On Thu, Sep 27, 2007 at 09:44:36AM -0600, John Doty wrote: > > On Sep 27, 2007, at 9:28 AM, Randall Nortman wrote: > > > I need to make an exposed area of copper (no soldermask), to act as a > > heat radiator. > > Why no soldermask? I'll bet its infrared emissivity is better than > copper's, making a better radiator. In space, the radiator tape we > use has a thin layer of teflon over the metal for this reason.
As sayeth the datasheet, so do-eth the designer! In fact, any exposed copper is going to be covered in shiny silver stuff (tin/lead/silver, depending on process) during board fab. Would that not have pretty darned good emissivity? It would certainly have better conductivity, which is important when you're not designing for vacuum. I suspect that most of my cooling is going to be from conduction to air and subsequent convection (natural convection; no fan), though a big chunk of it will be radiation. (I did say "heat radiator" in my post -- probably "heat sink" would have been more appropriate.) -- Randall _______________________________________________ geda-user mailing list [email protected] http://www.seul.org/cgi-bin/mailman/listinfo/geda-user
