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 Micro LED Inspection System

Micro LED Inspection for Wafers, Carriers, and Panels 

The Bandi Series is WEVE’s industrial product lineup dedicated to Micro LED inspection. Designed to support the full Micro LED manufacturing flow, Bandi systems provide advanced optical, structural, and colorimetric inspection for Epi wafers, CoW wafers, CoC substrates, and Micro LED panels.


By combining multi-modal inspection with high throughput and operational flexibility, the Bandi Series enables accurate evaluation of Micro LED performance across research, pilot, and production environments.

  • Industrial Micro LED inspection product lineup
  • Supports Epi wafers, CoW, CoC, and Micro LED panels
  • Simultaneous AOI, PL, and x,y,Y inspection
  • Non-contact, non-destructive measurement
  • Optimized for high-density Micro LED devices

Why Micro LED Inspection Requires a Dedicated Platform 

Micro LED manufacturing presents inspection challenges that differ fundamentally from conventional LED and display processes. High device density, diverse integration formats, and complex chip architectures require a dedicated inspection platform capable of adapting to multiple substrate types and process stages.

  • Millions of Micro LEDs per wafer, carrier, or panel
  • Multiple defect types across optical and structural domains
  • Different inspection requirements for Epi, CoW, CoC, and panels
  • Early-stage defects directly impact yield and cost
  • High repeatability required for process control

Multi-Modal Inspection Platform 

At the core of the Bandi Series is a multi-modal inspection platform designed to acquire comprehensive Micro LED data in a single scan. Appearance inspection, photoluminescence, and colorimetric measurements are performed simultaneously, enabling consistent evaluation across different substrate formats.

  • Simultaneous AOI, PL, and x,y,Y acquisition
  • Applicable to wafers, carriers, and panel substrates
  • Non-contact, non-destructive inspection
  • High-resolution imaging for micro-scale features
  • Deep-learning-assisted defect classification

Inspection Across the Micro LED Manufacturing Flow 

The Bandi Series is designed to support inspection at multiple stages of Micro LED manufacturing, from early material evaluation to final integration. This flexibility allows manufacturers to use a single inspection platform across multiple process steps.

  • Epi wafers: material uniformity and emission evaluation
  • CoW: high-density chip-level optical and structural inspection
  • CoC: inspection after transfer to carrier substrates
  • Panels: inspection of Micro LEDs after array or panel integration

Simultaneous RGB Micro LED Inspection 

One of the major advantages of the Bandi Series is the ability to inspect Red, Green, and Blue Micro LEDs simultaneously in a single inspection run, regardless of substrate type. Conventional systems typically require separate inspection attempts for each color, increasing total inspection time by two to three times.


Red Micro LEDs are particularly challenging due to the light absorption characteristics of GaAs, which significantly reduce PL signal detectability. The Bandi Series overcomes this limitation and enables reliable inspection of RGB Micro LEDs in a single process.


  • Simultaneous inspection of Red, Green, and Blue Micro LEDs
  • Applicable to wafers, carriers, and panels
  • Reliable inspection of GaAs-based Red Micro LEDs
  • No additional inspection runs per color
  • Reduced inspection time and process complexity


AOI


Simultaneous 

RGB PL inspection 

This image is an edited representation based on measured data; actual production samples are confidential and protected under NDA.

Bottom PL Inspection for Vertical Micro LED Chips 


PL Front




PL Back


Vertical Micro LED chip architectures introduce additional inspection challenges due to non-transparent materials typically located on the top side of the chip. These structures block conventional top-side PL inspection and significantly limit optical evaluation.


In addition, vertical Micro LED chips are inherently difficult to inspect using traditional EL (electroluminescence) techniques, as current injection paths, opaque electrodes, and complex vertical stacking reduce emission uniformity and complicate defect interpretation.


The Bandi Series enables physical chip flipping and bottom-side PL inspection, providing direct access to the optically active region. When combined with top-side AOI, this approach delivers complete optical and structural evaluation of vertical Micro LED chips.


- Supports vertical Micro LED chip architectures

- Bottom-side PL inspection after chip flipping

- Overcomes limitations of top-side PL inspection

- Combined bottom PL and top AOI analysis

- Accurate performance evaluation per chip

Flexible Inspection for Different Substrate Layouts 

Fully populated CoW


Micro LED substrates vary widely in layout and utilization. The Bandi Series supports flexible inspection strategies for fully populated substrates as well as designs with defined active areas, without compromising inspection quality or throughput.

- Fully populated wafers and carriers

- Active-area layouts on wafers and panels

- Flexible region-of-interest inspection

- No throughput penalty for partial inspection

- Suitable for R&D, pilot, and mass production

High-Speed, High-Precision, Repeatable Performance 

High throughput alone is insufficient for Micro LED inspection. Precision and repeatability are equally critical to ensure meaningful yield analysis and process control. The Bandi Series delivers all three.


A 6-inch CoW wafer with approximately 9 million Micro LED chips can be inspected within the ~9-minute range, while performing AOI, PL, and x,y,Y inspection simultaneously.

  • High-throughput inspection across substrate types
  • AOI, PL, and x,y,Y acquired in parallel
  • Stable and repeatable measurement results
  • Suitable for high-density Micro LED devices
  • Industry-leading balance of speed and accuracy

High-Speed, High-Precision, Repeatable Performance

High throughput alone is insufficient for Micro LED inspection. Precision and repeatability are equally critical to ensure meaningful yield analysis and process control. The Bandi Series delivers all three.


A 6-inch CoW wafer with approximately 9 million Micro LED chips can be inspected within the ~9-minute range, while performing AOI, PL, and x,y,Y inspection simultaneously.

  • High-throughput inspection across substrate types
  • AOI, PL, and x,y,Y acquired in parallel
  • Stable and repeatable measurement results
  • Suitable for high-density Micro LED devices
  • Industry-leading balance of speed and accuracy


Operator-Driven
Recipe Creation 

Given the current stage of the Micro LED industry, manufacturers frequently work with diverse samples, evolving designs, and changing processes. The Bandi Series software enables operators to create and modify inspection recipes directly on-site, without requiring direct involvement from WEVE.

This capability allows rapid adaptation to new substrate types, layouts, and inspection requirements.

  • Operator-created inspection recipes 
  • No direct WEVE intervention required 
  • Rapid setup for new samples and processes 
  • Supports frequent design and layout changes 
  • Ideal for R&D and early production stages 


Machine Learning-Based

Inspection Optimization

The Bandi Series incorporates machine learning tools designed to continuously improve inspection performance. Operators can train their local inspection systems using the samples they work with, allowing the inspection process to adapt to real production conditions rather than relying on static defect definitions.

Through a well-organized and intuitive user interface, operators can classify defect samples, manage training datasets, and guide the learning process directly on-site. This approach improves defect recognition accuracy and increases effective inspection rates as more production data becomes available.

  • Machine learning–assisted defect recognition
  • Operator-driven training on local systems
  • Sample-based learning using real production data
  • Intuitive UI for defect classification and dataset management
  • Continuous improvement of inspection accuracy and throughput


Experience with WEVE's solutions. Use Contacts to get in touch anytime.


A. 33, Sagimakgol-ro 62beon-gil, Seongnam-si, Gyeonggi-do, Republic of Korea (13211).


T. 031 548 2990  F. 031 548 2991

M. weve@theweve.com




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