TIM types
| Type | k (W/m·K) | Typical R (°C·cm²/W) | Pros / cons |
|---|---|---|---|
| Thermal paste (silicone) | 1 – 10 | 0.2 – 1 | Cheap; dries out over time |
| Thermal paste (metal-oxide) | 5 – 10 | 0.1 – 0.5 | Better performance than silicone |
| Thermal paste (CPU high-end) | 8 – 14 | 0.05 – 0.2 | Thermal Grizzly Kryonaut, Arctic MX-6 |
| Liquid metal (Ga-based) | 70 – 80 | < 0.05 | Highest performance; conductive; corrodes aluminum |
| Thermal pad (silicone) | 1 – 6 | 1 – 5 | No cure time, reusable; thicker = worse |
| Graphite pad | 5 – 15 (in plane) | 0.1 – 0.3 | Reusable, clean |
| Phase-change (PCM) | 3 – 7 | 0.3 – 1 | Melts at operating temp, fills gaps; one-time |
| Thermal epoxy | 1 – 8 | Bonded | Permanent; use for small heatsinks on ICs |
| Indium foil | 80 | 0.1 – 0.3 | High-end test / CPU lab |
Practical tips
- Thin layer beats thick layer — TIM is there to fill microscopic voids, not to be a layer.
- Pump-out: thermal paste migrates out with temperature cycling — replace every few years or use PCM.
- Aluminum + liquid metal: corrodes violently. Use only on nickel-plated copper.
- Thermal pad thickness: pick just thick enough to fill the gap — compressed ~30%.
- Contact pressure: most TIMs need 20–70 psi to hit rated thermal resistance.
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