imec has announced an important innovation in tackling the cooling demands of high-performance 3D chips and systems. The research firm demonstrated for the first time a low-cost impingement-based solution for cooling chips at package level.
“Conventional solutions cool through combining heat exchangers that are bonded to heat spreaders that are then attached to the back of the chip. These are all interconnected with thermal interface materials (TIM) that create a fixed thermal resistance that can’t be overcome by introducing more efficient cooling solutions. Direct cooling could be more efficient, but current direct cooling microchannel solutions create a temperature gradient across the chip surface”, imec noted in the announcement.
imec’s new chip cooler is an impingement-based cooler with distributed coolant outlets. It puts the cooling liquid in direct contact with the chip and sprays the liquid perpendicular to the chip surface. This ensures that all the liquid on the chip surface has the same temperature and reduces the contact time between coolant and chip.
Cost-effective Cooling Solution
The drawback of current impingement coolers are that they are silicon-based and therefore expensive. Or their nozzle diameters and use processes are not compatible with the chip packaging process flow.
In contrast, imec said that it’s new impingement chip cooler uses polymers instead of silicon, to achieve a cost-effective fabrication.
The solution features nozzles of only 300µm, made by high-resolution stereolithography 3D printing. The use of 3D printing allows the customization of the nozzle pattern design to match the heat map and the fabrication of complex internal structures. Moreover, 3D printing allows to efficiently print the whole structure in one part, reducing production cost and time.
High cooling efficiency
Imec says it’s impingement cooler achieves a high cooling efficiency, with a chip temperature increase of less than 15°C per 100W/cm2 for a coolant flow rate of 1 l/min. Moreover, it features a pressure drop as low as 0.3 bar, thanks to the smart internal cooler design. It is said to outperform benchmark conventional cooling solutions in which the thermal interface materials alone already cause a 20-50°C temperature increase.
Smaller Compared To Existing Solutions
Apart from its high efficiency and its cost-effective fabrication, imec says its cooling solution is much smaller compared to existing solutions, matching the footprint of the chip package enabling chip package reduction and more efficient cooling.
“Our new impingement chip cooler is actually a 3D printed ‘showerhead’ that sprays the cooling liquid directly onto the bare chip. 3D prototyping has improved in resolution, making it available for realizing microfluidic systems such as our chip cooler. 3D printing enables an application-specific design, instead of using a standard design”, explained Herman Oprins, senior engineer at imec.
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