A dense grid of vias can be used as heat pipes to land(s) the other side of the board. I think I read a usage note from Burr Brown for one of its 5DDPAK pkg amplifiers (or perhaps it was another mfgs app note) a few years ago that described the use of vias for increasing the effective area (heat is absorbed by a copper land proprotional to the thermal difference between the trasmitting (IC) and receiving (connected copper land) substrates. As was said in another post, a secondary heat sink can be mounted on the other side of the board, either for direct conductive release to an enclosure or similar, or to an active device such as a peltier cooler and/or fan/heatsink... For more detailed information regarding thermal transfer, one might consult a second or third year Thermodynamics text book. Unfortunately, my present job doesn't afford me anything more than time to write what is above.
I've used grids with 10-15 mil vias and spacings as small as 50 mils, but the area is of course usable only for heat sinking. aj >-----Original Message----- >From: [EMAIL PROTECTED] >[mailto:[EMAIL PROTECTED] On Behalf Of Linden >Sent: Wednesday, July 26, 2006 8:25 PM >To: [email protected] >Subject: [PEDA] Thermal Impedance of Copper Areas > >Greetings All, > >Can anyone direct me to information on the relationship >between copper area and thermal impedance for SMD devices? > >I have a D2PAK MOSFET that has a Thermal impedance of 40K/W >junction to ambient when mounted with a minimum of copper on >the mounting tab.. >I'd like to reduce this figure by adding a copper area >(polygon or fill) to the mounting tab. >The problem is I don't have a feel for how much copper is >needed for a particular reduction in thermal impedance. > > >Thanks in advance, > >Linden Doyle > > > > > > >____________________________________________________________ >You are subscribed to the PEDA discussion forum > >To Post messages: >mailto:[email protected] > >Unsubscribe and Other Options: >http://techservinc.com/mailman/listinfo/peda_techservinc.com > >Browse or Search Old Archives (2001-2004): >http://www.mail-archive.com/[email protected] > >Browse or Search Current Archives (2004-Current): >http://www.mail-archive.com/[email protected] > > This e-mail transmission and its attachments may contain information from Avtron Manufacturing, Inc. that is proprietary, privileged and/or confidential and is intended exclusively for the person(s) to whom it is addressed. Any use, copying, retention or disclosure by any person other than the intended recipient or the intended recipient's designees is strictly prohibited. If you have received this message in error, please notify the sender immediately by return e-mail and delete all copies. ____________________________________________________________ You are subscribed to the PEDA discussion forum To Post messages: mailto:[email protected] Unsubscribe and Other Options: http://techservinc.com/mailman/listinfo/peda_techservinc.com Browse or Search Old Archives (2001-2004): http://www.mail-archive.com/[email protected] Browse or Search Current Archives (2004-Current): http://www.mail-archive.com/[email protected]
