Been assembling some MK130s and noticed that max. 40W soldering iron warning, which probably is in assembly instructions of every kit.
That warning is somewhat misguiding.
It’s not power above some arbitrary limit which is bad, but too high temperature.
Properly set temperature controlled soldering station won’t do any harm, no matter if its 100W one.
But I could easily see some sub-40W cheap crappy “temperature somewhere between melting point of solder and copper” soldering irons burning traces off the PCB.
Some worst ones can make their tips start turning reddish, which would no doubt destroy circuit board almost instantly after touching.
Besides too high temperature burning flux fast and “in a way” solder itself, making whole soldering process pain in the butt.
Sure low heating power makes it harder to cause heat damage to small traces, but it also makes it hard to get good joints when soldering component to bigger copper area.
If that max 40W has to be there at least adding max temperature would be good.
(and really more important)