Development and application of Mini LED and Micro-LED chips

From traditional LEDs, small-pitch LEDs to Mini LEDs, Micro LEDs, etc., the development speed of LED chips is very fast. The definition of Mini LEDs and Micro LEDs has been discussed in the industry. At present, more definitions are based on size. The report analyzes the application characteristics of Mini LED and Micro LED in the display field and compares it with the existing display technology.

Mini LED and Micro-LED chip measurement

The current relevant measurement standards are: SJ / T 11399-2009 "Test Method of Semiconductor Light-Emitting Diode Chip", SJ / T 11394-2009 "Test Method of Semiconductor Light-Emitting Diode", GB / T 36613-2018 "Spot Test Method of Light-Emitting Diode Chip", CIE 235: 2019, CIE 238: 2020, CIE 127-2007, etc., there is no specific measurement standard for Mini-LED and Micro-LED.

For the relevant measurement indicators, the report details the latest developments and challenges of optical characteristics, light intensity and light intensity distribution measurement, luminous flux measurement, spectral characteristic measurement, and chip surface brightness distribution measurement.

The report pointed out that because the luminous intensity of Mini LED and Micro LED is very low, it is a challenge to the optical design and detection sensitivity of the measurement equipment, which needs to be specially designed. In addition, the power supply accuracy required for lighting is also high. The traditional LED measurement system cannot be practically applied to the photoelectric performance detection of Micro LED. In this regard, the report introduces the corresponding solution for the measurement of external quantum efficiency at very low currents: it is necessary to use a high stability nano-source to light up the LED chip, and use a high-sensitivity spectrometer with a special integrating sphere system to achieve the measurement.

For radiation flux measurement, in March 2020, CIE 239: 2020 "Goniospectroradiometry of optical Radiation Sources" was officially released. The standard technical report was drafted by the technical committee CIE TC 2-74, chaired by Professor Pan Jiangen, senior engineer, and was the first CIE publication chaired by an expert from mainland China. This technical report condenses the latest achievements and consensus of optical radiation measurement experts from all over the world in the field of spatial spectral radiometry of optical radiation sources.

CIE 239: 2020 is mainly related to the principle of measuring the full spatial distribution of optical radiation in the spectral range of 200 nm to 2500 nm of the optical radiation source. The main parameters involved are: total radiant flux, total luminous flux, regional radiant flux, and regional luminous flux , Average color coordinates, spatial color uniformity, etc.