Sometime electronics demand high-performance and durable PCB designs, manufacturers have adopted various advanced techniques to enhance functionality. One such crucial technique is PCB Edge Plating, also known as castellated holes, edge metallization, or side plating.
Edge plating is a process where copper is plated along the edges of the PCB, creating electrical and mechanical connections between layers while improving durability. It is widely used in RF circuits, high-current applications, and module-to-board interconnections.
What is PCB Edge Plating?
PCB Edge Plating is the process of applying copper plating to the edges of a PCB to create an electrical or mechanical connection. It is often used in:
PCB Edge Plating is the process of applying copper plating to the edges of a PCB to create an electrical or mechanical connection. It is often used in:
- RF and microwave circuits to improve signal integrity and grounding.
- Power PCBs to carry high currents more efficiently.
- Connector and module interfaces to provide stronger mechanical support and reliable electrical contact.
Edge plating is especially helpful when PCBs need to be connected to metal housings, shields, or stacked with other boards. Refer to Fig.52 for edge plated PCB example
Fig.52 :Edge Plated PCB
Why is PCB Edge Plating:
In the past, designers used standard vias or edge connectors to improve electrical and mechanical properties. However, these methods had limitations:
- Vias required extra routing space, making the PCB larger.
- Edge connectors were not strong enough for high-current or rugged applications.
- Edge plating solves these problems by providing a seamless, strong connection directly on the PCB edge.
Importance of Using Edge Plating
- Better Grounding & EMI Shielding – Essential for RF and high-speed circuits to prevent signal interference.
- Stronger PCB Structure – Prevents delamination and mechanical damage, making PCBs last longer.
- Improved Power Handling – Helps distribute high currents more efficiently in power applications.
- Seamless Module Integration – Used in castellated PCBs, where one board is soldered onto another.
How is PCB Edge Plating Implemented?
Preparing the PCB Edges
Before plating, the PCB edges are precisely milled or routed to ensure they are smooth and even. This helps copper adhere properly during plating.
Copper Plating the Edges
The PCB is then placed in a copper electroplating bath, where a thin layer of copper is applied chemically and then built up using electroplating.
Surface Finishing
To prevent oxidation and improve soldering, a protective surface finish is applied. Common options include:
Testing and Inspection
Once the plating is done, the PCB is checked for:
- Copper adhesion: Ensuring the plating is uniform and won’t peel off.
- Electrical continuity: Verifying that the plating provides a strong electrical connection.
Advantages of PCB Edge Plating
- Better Electrical Performance
- Improves grounding and reduces signal interference in high-frequency applications.
- Stronger PCB Structure
- Protects edges from cracks, peeling, and damage.
- Better Power Handling
- Supports higher current flow and improves heat dissipation.
- Stronger Connections for PCB Modules
- Ensures secure and reliable soldering for stacked PCBs and connectors.
- Improved Corrosion Resistance
- Protects copper from oxidation and environmental damage.
Challenges and Disadvantages of Edge Plating
- Higher Manufacturing Cost
- Extra plating and processing steps increase PCB production costs.
- More Complex Fabrication
- Requires precise edge milling and plating, making it harder to manufacture.
- Risk of Copper Peeling
- If not done correctly, the plating can peel off, affecting performance.
- Not Needed for All Designs