Causes of LED Beads Dead

 In the process of production, there will always be a phenomenon that some lamp beads cannot be lit when they are tested after the board is pasted. To make a summary for this phenomenon: the lamp is dead during the welding process.

7 reasons for dead lights in the welding process of LED lamp beads.
 
1. Common welding methods can be divided into electric soldering iron welding, heating platform welding and reflow soldering, etc.:
 
A. Electric soldering iron welding is the most common, such as sample making and maintenance. In order to save costs, most of the existing manufacturers buy back soldering irons that are substandard and low-quality products. Most of them are poorly grounded and have leakage currents. During the welding process, this is equivalent to the tip of the soldering iron that is leaking electricity--the LED being soldered-- The human body-the earth forms a loop, that is to say, the voltage that is dozens to hundreds of times greater than that of the lamp bead is applied to the LED lamp bead, instantly burning it out.
 
Note: The situation of connecting the electrostatic belt will be more serious, because when the human body is connected with the electrostatic belt, the resistance of the loop to the ground is smaller, and the current passing through the human body to the lamp bead will be greater. This is what many people say that there is obviously static electricity The belt still has the problem of so many lamp beads being damaged.
 
B. Dead lights caused by heating platform welding. Due to the continuous sample list of lamps, most enterprises meet the needs of small batches and sample lists. Due to the advantages of low equipment cost, simple structure and operation, etc., the heating platform has become the best production tool. However, due to the use environment (such as: the temperature cannot be kept constant in places with fans) and the control of the welding operator's proficiency and welding speed, it has become a big problem that caused dead lights. In addition, there is heating Equipment grounding of the platform.
 
C, reflow soldering, generally this soldering method is the most reliable production method, suitable for mass production and processing, if the operation is improper, it will cause more serious consequences of dead lights, such as unreasonable temperature adjustment, poor grounding of the machine, etc.
 
2. Improper storage causes dead lights:
 
This kind of problem is the most common. Because the moisture-proof problem is not paid attention to after opening the package, because the sealing glue of the lamp beads is mostly made of silica gel material, which has certain water absorption characteristics, the lamp beads after damp After the board, after the high-temperature welding process, the silica gel will expand with heat and contract with cold, and the gold wire, chip, and bracket will be deformed, causing the gold wire to shift and break, and the lamp will not light up. Therefore, it is recommended that the LED should be stored in a dry and ventilated place. In the environment, the storage temperature is -40°C- +100°C, and the relative humidity is below 85%. It is better to use the LED within 3 months in its original packaging to avoid rusting of the bracket; when the LED packaging bag is opened Finally, use it up as soon as possible. At this time, the storage temperature is 5°C-30°C, and the relative humidity is below 60%.
 
3. Chemical cleaning:
 
Do not use unknown chemical liquid to clean the LED, because it may damage the surface of the LED colloid, or even cause colloidal cracks. If necessary, please clean it with an alcohol cotton swab in a room temperature and ventilated environment. The time is best controlled within one day. The minute wind is done.
 
4. Deformation causes dead lights:

Due to the deformation of part of the lamp board, the operator will have to reshape it. Due to the deformation of the board, the lamp beads on it will also be deformed at the same time, the gold wire will be broken, and the lamp will not light up. It is recommended to have this type of board. It is best to carry out plastic treatment before production. Longer ones may be deformed and broken during production, assembly and moving. In addition, it is caused by stacking. For the sake of convenience and smoothness in the production process, the lamp panels are stacked randomly. Due to gravity, the lamp beads on the lower layer will be deformed by force and damage the gold wire.
 
5. The heat dissipation structure, the power supply and the lamp board do not match:
 
due to the unreasonable design or selection of the power supply, the power supply exceeds the maximum limit that the LED can withstand (overcurrent, instantaneous impact); the heat dissipation structure of the lamp is unreasonable, which will cause dead lights and overheating. Early light failure.
 
6. Factory grounding: It
 
is necessary to check whether the general grounding wire of the factory is good.
 
7. Static electricity:
 
Static electricity can cause the LED function to fail, it is recommended to prevent ESD from damaging the LED.
 
A. Operators must wear anti-static wristbands and anti-static gloves during LED testing and assembly.
 
B. Welding equipment and testing equipment, work tables, storage racks, etc. must be well grounded.
 
C. Use an ion fan to eliminate the static electricity generated by friction during storage and assembly of LEDs.
 
D. The material box for LED is anti-static material box, and the packaging bag is electrostatic bag.
 
E. Don't have a fluke mentality, touch the LED casually.
 
The abnormal phenomena that will appear in the LED damaged by ESD are as follows:
 
A. Reverse leakage current, the light one will cause the brightness to decrease, and the serious one will not light up.
 
B. The forward voltage value becomes smaller. LED cannot emit light when driven by low current.
 
C. Poor welding causes the lamp to not light up.

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