Phase-Change TIMs (PCMs) are solid at room temperature (often as a pre-applied pad on a heat sink) but undergo a phase change to a semi-liquid or highly plastic state at typical operating temperatures (e.g., 45-60°C). This combines the benefits of different TIMs:
- Ease of Assembly: The solid pad is easy to handle and position, unlike messy paste.
- Performance: Upon melting, it flows to fill microscopic gaps like a high-performance paste, achieving low interface resistance.
- No Pump-Out/Pump-Out Resistance: Unlike some pastes that can migrate over time (“pump-out effect” under thermal cycling), PCMs remain in place as they re-solidify on cooling cycles.
They are commonly used in pre-assembled cooling solutions for laptops, GPUs, and other consumer electronics.