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DFM Guide · Heat Sinks

Fin density.
Base thickness.
Thermal flow.

Heat sink design balances surface area (fins) with thermal conduction (base) and air flow. CFD analysis can optimize, or follow proven design rules.

01 · Key principles

Key principles.

Material selection

Cu vs Al

Copper 401 W/m·K vs aluminum 235. Copper better thermal but heavier and pricier.

Fin pitch

2-5 mm spacing

Standard fin pitch 2-5 mm. Closer for forced air, wider for natural convection.

Fin height

3-5× base

Fin height 3-5× base thickness. Diminishing returns above this.

Base thickness

3-6 mm

Base thickness affects spreading. 3 mm minimum for compact, 5 mm for larger sinks.

Aspect ratio

≤ 8:1

Fin aspect ratio (height/thickness). Above 8:1, manufacturing difficult, marginal benefit.

Anodize for radiation

Add 30%

Black anodize improves radiation heat transfer. ~30% improvement at moderate temps.

FAQ

Extrusion vs CNC?

Extrusion: cheap for high volume. CNC: precision, custom shapes, low volume. Hybrid: extrusion + CNC machining for features.

Forced vs natural convection?

Natural: open fin spacing, vertical orientation. Forced: tighter fins, fan-driven, optimized for specific airflow.

Heat pipe integration?

Heat pipes embedded for high-flux spreading. Specialty, expensive, but enables extreme designs.

Liquid cooling alternative?

Cold plate with liquid: 5-10× thermal capability of finned air sink. Specialty for high-power applications.

Surface treatment effects?

Anodize (Type II) preserves thermal but adds emissivity. Type III hardcoat slightly reduces conductivity. Bead blast OK for both.

CFD analysis worth it?

For high-power critical applications yes. For typical consumer electronics, design rules sufficient. We can refer to thermal partners.

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