How to Grip PCB Boards Only by Their Mounting Holes Without Touching Components

In electronics manufacturing, not every PCB can be picked from its edges.Some PCB assemblies contain delicate electronic components, exposed copper pads, or irregular profiles that make conventional gripping impossible. Any contact with these areas may cause cosmetic damage, component displacement, or product failure.Recently, we developed a solution for an application involving small PCB boards that could only be handled through their center mounting holes.

Application Overview

The PCB board had the following specifications:

• Weight: approximately 20 g
• Center hole diameter: 5 mm
• Maximum outer diameter: approximately 18 mm
• Two PCB boards picked simultaneously
• Hole center distance: 20 mm

The customer's requirement was straightforward: pick two PCB boards at the same time and place them accurately into the next station.The challenge, however, was far from simple.

Why Conventional Grippers Couldn't Work

Traditional parallel grippers are designed to grip the outside of a workpiece.For this application, external gripping was not an option because the PCB surface contains sensitive electronic structures. Contacting the board itself could damage components, scratch copper traces, or affect product quality.Vacuum cups were also unsuitable due to the uneven surface created by electronic components.The only allowable gripping position was the 5 mm mounting hole located in the center of each PCB.In addition, the two holes were only 20 mm apart, leaving extremely limited space for a dual-gripping mechanism.

A Customized Internal Expansion Solution

To solve the problem, Touch Robotics engineers designed a customized end effector consisting of:

• A flexible soft gripper
• A custom 3D contour positioning module
• A precision internal expansion mechanism

Instead of clamping the PCB externally, the expansion mechanism enters the 5 mm mounting hole and gently expands inside the hole.The custom 3D contour module precisely controls the spacing and alignment of both gripping points, allowing the robot to engage both PCB boards simultaneously without touching any sensitive areas.This approach ensures secure gripping while completely avoiding contact with the PCB surface.

Simultaneous Dual Picking

The most difficult aspect of the project was achieving stable dual picking.Because the hole centers were only 20 mm apart, even a slight alignment error could prevent one of the expansion pins from entering the hole.By combining precision positioning with compliant gripping, the system can:

• Grip two PCB boards in one cycle
• Contact only the mounting holes
• Avoid components and copper traces
• Maintain accurate positioning during transfer
• Release both parts consistently into the fixture

The result is a reliable and repeatable automation process that would be difficult to achieve with conventional grippers.

Why Customized End Effectors Matter

Many automation projects fail not because of the robot, but because of the end effector.When handling delicate PCB assemblies, success depends on designing a gripping solution around the product's allowable contact points—not forcing the product to fit a standard gripper.By combining customized mechanical design with flexible gripping technology, manufacturers can automate applications that were previously considered too difficult or too delicate.

Handling PCB boards through a small mounting hole presents a unique engineering challenge, especially when multiple parts must be picked simultaneously.For this project, a custom 3D contour module combined with an internal expansion soft gripper enabled reliable dual pick-and-place while ensuring that the gripper touched only the designated mounting holes.As PCB products continue to become smaller and more densely populated with components, customized internal gripping solutions will become an increasingly important part of electronics manufacturing automation.