Which solder to buy???

[Jason Long]

I've decided to bite the bullet and get away from the cheap Chinese solder and try some of "the good stuff". I've done a little research and based on what I've found so far I'm looking at Kester SN63PB37 .020" diameter. 
My question is what flux core type do I want. Is there any reason to pick #44 over #245 or vice versa? The #44 is a few bucks more $ but not enough be a major deciding factor. 

Any advise, especially from someone who's used both, would be appreciated.

Thanks in advance,

Jason

[IanB]

The number 44 is a traditional rosin flux with a proven performance. The 245 is a newer no-clean formulation. Unless you have a special need for no-clean flux, I would go with the 44.

[T4P]

I went for the #245 as i ... had no choice . But it's the reason why i love soldering now .

The no clean flux smells pretty bad as rosin smells better but it doesn't give you a giddy head if you inhale rosin smoke for 1 hour .

I used #44 as a loan from my friend and it smells like heaven .

I've also tried to use cheap 60/40 Chinese solder ($2.40SGD for 1/2kg of 1mm solder !) and they just wouldn't melt at 370C 
and the 0.6mm variant was equally shitty (i bought them in china , learnt my lesson but a cheap lesson)

I now use #58 0.3mm and i love it . ( I also have some 0.8mm/1.0mm Malaysia Solder that is from some decent comp named Asahi Solder that works pretty well )

[free_electron]

2 words on solder:
You need to get an eutectic alloy like sn63pb37. The 60/40 is not eutectic.
So, what is an eutectic alloy. When a mixture of metals , like solder, goes from solid to liquid or liquid to solid there is a stage at which it is like a syrup. any mechanical friction movement or vibration will cause the end product to be brittle ( a 'cold' joint).
An alloy (mixture of metals) that is eutectic has a very narrow, no to say inexistent, tempereture band where it is syrup. 63/37 goes from liquid to solid in a sub 0.1 degree C window. 60/40 has a 3 degree C window...

60/40 is 'ok' to use, but for quality assemblies we use 63/37. The cost difference is notable. Tin is much more expensive than lead. If you were to make a truckload of solder the price difference is several thousand dollars.

Moving on to lead-free ( a misnomer .... It is called RoHS : reduction of hazardous sunstances )
There are multiple alloys there.
SAC305 is the well known one.  The problem os that most of the SAC305 sold out there is not eutectic... Close, but not quite... SAC305 is patented... NASA a/ Sandia / university of iowa ...
Sac 305 is the lowest melting point,eutectic, alloy of tin,silver,copper. SAC= stannum, argentum, cuprum: sn,ag,cu.

Other companies hold patents on close neighbours.

Anyway, at 220 C the alloy has a higher melting point than snpb (183 c)

Alternatives :
Snag. Tin / silver. Sn ag
Snib tin indium bismuth. Sn in bi
Snab. Tin silver bismuth. Sn ag bi

Other alloys of sac suc as 317 332 and others
Sn99c
Sn100c

The last two are noteworthy. They were developed by the japanese electronics industry to be a mass production, good quality alternate for snpb.
Sn99c has 99% tin 0.7% copper and some antimony and germanium
Sn100c has 99.3% tin 0.65 copper and some Nickel and germanium.

Sn100c is bu far a superior alloy to SAc. Especially on wave soldering.

Other thing to consider : lead-free compatible tools.
Do not be fooled by statements as 'you need new soldering tips' this is misleading...
In the industry you cannot come off snpb and do lead free. Any residual pb in the system will contaminate and cause the alloy to go off balance. So yes you need to clean.
For handsoldering too. But , the construction of the tip itself is still a copper core, for heat transfer, with an iron plating and a chrome finish for areas where solder is not allowed to go.

Now, this being said, there is a second part. When soldering you are actually eating away a miniscule amount of iron and copper. Liquid tin is agressive and will rip away atoms of copper ( from the board ) and atoms of iron ( from the tip ) to make the solder bond.. Soldering is a molecular bond between dissimilar metals, welding is a molecular bond between the same metal...
The higher the tin content, the more agressive it is eating the iron...

So : lead-free tips just have a thicker iron plating ! If you use you old snpb tips with lead-free you will wear them out faster, thats all.. ( aside from the intial cross contamination with remnants of pb. But that is gone after a few re-tin,wipe,re-tin,wipe operations. )

For mass production equipment like wave soldering machines it is more complicated as the entire system needs changing. The heater, the tank, the pumps... And the new tank needs to be resistant to the higher tin content or it will eat through... Or , it will dissolve so much iron while 'waiting' that the soldering will go bad.. The alloy changes because fe is dissolved and it goes off-eutectic, you get too much dross ( the metallic 'scum' formed on the wave ) and other problems.

But for home use ... Stick to 63/37. Or switch to sn99 / sn100 and no need to toss out your existing tips. Use them until worn out, then switch.

Just my 2 cents ...

[Jason Long]

Thanks for the info, all of you!

I have 2 additional questions that I should have asked in the original post...

1) With the #44, do the joints need to be cleaned after soldering? The Kester description says "highly active flux", which I would take to mean you would need to clean it up, but it also says "non corrosive and non conductive", which I take to mean that there is no real down side to not cleaning it.

2) "New old stuff"... Kester shows a 3 year from date of manufacturer useful life on their solder wire. In Dave's soldering videos, he grabs an ancient roll of Multicore solder w/o any concern for its age. 
Is there any real reason to avoid the NOS we find on eBay if it's at crazy low prices?
Is there a better "cut-off date" than the stated 3 years?

Basically I'd just like to find the proverbial "gold standard" for hand soldering electronics. Something than I can use to judge other brands as I come across them in the future. 

Thanks, 
Jason

[KD0CAC John]

What I do when I come across some solder that is getting harder to find , 67/33 , or lead solder and want to buy so I do not run out , is wrap in plastic , need to get a vacuum pack machine is best .
The lead solder likes to oxidize .
   

[free_electron]

you can vacuum pack it but it is not necessary. the flux will do the work. i have another post here on the forum on flux...
in short : flux is a reactive agent that does two things : it decreases surface tension of liquid solder so it flows better (impreoves 'wettability' )
and, when heated it becomes very reactive with oxygen. it can actually strip oxygen molecules and atoms ( most oxygen in nature is a molecule of two oxygen atoms ) out of bond.
so if your copper has a thing oxidation layer, or the tin and lead have an oxidation layer the flux will strip the oxygen out of bond returning pure copper tun and lead. tin and lead oxidize different than iron. iron keeps on oxidizing. on tin lead and aluminum the oxidation is only a few microns thick. it does not keep going.

so there is no real need for vacuum pack .

water soluble fluxes must be stored in vacuum because they absorb moisture form the air .. mainly water .. and since they are water soluble ... they destroy themselves that way ...

[KD0CAC John]

While all that is true , having some extra rolls of solder sitting around waiting to be used , maybe yrs. , you can end up with enough oxidized solder , that it would be difficult to solder with .
As far as the food vacuum machine , its just makes for another reason to have one . 

[G7PSK]

In 1983 I purchased a pallet of welding wire and persuaded the rep. to throw in a reel of solder. When the supplies came I was surprised to find the reel of solder was 20KG of ersin multicore. I still have about 5KG of that solder which I still use on some jobs, all that is needed is to wipe the solder with a cotton rag. It still gives perfect joints without any trouble.

[Jason Long]

Thanks again for all of the replies! Tons of really good info.

My questions were related more to purchasing rather than storage. That is to say that I have no control over how it was stored previously and, therefore, need to assume the worst.

So... If I'm interpreting all of this correctly, when looking at NOS solder that has an active resin core (#44 & #48) there is no to steer clear of it due to age. The active resin flux will deal with any residual oxidation.

There may, however, be reason for concern when looking at older water soluble flux cores (poor storage in a damp or humid could ruin the flux) or the milder "no-clean" cores (the flux may not be active enough to handle excessive oxidation).

If I've misinterpreted anything please let me know.

Based on what I have so far, I think I'm going to give the Kester #48 sn63pb37 .020" a try. I'll also keep an eye out for good deals & steals on #44 stuff.

[T4P]

er ... #48 is fully activated which means you need an aggressive cleaner ... Nevermind the sheets , it's been proven you need a aggressive cleaner unless kester made it so that it wouldn't corrode copper .
But according to the tests you wouldn't need to worry about #48 , why wouldn't you consider #245 instead ?

[Jason Long]

Actually I may. According to the datasheet #48 is available in 63/37 but looking around the internet, it appears that it's only being marketed in lead-free varieties.
#245 is a very real contender. You said you had been using and loving it... Tough to argue with an endorsement like that.

If #48 requires cleaning then it stops being a contender anyway. Enough of my projects don't lend themselves to being easily cleaned. I would assume the same of #44.

I've actually learned a lot from this thread and the associated research. I'm figuring out that the best type to use varies based on what you are trying to do and the conditions you're doing it under. For example, I was just looking at the best methods for soldering batteries... Looks like a 60/40 (as opposed to 63/37) with an aggressive flux works best as it provides thicker tinning and a greater ability to form a  metallurgical bond with the terminals, and cleaning them isn't an issue... But that's not what I would want to use for the rest of my projects.

I'll go ahead and pick up some #245 as a start and maybe some #44 too. I'll chalk it up to the price of a hands on education.

[IanB]

If #48 requires cleaning then it stops being a contender anyway. Enough of my projects don't lend themselves to being easily cleaned. I would assume the same of #44.

Not necessarily. Lead-free solder is difficult to work with and needs an aggressive flux. Traditional lead solder can work well with a milder flux.

Consider history. If lead-free solder had the best properties for soldering performance then it would have been the original choice way back when. It requires special effort to make lead-free solder work, and that includes special fluxes.

[Jason Long]

Lead-free isn't even in the running. I'd call myself a hobbyist but I'm not even that far along. At this point I'm just a guy trying to learn enough to make this a hobby. I see no reason to increase learning/frustration curve by throwing lead-free into the mix.

Dave's "how to solder" videos along with many other sources (including some posts in this thread), has me convinced that I need to stick w/ sn63pb37 until there is a solid reason to switch.

[IanB]

I'm not recommending lead-free solder--quite the opposite.

What I mean is that flux #44 should not be assumed to be the same as #48. If #48 was developed for lead-free solder, you can expect it to be more aggressive and to need more cleaning than a flux developed for lead solder.

[mariush]

I've bought a roll of Multicore 63/37 a few months ago but it's 0.56mm Type 3C Crystal 502.    Now Digikey sent me an email a few weeks ago saying this particular type is discontinued by Multicore.

Here's the datasheet: http://www.farnell.com/datasheets/99610.pdf

Could you guys tell me how is (or how it should be)  the flux inside this variety compared with the two mentioned in this thread, 48 and 245?  All I can understand on a fast scan of the datasheet is that it's no clean and leave little residue on the pcb.

[Jason Long]

Yea.. I know you weren't advocating lead-free. It sounded like to were trying to dissuade me from going that direction. I was just letting you know that I didn't need to be dissuaded, being that I didn't have that intention to begin with.

I was looking at #48 because, according to the datasheet, it has a more aggressive resin core but still didn't require clean up. A turbo charged #44 with no added down side. The datasheet also said it was available in sn63pb37.  Sounded like a pretty tempting product mix.

But... All I could find for sale was lead-free versions of it. Plus... According to Dave S it does in fact require clean up despite what the datasheet says.

So... Not as appealing as it initially looked.

Sorry for the mix up! 

[Jason Long]

Could you guys tell me how is (or how it should be)  the flux inside this variety compared with the two mentioned in this thread, 48 and 245?  All I can understand on a fast scan of the datasheet is that it's no clean and leave little residue on the pcb.

Sounds closer to the #245, which is also a low residue, no-clean flux.
The #48 is a more aggressive, fully activated flux, that "most likely" would require cleanup.

[Jason Long]

I'm looking at six 1lb spools of #245, .020, 63/37 for $50 (current bid) plus $16 for shipping...
Date of manufacture... 7/22/2005

That puts it close to 7 years old.  Still good?
Is so, I'll bid on it.

[sonicj]

7 years is old.

i bought my last spool from parts-express. kester 44 63/37 .020" for around $35usd. it was born about a month prior to purchase. http://www.parts-express.com/pe/showdetl.cfm?Partnumber=370-072
-sj

[IanB]

You have to do a lot of soldering to use up a 1 lb or 500 g spool. My suggestion would be to buy various different kinds and sizes of solder in smaller spools and find out by experience which ones work best. I have 500 g spools in various different compositions, flux types, wire thicknesses and brands. They don't all work the same, but when I find for a particular job that one doesn't seem quite right, I can reach for another.

[Jason Long]

No... I don't have that much soldering to do. But at that price its easy enough to divide the total price by 4, sell 4 spools and keep 2 for free. Easy math.

But that's only if it's still good as new. If I got it and it turned out to be shit, I wouldn't try to sell it.

[TerminalJack505]

Actually I may. According to the datasheet #48 is available in 63/37 but looking around the internet, it appears that it's only being marketed in lead-free varieties.
#245 is a very real contender. You said you had been using and loving it... Tough to argue with an endorsement like that.

If #48 requires cleaning then it stops being a contender anyway. Enough of my projects don't lend themselves to being easily cleaned. I would assume the same of #44.

I've actually learned a lot from this thread and the associated research. I'm figuring out that the best type to use varies based on what you are trying to do and the conditions you're doing it under. For example, I was just looking at the best methods for soldering batteries... Looks like a 60/40 (as opposed to 63/37) with an aggressive flux works best as it provides thicker tinning and a greater ability to form a  metallurgical bond with the terminals, and cleaning them isn't an issue... But that's not what I would want to use for the rest of my projects.

I'll go ahead and pick up some #245 as a start and maybe some #44 too. I'll chalk it up to the price of a hands on education.

(Bold by me.)

I'm going to assume you know what you're doing so far as soldering batteries goes so I'm not directing this at you but anyone else that is reading this... 

Soldering directly to batteries can be dangerous.  Some types of batteries will explode, catch fire and/or vent toxic gases.

If you plan on doing this, do some research first.  I think a good rule-of-thumb is to completely avoid soldering directly to any button cells due to their small size and chemical composition. 

[IanB]

Soldering directly to batteries is generally a bad idea. They often have heat sensitive plastic parts underneath the metal caps--separators, insulators, spacers, that kind of thing. Unlike electronic components, batteries are not usually constructed with any heat resistance at their terminals.

Even though some people do solder batteries and get away with it, my experience has not been good. Damage or self-destruction of the batteries has resulted. In general, soldering to batteries is something best avoided.

[Jason Long]

I was just throwing that out as an example...

However I do have a battery back that I need to build that will require soldering (unless I find someone who knows how to weld them).
The reason that I was looking into it was that I killed 5 ni-cd cells just trying to wing it. No boom... Just turned them into paper weights.

Figured that I needed to do a little research before trying it again.

As for the boom potential... I'm not trying to solder lithium based cells, just ni-cd cells that were designed to be but in multi-cell packs.

If you have a non-solder / non-weld solution, I'm open to suggestions.