At 08:47 AM 3/18/2010, Mark E. Skeels wrote: >But my question is, will 105 deg C max be good long term for the FR4 pcb? What solder are you using? Is the PCB subject to high vibration or sudden high-G drops? My experience is that temperatures up to about 90C are fine. Question: do you have enough room on the PCB that you can do copper floods on each of the resistor leads? More copper area that each of the leads is attached to equals lower resistor temperature. Holes under the resistors may actually increase the temperature - a closed box has little air circulation and air is a better thermal insulator than the FR4 substrate. dwayne -- Dwayne Reid Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax www.trinity-electronics.com Custom Electronics Design and Manufacturing -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist