Why is temperature of printed boards so important?
Because there are limiting temperatures for operation:
- Secure maximum operational temperature of components
- Glass transition temperature of the board material
- Stability of solder joints
Why should temperature be known as good as possible?
Because too many items depend on temperature:
- Material properties, e.g. electric resistance of traces and thus voltage feed or impedance for transmission of signals
- Performance of components
- Derating of power for hot ambients needs knowledge of component temperature
Why don't simplifying spread sheet calculations work?
Because the local thermal conductivity (the artwork) controls the temperature of a component. It is impossible to include copper patterns, drills and influence from other components in a simple formula, a data sheet or a simple network. Better do a holistic simulation using dedicated software.