Integrated cooling concepts for printed circuit boards

Thermal management plays an increasingly dominant role in the design process of electronic products. Component sizes decrease while performance and functional demands increase, resulting in more power dissipation on smaller surfaces. In an effort to cope with these growing thermal challenges, industry continuously seeks cooling equipment with improved heat transfer performance. However, as thermal engineering is traditionally considered toward the end of the design process, the applied cooling solutions are often simply mounted onto the product. As such, cooling equipment for electronics is growing out of proportion compared to the electronic component it is supposed to cool. This thesis describes the development of innovative cooling concepts for electronic products. Thermal criteria are considered during the conceptual design phase, in order to find more integrated solutions. This multidisciplinary approach strives to develop improved thermal management systems for electronic products, in terms of thermal performance, compactness and flexibility. To develop a cost efficient solution focus is also put on utilizing standardized electronic manufacturing processes, such as Printed Circuit Board (PCB) and Surface Mounted Device (SMD) production technologies. Cost considerations for high product volumes, enabling mass-market applications, are especially taken into account. This research has led to the identification of two promising cooling concepts for electronic products. The first concept – directly injected cooling – is based on (jet) air cooling. By manufacturing a coolant inlet port into the PCB underneath an electronic component, this component can be cooled directly from the bottom side. This concept excels in the area of high component density cooling, where many components on an electronic board must be cooled both independently and simultaneously. The second concept – integrated heat pipe cooling – integrates a passive, twophase heat transport device directly into the PCB. As the heat transfer mechanism is based on phase change principles, it is capable of transporting large quantities of heat. The heat pipe is constructed inside the laminated structure that makes up the electronic board. This concept allows heat, dissipated by (multiple) components mounted onto the PCB, to be transported through the board structure with a very high efficiency. For both concepts detailed analysis and experimental investigation have been conducted. Both concepts show promising results compared to state-of-the-art cooling systems, in terms of thermal performance and flexibility. The integrated design also leads to a lighter and more compact electronic product. As thermal management systems are produced integrally, a significant cost reduction is reached. This is especially true for high volume production, where electronic manufacturing technologies, such as PCB production and SMD assembly, are appreciated for their low recurring cost. In the future, this allows engineers to design electronic products featuring full integration of thermal management systems and electronic circuitry. This research pushes the boundary further toward more functionality in a smaller form factor for electronic products at a lower cost.