Specify a complete ceramic/conductor system
HTCC often uses alumina-based ceramics with tungsten or molybdenum metallization. Other qualified systems exist. Conductors, vias, cavities and ceramic tapes must be compatible during firing. A generic high-temperature label is not a substitute for a controlled material specification.
Plan external attachment
Internal conductors and external pads serve different functions. Finished pads may require plating for soldering, wire bonding or brazing. Seal rings, leads and lids introduce additional expansion and hermeticity requirements. Include these components in the mechanical drawing and test plan.
Separate firing temperature from use temperature
A substrate surviving a manufacturing furnace does not mean the assembled package can operate at that temperature. Die attach, metallization, seals, wires and components can set much lower limits. Qualify the actual assembly at the intended conditions.
Engineering example
A hermetic package may have a sound ceramic body but leak at a lid seam or feedthrough. Test the completed sealed package using the specified method and acceptance criteria.
Before you release the design
- Specify ceramic and co-fired conductor materials.
- Define cavities, vias, external plating and seal interfaces.
- Set finished-package electrical and leak-test requirements.
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.