Need for Thermal Management in Electronic Systems
Consumer demands have been driving the design of new products in the electronics industry, and the industry has responded to market expectations by offering products that are smaller and more powerful. The need for greater miniaturization and ongoing performance enhancements contribute exponentially to increased power consumption and heat generation within the system. The high heat generation has adverse effects on the user’s health and product’s reliability and performance, creating the essential need for thermal management in all electronics products.
Consumers are more exposed to potential health problems when they are required to use electronics products close to their bodies (e.g., when a consumer wears an AR/VR headset). The possible adverse effects of heat generation by headsets include skin problems like burns or rashes, ear infections, and brain-related issues. (Source Trendshealth).
Thermal Management – History and Challenges
Thermal management is the ability to control the temperature and noise level of a system by means of technology based on thermodynamics and heat transfer. Advancements in the electronics industry have led to an increased need for innovative thermal management technologies to improve the system performance and reliability by removing high heat flux generated in the electronic devices. According to Thermal News, the thermal management market is expected to grow from $8.8 billion in 2013 to $15.56 billion by 2018 with a growth rate of 12.1%. (Thermal management includes the use of material, technologies, and tools to regulate excess heat generated).
The boom in the electronics industry demands innovative cooling solutions to meet the thermal management challenges. Those challenges can be understood by the wide range of heat generated by the electronic devices which varies from 5W/cm2 on a Printed Wiring Board (PWB) to 2000W/cm2 for a semiconductor laser. Traditional cooling methods can work for the former heat flux, but for the latter heat flux, more innovative solutions are a must.
In most cases, the junction temperature of the chip must be maintained below the allowable limit specified by the vendor for both performance and reliability. Reliability is defined as the probability that a device will perform its required function under stated conditions for a specific period. Product reliability is the most important factor in determining the quality and superiority of a product/technology.
Other thermal management challenges are:
- Reduced form factors
- Harsh environments
- Reducing product cost
- Reliability and performance constraints
- Meeting stringent standards
- Developing advanced technologies and materials
- Increasing consumer demands and needs
Thermal Management Solutions
The latest thermal management technologies function around basic heat transfer modes – i.e., conduction, convection, and radiation – and the development of technologies is moving from single-phase heat transfer to multi-phase heat transfer. The cooling technologies such as thermal vapor chamber, cold plates and jet impingement mechanisms have revolutionized the future of the thermal management landscape.
New coolants (like nanofluids and ioNanofluids) with superior thermal properties are replacing the conventional coolants. The modern CFD simulation software developed for challenging problems predicts the temperature and airflow distribution, which helps determine high-temperature locations and airflow deficiencies. This software can also be used to study the cost-effectiveness of the modifications to find ways to increase the cooling efficiency, according to “Using CFD for optimal thermal management and cooling design in data,” Siemens.
Main Cooling Methods in the Thermal Management Industry
Conduction cooling: Heat transfer from a hotter part to a cooler part by direct contact. Commonly used methods in conduction cooling are conduction in chip carriers, conduction in PCBs, usage of heat frames and thermal conduction modules.
Air cooling via natural convection and radiation: Natural convection is based on the fluid motion caused by the density differences in a fluid due to a temperature difference. The higher the fluid flow rate, the higher is the heat transfer rate. The fluid velocities associated with natural convection currents are naturally low, and thus natural convection cooling is limited to low-power electronic systems.
Air cooling via forced convection: Forced convection includes the addition of an air mover to blow the air through the surrounding electronic components to increase the fluid flow rate which, in-turn, increases the heat transfer rate. Forced convection is up to 10 times more effective than natural convection.
Liquid cooling: Because liquids have much higher thermal conductivity rates than gases, liquid cooling is far more effective than gas cooling. However, due to the possibility of leakage, corrosion, extra weight and condensation, liquid cooling is preferred for applications that involve power densities that are too high for safe dissipation by air cooling.
Immersion cooling: High-power electronic components can be cooled effectively by immersing them in a dielectric liquid and taking advantage of the very high heat transfer coefficients associated with boiling.
Advanced cooling technologies include cryogenics, refrigerant, hybrid, micro channel, spray and cold-plate cooling.
A few thermal conditions need a mix of cooling technologies. Common hybrid cooling technologies are electro wetting, spot cooling, heat pipes, compact heat generator, vapor-chamber cooling, phase change material, micro TECs, eTECs (embedded TECs), and jet impingement cooling. (source: Chapter Cooling of electronic equipment, Heat and Mass Transfer, by Yunus A. Cengel & Afshin J. Ghajar)
Cooling technologies are advancing at a good pace but need to develop further to solve the evolving thermal management challenges facing the electronics industry due to its explosive growth. In response, Molex has been working continuously toward innovative thermal management solutions, and product reliability is the focus of research. Discover more about Molex thermal management capabilities for the next generation of data centers.
To find out how Molex thermal management capabilities can help your organization, contact us at molex.com for more information.