Follow the complete heat path
Heat generated by a component must move through its package and the surrounding structure to the environment. The PCB, copper planes, thermal interface, enclosure, heat sink and airflow can all contribute. Improving one part of that path may have little effect if another part remains the main restriction.
Start with the operating conditions and power dissipation, then identify the component temperature limits and the thermal path you intend to use. Validate the result in the intended enclosure and loading conditions rather than treating a material label as a temperature guarantee.
Different structures solve different problems
- Copper areas and thermal vias help move heat through and across a PCB construction.
- A metal-core board uses a construction with a metal base and an insulating dielectric; the detailed stack matters.
- A heat spreader distributes heat over a larger area or to another structure.
- An external heat sink transfers heat to the surroundings through a defined attachment and environment.
For exposed-pad devices, follow the package-specific land, connection and assembly guidance. TI’s PowerPAD application report illustrates how a soldered exposed pad and the PCB’s thermal structure work together. Its example dimensions are not universal rules for every package.
Avoid misusing a single thermal number
Package thermal figures depend on the measurement or modelling conditions. TI’s semiconductor thermal-metrics guide explains the limits of applying these figures to a different board and system. Use the appropriate device data and a thermal analysis for the actual construction.
Keep electrical requirements visible during thermal design. A conductive attachment or thermal pad may need a particular electrical connection or isolation arrangement. Confirm those requirements from the device and system design.
What to include in a manufacturing inquiry
Supply the stackup, copper requirements, thermal-via details, any specified filling or capping, mechanical interfaces and assembly drawings. For a metal-core construction, identify the required dielectric and electrical isolation requirements as well as the metal base.
If a heat sink is part of the build, provide its part number, mounting method, interface material and acceptance criteria. Explain which thermal requirements are already validated and which still need engineering review.