Draw a section through the actual construction
For a power substrate, identify top copper, ceramic and bottom copper. Add braze or adhesion layers when their control is relevant. For LTCC or HTCC, identify fired tape layers, internal conductors, vias, cavities and external pad finishes. Distinguish conductive layers from dielectric layers.
Use finished dimensions
Bare ceramic thickness, finished metal thickness and final assembly thickness are different dimensions. Define tolerances, measurement locations and whether surface finish is included. Local pads, cavities and stepped features need separate dimensions rather than a single overall thickness callout.
Connect the stack to performance
Thermal, insulation, RF and mechanical requirements all depend on construction. Freeze the stack-up before detailed layout and require review for substitutions. Include an explicit revision and approved manufacturer drawing so quoting and production use the same definition.
Engineering example
A Cu/AlN/Cu power substrate and a multilayer HTCC package can both be called ceramic boards, yet their via formation, conductor materials and cost structures are fundamentally different. A cross-section prevents the ambiguity.
Before you release the design
- Label every layer and its role.
- Specify finished thicknesses and tolerances.
- Control revisions and material substitutions.
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.