Learning to solder

[ijor]

Thank you so much for all the comments and suggestions. They are indeed extremely helpful and encouraging. The actual result for this experiment still remains to be seen. My talent for breaking things with by bare hands is legendary, you could image what I could break with a soldering iron

About the gloves and the lead. It was a misunderstanding. I don't care (too much) about the lead. The reason for the gloves was for avoiding the sticky oily flux in my hands. When it happened to me I thought this was a pretty common issue. But you say it should be not, and that there is normally no need to use flux anyway for typical THT stuff.

Ok, but in some cases you do use flux, right? Let's say to desolder a chip or a socket in an old and may be even rusty Atari. Still you don't get your hands oily? May be I was over reacting a little bit about that, because I'm hyper sensitive to oil and grease on my hands.

I've been mostly using circuitworks CW8300 flux pen simply because I'm getting tired of having sticky fingers with every other flux.

Ah, so there is an issue of the sticky fingers with some types of flux! That's why I was considering the gloves. Will get one of those magic pens. Thanks for the tip.

I use a head-mounted loupe. Cheap and cheerful, preserves stereo vision and with interchangeable lenses to let you find what works.

Seems very affordable. Will try one. Thanks for this tip as well.

The only thing I can add that others haven't already said, is understanding the concept of heat transfer.

Yeah. I read a lot about the heat transfer concept. But one thing is to understand it with your mind. Another is with your hands

Make sure you use a good soldering station, at least 65 watts for THC (Through Hole Components) from a reputable brand

I purchased a decent "generic" T12 station. I understand it's at the "mechanic" level or so, if you know the brand. I got it very cheap. Next step I need to decide if going to a better T12 like Quick or Ksger, or to a top brand.

I purchased good 60/40 solder. Are the top brands really worth? Kester is much more expensive! Also difficult to know which type to get. There are so many variations

[ijor]

Btw, I was checking so many videos on the topic that I've found about this state of the art technique for de soldering and removing pins extremely quick and without any brad or wick. Probably designed with AI:

[exxos]

Yeah I do that trick. Also for clearing holes of solder sometimes.

Alternatively you can trap boards in a rubber jaw vice and heat up and pull pins with pliers while heating the solder. Then you don't have to fight the plastic on larger header strips.

Or put a huge blob of solder across all the pins at once and the strip often just drops out.. Heat the blob of solder after and flip it upside down and tap and the blob falls off the PCB..

[dml]

Repeating a few themes here but from my own perspective/experience (I was not trained but have been hobby-soldering a very long time),

On solder:

I find solder varies quite a bit between manufacturers even for the same 'mix', especially newer stuff.

I went through various rolls and measured what temp the iron agrees they melt and flow & scribbled a note on the drum. Most of the lead based solders seem to be around 185-225. They can melt below that but some of them don't begin to flow properly until a good bit higher (Some mixes will be a lot higher, around 300'c).

Some will flow easily and leave a shiny joint - others more dull or crystalline. It is worth trying a few different ones and practicing the same scrap board until you notice differences in the finished joints. If you don't notice any difference then at least you got in some extra practice

I still have some very (!) old rolls of solder which seem to work better than newer ones and I try not to waste it


On flux:

I don't use flux for thru-hole with clean components and clean pads because as you noted it does make a mess and needs cleaning - some are very hard to clean and cleaning with the 'wrong' solvent can make things even worse. I found some which only clean with WD40. (they all seem to have a different 'wrong' solvent e.g. some turn to chalky, degraded crust if you use acetone).

Flux is mostly not needed for this kind of work if the solder is flux-cored. Flux starts to get very useful for thru-hole when surfaces are slightly oxidised or when retouching very oxidised joints - and when removing solder (adding fresh solder makes the old stuff behave better). It is also good for activating desoldering braid and making it absorb solder better at lower heat.

For surfacemount work flux is essential because the spaces between pins is so small that surface tension of the solder under flux is 80% of what is controlling where the solder goes - the flux causes it to attract to pins and repel from the soldermask. Without it the solder just gets everywhere, makes bridges out of everything and exposure to air causes it to crust, wet non-metal surfaces and makes it even worse. Adding flux usually insta-fixes those problems or at least lets you wick it away and try again.

For removing individual bridges from surfacemount pins (without falling back to solder braid & starting again):

- add plenty of flux
- wet the tip of the iron so its shiny, then remove as much of it as possible with a wet sponge
- very quickly slide the iron tip, face down on the board/pins, back and forth onto the fluxed pins with the bridge and surface tension will pull the bridge onto the iron. can take a couple of attempts but it nearly always is enough.

The trick here is to have less solder on the iron than on the pins and the solder will move there to lower tension. the solder tip needs to be very recently wetted/cleaned - if it has time to oxidise and go dull it will not pull any solder to it.

[Maximilian]

About the gloves and the lead. It was a misunderstanding. I don't care (too much) about the lead. The reason for the gloves was for avoiding the sticky oily flux in my hands.

You should not use that much flux that you get a sticky PCB, as said, you mostly need the resin core in the solder itself.
Also make sure to have something like the nano cleaning sponges or chemwick wipes to soak up all of the flux you solved with IPA, otherwise you will get a thin film of flux/rosin on your board, and I really do understand the feeling .

Ok, but in some cases you do use flux, right? Let's say to desolder a chip or a socket in an old and may be even rusty Atari. Still you don't get your hands oily? May be I was over reacting a little bit about that, because I'm hyper sensitive to oil and grease on my hands.

Flux has a few different few jobs to do:
1. Help with oxides before and during soldering, this also improving heat transfer.
2. Help with the flow of solder.

In most cases it is easier to add a little bit of new solder, thus removing oxides and cleaning up the area a bit.

Yeah. I read a lot about the heat transfer concept. But one thing is to understand it with your mind. Another is with your hands

Transfer heat to the pad and the component leg(this does not take a long time), then add solder.

I purchased a decent "generic" T12 station. I understand it's at the "mechanic" level or so, if you know the brand. I got it very cheap. Next step I need to decide if going to a better T12 like Quick or Ksger, or to a top brand.

They are a cheap brand, and the quality differs a lot from product to product.
It should be enough, and if you have a good one, you can look at different options later, like a soldering station where you can change out the soldering pencil to use a smaller or bigger soldering system like the T210/C210 System for micro soldering.
For a lot of those type of soldering stations there are hacks to improve their performance, they mainly use the same PCB and just slap on a different brand sticker, so maybe you can borrow some mods from the no name models.(auto standby is a good one)
Make sure you are comfortable with modding before opening your (mains connected) tools.
You probably have one of the stations that uses an external PSU, then it is quite safe to work on.
If the PSU lives inside the station then please be aware of potential lethal voltages, even for some time after removing the mains plug.

Make sure you get a tip that is appropriate to your soldering job, using a fine tip to solder bulky power wires will not work, using a T12-K Knife or a T12-D52/D4 chisel is better for those things as it has more thermal mass

[rubber_jonnie]

Just to add my two pennies based on many years of hobby soldering:

When you're getting started, don't try and do anything on a PCB you care about. Get scrap boards and or soldering practise kits, and don't be too eager to dive into SMD boards until you're happy with through hole. Whilst SMD work and hot air soldering can be very satisfying, it is also a bit of a black art!!!

On the subject of flux I don't use anything for through hole because I use flux cored solder. Any flux dries relatively solidly and is easily cleaned with IPA.

For SMD work, that is when flux comes into it's own IME for both removal and installation of parts. I tend to use Kingbo RMA218 which was recommended to me and it cleans up very easily with IPA. So at this point all I'd suggest is flux cored solder.

One point which is important for good solder joints is to ensure you heat the via and the component leg at the same time before adding solder as otherwise your results may be inconsistent, and beware large GND and power planes that can suck the heat from your iron.

I tend to use my iron at 370C because that gives a reasonable compromise between heating and dwell time on the component. However it does depend on the tip size as to how the thermal mass of the iron is affected by large planes when soldering. Mine is a TS-101 type and can be run from a 20v laptop PSU or USB C PD and the tips can be changed.

Good luck, you'll find it very satisfying when you get going