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Design007-June2021

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94 DESIGN007 MAGAZINE I JUNE 2021 All the above points could influence the effi- ciency of the design produced and there are arguments for the importance of each one. In my opinion, you can separate these out into two categories, with high priority items including the correct choice of materials, the overall layout of the PCB, and the temperature of the surrounding environment. Factors such as the overall size of the PCB, the amount of heat dissipated, and the mounting peripherals are perhaps less important because they will all be dependent on the design; in some cases, they may have a large impact and in others, a negligible effect. e main point is that none of these factors should be considered alone. To achieve good thermal management, a holistic approach must be taken with suitable thermal analysis to ensure the best overall performance is being achieved. Identifying Components Is it possible to identify components with the potential to dissipate more heat and factor this into the design process? By reviewing the power consumption of components, you may get an indication as to the potential heat generation of a component, but this is not an ideal method to use. Each PCB will be designed differently and have an array of components. It is how these compo- nents interact with one another and how heat can flow through the assembly that should be considered in detail during the design phase. For example, heat-sensitive components should not be placed next to components with high heat generation. Components with higher power consumption should be placed near heat-dissipating technologies. Wherever pos- sible, a relatively even heat distribution should be maintained rather than having "hot" and "cold" areas of the board. Using heat dissipating technologies, such as thermal interface materi- als, can assist in achieving this successfully. Thermal Analysis Tools What thermal analysis tools exist to identify thermal problems with a PCB? At a basic level, thermocouples can be used to measure the temperature of specific com- ponents or areas of a PCB. More recent tech- nologies consider the use of heat flow sensors to show the movements of thermal energy throughout the board and specifically through components. ey can be used to show the generation of heat by a specific component, and the ability of the component to absorb heat generated by an external source. ermal imaging can be used in a similar way to show the various temperatures across PCBs. Infra- red cameras also carry out thermal imaging of the board and individual components. ey can give a clear view on where heat is gather- ing within the device and help to show where additional heat dissipation may be required. Removing Heat What are the most common methods to remove heat from circuit boards? Heat dissipation can be achieved in a num- ber of ways. As we have already discussed, the design of the PCB can help to manage the heat flow across the board and ensure successful heat dissipation. Where heat generating com- ponents are present, a heat sink and thermal interface material may be effectively utilised. In addition, if thermal analysis shows that there are still areas of the PCB where heat may be gathering, thermal gap-filling compounds may offer additional heat dissipation. In other tech- To achieve good thermal management, a holistic approach must be taken with suitable thermal analysis to ensure the best overall performance is being achieved.

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