To help you better understand how to optimize your components and thermal management systems, this article outlines the main aspects of thermal performance in electronics and identifies key parameters that can be manipulated at the component level to enhance system versatility and performance.
Intro to Thermal Resistance in Modern Electronics
Mar 19, 2021
As devices become more powerful and compact, optimal thermal management of electronics has remained a continuous challenge for engineers across nearly every industry. While there are many creative solutions for moving heat away from high-temperature components, such as fans, liquid coolers, heat pipes, and more, advances are also being made to the components themselves to optimize a system’s thermal performance at the foundational level.
Table of Contents
Operating Ambient Temperatures in Thermal Design
When designing an end product like an IoT device, medical tool, or industrial sensor assembly, nearly every component has a maximum ambient operating temperature as a defined parameter. This maximum ambient temperature is set by the component manufacturer to ensure acceptable device performance and to prevent physical degradation. For example, some switching transistors can handle very high power loads, but if exposed to excessive ambient temperatures, they can damage their internal semiconductor junctions. Additionally, temperature directly affects the conductive properties of materials and can alter or degrade component performance if the maximum operating temperature is exceeded.
Moving Heat Away from the Source: Heat Transfer Fundamentals
For devices with fixed internal power dissipation and ambient temperature limits, as is common in most power conversion devices and ICs, the surface temperature of the case depends on the internal thermal resistance and the efficiency of heat transfer to ambient. Internal thermal resistance measures how effectively heat is conducted from the source to the device surface.
When discussing thermal management, the focus is often on a component’s effectiveness in transferring heat to ambient – via convection, conduction, and/or radiation. These methods often rely on passive heat exchangers, fans, liquid cooling systems, heat pipes, heat sinks, and similar solutions.
Therefore, the best way to maintain an acceptable case temperature is to optimize both the internal thermal resistance of the device and its heat transfer to the ambient environment. A thermally ideal device would have zero thermal resistance and infinite heat dissipation to the environment. However, since components are made from real-world materials – each with unique thermal resistance properties – and no system can perfectly transfer heat, designers must optimize the thermal performance of every critical component from the earliest stages of design.
When discussing thermal management, the focus is often on a component’s effectiveness in transferring heat to ambient – via convection, conduction, and/or radiation. These methods often rely on passive heat exchangers, fans, liquid cooling systems, heat pipes, heat sinks, and similar solutions.
Therefore, the best way to maintain an acceptable case temperature is to optimize both the internal thermal resistance of the device and its heat transfer to the ambient environment. A thermally ideal device would have zero thermal resistance and infinite heat dissipation to the environment. However, since components are made from real-world materials – each with unique thermal resistance properties – and no system can perfectly transfer heat, designers must optimize the thermal performance of every critical component from the earliest stages of design.
Fixed Variables in Thermal Management Systems
As many designers know, various application parameters are often fixed and must be accommodated in the design. In some cases, a component’s efficiency, ambient temperature, and the system’s heat transfer mechanisms are determined by the end application. Often, the only way to achieve acceptable operating conditions and maintain low case temperatures is to select components with improved internal thermal design and lower internal thermal resistances.
Optimized Internal Thermal Resistance
Two critical parameters represent the overall thermal resistance of a component and the resulting operating temperatures of the thermal source and case: Ψjt and θja. Both Ψjt and θja are specific resistance parameters unique to each component and vary across different packaging methods. Ψjt is a thermal characterization parameter measuring multi-path thermal flow between the heat source and package surfaces, while θja represents the straight-line thermal resistance from the heat source to ambient. Ψjt is power-dependent, and an increase in Ψjt at higher power dissipation and case temperatures can reduce device performance. Even if Ψjt is optimized, a high θja can lead to excessive case temperatures and restricted ambient operating ranges.
Many improvements can reduce Ψjt and θja, including material selection, manufacturing techniques, and various junction-to-ambient heat transfer methods. A recent advance in thermal resistance reduction is 3D Power Packaging®. Using 3DPP techniques such as FCOL, embedded ICs, thermal vias, and more, RECOM has achieved significant improvements in Ψjt and θja values. By lowering these values in 3DPP products, higher power performance is possible without limiting the device’s ambient temperature. High power density 3DPP solutions are designed for high-performance, high-efficiency devices without requiring active cooling or large passive heat sinks.
For more information on RECOM’s advanced 3DPP technology and the importance of low thermal resistance in high-efficiency power designs, visit our 3DPP applications page or order the RECOM 3DPP evaluation board by contacting info@recom-power.com.
Many improvements can reduce Ψjt and θja, including material selection, manufacturing techniques, and various junction-to-ambient heat transfer methods. A recent advance in thermal resistance reduction is 3D Power Packaging®. Using 3DPP techniques such as FCOL, embedded ICs, thermal vias, and more, RECOM has achieved significant improvements in Ψjt and θja values. By lowering these values in 3DPP products, higher power performance is possible without limiting the device’s ambient temperature. High power density 3DPP solutions are designed for high-performance, high-efficiency devices without requiring active cooling or large passive heat sinks.
For more information on RECOM’s advanced 3DPP technology and the importance of low thermal resistance in high-efficiency power designs, visit our 3DPP applications page or order the RECOM 3DPP evaluation board by contacting info@recom-power.com.