One approach is a mechanical rather than solder connection to the resistor lead. 1. Tack or spot weld 2. Crimp 3. Screw terminal The resistor wattage rating and corresponding temperature rise curves describe what you can do with the resistor before the resistor fails (burst into flames). The actual resistor wattage selection is then a function of the system design. The 5 watt resistor is really good for 5 watts if the system usage has the resistor body and leads in contact with surfaces that can withstand the resulting temperatures. I am currently repairing a Ford F-250 overhead display console which has 1206 resistors that run so hot that they melt the solder and fall off the board. -----Original Message----- From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On Behalf Of David C Brown Sent: Tuesday, January 16, 2018 15:54 To: Microcontroller discussion list - Public. Subject: Re: [EE] Resistor temperature rise High melting point solder? On Tuesday, 16 January 2018, Bob Blick wrote: > What techniques are most effective in keeping power resistors from=20 > desoldering themselves from PC boards? I'm thinking there are=20 > basically three methods: > > 1. Don't use them at anywhere near their rated power. That's fine=20 > 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=20 > 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=20 > out, but the solder is going to melt. I imagine that won't give the=20 > greatest electrical connection :) > > Datasheet here: > > http://www.vishay.com/docs/28730/acac-at.pdf > > Thanks, > > Bob -- __________________________________________ David C Brown 43 Bings Road Whaley Bridge High Peak Phone: 01663 733236 Derbyshire eMail: dcb.home@gmail.com SK23 7ND web: www.bings-knowle.co.uk/dcb *Sent from my etch-a-sketch* --=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 --=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 .