When should you choose a copper cooling material?
When the power of a single light source is ≥ ≈10 W/pc or there are obvious local hot spots, and there are strict requirements for junction temperature or life, copper or copper-aluminum composite thermal bridges and bases are preferred. If you pursue lightweight and cost advantages, and power dispersion, aluminum is still the first choice.
1. Why is copper used in the heat dissipation structure of lamps?
Thermal conductivity: The thermal conductivity of pure copper at room temperature is about ≈380–401 W·m⁻¹· K⁻¹, which is much higher than that of aluminum, which directly reduces the thermal resistance of the device-to-environment and lowers the junction temperature (T_j). Transient buffering: Copper has a high specific heat and density, which can buffer the temperature rise during short-term thermal shock, which is beneficial for pulsed or intermittent driving lamps. Examples of applicable scenarios: COB – high-power spotlights, floodlights, street lamps with high heat flux density, packages that require local thermal bridges (such as placing copper near the heat source to form a thermal bridge).
2. Different copper processing techniques are suitable for lamp types
Extrusion / CNC Milling: Suitable for floodlights and street lights that require regular fins and large bases. Advantages: Low thermal resistance, can be made into an integrated shell; Disadvantages: High cost and tool wear. Stamping/bending (sheet): suitable for light discs, volume constraints, or large quantities of low-profile lamps; Advantages: Low cost and fast speed; Disadvantages: Fin rigidity and thermal contact surface are poor, not ideal for high power Copper-aluminum composite (local copper for thermal bridge): Preferred when cost/weight is limited but requires local high thermal conductivity (place copper around the chip and use aluminum to dissipate heat outward). Casting / Precision Casting: For complex shape heat sinks, suitable for decorative garden lights; It is necessary to control the pores and compactness to maintain thermal conductivity.
The tool wear is obvious during copper processing, and it is recommended to add the tool cost and machining allowance to the project quotation. The assembly surface needs to be finely ground or pre-treated with plating to reduce contact thermal resistance.
3. Commonly used material specifications
Common material grade: C10100 (OFC, oxygen-free copper): good thermal conductivity, suitable for prototypes with extremely high thermal conductivity requirements and small batches of high-end products. C11000 (ETP, Electrolytic Copper): Commonly used in industry, cost-effective, suitable for most heat dissipation applications.
FAQ
Q1: Do copper heat sinks “rust”? A: Copper will not rust like iron, but it will oxidize and produce a patina, affecting the thermal resistance and appearance of contact. Plating or protective coating is recommended outdoors.
Q2: How many degrees can copper heat dissipation be lower than aluminum? A: Depends on the design and power density. Copper can significantly reduce device junction temperatures by 5–20°C (example) at the same volume, ultimately subject to thermal simulation and prototype testing.
Q3: Can bare copper be used in outdoor salt spray environments? A: It is not recommended to expose bare copper to strong corrosive environments for a long time, nickel plating or other protective layers and passing the salt spray test are recommended.
Q4: Does copper significantly increase weight and cost? A: Copper is about 3 times denser than aluminum by weight and costs more. A compromise solution of local copper thermal bridge + aluminum heat sink can be considered.