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Production Process of LED display

SMT process

SMT process and its notices:

1.As the lamp beads IC and some other electronic elements are static sensitive elements, and in order to ensure the quality of SMT welding , we require SMT workshop to be dust-proof, anti-static, and keep constant temperature and humidity. Generally, the temperature in SMT workshop should be maintained at about 23 ℃,  and the environmental humidity should be controlled at about 65%.


2.Material dehumidification, all electronic components need to be baked to dehumidify in a high temperature environment before they are put on the production line , for the propose to ensure the quality of welding. The baking should be kept at 60 ℃ stably for 4 hours.


3.Thaw and mix the solder paste , the solder paste used in welding need to be stored at 5 degrees centigrade to ensure it’s quality. Before use it, the solder paste need to be unfreeze in advance to make it back to it’s normal temperature, and it need to be mixed completely. (solder paste is a mixture of various metals, the proportion and precipitation of various metals are different, so it need to be mixed evenly before use it.)


4.Printing: use the solder paste printing machine to print the PCB. We should pay attention to clean the steel net regularly according to the situation, and use the dust-free cloth and alcohol to reduce the bad rate of the patch.


5.Patch: use a mounter for patch processing. At present, we have a better way to ensure the consistency of the module: We use mixed lights for SMD products, that is, mix the lamp beads in different carriers through different mounter station.


6.Reflow soldering: reflow soldering of coated products. We currently use reflow soldering of ten temperature zone. The temperature is more accurate and the quality of the welding is more assured.


7.After furnace test: SMD products’ lighting test after furnace.


DIP Products——Plug-in processing—— wave-soldering ——After welding processing

1.Plug-in processing

 A.Mix the light: remove the outer packaging of all the beads and mix the light to ensure the consistency of the module.


 B.compile tape: use a tape machine to put the lamp beads into the tape.


 C.Plug-in: use an automatic plug-in machine to plug in

.

2.Wave soldering: wave soldering on plugged boards.

According to different types, different brands of lamp needs different furnace fixture to ensure the consistency of the lamp and to improve the display effect of the screen.


3.Post-solder

A.We need to weld the lamp plate and the drive plate together for the module which it’s light board and driver are separate. Light driver separation: as the name suggests, light plate and it’s drive surface (the side which place IC) are two separate, individual PCBA.


B.Welding connector, electrolytic capacitor, etc.


C.Test


Module aging: do an aging test on the normal module. We usually choose white screen to do the aging test and let the module work at full capacity. The module aging time is 24 hours.


Three proofing treatment: spray conformal coating to the drive surface of the module which is normal in the aging test.  During the use of the module, the circuit board may be corrosive and moldy in the chemical, vibration, high dust, salt spray, moisture and other environments, and that will cause a circuit failure of the board. Paint the conformal coating to the surface of the circuit board to form a layer of three proofing protective film. (Three refers to the moisture, salt spray and mildew).


Outdoor module: Assemble the bottom shell→brush the glue

1.Outdoor modules need to be glued, so firstly we need to assemble bottom shell for the module that finished the three proofing.


2.Glue filling

A. Use glue machine for filling.

B. At present, the glue we use is waterproof flame retardant silicone. Match it as A:B=10:1. The flame rating is 94V-1.

C. Dry glue: place the module that finished glue filling onto the drying rack. The drying rack must be very smooth and the time of the glue drying is 4 hours.



Assemble the module: assemble bottom shell and mask for the module and so on.


Module testing——Box assembly——Finished product testing——product packaging


Finished product testing:

1.Single cabinet’s electrical performance test.

2.Outdoor cabinet’s waterproofing test.

3.Cabinet’s pressure test.

4.Cabinet’s ground test.

5.Cabinet’s leakage current test.

6.Connect the entire screen for aging test.

7.Carry out a power off test to the whole screen.

8.Grouped equipment, accessories testing.




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Dakco LED display Tel:0086-755-29960601 Fax:0086-755-29106150 Copyright @ Dakco Industrial Holdings Limited.