Describe the operating mission
Vehicle load varies, creating power and temperature excursions. Record relevant current, switching conditions, cooling temperature and expected cycling. Use those conditions to identify whether ceramic cracking, die attachment or another interface is likely to limit reliability.
Compare qualified substrate systems
Evaluate silicon nitride, AlN or other candidates at thicknesses that meet electrical and mechanical requirements. Include copper geometry, attachment and cooling. A comparison of bulk conductivity alone misses much of the design problem.
Validate the integrated module
Terminals, die attach, encapsulation and thermal interfaces interact with the substrate. Define power-cycle, temperature-cycle and electrical tests using the final package. Any supplier qualification must apply to the relevant construction and controlled manufacturing process.
Engineering example
If a prototype’s hottest operating point is acceptable but repeated load transitions damage the attachment, a steady-state thermal improvement alone may not resolve lifetime. Investigate the cyclic strain path.
Before you release the design
- Record the vehicle mission profile and cooling conditions.
- Specify module voltage and insulation function.
- Compare failure modes, not just cycle counts.
Sources and further technical reading
Manufacturer references support the material and process context. Worked examples and checklists are engineering guidance; they are not test results or supplier guarantees.