The danger of cheap non-temperature regulated soldering irons is that the cheap soldering irons go from too hot when starting to solder the joint to too cold from cheap tip materials with poor thermal conductivity. This leads to joints that have cavities and are improperly flowed, especially a problem for radio frequency or high speed digital circuits. Cheap soldering irons lead the newbie or even the experienced user to burn parts, lift PCB traces off the board and get so hot they are very uncomfortable to hold. Often the cheap irons are not grounded, so you could be zapping the circuit you’re trying to fix.
For the beginner, there are $40 soldering stations available from reputable online sources–checkout the reviews or YouTube to get a better sense. For me as a life-long electronics guy, I went straight to Weller (Hakko is good, too). I strongly recommend the Weller WES51 temperature controlled soldering iron for those who outgrow the use of the local maker-space or borrowing a friend’s iron. It costs just under $100, and like many things in life if you waste your money on an inferior product, now you have that much less money to buy the proper tool. I emphasize the temperature controlled part because even the Weller WLC100 does not have closed-loop temperature control.
Many things we solder these days are of small size and delicate, so you don’t want to just guess at the temperature you’re using. The Weller WES51 is rated at maintaining the tip +/- 6 degrees Celsius from the setting. The WES51 has an analog temperature dial. This is the model I have, and it’s close enough for me, even with surface mount components, as you see in the photo below of me modifying an EF Johnson 8640 900MHz radio for use in the amateur 33cm band. It’s hard to see due to the focus, but the new white cap at the center of the picture soldered in like a dream, using the optional 1/32” tip.
If you have a bit more money, for about 50% more cost you get the digital temperature readout Weller WESD51. I have used that at various labs, but I find I prefer the analog WES51 because
- I can change the temperature setting more quickly on the WES51 (just spin a dial vs. push and hold button on the WESD51)
- I don’t need a perfect temperature setting or to lock the setting (perhaps something a factory assembly line would do). I just need +/- 15 deg. C or so, and in my opinion I can do that on the analog WES51
I have used the WES51 and WESD51 for projects, some of which individually where tens of thousands of dollars were on the line if something didn’t work (field expedition). In my teens I repaired in total several million dollars worth of equipment using these irons, so the payback for me was immense on this tool. For something like soldering, you just shouldn’t go cheap (or on tires for your car).