Edge plating (also known as side plating or edge metallization) is a PCB manufacturing process where a continuous conductive layer is plated along the outer perimeter of the board. This process creates electrical connectivity between internal and external copper layers at the board edge.
Board edges are milled, deburred, and chemically prepared, followed by electroless and electrolytic copper deposition to form a continuous conductive layer. An optional surface finish (e.g., ENIG) may be applied to ensure oxidation resistance.
Edge plating is used to improve electrical connectivity along PCB edges while enhancing mechanical strength. It also enables effective grounding, EM shielding, and reliable edge-based interconnections.
In addition to outer board edges, internal routed slots can also be edge plated. These structures are commonly used in RF and high-speed designs to form shielding walls, controlled ground paths, and isolated cavities within the circuit board.
Key design considerations for edge plating
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Keep at least 10 mil spacing between edge plating and nearby copper features. Ensure internal power planes are adequately pulled back to avoid unintended connections.
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Extend copper features (planes or polygons) 2 - 3 mil beyond the board edge to account for etch tolerances and ensure a reliable connection to the edge plating.
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Remove solder mask where side plating interfaces with enclosures or connectors. Maintain a typical pullback of 20 - 50 mil and ensure consistency on both sides.
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Do not place vias or critical components too close to the board edge. Provide cutouts in plating where required for edge-mounted connectors (e.g., SMA).
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Include panel tabs (solid and perforated), unplated segments, or temporary jumpers to support the board during plating. Keep these away from critical areas and define them clearly in production files.
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Clearly specify which PCB edges need plating and include diagrams if only certain edges should be plated. Indicate layer connections, copper thickness, jumper locations, surface finish (e.g., ENIG), and special requirements in the fab notes.
Note: Edge plating is different from castellations. While both involve copper at the board’s edge, castellations are partially plated holes used for module soldering, whereas edge plating forms a continuous conductive layer along the board’s perimeter.