LED will heat up when working, and too high temperature will affect the attenuation degree and stability of LED, so the heat dissipation design of the PCB board and the ventilation and heat dissipation design of the box will affect the performance of the LED

2. Mixed lights
LEDs of the same color with different brightness levels need to be mixed, or plugged in according to the discrete law design of the illustration diagram to ensure the consistency of the brightness of each color on the whole screen. If there is a problem in this process, there will be inconsistent local brightness of the large screen, which will directly affect the display effect of the large LED screen.
3. The current value is too high
The nominal current of LED is 20mA, and it is generally recommended that its maximum current is not more than 80% of the nominal value, especially for large screens with small dot spacing, due to poor heat dissipation conditions, the current value should also be reduced. As a rule of thumb, due to the inconsistency of the attenuation speed of red, green, and blue LEDs, the current value of blue and green LEDs is reduced in a targeted manner to maintain the consistency of white balance after long-term use of large screens.
4. Drive circuit design
 The arrangement of the driver ICs on the driver board on the large screen module also affects the brightness of the LEDs. Because the output current of the driver IC is transmitted too far on the PCB board, the voltage drop of the transmission path will be too large, which will affect the normal working voltage of the LED and reduce its brightness. We often find that the LED brightness around the large screen module is lower than in the middle, which is the reason. Therefore, in order to ensure the consistency of the brightness of the large screen, it is necessary to design the distribution diagram of the driving circuit.

5. Control the verticality of the lamp
 For in-line LEDs, there should be sufficient process technology to ensure that the LEDs are perpendicular to the PCB board when passing through the furnace. Any deviation will affect the consistency of the brightness of the LED that has been set, and there will be color patches with inconsistent brightness.

6. Virtual welding control
 When the LED does not light up on the LED screen, there is often more than 50% probability that it is caused by various types of virtual soldering, such as LED pin virtual soldering, IC pin virtual soldering, pin header female soldering, etc. The improvement of these problems requires strict process improvement and enhanced quality inspection. Vibration testing before leaving the factory is also a good inspection method.

7. Exceed the wave soldering temperature and time
 The temperature and furnace time of wave front welding must be strictly controlled, the recommendations are: preheating temperature 100 °C±5 °C, the maximum is not more than 120 °C, and the preheating temperature rise is required to be stable, the welding temperature is 245 °C±5 °C, the welding time is recommended not to exceed 3 seconds, do not vibrate or impact the LED after the furnace, until the normal temperature is restored. The temperature parameters of the wave soldering machine should be tested regularly, which is determined by the characteristics of the LED, overheating or fluctuating temperature will directly damage the LED or cause hidden dangers in the quality of the LED, especially for small sizes such as 3mm round and oval LEDs.
8. Anti-static
LED large screen assembly factory should have good anti-static measures. Special anti-static ground, anti-static floor, anti-static soldering iron, anti-static station mat, anti-static ring, anti-static clothing, humidity control, equipment grounding (especially foot cutting machine) and so on are all basic requirements, and should be regularly tested with an electrostatic instrument.