Re: Soldering Iron Temperature

John - KK4ITX

Probably all of the answers are correct.

I have found that soldering irons and their reported temperatures only at best estimate the tip temperature. While it’s true various solders melt at a specific temperature your iron may read hotter or cooler, so one needs to experiment with their own unit because one temperature reading might be the correct one but the actual temperature at the tip will probably be different..... so we need to apply the commonly accepted approach and heat the pad and lead a bit prior to applying the solder.  The objective is to surround the lead by flowing solder around it and into the hole leaving a shiny bump of solder behind.

I have found that the cleaning of both the board and the leads with alcohol (not Evan Williams) to remove the crap from the manufacturer is quite helpful in producing a good looking joint.

A too low temperature will actually overheat a component because everything has to then be heated to the melting point of whatever solder is used.  A higher temperature allows for extreme heat quickly at the point of contact between the tip and the joints and the heat dissipates before it gets to the component.  Sensitive components may require a heat sink between it and the point of soldering.

Practice is very educational and resistors by the hundreds are quite cheap, pick up some PCB project boards and play with your iron and components and make a mess..... in a short time you will know how “your” iron, solder and technique make a good looking soldering job, the temperature reading helps but only after you’ve identified all of the quirks of your equipment.  3 or 4 dollars in parts and solder plus an hour or so should do it.

By the way, there are “practice” boards for SMT parts also and those components are really cheap...... push yourself a little it’s much easier than you think.

Good luck,

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On Nov 21, 2020, at 19:49, Nate Bargmann <n0nb@...> wrote:

I guess I am the outlier, I use 640-645 typically unless it's a large
ground pad or joint and then I'll run it up past 700.  I like the lower
temperature as it doesn't burn the tip.  But maybe that was the cheap
Radio Shack iron I had in the '80s that did that...

72, Nate


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