WheelchairDriver

Member of my model plane club struggling to make any soldered joint "stick"... He is building a quadcopter and has lots of small wires to solder to a buch of tiny solder pads.

He brought his iron, solder and flux that he is using with him. And I watched...
1. His new circuit board - a flight controller board - was already abused! All the solder pads were blackened ad oxydised with the remains of dirty burned flux on them. He thought he could solder over this...
2. His iron was black, not timed and not thermostatic. As such was way too hot and getting ever hotter... And was useless.
3. His no name flux was no good. I tried it. It did nothing but burn and turn black. It didnt appear to work at all even on clean copper and my ow iron.
4. His solder... Cheap chinese roll, supposedly flux cored but with wjat I dont know. I couldnt make that stuff run at all. It went into balls and fell off!

FIX
1. I threw away his iron. Not thermostatic, impossible to have it at the correct temperature and so impossible to keep properly tinned and shiny. It just burns off the flux and the tip oxidises. Even if you turn it off when not soldering. Instead he used mine.
I then spent 20 mins explaining WHY it must be shiny clean, tinned and looking good at ALL TIMES. And how to keep it this way. Mine is set to 340 degrees C and this changes depending on what you are soldering.
It is always properly tinned and KEPT THIS WAY! Has a shiny coat of solder on its tip always. If yours does not, you simply cannot solder anything efficienty. So: How to TIN it. How to KEEP IT TINNED. Below.

TINNING THE IRON
If your iron tip is not already tinned, do a) below. If it now has a solder coat over all of its surface then throw it away and buy a new tip. These are cheap. Get a pack of 5 or 10.
BUY a ball of brass wire in some type of holder. Ebay or Amazon. Drag the hot iron (at around 360 or so C) through the brass wool. Then dip the tip in FLUX and tin (melt some solder onto the tip) and it will stick and be shiny. Do this iron tinning with LEAD FREE solder. This requires a little higher temperature than lead based solder. Why LEAD FREE? The iron will stay tinned better as it thakes ore heat to melt this. Dont use lead free on the solder job, just on the iron!
Use this brass wool 10 times a minute by dragging the irons tip through it. And reaplying flux/solder in order to keep the iron shiny. Switch it off, allow to cool or the flux will burn away (you see smoke) and the iron will oxidise if not. When the tip isnt clean, tinned and shiny you CANNOT solder things properly. If its not possible to get a shiny tinned tip, replace it. Lower temperature to 330 to 350 after you tin the iron and use lead based 60/40 quality branded cored solder like kester or whatever.

FLUX
For circuit boards, components, etc a fibreglass "pen" is great for de-oxidising the copper or brass on a circuit board. Fine abrasives, scotchbright cloth, or scraping with a blade all expose clean non oxidised metal. You must do this to every surface you intend the solder to stick to unless its all brand new in sealed bags. Solder will not stick to or run to cover the surface if any oxides are present. So CLEAN IT FIRST!!!
You need to add FLUX (of the right type) to all the surfaces you intend to heat up. Or solder. When soldering the flux serves several purposes.
1. It can remove oxides as it is heated up. Which is why having some in the solder is NOT ADEQUATE. That arrives far too late by which time warming up the joint has already caused it to oxydise. Cored solder is a help, its not adequate on its own.
SOME flux type is mildly acidic. It cleans off mildly oxidised surfaces. But this should not be used in electonics as everything will go green and corrode later. We need mild fluxes. Like Rosin or non agressive types. Most cheap flux is crap. I use an old traditional one called FLUXITE which is hard to find today for most jobs. It works great on practically everything. But a big pot... I also use some liquid stuff from a syringe that is suposed to be "no clean" for surface mount stuff. But thats not essential.
2. It stops the solder or the iron oxidising and stay shiny!
3. It causes the solder to flow. As in it will cover the full metal surfaces, soak by capilliary attraction into wires, and cause the joint to look good, flow into position naturally.
4. It helps the iron transfer heat to the joint.

SOLDERING
SET IRON temperature to suit job. big heavy connectors etc may need to be 400.
Tiny circuit boards and small wires may only need 300 or 320C.
Remember that the hotter the iron the faster IT will oxydise (dip in flux to keep it shiny) and then all soldering fails as it needs to be shiny and tinned to transfer the heat to the job.
Remember that you should FLUX the clean fresh wire then tin it before attempting the joint.
Then FLUX and TIN the solder pad or connector before attempting the joint too.
Then re-tin the iron!
Now you should have a shiny tinned wire, a shiny tinned pad or connector, and a shiny hot iron.
The iron should NOT be used to "melt some solder to stick to a joint"...
READ THIS BIT SLOWLY! The irons job is to HEAT UP the two surfaces. So they can melt the solder that is already present as you tinned the pads or connector in advance.
To DO this press the iron and the wire against the connector. All 3 parts should be in contact with the iron. The iron needs to heat up the two parts to be joined. When the solder melts that you already pre applied on both parts it will naturally flow due to the flux and give a nice smooth shiny joint. The moment the solder flows, and goes smooth REMOVE THE IROM. DO NOT MOVE IT TILL COOL!

This all sounds compicated.
Its not. And if it takes moe that 5 seconds to actually solder a wire to a board, or 10 seconds to solder a big connector then you are doing something wrong.

My club member went from could not do a single joint to expert in 1 hour. Now he finds it easy. Get any of the simple things wrong and you will struggle. When it right its trivially easy and quick.

https://www.amazon.co.uk/Fluxite-FLU450 ... 0108FM9WI/

Used this stuff since I was 17. Technically it was for pipes. Plumbing. And small tins were used by anyone with a soldering iron... Made in a day where no electronics existed.
Hard to find now but it seems to work on everything.

I did a lot of intricate soldering this weekend. DB25 connectors. I've never tried the lead free stuff to tin the tip with. Never thought about it. I'll have to try that if I can find some left here. I've banned it from my house! I'll never do anything needing to be ROHS compliant and I've never had any good luck using it except on big lugs. Also had trouble desoldering components that used the lead free stuff. Probably my technique was not good for it.

I do keep a wet rag nearby and wipe the tip on it instead of using a brass or stainless wool. Mainly because mine disappeared from my solder station so I tried a wet rag and it worked great. I haven't gotten around to replacing it.

I highly suggest that anybody who does soldering even occasionally purchase a decent soldering station. Being able to control the temperature makes a huge difference and I really like having a hot air nozzle. Most of the irons I bought that were cheap were too hot. It's weird that the solder doesn't melt and flow as good with too much heat because, as you said, it burns the flux away too quickly.

I also want to try some of the flux paste like you linked one day. I've used nothing but rosin in a little can. It works quite well for my use and not corrosive. I've never tried the actual flux paste though.

I never do the damp sponge thing any more because it seems to cause the tip to go dull and need re-tinning. Or rather it causes it to oxidise or remove flux. The brass wool things are ebay/amazon cheap!

The guy that came here was amazed that he actually could solder things after all cleanly and professional looking. He was surprised that it was so easy. He had been struggling with the wrong stuff, bad information, for years. He was told that the cored solder was all the flux he needed for e.g. Just to start with...

Yes that tinning the iron with what is basically almost pure tin at higher tempertaure means it stays tinned better used at a lower temp for lead/tin solder. I worked that out only recently!

I tried lead free by mistake at one point. After a couple of days of frustration I couldnt understand why it was so difficult! I ruined a flight controller board. My soldering either didnt work or looked like crap. Then I examined everything. And spotted LEAD FREE on the solder roll...

Never tried a hot air nozzle. Dont really do components. When doing things like connectors on say andersons I use one of those turbo cigarette lighters. Those work great where an iron struggles. But YOU are the temp control. Since I was once a plumber thats not an issue!

A brass wool ball does a better job of cleaning tips than a wet sponge / rag - it took a lot to convince me, but it's all I use today... If you DO use the wet sponge, wet it with DISTILLED water. Supposedly if you use tap water the minerals in it will build up on the tip and both mess up the joints and make the tip oxidize and pit faster.

What I've found the big secret to desoldering / removing stuff that was done w/ Lead-Free is to add a good gob of LEAD solder to it, and then use a solder-sucker to remove the larger molten blob... The larger blob seems easier for the sucker to pull in, and the added lead makes the molten solder more fluid...

ex-Gooserider

I just ordered three new brass wool balls for my soldering station. I'll probably find the one for my station about 15 minutes after they are delivered.

What about the 63/37 solder? I have some of it but can't recall being able to tell any difference when I used it.

I don't use the hot air nozzle as intended. I don't do components much. I mostly use it for heat shrink, those solder heat shrink connectors, forming plastic, cleaning up 3d prints, and stuff like that. When turned down low it also works good for blowing away excess rosin. Set it just warm enough to make the rosin soft and not harm the nearby plastic. The little nozzles you can put on it make it fairly intricate.

I keep the same type cigarette lighter torch for the same purposes. I've got to get another one soon. The one I use leaks the butane out and has to be refilled every time I want to use it. I've had it for probably 15 years and have dropped and ran over it dozens of times. It's hard for me to find one that my fingers can operate though. Stupid child safety bs. A Mapp gas torch is easy for me to use. Go figure.

Goose, that's pretty much how I had to remove the solder from a Robotech that I had to replace some mosfets on. You are the one that told me to try that. I wouldn't say it worked great, but it did get the job done, albeit ugly.

What about the 63/37 solder? I have some of it but can't recall being able to tell any difference when I used it.

Same here. Probably doesent matter. I just stick to what I know. 60/40 (non chinese) branded stuff like kester or multicore.

I keep 1.2mm and 0.7mm diameter depending on job. And MAGNIFYING prescription glasses! And a big block of Bluetack (2 in fact) to hold stuff for me, not enough hands.

With decent flux and cleaned (or brand new solder pads) on a board, you can use a biggish heat retaining tip, thats bigger than the pads to get perfect solder blobs across all of the solder pads at once that is well defined. Not enough flux or crap solder/flux or non tinned iron and you get bridging, flux burned off, oxidised pads. Not pre cleaned with abrasive or a fibre pen and you can get the "it wont tin" and gone all black thing happening! (Like my freind was also getting because of cheap non tinned, too hot iron...)

I use to have a cheap non thermostatic iron that was just 15 watts. It would glow orange if left plugged in. WAY too hot. Impossible to tin. And it had little thermal mass, no power so it went too cold when you touch it to a terminal or a copper trace...

I now just use a Hakko for the last 15 years. This model FX-888D is now recently discontinued. I would buy it again... Its only 70W but its temp control is fast! If it cools a degree or two in contact with work it rapidly responds. It aso does not get hotter than you set and so doesent oxidise fast.

But theres plenty of decent cheaper alternatives today. I like the weight of the holder/cleaner too. And the un-meltable ultra flexible silicone cable, and the multitude of different tips that are cheap on amazon!

Cleaning depends of what it is.

Boards I ise a fibre pen. Amazon. Then a smear of flux.

Wires I dont clean, as they are usually clean straight after you strip them. Dip in flux...

Connectors are usually clean, or pre tinned, zinc coated or gold plated. No need to clean. A trace of flux is all thats needed. Then TIN or add solder and crimp! And then heat it later...

Big bits of metal like pipes, or large copper traces may need scotchbright green stuff, steel wool, or whatever before flux and tinning. If the metal is not shiny copper or brass, with zero oxides it will never solder. And will get worse when you try.

Secret to soldering is easy.
1. CLEAN and remove all oxides whatever that takes.
2. Flux BEFORE oxides re-form. That happens faster when warmer. So dont heat the metal first!
3. Tin with solder.
4. Assemble pre tinned joint and heat. Add some extra solder if needed as you do so. Use the solder you add to melt and transfer the heat to both sides of the joint. When it runs and looks shiny stop!

As well as the ability to solder things. We all have needs to strip and build or repair things. Homes, heating systems, hobby stuff, furniture, cars, garden tools, electric beds etc etc. We need to fix and maintain or even put up a shelf or modify something.

So we all need tools. Money spent on tools that last a lifetime, is money well spent. I go a little overboard here. I have pillar drills, lathe, workbenches, vices, all kinds of wrenches, spanners, sockets, big power tools, hammer drills etc. Gas powered torches, and any number of connectors, pipe fittings etc.

And I have many useful 12V small portable tools.

For e.g to strip and work on anything easily and quickly you need a powered recoil free wrench! Works on screws, bolts, allen deads, etc.

Like below.

And we need to drill holes.

That needs a drill.
Below is a drill, with a half inch chuck, so that you can fit larger drills into it, and the big orange hole saws etc. And taps to thread holes. And so on.

And we need to grind, cut, and strip paint etc too.

So a tiny 12V grinder...
WITH adequate blades, polishers, grinding wheels etc.

Also have a bosch version of the Dremmel, which is useful. And many aerosol cans of paints, and every type of epoxy, superglue, wood glue, filler, loctite, activators, syringes, oils, and a bench grinder to keep stuff sharp like lathe tools.

Also have degreasers, and oild, fuels, solvents, acids, and stuff. You never know what you will need. Like I have a mass of stainless metric bolts of every size and type imaginable. And chargers, cables, adapters, clamps, measuring tools end so on.

Also multimeters, antenna tuning meters, current clamps, 4 power supplies, a mountain of chair spares and R-Net control systems and programmers etc.

All this stuff was built up over years. And has freed me from the "experts" and allowed me to build and repair and improve everything in and outside of my house. From cars, house repairs, fixing everything imaginable all my life. So it looks expensive. In reality its saved me tens of thousands. DIY solar system for e.g. And everything to do with chairs.

shirley_hkg wrote:
Yes. Get a soldering station.

This is more than you need, but why not if it is very affordable @£37.

Over 200w max, and many types of tips T12 / C245 ...


https://youtu.be/UPuScab-H4w?si=wAFO5mOZbtY3BW0k

I want to upgrade the solder station. The one like in the video is not sold here. I only find GVM T245 (130W), ESD T210 (75W), OSS T12-X (72W). GVM and ESD are advertised using Japanese electronic components. OSS is a little cheaper. Can you recommend which one should I choose?

Genuine JBC C245 tips are expensive, while clones are still need to be better.

I suggest T12. Save money for more tips to suit various applications.


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Video in English.

https://youtu.be/_gDebglRAv4?si=6bg5XQKKrrtAd0WW