Higher conductivity. Lower weight + cost. Pick your trade-off.

Depends on thermal need. Thermal conductivity difference: 2.4× (copper better). Price difference: 3× (copper more). For most applications, aluminum is adequate — use bigger aluminum heat sink at same effective thermal performance for lower cost. Copper wins when: (1) Space constrained (can't make heat sink bigger). (2) Heat flux so high that even larger aluminum can't keep up. (3) Thermal margin matters (safety factor). (4) Aesthetic appeal in premium product.

Common compromise. Copper base plate (direct contact with heat source) + aluminum fins (convective cooling). Copper spreads heat efficiently to fins; aluminum fins provide cheap large surface area. Common in CPU coolers. Manufacturing: copper base CNC machined, fins extruded aluminum, soldered or epoxy bonded. Best thermal performance per dollar for many applications.

Aluminum is 1/3 copper weight. For aerospace, handheld devices, portable equipment: aluminum wins on weight. Copper heat sink for 100W CPU weighs 1-2 kg. Equivalent aluminum: 0.4-0.7 kg. For desktop applications, weight not critical — copper fine. For mobile devices, aluminum required and performance compromised accordingly (smaller heat sink, lower sustained power).

Aluminum: extrudes easily cold or warm. Complex fin profiles with thin walls. 80% of aluminum heat sinks are extruded profiles. Copper: extrudes only hot (high temperature, high pressure). Limited to simpler profiles, thicker walls. Much higher cost. Most copper heat sinks are CNC machined from plate, not extruded. This contributes to copper cost premium — no cheap extrusion process.

Both materials work with standard thermal interface materials (TIM). Thermal paste: silicone-based, thermal grease, thermal pads. Both interface well. Copper: slightly better wetting with thermal paste. For liquid-metal TIM (gallium-based): must not contact aluminum (corrodes aluminum). Copper compatible with all standard TIMs.

Copper: oxidizes to dull brown over time. Oxide layer has lower thermal conductivity than bare copper. For long-term performance: nickel plating on copper (3-5 µm) maintains surface integrity. Aluminum: forms passive oxide immediately, stable long-term. For both: anodize aluminum or nickel plate copper for outdoor service. Black anodize adds ~3-5°C cooling via radiation enhancement.