First, simple identification of dead soldering lights
A relatively simple but quite effective way to identify LED dead lights is to heat the off lamps. We heat the LED leads of some non-bright LED lights to 200-300 ° C, remove the fire source, connect the LEDs with positive and negative electrodes with a 3 volt button battery, if the LED lights can be lit at this time, but with the lead temperature Decrease the LED light from light to off, which proves that the LED light is a virtual solder. The reason why the heating can be lit is to use the principle of thermal expansion and contraction of the metal. When the LED lead is heated, the expansion elongation is connected to the internal solder joint. When the power is turned on, the LED can normally emit light, and the LED lead shrinks with the temperature drop. When it returns to the normal temperature state, it is disconnected from the internal solder joints, and the LED light is not lit. When this happens, it is a dead light caused by the virtual soldering.
Second, simple solution to LED dead light method
1, solve electrostatic damage to the LED chip, so that the PN junction LED chip failure leather lead to dead lights of the method. The PN junction of the LED chip is invalid, and most of the dead lights are caused by the workers themselves. The static electricity of the human body is related to the different fabrics worn by people and the physical condition of each person. We take off clothes in autumn and winter nights. It is easy to see the discharge phenomenon between clothes, so you should wear anti-static clothing when working, with an electrostatic ring, the electrostatic ring should be well grounded, there is a static ring that does not need to be grounded. The anti-static effect is not good, it is recommended not to use the belt. This kind of product, if the staff violates the operating procedures, should receive corresponding warning education, and also play a role in notifying others.
2, the negligence of a certain link in the packaging process is the cause, the cause of this LED dead light is mainly caused by the negligence of the staff. If the staff accidentally puts the silver glue (for a single solder joint chip) a little more or less, it will not work. If more glue is returned to the chip gold pad, it will cause a short circuit, and the chip will not stick well. . The welding process, the temperature is generally 280 ° C is the best, the pressure, time, temperature, power of the gold wire ball welder four parameters should be just right, otherwise, the pressure is easy to crush the chip, too small is easy to solder.
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