---
title: "Lead-free solder (SAC305) — density, melting point and propert"
description: "Lead-free solder (SAC305) has a density of 7,380 kg/m³. Melting point, strength, conductivity, what it is used for, and whether it floats, rusts or is magnetic."
url: https://atoneplace.net/material/solder-lead-free/
site: "At One Place"
---

# Lead-free solder (SAC305)

**Density of lead-free solder (SAC305): 7,380 kg/m³**

7.38 g/cm³ · 460.7 lb/ft³

96.5% tin, 3% silver, 0.5% copper, and the industry default since the RoHS directive took lead out of consumer electronics in 2006. It melts at 217-220 °C, which means hotter irons, more thermal stress on components, and a matt grey finish that is normal rather than a sign of a cold joint. It is also stiffer and less forgiving than leaded solder, which is one reason reflowed BGA joints on early lead-free boards failed under thermal cycling.

## Properties

- **Density:** 7,380 kg/m³ — 7.38 g/cm³
- **Melting range:** 217–220 °C
- **Tensile strength:** 40–50 MPa
- **Young's modulus:** 50 GPa
- **Thermal conductivity:** 58 W/(m·K)
- **Thermal expansion:** 21 µm/(m·K)
- **Floats in water:** No
- **Magnetic:** No

## What it is used for

- All RoHS-compliant electronics manufacturing
- Reflow and wave soldering
- Consumer product assembly
- Potable water plumbing (as tin-copper or tin-silver)

## How it compares

*Water is 1,000 kg/m³. Anything with a shorter bar than water floats in it.*

- air: 1.2 kg/m³
- expanded polystyrene foam: 20 kg/m³
- rigid polyurethane foam: 40 kg/m³
- Water — the float line: 1,000 kg/m³
- lead-free solder (SAC305): 7,380 kg/m³
- tungsten: 19,250 kg/m³
- gold: 19,300 kg/m³
- platinum: 21,450 kg/m³

*Water is 1,000 kg/m³. Anything below that floats.*

| Material | Density | Relative to water |
| --- | --- | --- |
| rigid polyurethane foam | 40 kg/m³ | 0.04× |
| expanded polystyrene foam | 20 kg/m³ | 0.02× |
| air | 1.2 kg/m³ | 0.00× |
| lead-free solder (SAC305) ← | 7,380 kg/m³ | 7.38× |
| platinum | 21,450 kg/m³ | 21.45× |
| gold | 19,300 kg/m³ | 19.30× |
| tungsten | 19,250 kg/m³ | 19.25× |

## Does it rust?

Lead-free solder (SAC305) does not rust — rust is iron oxide specifically — but it does corrode, forming its own oxide or salts over time.

## Is it magnetic?

Lead-free solder (SAC305) 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.

## Common questions

### What is the density of lead-free solder (SAC305)?

7,380 kg/m³, or 7.38 g/cm³.

### Does lead-free solder (SAC305) float?

No. At 7,380 kg/m³ it is denser than water.

### Is lead-free solder (SAC305) magnetic?

Lead-free solder (SAC305) 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.

## Related pages

- [Does lead-free solder (SAC305) float?](https://atoneplace.net/does-it-float/solder-lead-free/)
- [Mild steel](https://atoneplace.net/material/mild-steel/)
- [Stainless steel 304](https://atoneplace.net/material/stainless-304/)
- [Brass](https://atoneplace.net/material/brass/)
- [Gray cast iron](https://atoneplace.net/material/cast-iron/)
- [High-carbon steel](https://atoneplace.net/material/carbon-steel/)
- [Stainless steel 316](https://atoneplace.net/material/stainless-316/)
- [Aluminum 6061](https://atoneplace.net/material/aluminum-6061/)
- [Bronze](https://atoneplace.net/material/bronze/)

## Sources

- Typical range compiled from manufacturer specifications — At One Place (/about/)