When designing a PCB, one of the critical decisions you’ll face is whether to use plated or unplated mounting holes. These holes are essential for securing the PCB to an enclosure or package, but the choice between plated and unplated holes depends on your design requirements, grounding needs, and mechanical considerations. Let’s explore the differences, advantages, and best practices for each type.

Plated vs. Unplated PCB Mounting Holes

Plated Through Holes

• Electrical Connection: Plated holes allow electrical connections between the PCB and the enclosure, making them ideal for grounding purposes.
• Grounding Options: Can be connected to system ground or chassis ground.
• Fastener Compatibility: Best used with metal screws, as they create a conductive path to ground. Can also be used with plastic screws or standoffs.
• Applications: Commonly used in designs requiring EMI shielding or grounding to reduce noise.

Unplated Through Holes

• Electrical Isolation: Unplated holes provide no electrical connection, making them suitable for designs where grounding is not required.
• Fastener Compatibility: Compatible with both plastic and metal fasteners. If metal screws are used, they will not connect to ground.
• Clearance Requirements: Must have sufficient clearance around the hole to prevent accidental grounding.
• Applications: Ideal for non-grounded applications or when electrical isolation is necessary.

Mechanical Strength: Plated vs. Unplated Holes

• Negligible Difference: The mechanical strength of plated and unplated holes is nearly identical. The rigidity of the PCB comes from the materials used in the stack-up, which harden during the curing process.
• Testing Considerations: Mechanical properties of the PCB materials should be considered during testing or simulation, as they determine the overall strength of the mounting holes.

Designing with Plated and Unplated Holes in OrCAD

In OrCAD, you can easily switch between plated and unplated mounting holes without updating the footprint in the library. Here’s how:

1. Modify Padstack:
   • In the PCB Editor, hover over the hole and select Modify Design Padstack.
   • Choose Single Instance to modify one hole or All Instances to update all matching holes.
2. Set Hole Type:
   • In the Padstack Editor, navigate to the Drill tab.
   • Select Plated or Non-plated and adjust other parameters like drill size and tolerance.
3. Update the Design:
   • Save the changes and select File/Update to apply the modifications to the PCB layout.
4. Net Connections:
   • For plated holes, use the Net Short option to connect the hole to a ground net or copper pour.
   • Right-click the plated hole, select Net Short, and click on the desired net or pour to complete the connection.

Key Considerations for Choosing Mounting Holes

• Grounding Requirements: Use plated holes if grounding is needed; otherwise, opt for unplated holes.
• Fastener Type: Match the hole type to the fastener material (metal or plastic).
• EMI Shielding: Plated holes are preferred for designs requiring EMI shielding.
• Design Flexibility: OrCAD allows easy switching between plated and unplated holes, enabling quick design iterations.

Choosing between plated and unplated mounting holes depends on your PCB’s electrical and mechanical requirements. Plated holes are ideal for grounding and EMI shielding, while unplated holes provide electrical isolation. With tools like OrCAD, you can easily modify hole types and optimize your design for performance and reliability.

KKPCB conducts research on special processing technologies such as ordinary double-sided boards, thick copper circuit boards, high-frequency circuit boards, HDI circuit boards, rigid-flexible circuit boards, FPC flexible boards, buried blind hole circuit boards, and IC carrier boards. Provides PCB design, PCB layout, PCB prototyping and PCB assembly services.