glass and mask, not very efficient ~ .5 w/Mk or less.
Some materials designed for thermal management are ~ .7 w/Mk but this is
still fairly low.  Add a via farm plot and conductive fillers and you
can see a 10X improvement to the base materials properties.  Depending
on the heat levels of the device and the geometry of the PCB the via
dissipation technique can be problematic.

Jeffrey Bush
Director, Quality Assurance and Technical Support
VERMONT CIRCUITS INCORPORATED 
           76 Technology Drive - POB 1890 
              Brattleboro, Vermont 05302
                Voice - 802.257.4571 ext 37 
                    Fax - 802.257.0011
                       <http://www.vtcircuits.com/> 
                           

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Selva Suganthi
Sent: Monday, January 09, 2006 6:24 AM
To: [log in to unmask]
Subject: [TN] Thermal dissipation factor

Dear All,

what is the Thermal dissipation factor for  pcb(with mask) ?

Thanks and Regards
Suganthi

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