Here's a design guide for a product where they suggest building the heatsink into the PCB: http://www.irf.com/technical-info/appnotes/an-1029.pdf A lot of the general recommendations will apply to your situation. I haven't been able to find a pcb/copper thermal calculator though. You may need to experiment. In a previous design I used a 1 square inch area, both sides with plated through holes every 0.1" to heatsink a linear regulator with about 1/2 watt dissipation. It was hot to the touch, but well below 100C. I've heard rules of thumb that surface mount devices can only push 1-2W into the PCB pads, so while this would help, if you are pushing more than a watt or two you really should consider resistor packages meant to dissipate more heat. How much power are you dissipating per resistor? -Adam On Thu, Mar 18, 2010 at 11:44 AM, Mark E. Skeels wrote: > I thought about it........seems like you'd have to try it to see how > much benefit would be derived...... > > Mark Skeels > Engineer > Competition Electronics, Inc. > TEL: 815-874-8001 > FAX: 815-874-8181 > www.competitionelectronics.com > > > M. Adam Davis wrote: >> [SNIP] >> Have you looked at using copper and plated through holes to make PCB >> heat sinks for the resistors? =A0It can make a huge difference. >> >> -Adam >> >> > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > -- = http://chiphacker.com/ - EE Q&A site -- = http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist