Solder types?

[jimjam]

My goodness, all my life I've only known about 60/40 lead solder vs 70/30 (which I don't use). Now I came to this forum and started reading about lead free vs lead solder, and then I read about 63/37 ratio, etc.

So without getting into too much technical / scientific detail... which one should I use?

[zapta]

Dave discusses it here around the 10 minutes mark 

[TVman]

60/40 Lead Solder is the one I have(with Flux)......

[echen1024]

60/40: Long considered industry standard. Has a ~10* range of "plasticity" where it is both solid and liquid
63/37: Eutectic. It has a definite melting point of 183C, which means that it has no plastic range and is either solid or liquid

I prefer 63/37, as there is no time needed for cooldown, especially with SMD, but the choice is ultimately up to you. I would ust go for the more modern 63/337.

[mariush]

You have  A LOT of information here about solder, you just have to be curious enough to search for it and read: http://en.wikipedia.org/wiki/Solder

Like echen, I prefer 63/37 (0.56mm wire) simply because the solder hardens right away (it's eutectic), as you remove the heat and temperature goes down to 183c. But I sometimes also use 60/40 taking advantage of the fact that it stays plastic for long time, for example when I try to desolder some stuff (add solder to all pins, keep solder liquid, pull out part)

You may want to watch a few of the videos here as well:

https://www.youtube.com/playlist?list=PL926EC0F1F93C1837

Part 1 discusses solder and flux:

[jimjam]

WOW Amazing information! I always do a great solder job but never knew what was really happening. I just know what a good solder job looks like and how to achieve it. Now I understand it better! Thank you so much.

Now a new question arose. Is Flux considered dangerous goods (flammable), i.e. one that cannot "fly" with you on an aeroplane?

[mariush]

Fluxes are acids ... light ones, that are activated when heated most of the times, they're harmless at room temperature. So I would say you're fine with carrying them on planes.

Stuff that may raise eyebrows would be some thermal compounds/pastes... some have Beryllium oxide which is toxic and cause cancers and a specific disease...see wikipedia page for it. You also wouldn't be allowed with Gallium, which weakens some metals:

[Nerull]

Check the MSDS on your flux. Many use flammable liquids as solvents, often alcohol. Those are considered hazmat and special shipping regulations apply. That doesn't mean they can't be shipped air, but there are rules to follow.

[John Coloccia]

My goodness, all my life I've only known about 60/40 lead solder vs 70/30 (which I don't use). Now I came to this forum and started reading about lead free vs lead solder, and then I read about 63/37 ratio, etc.

So without getting into too much technical / scientific detail... which one should I use?

You should use 63/37 if you can.  It has every advantage over 60/40 for hand soldering.  You can't even buy Kester 48 in any lead mix other than 63/37.  60/40 is anachronistic.

[jimjam]

Revisiting this topic again. I ended up buying a roll of 60/40 solder roll. However I got some lead-free tube to try out, and it doesn't seem all that different compared to lead solder. I probably need to work more with it to know the real difference.

[GreyWoolfe]

If you are going to play with lead and lead-free, make sure you have separate tips for each.  Mixing lead and lead-free solder will give poor solder joints.  IIRC, lead free requires more heat and is more corrosive to tips, shortening the life of the tip.  As always, if I have provided wrong info, someone please correct me.

[jimjam]

If you are going to play with lead and lead-free, make sure you have separate tips for each.  Mixing lead and lead-free solder will give poor solder joints.  IIRC, lead free requires more heat and is more corrosive to tips, shortening the life of the tip.  As always, if I have provided wrong info, someone please correct me.

Thankfully my soldering iron came with two tips!

But ideally I'd like to just stick with one type of solder. I guess I'll work with both for a bit and make up my mind.

[exxon]

Nobody here seems to care about RoHS Directive.
Lead alloys are forbidden in EU and a lot of other places.
It is around 10 years now we are using Sn-Cu alloy only.

[Monkeh]

Nobody here seems to care about RoHS Directive.

Because it doesn't apply to us.

Lead alloys are forbidden in EU and a lot of other places.
It is around 10 years now we are using Sn-Cu alloy only.

Restricted, and no, there are many alloys in use, including lead ones.

[exxon]

We discussed a lot this matter inside our company.
Today you find only RoHS compliant components, they have pure Sn or Sn-Cu finishing on their pins. Soldering them using Sn-Pb alloys can drive to poor reliability because of the weak interface between low-temp melting alloy and hi-temp melting pin plating.
Using a hi-temp Sn-Cu alloy assures a perfect joint that Sn-Pb can't attain.

[nixfu]

63/37 .... There is NO alternative. 


Seriously....beginners.  Get 63/37, you will have more consistent joints because there is little chance of you moving it while its cooling and causing a bad joint.


I consider 60/40 to be for more advanced and specialized uses, and really recommend beginners get 63/37.  63/37 is also the best go-to solder for the bench in most cases. 


Once you use it, you wont go back to 60/40 without a reason.

[peter.mitchell]

We discussed a lot this matter inside our company.
Today you find only RoHS compliant components, they have pure Sn or Sn-Cu finishing on their pins. Soldering them using Sn-Pb alloys can drive to poor reliability because of the weak interface between low-temp melting alloy and hi-temp melting pin plating.
Using a hi-temp Sn-Cu alloy assures a perfect joint that Sn-Pb can't attain.

Pb free for production, but for the lab, Pb stick things together easier and isn't sold to customers.

[exxon]

Pb free for production, but for the lab, Pb stick things together easier and isn't sold to customers.

At the beginning of the "leadless nightmare" we followed this way. We were happy to have an easier life in the lab than in production line.
Then this double-life caused more troubles than benefits (reworking i.e.). Now we become accustomed in soldering with Sn-Cu in the lab too, and we do not regret the past at all.

[zapta]

I consider 60/40 to be for more advanced and specialized uses, and really recommend beginners get 63/37.  63/37 is also the best go-to solder for the bench in most cases. 

I followed Dave's advise in one of the videos and got 60/40. Does 60/40 has any advantage over 63/37?

Also, my solder paste is 63/37 and I am doing reworking with 60/40. Any problem with this mixing?

[zapta]

At the beginning of the "leadless nightmare" we followed this way. We were happy to have an easier life in the lab than in production line.
Then this double-life caused more troubles than benefits (reworking i.e.). Now we become accustomed in soldering with Sn-Cu in the lab too, and we do not regret the past at all.

Your company switched to Sn-Cu only when your government forced you. It didn't do it when it had a choice.

Some of us are still free to choose. ;-)

[Monkeh]

Pb free for production, but for the lab, Pb stick things together easier and isn't sold to customers.

At the beginning of the "leadless nightmare" we followed this way. We were happy to have an easier life in the lab than in production line.
Then this double-life caused more troubles than benefits (reworking i.e.). Now we become accustomed in soldering with Sn-Cu in the lab too, and we do not regret the past at all.

If you were having soldering issues in the lab, you have bigger problems than using leaded solder with lead-free components.

[free_electron]

Nobody here seems to care about RoHS Directive.
Lead alloys are forbidden in EU and a lot of other places.
It is around 10 years now we are using Sn-Cu alloy only.

nonsense. there are many categories of equipment that are not subject to ROHS or WEEE. prototypes and hobby are not subject.

If you really want to go lead-free in a lab environment get SN99c or SN100c. Stay far away from that SAC305 junk.

[theatrus]

I've had good success with Kester K100LD. It's far better than SAC305 for wire solder.

[jimjam]

Translation please, what are those SN99c, SN100c, SAC305 and K100LD?

[nanofrog]

Translation please, what are those SN99c, SN100c, SAC305 and K100LD?

Different lead free alloys.

SAC alloys are named for the first letter of each element in the alloy, and the numbers represent the silver and copper content. SAC305 would be Sn 96.5, Ag 3.0, Cu 0.5 for example (there are a couple of others, SAC387 and SAC405). It's the most common because it's cheap (certainly not the best performing). SN100C and K100LD are more recent, and the marketing literature insinuates performance is similar to 63/37 (i.e. good wetting, nice and shiny joints, low erosion, and cost effective).

This link might help, as it gives a brief description of what some of the different alloys are used for in the Comments column (.pdf).