Please recommend a good quality flux and solder

[castingflame]

1) While I have several cheap tin/lead leaded solder and lead free solder I am looking for some good quality replacements.


2) More importantly, I am looking for a better flux that the ones I currently use.




My current flux options





The bottled Flux
The flux in the bottle is very good but it leaves a very stick mess behind it. Obviously this can be cleaned with alcohol but it makes the process longer an messy and not very practical when doing a lot of joints. I would prefer a flux that I could use that is easier and leaves not residue.

The Pen flux
The pen flux is the other end of the scale as it leaves little residue but does not do such a good job.


I guess I am looking for something in between of great quality!




So please feel free to recommend some decent leaded solder, Lead free solder, Flux.



Cheers 

[wraper]

You could use LP-1 from the same manufacturer if you want a flux which does not leave much residues. TK-83 has very high rosin content and any such flux will leave a lot of residues.

[Ian.M]

You are probably over-applying the TK83 flux.   Used sparingly, most liquid RMA fluxes can be treated as no-clean.   Try diluting a small quantity with four parts of dry IPA^*, to reduce its solids concentration to about 5%, then apply it sparingly with a lightly wetted Q-tip.  If it not active enough at 5%, dilute it less (or mix in a bit more TK83).  Once you've figured out a workable dilution, you can get a cheap refillable paint pen suitable for solvent paints & inks, and fill it with your diluted TK83 to make your own flux pen.

Worst case: you may need to heat the board with a hot air gun to about 120 deg C to drive off the solvent in the flux so the rosin residue sets hard and non-sticky.

* i.e. >99% pure  Isopropyl alcohol.  Don't use drugstore 70% IPA solution or similar as its water content is likely to separate out after mixing forming an aqueous layer that may strip activators from the flux.

[exe]

LP-1

I'm not sure it is no-clean.

I used to use tk83, and I liked it. Afaik, it's only sticky until it dries out. I think it's just a mix of rosin and alcohol, once alcohol is evaporated it becomes solid and inert.

PS I now use Russian fluxes like FN-255 which claimed to be non-conductive and suitable for sensitive equipment (I don't have an electrometer to test the claim). It even provide a sort of test protocol how they verify flux performance, I haven't seen such claims from any other manufacturers. If interested in details and "datasheets", see https://www.eevblog.com/forum/buysellwanted/fs(nlams)-cyberflux-group-buy-(russian-fluxes-non-corrosive-non-conductive)/ . I believe you can buy them from ebay, although they are now produced by multiple companies, and I'm not sure how good they are now. They are also sticky (unless they solidify after extended heating, which makes it painful to remove it), so, probably, not suitable for you.

[wraper]

LP-1

I'm not sure it is no-clean.

https://termopasty.pl/wp-content/uploads/2019/07/Topnik-LP1_EN.pdf

[exe]

Ah, missed that part. I was scared away by "Solubility in water", and not sure how to interpret it. Can it absorb moisture?

[tooki]

1) While I have several cheap tin/lead leaded solder and lead free solder I am looking for some good quality replacements.

This question gets asked every few months on average (sometimes just days apart) and the answers are always the same. If you spend a little time looking for those discussions, you’ll find all the info you ever dreamed of. (Try googling “site:eevblog.com solder recommendation” and the like, since the forum’s own search kinda sucks.)

[exe]

I'd also say that fluxes are over-rated. I spent years finding the best non-conductive flux, but, frankly, it's not that important unless parts and wires are severely corroded. And if it's corroded, then it can be cleaned and tinned before soldering.

[Ian.M]

Its not that fluxes are over-rated (though some seem to think they are capable of magic), its that most wire solder and all solder paste contains enough flux to do a good job in all but the most challenging  circumstances, provided you don't 'cook' it off before making the joint. 

There's no need to flood the area round the joint with flux 'Louis Rossman' style.  He does that because he is often working with badly corroded pads and leads, and, as he has an ultrasonic cleaning tank, and the boards must be fully cleaned anyway, excess flux is cheaper than the extra time it takes to use just enough flux at New York labour and overheads costs.

[exe]

He also uses a conductive flux (amtech 559 or something) which I don't recommend.

PS by "over-rated" I meant there is no need to look for the "best" flux. In my opinion there is no big difference between them unless the board and/or parts is a mess.

[bdunham7]

Leaded solder: Kester 44 core 63/37 in 0.8mm, 0.5mm and 1.0mm, in that order.

Flux:  I like https://www.allelectronics.com/item/sp-802/rosin-soldering-flux/1.html  for those occasion I need extra flux.  It's a paste, you can use a toothpick to put a tiny bit on and it stays until you melt it.

ROHS solder:  I have AIM 2.5 Glowcore 1.0mm that I can use for lead-free new work if needed.  If you are reworking lead free and can't use leaded, then life is tough. 

And then maybe you want some silver solder for a hundred bucks sixty bucks a roll or so: https://www.rshughes.com/p/Kester-44-Lead-Solder-Wire-1-Lb-0-031-In-Wire-Diameter-Sn-Pb-Ag-Compound-36-Lead-Content-24-7150-0027/24_7150_0027/

[tooki]

Silver bearing solder doesn’t have to cost $100 a roll. Also, you posted the same link twice.

[exe]

My favorite solder wire is stannol HS10. It has rosin core. Not the best flux, but does the job.  I also tried some non-rosin flux because I don't like rosin residue, but it got me severe headaches even after short exposure to fumes.

[Unixon]

Leaded solder: ASAHI with CF10/FC5005 flux 0.5/0.6/0.8mm for through-hole stuff + 0.25mm for small SMDs.

Lead-free solder: FELDER Sn97/Cu3 or Sn95.5/Ag3.8/Cu0.7 (maybe not the best choice but not much worse than leaded ASAHI counterpart)

Flux: difficult question, flux choice heavily depends on particular soldering process (leaded/lead-free solder, soldering iron/hot air/IR, wire/pin/pad material).
Some fluxes may leave residue that's difficult to remove if soldered with hot air/IR, but perfectly safe for use with soldering iron,
other fluxes may colorize the solder mask on PCB at certain temperatures and can't be used with lead-free solder, but may be OK for leaded solder,
some fluxes are active enough may damage gold pad finish and this depends on the temperature.

[wraper]

Lead-free solder: FELDER Sn97/Cu3

Really? It's a high temperature solder, not something you should normally use for electronics.

[Unixon]

Lead-free solder: FELDER Sn97/Cu3

Really? It's a high temperature solder, not something you should normally use for electronics.

Almost all lead-free solder is high temperature, and as I said, these two I've listed may be not the best choice.
I've seen leaded solder that is much worse at typical lead-free solder temperatures than these two alloys.
Can't say it's really good for soldering semiconductors, but it works well for passives and mechanical components, at least it is not bad - flows well, has enough flux, makes clean joints, doesn't drag after iron. I don't use lead-free as much as leaded solder, so maybe I'm wrong on some account.

p.s. Once I had a very funny Chinese leaded solder which loved to be stuck to soldering iron so much that it barely left any footprint on components except for a tiny film, at any temperature. The only thing it was good at is desoldering, because putting it on board and components was nearly impossible - all of it remained on the soldering iron tip.

[wraper]

Almost all lead-free solder is high temperature, and as I said, these two I've listed may be not the best choice.

Then this is a very high temperature stuff if you call regular lead free high temperature. If talking about SnCu alloys, for electronics SN99.3Cu07 and Sn99Cu1 are used. Sn97Cu3 is more suitable for soldering pipes rather than electronics.
EDIT:
https://www.felder.de/products/copper-pipes-sanitary-installations/soft-solders-drinking-water-heating/fittingslot-cu-rotin-3-149727201.html

According to DVGW, worksheet GW2, permitted for soft soldering of copper pipes in the cold and hot water installation.

[Peabody]

Can I ask about Radio Shack solder?  I used it for decades, and am about to run out.  Specifically this one in the 0.032":

https://www.radioshack.com/collections/solder/products/snpb-60-40-rosin-core-solder?variant=31204770021446

 I never really paid any attention to the specifics before, but notice that it has an RA flux, which I understand is more aggressive than something like Kester 44, which is RMA, and in theory needs to be cleaned off afterwards whereas 44 doesn't.  I've never really bothered with doing that, and don't recall having any problems.

Anyway, this is even the right amount to last me for several years, so I thought I would order it.  Is this not a good choice because of the RA flux?  Does anyone else like this solder?

[james_s]

Any name brand 60/40 solder ought to be fine, some prefer 63/37 but after using some for a while I'm not real fond of it. The biggest difference is the flux, I have two different types of Amtech paste fluxes, RMA-223-TPF and 4300/LF. One is a rosin flux and the other is water soluable which I use with some solder that contains a similar flux. I like the water soluble stuff because it cleans up so easy however you HAVE to clean it up so I only use it when I can wash the thing I'm soldering. I don't use extra flux all the time but it really does make hand soldering SMD stuff easier as I can just use the solder that's carried on the tip of the iron. It's also helpful for soldering things that are a bit corroded. 

[Unixon]

Then this is a very high temperature stuff if you call regular lead free high temperature. If talking about SnCu alloys, for electronics SN99.3Cu07 and Sn99Cu1 are used. Sn97Cu3 is more suitable for soldering pipes rather than electronics.

Well, maybe...
According to FELDER catalog, Sn97/Cu3 melts at 230-250C (top of the range) and Sn95.5/Ag3.8/Cu0.7 melts at 217C (bottom of the range), other alloys are between these two.
To melt this 230-250С stuff one would need 300C+ on the tip so ... yes, only for passives and connectors.

[exe]

To melt this 230-250С stuff one would need 300C+ on the tip

Uhm, isn't 300C+ a normal temperature for the tip, is it? I solder at 320-330C, I've seen other people use as high as 360C (motivation: get the job quicker to reduce exposure to heat).


PS Sometimes I go over 400C when reworking heavy connectors on ground planes...

[m3vuv]

ive brought a few reels of supposed 60/40 leaded solder from uk ebay sellers,when it is delivered,says made in china on the reel,turns out its lead free rubbish,just sommat to look out for,had one guy wanted me to send him pics of the crappy looking joints,my reply was dont you know what a dry joint looks like?,in the end i got %50 of my money back,not the ideal solution tho!!.

[Unixon]

Uhm, isn't 300C+ a normal temperature for the tip, is it? I solder at 320-330C, I've seen other people use as high as 360C (motivation: get the job quicker to reduce exposure to heat).
PS Sometimes I go over 400C when reworking heavy connectors on ground planes...

That depends on what you're soldering. For refreshing thermal pads on ICs and preparing DFN/QFN packages I go down to 200-240C, for soldering semiconductors 260-270C, for soldering passives 280-320C depending on heatsinking properties of a board, for mechanical components 320-340C and if I want to go fast on them 360-400C.

Once I had a bunch of BSS138 that would be dead on the spot if you touch them with a hot tip, I had to go with tip as cool as it can barely melt solder or switch to low temperature solder for them, otherwise they started to conduct through the closed channel and through the gate too.

[exe]

Once I had a bunch of BSS138 that would be dead on the spot if you touch them with a hot tip, I had to go with tip as cool as it can barely melt solder or switch to low temperature solder for them, otherwise they started to conduct through the closed channel and through the gate too.

Sounds like an esd-issue or a reliability problem. The datasheet says it can be soldered with 300C for 10s. I believe these ratings are conservative.

I have a level shifter made of, afaik, bss138 (the boards was bought on aliexpress). I'll resolder it with 400C tonight to see if I can damage it...

[Unixon]

Sounds like an esd-issue or a reliability problem. The datasheet says it can be soldered with 300C for 10s. I believe these ratings are conservative.

At first, I also thought that it is an ESD problem. But if this was an ESD, those MOSFETs would be damaged at the same rate at low temperature too, and other similar MOSFETs would have same problems, but they were not and the same fault mode later confirmed with a different batch of parts in different setting.

Later we dropped BSS138 completely for 2N7002K.