Post-Bonding Inspection of Mini LED Panels
Locate and identify mini LED bonding flaws
When producing OLED or mini LED display screen panels, machines bond LEDs directly to the panel substrate in an array format. Multiple substrates (zones) are electronically connected to form one large display panel. To achieve consistent quality, high-speed inspections are conducted of each die that is bonded to the panel. For example, it is important to make sure the volume of solder dispensed to connect the mini LED die to the contact pad on the panel is within an acceptable range or to check to see if the LED is either missing or misaligned between the contact pads. These anomalies can negatively affect the quality of the display once illuminated or contribute to degraded screen performance over time. Solder balls connecting the LEDs to the contact pads can vary in size and volume, making it challenging for traditional machine vision tools to perform this inspection.
Cognex AI-based tools help mini LED screen producers minimize defects associated with the bonding process, such as solder volume and the positioning of the bonded LED die between the contact pads. The inspection system is trained using a series of images that represent both good and No Good (NG) results. It learns to flag significant defects while ignoring anomalies that are within tolerance. The tools locate and identify the Region of Interest (ROI) as well as any potential significant defects within that area. Using this information, production managers can more effectively manage the quality of their display screens, which reduces costs and increases profitability.