Replace a broad label with a layer requirement
Heavy copper describes a construction using relatively thick conductors, but the label alone is not a complete purchasing specification. State the required copper on each layer and clarify starting foil versus finished copper. Outer-layer plating can make those different quantities.
Define the actual electrical objective: current, voltage drop, loss and allowed temperature rise under relevant operating conditions. More copper can improve one part of the path while leaving a connector, component lead or narrow transition as the limiting feature.
Review geometry and manufacturing together
Thicker copper affects the relationship between etching, conductor shape and achievable spacing. Dense signal features and large power conductors may require different compromises within the same board. Ask the fabricator to review the finished geometry rather than applying thin-copper design rules unchanged.
Multilayer constructions also need a suitable dielectric and bonding arrangement around the copper pattern. Consider copper distribution, resin fill and stack symmetry. A requested copper weight does not establish that every outline, hole size and fine feature can be manufactured in that construction.
Follow power through every transition
Review plane connections, neck-downs, vias, terminals and contact interfaces. Use realistic finished conductor dimensions in loss and thermal models. Increasing plane copper does not automatically increase hole-wall copper or qualify a via array for the same current.
Assembly thermal mass can also change soldering behavior. Coordinate land design, thermal connections, component limits and the proposed soldering process. A process that worked on a lighter prototype construction may require revalidation on the production board.
Agree the build and verification package
Supply the layer-by-layer copper requirement, stackup, critical geometry and load conditions for quotation. Request confirmation of the proposed fabrication route, any design adjustments and the evidence needed for copper and interconnect acceptance.
Validate representative boards under the intended load, cooling and enclosure conditions. Check temperature and voltage drop at relevant locations, including transitions. Release substitutions only after evaluating their effect on the complete assembly; an advertised maximum copper weight is not a guarantee for an unreviewed design.