‘Soft-touch’ approach advances nondestructive testing for micro-LED wafers

Tianjin University scientists have developed a pioneering nondestructive testing technology for micro-LED wafers, offering a much-needed solution to a long-standing industry challenge through a novel “soft-touch” approach.

Micro-LEDs are widely recognized as a fundamental technology for next-generation high-end displays. Achieving near-perfect yields during wafer fabrication is essential to ensure product quality and control repair costs. Yet, the absence of effective nondestructive wafer-level testing methods remains a major technical challenge.

A research team led by Professor Huang Xian from the School of Precision Instrument and Opto-electronics Engineering at Tianjin University has addressed this critical gap in an article published on June 13 in Nature Electronics.

The team introduced a flexible three-dimensional probe array capable of adapting to the microscopic contours of micro-LED wafers, applying a pressure as low as 0.9 MPa, comparable to the softness of a gentle breath. This soft-contact approach allows for high-throughput electrical testing without scratching or damaging the wafer surface.

“The contact pressure exerted by our flexible probes is just one-ten-thousandth that of conventional rigid probes,” Huang explained. “This not only preserves the wafer surface but also significantly extends the probe’s service life. Even after one million contact cycles, the probes retain their original condition.”

To support this innovation, the team also developed a custom-designed measurement system that integrates with the flexible probes. Together, they provide a powerful tool for process control and yield screening in micro-LED manufacturing.

“This breakthrough establishes a new foundation in the field,” said Huang. “It closes a major technical gap in micro-LED electroluminescence testing and paves the way for broader applications in advanced wafer inspection and biophotonics.”

Currently, the technology is progressing toward commercialization at the Tiankai Higher Education Innovation Park. It promises to provide a scalable, low-cost, and nondestructive testing solution for the rapidly growing micro-LED industry, while also expanding the practical applications of flexible electronics across a variety of high-tech fields.

Provided by
Tianjin University