Kester 24-6337-8806 245 No-Clean Flux Core Solder Wire - 63/37 Tin/Lead Alloy, 0.015" Diameter, 1 lb Spool - Ideal for Electronics Repair, PCB Soldering & DIY Projects

This is my second pound of 63/37 .015" Kester solder. The first roll I picked up quite by accident, without consideration as to why I would buy a particular diameter or alloy. It is what they had on the shelf at Fry's when I needed to solder some pieces at home for an electrical engineering class that actually required we build things. (Thank you, Dr. Losh.)For this purchase, the product was much more carefully considered. I chose a very small diameter solder, because that makes it easier to put the right amount of solder on a component: you get 1 pound regardless of the diameter. I specifically chose the 63/37 mix rather than 60/40 because 63/37 goes directly from a liquid to a solid, where 60/40 has an extended plastic state where it can move around but not wet and pieces. It is much easier to a get a cold solder joint with 60/40.