How to Design PCB Edge Plating?

June 5, 2025

Today, we will share about: PCB edge plating, types of PCB edge plating, and how to design PCB edge plating.

1. What is PCB Edge Plating?

PCB edge plating, also known as edge coating, refers to the copper plating that extends from the top to the bottom surface along at least one peripheral edge of the board. This plating enhances the PCB's solid connections and reduces the likelihood of equipment failure, especially in small PCBs and motherboards. Such plating is commonly found in Wi-Fi and Bluetooth modules. During the manufacturing process, the edges to be metallized should be milled before the copper plating process. After copper deposition, appropriate surface treatment is applied to the PCB edges.

PCB design: Based on the circuit schematic diagram and functional requirements, use EDA (Electronic Design Automation) tools to design the layout and routing of the PCB.

Package library production: Produce and maintain component package libraries to ensure the accurate placement and connection of components on the PCB.

SI/PI simulation: Conduct signal integrity (SI) and power integrity (PI) simulation analysis to optimize PCB design to meet the requirements of high-speed signal transmission and electromagnetic compatibility (EMC).
PCB board delivery: Submit the designed PCB files to the board manufacturer for production, and track the progress and quality of the board delivery.

Testing and Verification: Test and verify the fabricated PCBS to ensure they meet the design requirements and functional specifications.

Technical support and assistance: Provide technical support and assistance in PCB design for the project, and solve technical problems in design and production.

Document writing: Write PCB design documents, test reports, user manuals, etc.

What does PCB mean?

What is a high-speed and high-frequency PCB board?

PCB (Printed Circuit Board, printed circuit board), because it is made by electronic printing technology, is called a "printed" circuit board. PCB circuit boards are hidden in various IT and electronic devices, ranging from servers to smart terminals, from electric vehicles to satellite communications, serving as the "carrier" for signal transmission and connecting hundreds or even thousands of components.

2. When to Use PCB Edge Plating?

Edge plating is implemented under the following circumstances:
To enhance the electrical conductivity.
Connections are required at the PCB edges.
To prevent lateral impacts.
Secondary PCBs connect to the motherboard via edges.
Edge soldering is needed to improve assembly.

3. Types of PCB Edge Plating

(1)Surround Edge Plating

Surround plating involves routing along the metal edges after drilling. This process exposes the PCB sidewall to chemical plating with copper, allowing simultaneous application during drilling.
This case creates a conductive surface for applying thicker, more durable copper layers with better adhesion.

(2)Copper Board Edge

To prevent copper damage, a minimum distance between copper features and the PCB edge is typically required:
Outer layer: 0.25 mm
Inner layer with break: 0.40 mm
Break on all layers: 0.45 mm

The distance should only apply to planar and large copper areas, where minor copper damage does not affect performance.

If pads are found within the minimum distance of the board edge, they will be cut back to restore the minimum copper-free space, unless:
the pads are part of the edge connector (usually with beveled edges),
the pads are marked "up to the edge of the circuit board" in a separate mechanical layer,
and the cutting exceeds 25% of the pad surface. In this case, it is actually quite abnormal.

(3) Board Edge PTH

Board edge PTH refers to plated holes cut into the edge of the circuit board, also known as butterfly holes, used for direct soldering or connecting two PCBs. Adequate free space must be maintained at the PCB edges during manufacture to secure the PCB in the production panel.

The top and bottom layers must have pads to firmly fix the electroplating onto the circuit board. For smaller sizes, gold surface treatment is preferred.

Here are some points to note:
1.The edges of the PCB must have sufficient free space so that we can fix the PCB in the production panel during the manufacturing process.
2.Solder pads must be placed on the top layer and the bottom layer (and possibly the inner layer) to firmly fix the electroplating onto the PCB.
3.As a general rule, the holes should be as large as possible to ensure good soldering with the master PCB.
4.It is recommended that they be 0.80 millimeters or larger. All surface treatments are fine, but I prefer to choose gold over nickel for smaller sizes.

(4) Round Edge Plating

Round edge plating means plating most or part of the PCB or cutout from the top surface to the bottom. This is primarily for establishing good grounding for metal enclosures or shielding. The PCB profile must be milled before through-hole plating, as 100% edge plating is not feasible during the processing due to securing the PCB in the production panel.

4. How to Design PCB Edge Plating?

1. PCB Edge Plating Guidelines

Use overlapping copper in the design/layout files to define the copper plating area. This extra copper can be copper pads, surfaces, or traces. The minimum overlap should be 500 μm, and connecting copper lines must be defined at a minimum of 300 μm.

(2) Metallization Plating Process

Follow these four steps in sequence:
Drill
Mill metal grooves
Remove dirt
Chemical copper plating

(3)Manufacturing Issues

1.Copper Peeling: Insufficient adhesion may cause copper to peel off. This can be resolved by roughening the surface using chemical and proprietary methods.
2.Burrs: Edge plating may cause burrs during final processing, requiring a modified proprietary process to polish them to the feature edges.

5. Benefits of PCB Edge Plating

1.Enhanced Current Conductivity: Improves current-carrying capacity, enhancing reliability and quality.
2.Signal Integrity: Prevents interference and enhances signal integrity.
3.Heat Distribution: Provides additional cooling surface area to dissipate heat efficiently.

6. Applications of PCB Edge Plating

Enhances EMC performance by shielding internal areas of multilayers, serves as an additional cooling surface, and connects boards via active cooling enclosures.

This concludes our overview of PCB edge plating design and its applications.