- Peking University develops embedded cooling system, enhancing chip heat dissipation performance.
- System uses electrically insulating liquid to remove heat; preliminary tests show critical heat flux reaches 1,570 watts.
- Researchers select HFE-7100 as coolant, design channels to optimize heat transfer.
- Technology can integrate with standard semiconductor processes; further testing needed to validate performance.
Researchers at Peking University have developed an embedded cooling system that uses an electrically insulating liquid to remove heat from electronic chips. Preliminary tests show the system achieves a critical heat flux of 1,570 watts per square centimeter. The design places microscopic cooling channels near the heating region of the chip substrate; as liquid passes through these channels, it absorbs heat and partially vaporizes, then exits through specially configured outlets.
Integrated circuits contain interconnected components used to process information or control electrical signals. Their operation generates heat, making effective cooling crucial for performance and long-term stable operation. Embedded cooling addresses this by carving microscopic channels directly into the material supporting the circuitry, bringing coolant to where heat concentrates so it can absorb and carry away heat. Water has excellent thermal properties, but its potential electrical conductivity requires precautions to protect chip components. Researchers Wei Xiao, Wu Zhihu, and colleagues noted: "Embedded cooling — directly etching microfluidic structures onto the chip substrate to deliver liquid coolant near hot spots — can use water as a coolant to achieve heat flux dissipation of up to 3,000 W cm−2."
Principles of embedded cooling technology
The team chose HFE-7100 as a dielectric coolant and designed the system around the liquid's phase change from liquid to vapor. Researchers fabricated the cooling structure using techniques widely employed in electronics manufacturing. Near the test chip's heating region, in addition to creating channels, they designed a manifold to distribute incoming coolant and collect fluid exiting the channels. This configuration combines horizontal inlets and vertical outlets. Fresh liquid enters horizontally to replenish coolant, while vertical channels facilitate vapor removal. HFE-7100 absorbs heat as it boils inside the channels, and the resulting liquid–gas mixture then exits through the outlets, carrying away energy.
The researchers stated: "The core of enhanced heat transfer lies in the engineered horizontal manifold, designed with horizontal inlets to promote liquid replenishment and vertical outlets to accelerate vapor removal." Preliminary tests recorded a critical heat flux of 1,570 watts per square centimeter, a value marking the threshold where boiling no longer provides effective cooling. This figure describes heat transfer per unit area, not total heat removal from the entire chip. The researchers reported that previous dielectric cooling technologies were typically limited to below 1,000 watts per square centimeter, even with pre-cooling and pre-pressurization.
Future applications and challenges
The researchers noted: "Because our approach uses microelectromechanical systems technology, it can integrate directly with standard semiconductor processes and scale for future electronic products." Further testing on commercially available devices and long-term operation remains necessary to determine performance and reliability. These experiments will clarify how effectively the design handles heat in real electronic systems. Dielectric liquids reduce the risk of short circuits, although their cooling performance is typically lower. The study was published in the journal Nature Electronics, examining a trade-off in chip cooling: water removes heat effectively, but dissolved impurities can make it electrically conductive.
Impact of new cooling technology on electronic products
As electronic device performance improves, heat dissipation issues are becoming increasingly prominent, and embedded cooling systems offer an effective solution. This technology not only increases heat flux but also reduces short-circuit risk, bringing potential advantages for future electronic product design. Although current test results show good cooling performance, further long-term testing is still needed before commercial application to ensure reliability and performance, which is crucial for advancing future electronic technology.