Tin-lead solder (60/40)

The classic 60% tin, 40% lead alloy, which starts melting at 183 °C and is fully liquid by 190 °C — a mushy zone of only 7 °C, narrow enough to behave almost like the true eutectic 63/37. That narrow range is why it makes shiny, reliable joints and why experienced hands still prefer it for rework. Lead-free replacements melt 35 °C hotter and look dull even when perfect, which trips up people used to judging joints by shine.

Properties

Density

8,520 kg/m³ — 8.52 g/cm³

Melting range

183–190 °C

Tensile strength

40–55 MPa

Young's modulus

30 GPa

Thermal conductivity

50 W/(m·K)

Thermal expansion

24 µm/(m·K)

Floats in water

No

Magnetic

No

What it is used for

• Hand soldering of electronics
• Repair and rework of older boards
• Stained glass leading
• Plumbing joints (historically, now banned for potable water)

How it compares

Does it rust?

Tin-lead solder (60/40) does not rust — rust is iron oxide specifically — but it does corrode, forming its own oxide or salts over time.

Is it magnetic?

Tin-lead solder (60/40) is not ferromagnetic. It is often assumed to be because it is a metal, but most metals are not — only iron, nickel, cobalt and a few alloys are attracted to an ordinary magnet.