Analysis of several factors causing pixel loss of control in LED display screens

LED display manufacturers often encounter the problem of pixel loss of control in LED displays. Today, LED display manufacturers are here to tell you the factors that cause pixel loss of control in LED displays.

The main cause of pixel loss of LED display screen is LED failure, which can be divided into two aspects: 1. Poor quality of LED itself; 2. Improper usage method.

Many LED failures are usually not detected during routine inspection and testing of LEDs. In addition to improper use such as electrostatic discharge, high current (causing high junction temperature), and external forces, many LED failures occur under high temperature, low temperature, rapid temperature changes, or other harsh conditions due to differences in thermal expansion coefficients of materials such as LED chips, epoxy resins, brackets, inner leads, die bonding adhesives, PPA cups, etc., resulting in different internal stresses.

The quality inspection of LED is a very complex task. Furthermore, for GaN based LEDs, electrostatic discharge is the biggest cause of their failure. The mechanism of LED failure caused by electrostatic discharge is very complex. Equipment, tools, containers, and human bodies may all carry static electricity and discharge it. This static electricity can range from several hundred volts to tens of thousands of volts, and the discharge time is at the nanosecond level. The blue-green tube failures that occur during the production, installation, and use of display screens are often caused by the breakdown of LED-PN junctions due to electrostatic discharge. The International Electrostatic Association strictly regulates standard electrostatic discharge modes, mainly divided into human body discharge mode (HBM) and machine discharge mode (MM). The electrostatic discharge sensitivity (ESDS) of devices in China is divided into three levels (human mode): level 1 is from 0 to 1999V; Level 2 is between 2000 and 3999V; Level 3 is above 4000V.

In general, the electrostatic discharge sensitivity of LED is between several hundred volts and tens of thousands of volts in human mode, while it is only around tens of volts to five hundred volts in machine mode. Due to the complex production process of LED displays, it is difficult to prevent electrostatic discharge. Therefore, the sensitivity of LED electrostatic discharge should be selected as level 2 or above (human mode), and electrostatic protection must be implemented throughout the entire production process.