Where to buy solder

[Dennis Cherry]

To add to what Dennis said - With the .015 DIA solder you do have better control on the amount of solder that is applied.  You will have to feed a longer piece of solder into the joint do to the smaller diameter solder having less volume per inch.  It feels you are using more solder but you are not.  (Which weighs more?  A pound of 0.031 DIA solder or a pound 0.015 DIA solder?)

It's not so much a matter of weight as a matter of time.  The longer you are feeding that thin solder into the joint, the longer you are keeping heat on the joint and th components.  If you are using flux core solder then you are probably not getting the proper amount of flux on the joint either if you are using thin solder on a large joint.  They make different size solders for a reason and it really is best to use the correct size for the joint that you are soldering.  I have about 3 different sizes with .031 on the stand and .015 near by.  I don't remember the size of the third one but it is a heavy solder that I use for large components and heavy wire.

I don't not understand your difference using the 031 or 015 solder sizes.

Let me explain, the issue is enough heat and solder to make a proper solder joint.  Using a large diameter solder means you have to keep the soldering tip longer on the joint because it takes some time for the heat from the tip to melt the solder and heat the joint for the solder to flow properly.

Using smaller solder diameter your have the tip still there and yes the solder will melt quicker as the volume sizes of the solder is smaller, but you still need the proper amount of heat on the entire solder joint to make it flow properly, adding a little more small diameter solder satisfies the heat needed on the solder joint.

Either way using the larger or smaller diameter solder on the regular size solder pad will work, it is having enough heat for the flux to clean the area, the solder to flow properly and the right amount of solder to make a good solder joint.

Solder tip size and temperature must be correct to make either size diameter to work correctly. So the recommendations on this site for soldering irons and temperature are good.

It takes some practice to get into the rhythm on making good solder joints and you will know when you are applying enough heat and solder to a joint.

I will get off my soap box now.

 

[tbone321]

Solder melts at the temp it melts at, depending on the composition of the solder.  It has nothing to do with the solder diameter.  Now a larger diameter can draw a little more heat away so if you are using too small of a tip on your iron or you have the irons temp a little too low then you may have issues like these.  If there was no difference, there would be no need to create and sell different sizes.  If you are using solid core solder and seperate flux, then there probably isn't all that much difference other than spending more time to do the same joint but when using rosin core solder there is a difference.  The amount of rosin in the core of .15 is next to nothing but for the joint size that it is sized for, it really doesn't need all that much.  On a larger joint more rosin is needed to properly clean it.  Just using more thin solder doesn't help here because once the pool starts to form it will burn off any rosin coming from the core before it does its job.  The principle that you talked about for the melting speed of thinner solder applies to the flux as well.  The less flux applied to a given area, the faster it burns off and if there is too little, it burns off before it has a chance to do anything at all.  This can create a weak joint.  The heavier 031 has a larger core and more flux or rosin which flows out faster and takes a little longer to burn off so it can properly clean a larger joint before burning off. 

You can ask 20 different people and get 20 different answers when it comes to soldering.  There is much more to it than "enough heat" to make a proper solder joint.  It's more like having the right sized tip for the work being performed, a temp hot enough to do the job, enoug flux to properly clean the joint, and the solder sized to match it.  If you are using rosin core solder (and most of us are) then it needs to supply enough to properly clean the joint without it burning off before it has time to do its job.  One size does not fit all here but if the way you are doing it works for you then keep doing it.

[RJ]

I would have to agree with Tom on this. That solder is a little small for the job on the through hole items. But if you up the speed at which you insert the solder on the joint to compensate then it works fine. But most people are going to find it easier with .031 dia solder.

There is really only two points to electronic soldering if you boil it all down to the very basics.

The right heat - This in itself has to do with /solder tip size and condition / iron rating /iron settings / time on joint / correct contact with both items / not over heating the part / ....

Clean enough -  this has to do with  / condition of the surfaces / flux type / amount of flux / lack of contaminates ect. / ...

Luckily it is very forgiving of some of this and works well even when it all is not perfect. so soldering is nothing to fear for newbies but I would start them out on the middle of the road instead of very small solder like that.

RJ

[barbotte]

i used .61 mm ( .024) 63/37 and i loved it ... its small but not too small and melt pretty fast so i never over burn anything ,,, but i would thing that the 31 is what most people used ,,,, 63/37 will melt faster than 60/40 therefore not putting excess heat on part
 cheer

[tbone321]

LOL, that's my HEAVY solder that I use on heat sinks and LARGE components.  If it's working for you then great.  The only issue that I have with it sometimes is an increased probability of bridging in tight areas.

[n1ist]

I too have two rolls on the bench - 0.031 for thru-hole stuff, and 0.015 for SMT (along with a spool of solder-wick...)  Both SN63. 
/mike

[Kwajtony]

I too have two rolls on the bench - 0.031 for thru-hole stuff, and 0.015 for SMT (along with a spool of solder-wick...)  Both SN63. 
/mike

The way I learned it was by the size of the area being soldered.  You wouldn't want to use thin (.015) solder for large surface areas.  As pointed out 0.015 is probably most appropriately used in SMT and other applications not requiring lots of solder area coverage.

This is my $0.015 worth, you can keep the change.

R,
Tony "C"