Buying solder: Going through hell! Kester 44: 60/40 -VS- 67/33

I have been going through hell with solder lately since Radio Shack closed. Never had trouble, just bought big spools and the solder pretty much always behaved the same. And by the same - for ME, is:

  1. Apply tinned / wet iron to a lead, soldering iron heat set at 300(c)
  2. Apply solder to the lead while iron held on the lead (20-gauge uninstalled wire on 2-sided protoboard)
  3. Solder turns into fluid, creates a wet structure around heated lead with convex arc radius around a lead similar to a meniscus
  4. Let go of solder, THEN iron, count MAYBE 1/2 or 1 SECOND... Solder turns from fluid wet glossy mercury, to matte/shine solid.

I do not want to get STUCK with ANOTHER big roll of useless expensive solder. So, I buy 2 different SAMPLES of "KESTER 44 solder" - 60/40 and 63/37. The "60/40" solder behaves weird - it will get hot, and not really turn into a fluid - (does not get wet around the pins). It just kind of becomes hot and acts like sticky play-dough. The "63/37" solder appears to work PERFECTLY so far, it does exactly how I described what I am used to using. I am very pleased with the "63/37" solder.

So my question is: does "KESTER 44 60/40" solder ALWAYS act like sticky play dough without getting wet? Or did I buy a bogus sample of that solder? Is there ANOTHER variation that I am over-looking when ordering solder?

So my question is: does "KESTER 44 60/40" solder ALWAYS act like sticky play dough without getting wet?


The keyword is eutectic. 60/40 is not (Wikipedia has it labeled as "near"). 63/37 is.

Does adding liquid flux make any difference ?

I’ve used ‘Multicore’ 60/40 for years and always got clean bright results…

Mind you I use a Weller #7 tip at 370C

Different flux, perhaps?

See my offering in the ‘Wall of Shame’ thread in ‘Bar Sport’



Either I have always been very lucky, or I did something wrong all the time and my joints will all fail in the next few years.
I do it like DocStein99 describes, with 2% copper, 60% tin, 38% lead solder, the bestseller solder on German amazon, 100g for 5,70€. I apply it with a self-made small chisel that I made from another tip by filing it down to the bare copper and then sticking it into tip activator and tinning it ... If my joints will not fail, I don't know how so many people find so many problems with soldering :slight_smile:

Liquid flux - no I do not normally use that, or any other type of flux. I use flux with huge wires, or when desoldering, or lately to struggle through this mystery solder that seems to solidify before I remove heat from the joints. The flux I use comes from a box filled with rusty filth small tins of flux, which were probably manufactured before computers were invented.

64/40 solder will fully melt/liquefy but it requires a slightly higher temperature (I don't remember how much higher, but you can check the specs). The "magic" of the tin/lead alloy is that it has a lower melting temperature than either lead or tin, and the eutectic 63/37 blend has the lowest melting temperature of any tin/lead blend.

The temperature of the solder & joint is, of course, slightly lower than the temperature of the tip, and the tip begins to cool when you touch it to something colder & larger... If your tip is 300 degrees, the soldering temperature is lower than that. I think you just need more heat...

I've never noticed a difference between 60/40 and 63/37, but I've never done a side-by-side comparison. 60/40 does have a "mushy" state, whereas 63/37 is eutectic and goes "instantly" from liquid to solid. But 60/40 has a small mushy range and it's usually "close enough".

I've noticed a bigger difference with lead-free solder or different flux. And, I'd say the 'old' 60/40 or 63/37 solder with rosin core flux is the easiest to work with. Some of the water soluble fluxes can work very-well, but the "strongest" ones have to be thoroughly washed-off, or the circuit will begin to corrode. (And, all of the water soluble fluxes are supposed to be thoroughly washed-off.) I don't have a lot of experience with the "no clean" fluxes, but I don't like they way they look.

If you reckon Babbage made the first computer, that's a pretty ancient tin of flux!


Ok, this is good information. Thank you. If I make a project for someone else, or want to showcase my stuff, I'm extra tidy with the board, clean it up nice and presentable (as possible). Most of the time I just make a bunch of mistakes and find myself changing, so it rarely gets to be seen by someone besides me.

If I remember right, I picked out "SILVER SOLDER" from Radio Shack, when I bought it which was more expensive, but I felt happy knowing it was a pleasure to use. I figured it would be better conductor - and it seemed to flow just the same way as this nice 63/37 solder.

I want to use as little heat as possible, maintain a strong contact and healthy joint. This "lead free" stuff has my iron so hot, I'm popping little capacitors, and sometimes melting dc-jack plastic housing. Definitely ruin ends of 24 gauge insulation wires. These guys who repair iPhones with lead-free solder? They are not being paid as much as they should for the aggravation of those microscopic leads with evasive solder.

Babbage first computer? I thought the Alan Turing's decryption machine was the first computer. Some people believe an ABACUS was the first computer. Does a computer need to use electricity - to be considered a computer? If not - then I can argue that a checker-board is a computer, since it stores memory of where chips are laid out on a board. Or a human brain (or ANY brain) was actually the first computer.

Who was the person to invent "LEAD FREE SOLDER" ? Does anyone here on Arduino forum have schematic for a time machine circuit? I would like to build time machine, send a terminator robot to go back in time - and find the person who invented "LEAD FREE SOLDER".

2) Apply solder to the lead while iron held on the lead (20-gauge uninstalled wire on 2-sided protoboard)
3) Solder turns into fluid, creates a wet structure around heated lead with convex arc radius around a lead

I trust you mean 'uninsulated' wire and
I trust you mean a 'concave' form of solder around the lead. If your solder is 'blobby' (ie convex) then you haven't properly wetted the heated components which will result in a poor joint.

You don't mention the use of multicored solder. If you use that then you shouldn't need any extra flux.
Lead-free solder is an absolute pain and best avoided. Those who decided to save us from death by endeavouring to ban lead-based solder obviously never did electronic soldering.

You shouldn't even be trying to solder components until you have your iron at the correct temp for the solder you're using.
Turn up the heat for the 60/40, problem solved.
Don't have adjustable heat, get an iron that can, or just put the 60/40 away until you can in the future.
I use Kester 63/37, I don't think there is a '67/33'.

lol! I use "uninstalled" wire. these are the tricks my spell-checker plays on me. Yes I use un-insulated, 20 gauge hook-up wire, which is (according to the label) tinned copper wire.

So yea, whatever shape the solder forms when it turns to wet liquid and surrounds a pin - concave if that's the word I should be using. If I use "lead free" solder it makes a TOOTH-PASTE pile of crap around my pins, partially solid lumps that - for reasons unknown, appear to solidify and flake off while heat is still applied. It is like they designed the solder so that every joint will be a cold fracture.

"multi-core" solder is probably the stuff I'm used to using - I do not normally use any flux, just solder my wires, pins, etc... and that's that.

I also bought a solder pot, I hooked up and put on my desk. Tried to dip my stripped wires, expecting them to come out with a nice tinned layer of solder. For reasons unknown, a SLAG appears to form on the top of the solder pool - and the solder doesn't seem to grab the wires. I've not used a solder pot ever, just saw one and figured it would help me save some time. I filled it with thick gauge plumbing solder I found in the tool box - and did not take notice to what kind or brand, core mix or whatever. (this was before I discovered my recent trouble trying to buy correct solder for my usual PCB stuff).

I checked with some friends of mine who still work in the manufacturing side.....

For leaded solder use at least 350C. For unleaded use 400C

"multicore" is a trade name in the UK.


'multicore' may well be a trade name as is 'hoover' used as a generic term for vacuum cleaning.
I was of course referring to solder with a number of cores of flux compound running throughout its length.

I want to use as little heat as possible

That does not necessarily mean to keep your iron as cold as possible. Low heat means you have to apply it for longer to get the components to temperature. This means a larger part of the component heats up. You can have the component itself colder with a short application of 400°C to the joint than a long application of 300°C.

Sometimes I solder 1,5mm^2 solid core to a board, e.g. for higher amp 12V room illumination. If I go below 400°C, the whole wire becomes super hot before it wets at the solder joint. When it does, it basically melts everywhere. For small components, the sweet spot is certainly lower, but the effect still exists.
Recetnly, I soldered 73°C thermal fuses, that also worked better with higher temps.

Plumbing solder! There's your problem. Plumbing solder has been lead free for longer than electronics solder, and may be a different formulation than lead-free solder for electronics. It typically uses acid flux.

But even 63/37 lead-tin solder will have a hard time wetting wires without flux.

I expect to heat the pin in about the time it takes for me to breathe. Apply the solder, tin - merge/weld - blink my eyes a few times then remove heat. After remove solder iron I expect no more than "1 Mississippi" for that joint to freeze into solid. This would be for all my DIP components. No flux or anything else special unless, I'm doing connectors, bigger stuff, repair/de-solder.

For the plumbing solder pot, now that I think of it... There were a BUNCH of big fat solder spools I just mixed them all together and did not read any of the labels, I assumed they were all the same. But now, thinking back- that person probably had a DIFFERENT SPOOL of DIFFERENT TYPE of specific solder for different jobs. I just mixed it all into one put of useless junk. I'd probably need to be a blacksmith in order to figure out how to correct that recepie gone wrong.... I dont know what I am doing with it, so I just kept trying different things to make it work. I think at one point the heat was so high it looked orange (if that were possible?). I think if I dip the leads in flux first, then dip in the pot - they might actually take to it....

it looked orange

You've got some of the modern antimony-based solder in there. Higher melting point, not so easy to use, much lighter then lead...


You've got some of the modern antimony-based solder in there. Higher melting point, not so easy to use, much lighter then lead...


It seemed like I had to keep scraping the top layer of slag off, in order to dip anything. It created a force-field to the solder pool succeeding in ever way to prevent me from tinning the wires. It was like trying to dive into a swimming pool that was covered with an entire sheet of latex-glove material.

I have succesfuly used lead free solder for the last 2 years for thru hole projects. Sn 96%, Ag 3%, Cu 1%.

I have my solder tip at 630° F (330°C) with the the .81mm (21ga) diameter spool.