Aaah, this is really not a good beginner's guide to soldering! Cranking up to max temperature might work a lot of the time but runs the risk of frying ICs and causing PCB traces to come off. Also using a wet sponge can cause the tips to rust. It's much better to clean them with a brass "sponge" leaving the tip tinned to protect it. Finally the real key to easy soldering is solder flux (and leaded solder if you're allowed).
A wet sponge doesn't cause rust, it's occasionally blamed for cracking plating when you use a high temperature.
If you use a moderate temperature (650°F/340°C) it's a gentler way to clean flux residue off the tip.
Brass wool I reserve for scrubbing oxidation off the tip, but this eventually wears through the plating so I don't do this often.
Leaded solder is both toxic and completely unnecessary for hobbyist use. I like SAC305 but SN99.7 works well too—the key is a good quality flux core.
No-clean flux is convenient but if you do want to clean it, it's gummy and makes a mess. "Yes-clean" flux leaves conductive residue so it must be cleaned, but it is easier to clean.
As far as temperature goes, the better your iron is at transferring heat, the lower the tip temperature you can use, which improves tip life and, as you mention, reduces the chance of part damage.
I am a lead dev on an open-source hardware project (PhobGCC) and I've seen damage caused by bad soldering irons time and time again. Don't cheap out. I recommend a Weller WE1010.
Seconding this. Have been using the same JBC tips for 4 years with great success.
When using the brass wool, I tend to lightly rest the tip in a clean area. Maybe sometimes I will rotate it a few times, but I never use pressure or make wiping or scrubbing motions. I'm not sure if it really matters though (ie. how do the hardness of the tip plating and the brass compare?).
Sponges - if you have a decent iron, you should be using a clean, damp-not-wet, sulfur-free, cellulose sponge. This means: buy the type sold for use with a soldering iron, squeeze the water out of it after wetting it, and switch to a fresh one when it gets cruddy. I have never had an issue.
Flux - hobbyists either try to use 50-year-old parts with totally oxidized plating and no flux, or they use too much flux. New parts should not need more flux than you have in your flux-core solder or in your paste.
The next thing that happens after people discover flux is that they want to clean it off, and 99% of the time, hobbyists should not be cleaning flux. If you cannot measure the reason for cleaning your board, leave it alone. The manufacturers will tell you that modern RA and RMA type fluxes do not require cleaning for "most applications" - and "most applications" almost certainly means you.
No-clean flux should be called "never-clean" for the reason you outline. You shouldn't try to clean it, and it will never get as clean as you'd like if you do. I like no-clean for stuff I'm going to show to other people. You will almost certainly use no-clean in production if you go to production.
Water-clean is lovely stuff but it's very unforgiving. It will corrode if not cleaned, and you have to plan to wash your board by using sealed parts or adding water-sensitive parts afterward. You have to be careful with tip temperature too or it will destroy your tips. I have a spool of 63/37 water-clean I've used maybe twice - the boards sparkled but it was just too much trouble.
"Yes-clean" flux has absolutely been the cause of controller malfunctions due to its conductivity for makers of my controller project. It needs to be removed.
Could be so, and it can depend on the flux and the processing, but it's almost never the flux. From a 10,000 ft look at your project, I wouldn't expect it to need the high isolation or high impedances that would drive a serious cleanliness spec. You could have other issues that a temperature and humidity test would uncover with no-clean, for example. We can discuss them if you'd like.
Depends on what you mean by "yes-clean" though - "water-clean" OA flux must absolutely be cleaned - it can start to corrode overnight even.
The "yes-clean" flux I'm talking about is high-solids rosin flux that leaves a conductive residue. The conductivity can definitely cause a circuit to fail.
Makers come to our discord chat, asking why their builds aren't working and post a pictures.
I suggest cleaning the flux off, and they start functioning.
As an aside:
My current solder brand (Chip Quik) has a "no-clean water-soluble" flux that I'm curious about. Surely that's not going to be as corrosive as the flux you're talking about. (I probably wouldn't use it myself because it needs 140°F water to dissolve)
Without answering how much conductivity you had, how it caused the circuit to fail, what part of your circuit failed, and in what way, you haven't really narrowed it down to the flux, even if cleaning helped. There are a number of more likely root causes of the kind of issue you describe. I can make time for going into that if you're interested.
"No-clean water soluble" is news to me. Don't know if I'd trust that in a humid environment.
My budget is more in the $20 - $25 range. Cheap adjustable-temp soldering irons are available for under $4 [0], surely there is some middle ground between those irons and the $115 unit you suggest?
The problem is that bad soldering irons are infuriating. I started with super cheap one and it didn't work at all. I upgraded to $20 adjustable one that worked for a while but is inconsistent. I thought it was my bad technique until this thread but sounds like it is the quality.
The $25 Pinecil sounds good and is probably your best option. I may go for soldering station since I can afford it.
Thanks. The Pinecil comes out to $60 with the $35 shipping to my corner of the world. )) Other than that it looks terrific. If I'm ever in the US or Europe and I can receive mail, I'll try to order one.
Yes, I actually do have an iron similar to the one I posted. I like it, but I typically leave it at its highest temperature (which, as you state, just means full power).
I use leaded solder and have for years but I’d love to replace it with something less toxic. The trouble is that lead-free solders I’ve tried require high temp and flow very differently from leaded solder.
Does SAC305 (for example) flow and cool in a similar way to good old 63/37?
340c would be a pretty high setting for most casual use... Good chance you'll ruin a board like that. Modern solder is pretty easy to work with around 250c and the risk of overheating the board is a lot lower. Unless you're soldering giant connectors there's no reason to tell a beginner to crank it over 300c.
No mention of solder suckers or tinning either. Mention of how to reflow connections using a heat gun is a simpler alternative to an iron for fixing some problems too.
