Choice of solder - 63/37 vs 60/40


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Geek

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After doing a bit of googling, I can't find a whole lot of information.

I am curious is there any disadvantage to 63/37 solder over 60/40? I know it is a little more expensive, but 63/37 gives far better results, so I tent to waste much less of it.

Is there anything else I should know? Is there a reason to avoid it?
 

w0067814

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63/37 ratio is a Eutectic alloy of Tin Lead solder. As such it melts at a temperature that is lower than each of its constituents, and at a very precise single temperature rather than a range of temperatures. In the case of 63/37 it is 183 degrees. 60/40 melts around 188 degrees C.

As the melting point is a single temperature it will transition fast than non-Eutectic alloys which means lower chances of dry joints. In non-Eutectic alloys one metal will melt before the other, and the same is true when solidifying.
 

Korishan

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Interesting.....
 

Geek

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w0067814 said:
63/37 ratio is a Eutectic alloy of Tin Lead solder. As such it melts at a temperature that is lower than each of its constituents, and at a very precise single temperature rather than a range of temperatures. In the case of 63/37 it is 183 degrees. 60/40 melts around 188 degrees C.

As the melting point is a single temperature it will transition fast than non-Eutectic alloys which means lower chances of dry joints. In non-Eutectic alloys one metal will melt before the other, and the same is true when solidifying.

Thank you. That so far has been the most helpful information so far. So 63/37 it is.
 

daromer

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Yeah thats the difference Im aware of as the main difference.
 

Crimp Daddy

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Kester 44 63/37 is the only solder I really use now... the quality of Kester in general is fantastic and the 63/37 is a pleasure to work with.

Kester has other really interesting stuff too, like the 245 and 275 No Clean, but for 90% of us, good ole Rosin core 44 will do just fine. Rosin from what I understand is the most aggressive cleaning flux anyways which is really good for stuff we do. Some of the other fomulas are better for clean, brand new parts you would probably find in a production environment, but I do like the no clean portion of it. The joints come out looking like professionally manufactured PCBs without any of that weird colored flux pool.

Edit:
(with 60/40 if you are holding the wire trying to solder it and its moving as it cools, you can keep moving it as it start to solidify, too much movement and you get what starts to look like a cold joint. With 63/37 that transition from fluid to solid is about near instant. The second it crosses that temperature threshold it just goes solid and holds in place.) Kinda hard to explain, but I still have plenty of 60/40 left and every time I use it, it becomes more and more apparent. 60/40 seems to glob more, where 37/37 feels thinner and seems to flow better. Wire joint look a bit cleaner, but for through hole its harder to tell.
 
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General industry has been moving towards "lead free" solder, and the most common appears to be SAC305, so I got some. It is a Tin/Silver/Copper alloy, and 96.5% Tin. What a pain, and even with using a 100W soldering iron (because of the higher melting temps), results are poor.

If you ever hear that 63/37 is going to be phased out, buy up a bunch of it. So much easier to get good results quickly.
 

Crimp Daddy

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Why in the world would you buy lead free solder if you are doing hobby work? That stuff sucks.

Unless you need to comply with RoHS, bring on the LEAD.
 

Geek

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CrimpDaddy said:
Why in the world would you buy lead free solder if you are doing hobby work? That stuff sucks.

Unless you need to comply with RoHS, bring on the LEAD.

Agreed! Lead free solder is the worst invention ever! Don't get me started on the topic. Too late -acid flux and extra heat eats the tips on the iron. Tin whiskers are prevalent. Stress cracks are far more common. Repairs are difficult, as it requires more heat to melt, so more chance of lifting a PCB track.

As for 63/37, I just wondered if there were disadvantages. 60/40 seems far more common. Yet from my experience, 63/37 is far more practical to use, and the results are far superior.


CrimpDaddy said:
Kester 44 63/37 is the only solder I really use now... the quality of Kester in general is fantastic and the 63/37 is a pleasure to work with.

Kester has other really interesting stuff too, like the 245 and 275 No Clean, but for 90% of us, good ole Rosin core 44 will do just fine. Rosin from what I understand is the most aggressive cleaning flux anyways which is really good for stuff we do. Some of the other fomulas are better for clean, brand new parts you would probably find in a production environment, but I do like the no clean portion of it. The joints come out looking like professionally manufactured PCBs without any of that weird colored flux pool.

Edit:
(with 60/40 if you are holding the wire trying to solder it and its moving as it cools, you can keep moving it as it start to solidify, too much movement and you get what starts to look like a cold joint. With 63/37 that transition from fluid to solid is about near instant. The second it crosses that temperature threshold it just goes solid and holds in place.) Kinda hard to explain, but I still have plenty of 60/40 left and every time I use it, it becomes more and more apparent. 60/40 seems to glob more, where 37/37 feels thinner and seems to flow better. Wire joint look a bit cleaner, but for through hole its harder to tell.

I have never tried Kester. Would like to, but it is very expensive. I have tried a few AliExpres 63/37. Most are good, although I have had a couple of bad rolls. I have a seller who I get consistent results from their solder. Basically I just bout a couple of 50g rolls from various sellers. Picked the best one, and bought a couple of 100g rolls from them. The joints come out clean. However, the surface has to be reasonably clean to begin with, or I have to use a little rosin.
 

Crimp Daddy

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I dunno, I don't mind paying for quality sometimes. With the little time I do have to hobby and project the last thing I need to be doing is chasing down problems, or worring about tools and equipment not being up to then task.

I know it's just solder, but it's the best ones I've used to date. I don't even add external flux depending on what I am doing. It's just good stuff that's used by actual industry professionals. Good enough for them, good enough for me.

Considing some of the repairs I have had to do on Chinese boards with crap solder joints, I prefer not to use the same solder as them.
 

BlueSwordM

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I personally just use flux on all of my projects. It makes things so much easier by getting rid of all the oxides, and making the solder flow so well.

Even with my worst solders, it helps tremendously IMO.

What can also help is preheating the surface. I will never preheat the cells for obvious reasons, but heating a PCB to say 40-60C, or even 80C, can help a lot with soldering.

TLDR: Use good solder, good flux, preheat your work surface so you make your work as easy as possible. Time is worth more than money.
 

Crimp Daddy

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Flux really is nessasary for good solder flow and wetting... It's rare that I won't use it, but on new/clean components (through hole / PCB soldering) what is inside good solder does an amazing job without extra.

I do have a tendency to over flux, making a mess, but without it the work is difficult to do.

It took many years in my earlier days before I learned about flux haha.
 

Geek

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CrimpDaddy said:
Flux really is nessasary for good solder flow and wetting... It's rare that I won't use it, but on new/clean components (through hole / PCB soldering) what is inside good solder does an amazing job without extra.

I do have a tendency to over flux, making a mess, but without it the work is difficult to do.

It took many years in my earlier days before I learned about flux haha.

I usually don't use flux on clean surfaces. I clean the surface with isopropyl alcohol if it is dirty. I use a damp soldering sponge to keep my iron clean. If I require it, I use a rosin block to clean the tip of my iron. I find that thin solder with 2% flux is heaps, so long as the iron and surface is clean.

When tinning wire, I like to dip in soldering paste. It sucks up the solder like a sponge.

What do you use for flux?
 

daromer

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I rarely use extra flux. I have it in the solder directly and it works fine. Been doing like that for over 20 years now.
I add extra flux on for instance very very dirty cells since I would never sand a cell.. They DO corrode over time if you do that... :)
 
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