Power supply engineers will encounter such a situation. During the production process, some of the lamp bead will have a string or strings of lights that cannot be illuminated during the test. So why is this? I think everyone wants to figure it out. The electronic fever network Xiaobian is also very curious, so today we will work with the power engineer to reveal the secret, and in-depth discussion about why the LED lamp beads will appear dead lights.
Welding process dead light
1. Common welding methods can be divided into electric soldering iron welding, heating platform welding and reflow soldering, etc.
A. Soldering iron welding is the most common, such as sample preparation and maintenance. Since most existing manufacturers save the cost, the purchased soldering iron is mostly unqualified and slightly defective. Most of the grounding is poor, there is leakage, and the welding process This is equivalent to the tip of the electric iron in the leakage - the LED being welded - the human body - forming a circuit in the earth, that is to say tens of times - hundreds of times the voltage of the lamp bead is applied to the LED lamp bead, instantaneously Burn it out. Note: The situation of connecting the static electricity belt will be more serious, because when the human body is connected to the static electricity belt, the resistance to the ground forming circuit is smaller, and the current through the human body to the lamp bead will be larger, which is also said to be electrostatically charged by many people. There are still so many problems with lamp bead damage.
B. Dead lights caused by heating platform welding, due to the continuous sample of lamps, most enterprises have become the best production tools in order to meet the needs of small batches and sample sheets. Due to the low cost of equipment, simple structure and operation, etc. However, due to the use environment (for example, the temperature of the fan can not be constant) and the control of the welding operator's proficiency and welding speed has become a major problem causing the dead light, in addition to heating Grounding of equipment on the platform.
C. Reflow soldering, generally this type of soldering is the most reliable production method, suitable for mass production and processing. If it is not properly operated, it will cause more serious dead light consequences, such as unreasonable temperature adjustment and poor machine grounding.
2. Improper storage causes dead lights
This kind of problem is the most common. Because it does not pay attention to the moisture-proof problem after opening the package, because the sealing material of the lamp bead is mostly made of silica gel material, it has certain water absorption characteristics. After the damp after the lamp bead is attached, the high-temperature welding process The silica gel will expand and contract, and the deformation of the gold wire, chip and bracket will cause the gold wire to shift and break, and the light spot will not be bright. Therefore, it is recommended that the LED be stored in a dry and ventilated environment with a storage temperature of -40. °C- +100 °C, relative humidity is below 85%; LED is used within 3 months under its original packaging condition to avoid rusting of the bracket; when the LED packaging bag is opened, it should be used as soon as possible. The storage temperature is 5 ° C - 30 ° C, and the relative humidity is below 60%.
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