Tag Archives: cooling

Imec Invented Unique Cost-effective Cooling For High-Performance Chips

Imec, the distinguished Belgian research center has invented a new and cost-effective method of cooling chips. This achievement can be an important innovation to tackle the ever-increasing cooling demands of high-performance 3D chips and systems.

Present powerful electronic systems have high cooling demands for integrated semiconductor chips. Conventional solutions operate with various passive (or occasionally active) heat sinks. The main bottleneck in the heat-transfer path occurs at the interface between the semiconductor and the heat sink. It is proven that direct cooling on the back of the chip is more efficient, but current microchannel solutions do more harm than good. It leads to stress and a temperature gradient across the chip surface. Thus a new way of cooling in that method was much needed.

Imec's cost-effective cooling solution for high performance chips
Imec’s cost-effective cooling solution for high-performance chips

The ideal solution is to use an impingement-based cooler with coolant outlets distributed across the chip’s surface area. This system directs the liquid perpendicular to the chip surface and ensures the liquid is at the same temperature throughout. It also reduces contact time between the coolant and the chip. Until now, cooling solutions based on this principle have the disadvantage of being very expensive. In some other alternative implementations, the nozzle diameter and necessary fabrication techniques are not compatible with chip packaging processes.

Imec has developed a new impingement chip cooler that uses polymers instead of silicon, to achieve a cost-effective fabrication. Moreover, imec’s solution features nozzles of only 300µm diameter, made by high-resolution stereolithography 3D printing. The use of 3D printing allows customization of the nozzle pattern design to match the heat map and the fabrication of complex internal structures. Moreover, 3D printing allows to efficiently printing the whole structure in one part, reducing production cost and time.

Schematic of multi-jet cooler
Schematic of multi-jet cooler

Our new impingement chip cooler is actually a 3D printed ‘showerhead’ that sprays the cooling liquid directly onto the bare chip,” explains Herman Oprins, senior engineer at imec. “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.

Imec’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, because of the smart internal cooler design. It outperforms benchmark conventional cooling solutions in which the thermal interface materials alone already cause a 20-50°C temperature increase. It is a highly efficient and cost-effective fabrication. Imec’s cooling solution is much smaller compared to existing solutions, matching the footprint of the chip package enabling chip package reduction and more efficient cooling.

ICECool – An Intra-Chip Cooling System That Is More Efficient

In the Moore’s Law race to keep improving computer performance, the IT industry has turned upward, stacking chips like nano-sized 3D skyscrapers. But those stacks have their limits, due to overheating. Researchers from IBM have solved this problem by developing an intra-chip cooling system as a contribution to ICECool program research project by the DARPA (Defense Advanced Research Projects Agency).

ICECool - intra-chip cooling system by IBM
ICECool – intra-chip cooling system by IBM

Today, chips are typically cooled by fans which blow air through heatsinks that sit on top of the chips to carry away excess heat. Advanced water-cooling approaches, which are more effective than air-cooling approaches, replace the heatsink with a cold plate that is fixed on the top of the chip.  But this approach requires extra protection and proper insulation of the chip because of the electrical conductivity of water. Neither of these technologies can cool down the chip much efficiently. Here comes the ICECool that cools the chip down from the inside rather than just from the upper surface.

ICECool uses a nonconductive fluid to bring the fluid into the chip. This completely eliminates the need for a barrier between the chip and fluid. It not only delivers a lower device junction temperature, but also reduces system size, weight, and power consumption significantly. The tests performed on the IBM Power 7+ chips demonstrated junction temperature reduction by 25ᵒ C, and chip power usage reduction by 7 percent compared to traditional air cooling. This is clearly a great achievement when the operating cost is much smaller than the conventional cooling technologies.

IBM’s ICECool intra-chip cooling system solves the problem of cooling the 3D “skyscraper” chips by pumping a heat-extracting dielectric fluid right into microscopic gaps, some no thicker than a single strand of hair, between the chips at any level of the stack. Being nonconducting, the dielectric fluid used in ICECool can come into contact with electrical connections without causing any short circuit, so is not limited to one part of a chip or stack. Based on the tests with IBM Power Systems, ICECool technology could reduce the cooling energy for a traditional air-cooled data center by more than 90 percent.

Researchers Developed New Efficient, Thin, and Flexible Cooling Device

Engineers and scientists from the UCLA Henry Samueli School of Engineering and Applied Science and SRI International, California, have created a thin flexible device that could keep smartphones and laptop computers cool and prevent overheating. The component is based on the electrocaloric effect – a phenomenon where the temperature of material changes when an electric field is applied to it. The research has been published in Science.

Thin, flexible cooling device
Thin, flexible cooling device

The system’s flexibility also allows it to be used in wearable electronics, robotic systems, and new types of personalized cooling systems. It is the first demonstration of a solid-state cooling device based on the electrocaloric effect. The method devised by UCLA and SRI researchers is very energy-efficient. It uses a thin polymer film that transfers heat from the heat source – a battery or a processor – to a heat sink, and alternates contact between the two by switching on and off the electric voltage.

Because the polymer film is very flexible, the system can be used in devices with complex shapes or moving surfaces. Body tracking wearable devices can easily accommodate this flexible cooling device. Such cooling pad could keep a person comfortable in a hot office and thus lower the electricity consumption for air conditioning. Or it could be placed in a shoe to keep a runner comfortable while running in the sun. It’s like a personal air conditioner.

The tendency of flexible electronics to overheat remains a major challenge for engineers. The cooling systems in larger devices like air conditioners and refrigerators, which use vapor compression, are just too large for mobile electronics. The new cooling device produces a specific cooling power of 2.8 watts per gram and a COP of 13. This is more efficient and compact than the existing surface-mountable solid-state cooling technologies, opening a path to using the technology for a variety of practical applications.

Roy Kornbluh, an SRI research engineer, said,

The development of practical efficient cooling systems that do not use chemical coolants that are potent greenhouse gases is becoming even more important as developing nations increase their use of air conditioning.

Hot rods keep the die cool

20160223104825_hotrod-qfn

Clemens Valens @ elektormagazine.com shows us a new IC Package that keeps the IC cool.

Texas Instruments’ HotRod QFN is a thermally enhanced plastic package with solder lands on all sides as well as power buses for enhanced current carrying capability. Inside the package the die is mounted on a copper lead frame which eliminates the power wire bonds, improving electrical and thermal performance. This technique also improves application efficiency and minimizes package parasitic radiation.

Hot rods keep the die cool – [Link]