The Adhesive Force Measurement between Single μLED and Substrate Based on Atomic Force Microscope

Compared with traditional liquid crystal and organic light emitting diode (OLED), micro light emitting diode (μLED) has advantages in brightness, power consumption, and response speed. It has important applications in microelectronics, micro-electro-mechanical systems, biomedicine, and sensor systems. μLED massive transfer method plays an important role in these applications. However, the existing μLED massive transfer method is faced with the problem of low yield. To better transfer the μLED, the force value detached from the substrate needs to be measured. Atomic force microscope (AFM) was used to measure the force of a single μLED when it detached from the substrate. The μLED was glued to the front of the cantilever. When a single μLED was in contact with or detached from the Polydimethylsiloxane (PDMS), the maximum pull-off force can be obtained. The force at different peel speeds and preload was measured, and the experimental results show that the separation force between a single μLED and PDMS substrate is not only related to the peel speeds, but also related to the preload. The force values under different peel speeds and preload were measured to lay a theoretical foundation for better design of μLED massive transfer system.