Selecting The Right Solder

Dan,

Kester solder has a informative drop down menu under the general heading Knowledge Base, I use the 60/40 1/32 and 1/16 dia. Kester rosin core solder. 

John

63/37 is the lowest melting temp of the Pb/Sn and is eutectic which means it transitions from liquid to solid at a lower temperature than either of its constituents or any other mixture of them. This also means that it avoids a slushy mixture during heating and cooling. It's my choice.

From wiki...

Alloys commonly used for electrical soldering are 60/40 Sn-Pb, which melts at 188 °C (370 °F), and 63/37 Sn-Pb used principally in electrical/electronic work. 63/37 is a eutectic alloy of these metals, which: has the lowest melting point (183 °C or 361 °F) of all the tin-lead alloys

Thanks 

I'm with Chuck, I use 63/37 rosin core exclusively.  None of the lead-free junk for me, it doesn't work nearly as well!  Since I've survived all this time using lead based solder, I figure if it was going to kill me, it would have done so before now.

Muliticore solder 

gunrunnerjohn posted:

I'm with Chuck, I use 63/37 rosin core exclusively.  None of the lead-free junk for me, it doesn't work nearly as well!  Since I've survived all this time using lead based solder, I figure if it was going to kill me, it would have done so before now.

Right on. I just don't hold the solder in my teeth any more for a third hand when soldering...

Yep, sucking on the lead based solder is considered bad form.

And for SMD a friend made this for me...

Which does this...

...it's a third hand to steady the part...

Neat toy Chuck, I could use that.

Somebody on a forum made one and it looked like a good thing.

gunrunnerjohn posted:

I'm with Chuck, I use 63/37 rosin core exclusively.  None of the lead-free junk for me, it doesn't work nearly as well!  Since I've survived all this time using lead based solder, I figure if it was going to kill me, it would have done so before now.

Years ago I was working on College Hall at U of P.  We were restoring the original double hung windows.  Well the original paint was lead based of course.  So we all had to be tested during the job for the amount of lead we may have absorbed.  I passed out from the test !   

Looking at Cjack's post from wikipedia, in practice, is the 9 deg F difference between melting points of 63/37 and 60/40 noticeable?  I agree that the lead-free is a bear to use. 

I have found that using the very thin 60/40 (I haven't found any 63/37 locally), permits use of one of the otherwise poor 8-watt battery irons for thin wires in out-of-the-way places.

I like the 63/37 'Leaded' as well. The lead free stuff is terrible to use, as others have said. Just don't use any type of 'leaded' solder for anything that could be used for human consumption. Nowadays, I believe that is also illegal too, but it's fine for 'non-edible' electronics. 

DigiKey has a good selection, but may cost more than ebay though? I got some small 63/37 from them a couple years ago when I was ordering some other stuff. It didn't really seem all that expensive when I ordered it? It was the size that GRJ said he used for small work, 0.020 and 0.031, but I don't remember the brand?

rtr12 posted:

...but I don't remember the brand?

Kester most likely, it's a very popular brand.

Dan:

As others have said go with eutectic lead tin solder 63/37. For model train stuff you want the lowest melting temp solder you can get to protect sensitive components such as LED lights. You want the low temp especially if you are soldering microelectronic components on a circuit board.

I was a microelectronics packaging engineer in my other life. During my tenure the government force all microelectronic industries to switch to non leaded solders. The next lowest temp solder was silver based. With tin lead solder max furnace temperatures were set at 200-220C. With the change to silver based solders the max temp had to be increased to 260C. The difference of just 40C was disastrous for microelectronic packages based on plastic encapsulation (the little black packages with metal leads sticking out of them). If there was just a little bit of moisture in the plastic the packages would literally explode while in the furnace. This was called the popcorn effect because that was what it sounded like. Even now the industry is still struggling to come up with a good plastic mold compound formula that can withstand what is called 260C Moisture Level 1 criteria.

Also if I remember correctly - this was reliability while I was packaging, silver based solders have yet to attain the quality lead tin has enjoyed for centuries.

Joe