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Comment by sdcfgy | Hacker News Reader

Find some trash and practice removing parts and soldering them back on first.

Not mentioned here yet but the majority of early soldering attempt failures mostly come from crap irons and crap solder not human issues. You need a decent quality temperature controlled iron and decent quality solder, preferably flux cored if you're doing repairs. Here, I have a second hand Metcal iron which cost less than the much recommended Hakko irons and is orders of magnitude better. Solder, I just use thin 60/40 multicore. Avoid the lead free initially until you have some practice.

Watch soldering videos on youtube. Check the comments to make sure people aren't slating their technique.

Removing some parts, like DIP packages really does need specialist irons with vacuum pumps built in to not mangle them. Desolder braid and solder suckers are absolutely no good for that sort of stuff and tend to lift pads.

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Metcal’s are amazing!

They use a high mghz signal to measure the tip temperature using impedance measurements IIRC. Then they control the tip temperature using a feedback control loop. Humans suck in comparison for heat control.

Trying to use a Hakko afterwards will make you want to curse in my humble opinion.

> They use a high mghz signal to measure the tip temperature using impedance measurements IIRC. Then they control the tip temperature using a feedback control loop.

That's not how Metcal fixed temp induction soldering irons work. They don't have a control loop, which is what makes them so much better than other soldering irons.

They exploit the Curie temperature [1] of some alloys, in which the metal loses its inductive properties when it hits a certain temperature. A Metcal power supply pumps a simple 13.56 Mhz signal into the tip which heats it up and when it reaches its Curie temperature, it just stops heating. Since the signal is constant, whenever the temperature of the tip drops it just heats back up without any PID loop. The downside is that you have to switch tips (alloys) with a pair of pliers to change temperatures, but the upside is that there is no control loop delay.

It's also why their station are so reliable. There's basically no "modern" electronics in them and the worst you have to do to fix them is replace an electrolytic capacitor. I've got a power supply manufactured in the late 90s that's still as good as new and like you said, going back to a Hakko or any other soldering iron is downright painful.

(Side note to anyone who cares: when the patents expired, a couple of Metcal engineers left to form Thermaltronics, which sells cheaper stations and Metcal-compatible tips)

[1] https://en.wikipedia.org/wiki/Curie_temperature

Thanks for filling in how the metcal's work! The 13.56 mghz signal made me figure an impedance measurement. Though as you say that explains why metcals are so bulletproof.

Side note: I found Thermaltronics stations to not be much cheaper than Metcal ones. At least for the lower end stations. Gotta love capitalism.

Correct, half the skill in soldering is picking a good iron with good tips. After that it's the solder.

Only at the very end does your own soldering skill matter.

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