The overriding requirement for any thermal solution is to maintain the device temperature within operating specifications. However, for most applications, there are several other important considerations such as cost, area, weight, acoustical noise, reliability, ability to be manufactured, and many more. An optimal thermal solution balances all these requirements. However, in most applications these requirements are different, and some of these considerations could be more important than others. Other unique parameters of any given application are the operating environment and power consumption. Differences in local ambient temperature seen by the device, airflow variation, case and chassis size, orientation and configuration, and other parameters are often unique to a given design, as is the operational power depending on how the device is used. While devising a thermal solution, you should be mindful of all of these considerations and how they apply to the specific design to ensure the solution not only meets the thermal requirements, but also does so in a way that meets all of the goals and specifications for the system. The following figure demonstrates how the thermal design must balance many goals for any application.
Figure 1. Thermal Design Balancing Example