Summary
Cooling is the longest segment of a TC bonder cycle. This report examines why the air jet approach reached its ceiling, and what changes when the heat escape path moves from gas to solid.
The bonding cycle has been optimized from both ends. Heating ramps faster, pressing is more precise, and placement accuracy has improved by an order of magnitude. Cooling, however, is still handled the way it was handled a decade ago: by blowing air.
Where the air jet reaches its ceiling
Air conducts heat at 0.026 to 0.037 W/m·K. Solid contact conducts at 170 to 400. The interface coefficient differs by more than an order of magnitude. Raising the flow rate does not close that gap, because vibration and particles constrain bonding precision before the thermal gain arrives.
The world's most advanced chips are cooled in a third-rate way.
What changes with solid conduction
Throughput and accumulated thermal exposure are bound to the same cooling time constant. That is why they have behaved as a trade-off. Once the path changes, the constant changes, and both move in the same direction.
References
- 1. JEDEC. Package height revision under review, 2026.
- 2. Cools Co., Ltd. First validation run, measured cycle reduction 51%, 2026.
How to cite
Cools (2026). Why is the world's most advanced HBM still air-cooled? Cools Insights in-2026-001. https://cools.co.kr/en/insights/in-2026-001/
Topics
- Thermal control