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PCB Edge Plating

Published Date
Author Cadence PCB Solutions

Key Takeaways

  • Edge plating, also known as castellation or side plating, involves applying a metallic coating to the exposed copper connections along the edges of a PCB to enable electrical connections.

  • The advantages of edge plating include EMI shielding, improved chassis grounding, increased structural rigidity, and consistent electrical connections along the edge of the PCB.

  • The electroplating materials used in edge plating are copper, gold, silver, tin, and nickel. There are three types of edge plating: regular plane edge plating, wrapping edge plating, and tooth edge plating.

PCB with edge plating used as a connector

PCB with edge plating used as a connector

PCB edge plating is the process of applying a metallic coating to the exposed copper connections along the edges of a printed circuit board (PCB) to facilitate electrical connections. This metallic coating is often called edge plating, castellation, or side plating. The copper edge plating extends from the top to the bottom surfaces of a PCB and runs along at least one of the board's perimeter edges. 

PCB Edge Plating Process Overview

Process Step

Description

Design

Designers specify which board edges require edge plating for connectors or components.

Panelization

For efficiency, multiple PCBs are often fabricated on a larger panel. The edge plating is applied to the entire panel and the PCBs are separated later.

Drilling Holes for Edge Contacts

Vias—drill holes—are created along the board's edges for edge contacts, providing access points for plating.

Surface Preparation

The PCB panel edges are cleaned, degreased, and sometimes roughened for good plating adhesion.

Electroless Plating

Through a chemical process, electroless copper plating is applied. This thin layer creates a foundation for subsequent plating.

Electroplating

Additional copper is electroplated onto the edges to achieve the desired conductivity and durability.

Etching

Through chemical etching, excess copper is removed, which defines and isolates copper traces for desired connections.

Tin or Other Finish

Optionally, a final finish like tin or gold can be applied to plated edges for improved solderability and corrosion resistance.

Routing and Separation

After edge plating, PCBs are separated individually by routing or cutting the larger panel, leaving desired copper-plated edges.

Quality Control

Quality control inspections ensure that the edge plating meets the required specifications for thickness and continuity.

Understanding PCB Edge Plating

Edge plating is used to plate the sidewalls of the PCB substrate with copper to encase the exterior of the PCB with this conductive material. This process is also known as metalized edge plating, border plating, plated contour, side plating, and castellation. Edge plating can be applied to single-axis or multi-axis edges of PCBs. 

Reasons for PCB Edge Plating 

  • EMI (Electromagnetic Interference) Shielding: Edge plating helps to reduce electromagnetic interference by providing a continuous conductive path along the edges of the PCB, which mitigates EMI.

  • Improved chassis grounding for signals.

  • Increased structural rigidity, making the PCB more resistant to bending and warping, an important quality for larger or more rigid PCBs.

  • It ensures that the electrical connections on the edge of the PCB are reliable and consistent.

Materials Used in PCB Edge Plating

The electroplating materials used in this process include copper, gold, silver, tin, and nickel. PCB edge plating is further categorized into three distinct types:

  1. Regular plane edge plating

  2. Wrapping edge plating

  3. Tooth edge plating

PCB Edge Plating Application Methods

There are two ways to add edge plating:

  1. Applying the edge plating as an independent copper structure that is isolated from other copper pours on the PCB. This technique creates a guard ring around the perimeter, a common practice when establishing a chassis ground connection.

  2. Encircle the edge of the PCB with a polygon pour layer that extends back to the opposite surface layer. This technique establishes a system ground connection, and it requires the same clearance on the top layer as the previous method. 

Using Cadence AWR Software for Relevant Simulations

Ready to harness the full potential of PCB edge plating and its remarkable advantages? Dive into the world of advanced PCB design and RF simulation with Cadence’s software suite. With Cadence AWR software, you can seamlessly integrate EMI mitigation strategies and conduct essential simulations for your RF designs.

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