Find the limiting material or interface
Components, die attach, wire bonds, finishes, coatings and connectors may set the practical limit. Define continuous and transient temperatures and consider oxidation, diffusion, electrical leakage and mechanical stress as appropriate to the construction.
Select compatible circuit processes
Thick-film, thin-film and co-fired systems have different conductors and interfaces. Review their behavior at the intended temperature and atmosphere. A process proven at assembly temperature for a short time is not automatically proven for long service exposure.
Test duration as well as temperature
Qualification should include the relevant exposure time, cycling, electrical bias and environment. Monitor functional drift and insulation performance. Avoid claiming that an entire PCB operates at the temperature used to sinter its ceramic.
Engineering example
A ceramic body may remain physically intact while a resistor drifts or an attachment degrades. Functional measurements during and after exposure are essential to a useful qualification.
Before you release the design
- Separate manufacturing, transient and continuous temperatures.
- Review every component and interface.
- Define time, bias and environment for qualification.
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.