RestrictCopper layer

The RestrictCopper layer defines areas on a PCB where copper is not allowed. Any copper object—trace, polygon fill, pad, or via—that overlaps a restrict area on one of its targeted routing layers is flagged as a design rule violation.

Use restrict areas when a region of the board must remain copper-free for mechanical, electrical, or RF reasons. Common use cases include:

• keeping copper away from antenna structures to avoid detuning,
• maintaining clearance underneath connectors or mechanical mounting hardware,
• creating keep-away zones around high-voltage components,
• preventing copper fill in areas reserved for fiducials, tooling holes, or test points.

Targeting routing layers

Each restrict object targets one or more signal layers through the Restricted Layers property. A single restrict area can apply to any combination of routing layers—for example, restricting only the Top layer while leaving inner layers free, or covering Top, Route2, and Bottom simultaneously.

This per-object layer targeting means you can define highly specific routing constraints without creating separate restrict areas for each layer.

Drawing restrict objects

Restrict objects are drawn on the RestrictCopper layer. Fusion supports polygons, rectangles, circles, and wires on the RestrictCopper layer, so you can match the shape of the restrict area to the geometry of the component or region you are protecting.

Visibility

The RestrictCopper layer visibility toggle in the Display Layers panel controls restrict object visibility in two distinct modes:

• RestrictCopper eye on: The layer acts as a master override. All restrict objects are visible regardless of whether their targeted routing layers are hidden.
• RestrictCopper eye off: Granular visibility applies. Each restrict object follows the visibility of its targeted routing layers—the object is hidden only when every one of its targeted layers is hidden.

Legacy layers: RestrictTop and RestrictBottom

Older Fusion designs used two separate copper restriction layers—RestrictTop (tRestrict) and RestrictBottom (bRestrict)—one for each outer layer. These layers are deprecated and replaced by the unified RestrictCopper layer with per-object Restricted Layers targeting.

Migration on load

When you open a legacy design, Fusion migrates restrict objects automatically:

• Objects on RestrictTop are kept on the RestrictCopper layer and assigned Restricted Layers = Top.
• Objects on RestrictBottom are moved to the RestrictCopper layer and assigned Restricted Layers = Bottom.
• If identical geometry exists on both RestrictTop and RestrictBottom (a common pattern in legacy files), the duplicate is merged into a single object whose Restricted Layers combines both targets.

No manual action is required. The migrated design behaves identically to the original for DRC purposes.

Saving files with legacy content

If a migrated design has not had any inner-layer restrictions added or modified, Fusion saves it back in the legacy format, preserving compatibility with older versions.

If the design contains any restrict object that targets inner routing layers, Fusion saves in the new format and displays a warning:

This design uses inner layer routing restrictions which are not supported in older versions of Fusion. Saving in the new format will make this file incompatible with older versions.

Design Rule Check enforcement

When you run a Design Rule Check (DRC), Fusion reports a violation for every copper object that overlaps a restrict area on one of its targeted layers. Restrict areas do not affect via placement. Via exclusions are managed separately using the RestrictVias layer.