Since this thread seems to be still alive, I'll add my $0.02: The degrees rise figure is the typically body temperature, not the temperature of the leads at the board, which be much cooler. Note that on page 10 of the datasheet you linked it shows recommended lead termination bending, effectively offseting the resistor off of the board by 8mm. I was trying to find a good thermal camera picture to show this, the closest was at https://www.youtube.com/watch?v=3D-e-qIjttIIY&t=3D134s , at = 1:57 in, there is a thermal camera pic which shows the leads basically being cold, while the resistor body itself being hot. I wouldn't be surprised to find that when mounted as recommended, the units will not desolder from the board. Personally I try to run things as cool as possible, if I was engineering for 5W dissipation, I would use at minimum a 7.5W if not a 10W resistor. Unless I was *very* sure of the engineering. Also, be mindful that the rating is at 40*C ambient *around the resistor*. If you don't provide adequate airflow around the resistor to eliminate a thermal air hotspot around the resistor, you're actually going to have an even lower rating. On Tue, Jan 16, 2018 at 12:15 PM, Bob Blick wrote: > What techniques are most effective in keeping power resistors from > desoldering themselves from PC boards? I'm thinking there are basically > three methods: > > 1. Don't use them at anywhere near their rated power. That's fine except > if you need to tolerate the occasional overload condition. > > 2. Pour extra copper on and around the pads. > > 3. Use as much length of the wire leads as possible. That could really > decrease the rigidity of the mounting. > > 4. ?? > > Attached is a picture of the temperature chart. I'm using the 5 watt AC05= .. > Note the 260 degree K rise at rated power. > > If I fold or clinch the leads it will keep the resistor from falling out, > but the solder is going to melt. I imagine that won't give the greatest > electrical connection :) > > Datasheet here: > > http://www.vishay.com/docs/28730/acac-at.pdf > > Thanks, > > Bob > -- > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > > --=20 *Forrest Christian* *CEO**, PacketFlux Technologies, Inc.* Tel: 406-449-3345 | Address: 3577 Countryside Road, Helena, MT 59602 forrestc@imach.com | http://www.packetflux.com --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .