It's also a pain to solder/desolder small components to/from. Makes for a very good heat sink. Computer motherboards use these liberally around the switching regulators that power the CPU. The negative end of the filtering caps (you know, the caps that fail and have to be replaced?) usually ends up in one of these via stitched areas. But it's not so bad that I'm going to throw away essentially free computers either... -Adam Douglas Wood wrote: > There's a PCB layout technique called "via stitching" that is > basically a number of regularly spaced plated-through vias (holes) in > the pad's area that connects copper between the two sides (assuming a > double-side PCB; it was also work multiple layer boards). During board > assembly, the via are filled with paste (you could also hand solder > the vias, although I not sure if wave soldering would fill all of the > vias). This adds additional metal to the heat sink. I use this method > on all of my voltage regulators and power transistors (TO-220, > TO-252/D-PAK, TO-263, SOT-23, etc.). If you'd like to see a photo of > what this looks like, please let me know. > > Douglas Wood > > ----- Original Message ----- From: "Peter L. Peres" > To: "Microcontroller discussion list - Public." > Sent: Wednesday, January 19, 2005 3:04 PM > Subject: Re: [EE] Copper Heat Sink > > >> >> >> On Tue, 18 Jan 2005, Lawrence Lile wrote: >> >>> Thanks Russel, This paper says that 1.2 watts is the practical >>> limit, and that above 0.8 watts PCB cooling area starts going up >>> rapidly. Anything over a watt (as someone else said) makes one get >>> nervous. This explains why my attempt at cooling a 2 watt resistor >>> one time, by adding some PCB copper area under it, wasn't very >>> effective. I tried it just for grins, but no calculations. >> >> >> You can cool it by mounting it on 'standoff' tubes (brass usually). >> These can be finned at the top. >> >> There is also a 'mushroom' style heatsink that can be screwed >> directly onto a TO220 etc mounting hole. I saw it in some equipment >> and have been looking for something like this ever since. >> >> Another trick is to mount the board with the parts flush with the >> bottom (metal) plate of the casing, with some thermal compound for >> contact. >> >> Peter >> -- >> http://www.piclist.com PIC/SX FAQ & list archive >> View/change your membership options at >> http://mailman.mit.edu/mailman/listinfo/piclist >> > > -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist