Custom fin geometry. Pin fin arrays. Liquid cold plates.

Aluminum 6061: 167 W/m·K conductivity. 6063: 201 W/m·K (extruded alloy). Copper C101: 391 W/m·K (2.4× aluminum). Weight: copper 3× aluminum. Cost: copper 2-3× aluminum. For cost-sensitive consumer/industrial: aluminum. For maximum thermal performance regardless of cost/weight: copper. Common compromise: copper base/embedded heat pipes with aluminum fins. We can design and manufacture either.

Air-cooled: simpler, cheaper, no fluids or pumps. Limited to ~100 W/cm² thermal flux with aggressive fan cooling. Liquid-cooled: 500-1,000+ W/cm² achievable. Requires pump, coolant, plumbing, reservoir. For very high-density (EV motor controllers, laser diode arrays): liquid. For moderate density (most industrial): air cooling adequate. Design decisions made with thermal analysis.

Practical CNC fin minimum: 0.5 mm thickness, 5 mm spacing (for machining access). Below 0.5 mm, fins bend during machining. For very fine fin geometry, extruded profiles (0.8 mm thickness, 1.5 mm spacing achievable) are better than CNC. Or: skived fin geometry (specialty process) for very fine features. CNC wins on custom shapes extrusion cannot produce.

Black anodize: +3-5 °C improvement vs bare aluminum on radiation-dominated cooling. Also provides thermal emissivity ~0.85 vs 0.1 for bare. For radiative cooling in vacuum or high-temperature: critical. For forced-air convection: marginal benefit. Nickel plating: protects copper from oxidation in long-term service. Specify surface treatment during design based on thermal analysis.

Heat pipes dramatically improve heat sink effectiveness by spreading heat from concentrated source across fin area. Standard practice: machine heat sink base with grooves matching heat pipe diameter, solder or thermally-epoxy heat pipes into grooves, ensure continuous thermal path. Heat pipe performance up to 50,000 W/m·K effective conductivity. For high-heat-flux point sources, heat pipe integration is often essential.

CNC-machined heat sinks: 7-14 days. Liquid cold plates with brazed lids: 3-4 weeks. Custom extrusion-based (requires die): 6-8 weeks if new die needed, 2-3 weeks if existing extrusion. Complete thermal systems with integration (pumps, controls): 8-16 weeks. For prototype validation, CNC is fastest path; for production, consider extrusion economics.