Eight quality control of LED display screen

1、anti-static LED display assembly plant should have good anti-static measures. Special anti-static, anti-static flooring, anti-static, anti-static soldering pad, anti-static ring, anti-static clothing, humidity control, equipment grounding (especially cutting machine) are the basic requirements, and the use of electrostatic detection instrument regularly.

2、mixed lights, the same color, different brightness files LED need to mix lights, or in accordance with the discrete rules of the design of the plug lamp diagram to plug in, in order to ensure the consistency of the brightness of each color of the whole screen. If there is a problem in this process, the local brightness of the display will not be consistent, which will directly affect the display effect of the LED display screen.

3、drive circuit design, LED display module on the driver circuit board driver IC arrangement will also affect the brightness of LED. Because the driving IC output current is too far away on the PCB board, the transmission path pressure drop will be too large, which will affect the normal working voltage of LED, resulting in lower brightness. We often find that the LED brightness around the LED display module is lower than that of the middle, which is the reason. Therefore, to ensure the consistency of the brightness of the display, it is necessary to design a good driving circuit distribution map.

4、weld control LED display on the LED is not bright, often more than 50% probability caused by various types of weld, such as the LED pin IC pin weld, weld, weld and base pin row. The improvement of these problems requires strict improvement of process and strengthening of quality inspection. The vibration test before leaving the factory can be regarded as a good test method.

5、wave soldering temperature and time required to strictly control the wave front welding furnace temperature and time, suggestions are: preheating temperature of 100℃±5℃, the maximum not more than 120℃, and preheating temperature rise for a smooth, welding temperature is 245℃±5℃ the welding time that no more than 3 seconds. After the furnace avoid vibration or shock LED, until the resumption of normal state. The temperature parameter of crest welder should be checked regularly, which is decided by the characteristics of LED, overheating or fluctuating temperatures will directly damage the LED or LED caused by quality problems, especially for small size such as round and oval LED 3mm.

6、heat dissipation design LED work will heat, the temperature is too high will affect the attenuation speed and stability of LED, so PCB board heat dissipation design, box ventilation and heat dissipation design will affect the performance of LED.

7、the design of current value LED nominal current is 20mA, the maximum current is generally recommended for not more than 80% of the nominal value, especially for some small space display, due to poor cooling conditions, should also reduce the current value. According to the experience, due to the inconsistency of red, green and blue LED decay rate, the current value of blue and green LED is reduced to keep the consistency of white balance after long time use of the display screen.

8、control the verticality of the lamp, for the straight in LED, the furnace should have enough process technology to ensure LED perpendicular to the PCB board. Any deviation will affect the already set LED brightness consistency, appear uneven brightness of the color block.