Rosin core solder (63% tin, 37% lead)

Kester 24-6337-0027 Solder Roll, Core Size 66, 63/37 Alloy, 0.031 inch Diameter

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We recommend Kester 63/37 (63% tin / 37% lead) eutectic tin lead solder with flux type 44 at 66%. Middle of the road 0.031" diameter is perfect for general soldering.

Kester 63/37 is available in 1 lb spools (shown in picture) and smaller 1 oz Dispense-Paks (approx 24 feet) which is enough for the soldering work required here.

The ratio of 63/37 gives this solder a slightly lower melting point than 60/40 solder (183C instead of 190C) which some say allows you to heat and solder the connection quicker, reducing the chance of damaging components or wiring. The primary advantage of this solder is not the lower melting point however, but its eutectic property. Non-eutectic solders, like 60/40, have a semi-solid state between solid and liquid. If a joint is moved during this stage, it can result in what is called a cold solder joint which tend to be unreliable. Eutectic solders, like the 63/37, do not have this semi-solid state and are thus considered easier to work with as it produces fewer bad joints.

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