Simple identification of LED dead lights and solutions

1. Simple identification of cold solder joints and dead lights

A relatively simple but effective way to identify dead LEDs is to heat the lights. We heat the LED leads of some dead LEDs to 200-300℃, remove the fire source, and connect the LEDs with a 3V button battery according to the positive and negative poles. If the LED lights can light up at this time, but as the lead temperature drops, the LED lights go from bright to dark, which proves that the LED lights are poorly soldered. The reason why heating can light up is that it uses the principle of metal thermal expansion and contraction. When the LED leads are heated, they expand and elongate and connect to the internal solder joints. At this time, when the power is turned on , the LED can emit light normally. As the temperature drops, the LED leads shrink and return to normal temperature, disconnecting from the internal solder joints, and the LED lights will not light up. When this happens, it means that the LED is dead due to poor soldering.

2. Simple solution to LED dead light

1. Solve the problem of static electricity causing damage to LED chips , which causes the PN junction of LED chips to fail and lead to dead lights. Most of the dead lights caused by the failure of the PN junction of LED chips are caused by the staff themselves. The amount of static electricity on the human body is related to the different fabrics of clothes people wear and their physical constitution. When we take off our clothes in the dark night of autumn and winter, it is easy to see the discharge phenomenon between clothes. Therefore, we should wear anti-static clothing and wear anti-static rings when working. The anti-static rings should be well grounded. There is an anti-static effect that does not need to be grounded. It is not recommended to use this kind of product. If the staff violates the operating procedures, they should receive corresponding warning education, which also serves as a notice to others.

2. Negligence in a certain link during the packaging process is the cause. The main reason for the LED dead light is the negligence of the staff. If the staff accidentally applies too much or too little silver glue (for single solder joint chips), it will not work. Too much glue will return to the chip gold pad, causing a short circuit, and too little glue will make the chip not stick firmly. In the welding process, the temperature is generally 280℃ as the best. The pressure, time, temperature, and power of the gold wire ball welding machine must be matched just right. Otherwise, too much pressure will easily crush the chip, and too little pressure will easily cause cold soldering.