Copper Powder (Conductive Composite Filler)
Key Features
- High electrical conductivity (bulk Cu: 5.8×10⁷ S/m) for EMI shielding applications
- High thermal conductivity (401 W/m·K) for thermally conductive adhesives
- Dendritic grade achieves percolation at lower volume fraction
- Suitable replacement for soldering in heat-sensitive electronics assembly
- Available in range of particle sizes and morphologies for application optimization
Copper powder is a high-purity metallic filler used to impart electrical conductivity and thermal conductivity to composite resin systems. With electrical conductivity of approximately 5.8 × 10⁷ S/m (bulk copper), copper powder enables the formulation of highly conductive composite coatings, adhesives, and potting compounds that far exceed the conductivity achievable with carbon black.
In filled resin systems, copper powder forms conductive pathways through direct particle-to-particle contact when the volume fraction exceeds the percolation threshold (typically 15–35 vol% depending on particle shape and size). Dendritic or flake-shaped copper particles create conductive networks at lower volume fractions than spherical particles due to their higher inter-particle contact area. The composite electrical resistivity can range from 10⁻² to 10⁻⁵ Ω·cm depending on the filler loading, particle shape, and matrix resin type.
Major applications include EMI/RFI shielding composites and coatings, electrically conductive epoxy adhesives for electronics assembly (replacing soldering in temperature-sensitive applications), grounding compounds, and conductive primers for plastics. Copper's high thermal conductivity (401 W/m·K for bulk copper) also makes copper-powder-filled epoxies valuable as thermally conductive adhesives and encapsulants. Surface oxidation must be managed — copper oxidizes readily in air, reducing conductivity. Passivated grades or formulations including reducing agents are recommended for long-term performance.
Specifications
| Parameter | Value |
|---|---|
| Appearance | Reddish-brown powder |
| Copper purity | ≥ 99.5% Cu |
| Oxygen content | ≤ 0.3% |
| Particle shape | Dendritic or spherical (specify on order) |
| Apparent density | 1.5–2.5 g/cm³ |
| Bulk density (tapped) | 2.0–4.0 g/cm³ |
| Median particle size (d50) | 10–45 µm |
| Specific surface area (BET) | 0.2–1.5 m²/g |
| Electrical conductivity (bulk) | ~5.8 × 10⁷ S/m |
Applications
FAQ
Silver (electrical conductivity ~6.3×10⁷ S/m) and copper (~5.8×10⁷ S/m) have similar conductivity, but silver has two key advantages: it forms a stable silver oxide surface coating that still conducts electricity, while copper oxide (CuO/Cu₂O) is insulating. Silver is therefore preferred for the most demanding long-term conductivity applications. Copper is significantly cheaper (10–50× lower cost) and performs well when proper anti-oxidation formulation practices are followed.
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