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Reason of LED screen Death lamp
LED death lamp is the key to affect the product quality, reliability, and how to reduce and eliminate dead lamp, improve product quality and reliability, encapsulation, application, the enterprise needs to solve the key problems. Here is make some analysis on some cause of death light: LED die light is the key to affect the product quality, reliability, and how to reduce and eliminate dead lamp, improve product quality and reliability, encapsulation, application, the enterprise needs to solve the key problems. Here is make some analysis on some cause of death lamp:
1. Electrostatic cause damage to the LED chip, the LED chip of p-n junction failure, leakage current increase, become a resistor
Static electricity is a kind of harm of the devil, the world because of electrostatic damage to electronic components are countless, causing tens of millions of dollars in economic losses.So to prevent electrostatic damage to electronic components, is a very important job in electronics industry and LED encapsulation, application, enterprises do not take lightly.Any link problems, will cause the damage to the LED, the LED performance worse and even failure.We know about the human body can achieve 3 kv (ESD), electrostatic, foot LED chip can be broken down, in the LED packaging production line, the grounding resistance is in line with the requirements of all kinds of equipment, it is also very important, the general requirement for grounding resistance of 4 ohms, some requiring high its grounding resistance to reach even two or less ohm.
2. LED lights inside the attachment welds opened cause die modulation phenomenon
2.1 the production process of encapsulation company is not sound, backward incoming inspection, is the main reason cause LED display death lamp.
Usually use stents encapsulate leds, row is to use copper or iron by precision stamping die, metal materials as copper more expensive, the cost is high, affected by the market fierce competition, in order to reduce the manufacturing cost, market mostly about using cold rolled low carbon steel with stamping LED stent, iron stent through silver, silver plated has two, one is to prevent oxidation rust, 2 it is convenient for welding, electroplating stents row quality is critical, it is related to the LED life, should be dealt with in accordance with the procedures before plating, such as cleaning, degreasing, phosphating process should be meticulously, to control the current plating, silver plating layer thickness to control good, high cost of coating is too thick, too thin affect quality.
2.2 Encapsulating every working procedure must be seriously in the process of operation, a link any carelessness is the cause of death lamp
In point, solid crystal process, silver glue (for single chip solder joints) point more and not less, the glue will be return to chip gold mat, cause short circuit, chip, sticky rickety. Double solder chip point insulation glue is the same, point more insulated will return on chip gold mat, when welding the virtual welding resulting death lamp. Points less chip, sticky rickety, so point glue must be just right, neither more nor less.
Welding process is also key, gold ball pressure, time, temperature of welding machine, with the power of the four parameters are just right, in addition to the fixed time, the other three parameters are adjustable, the adjustment of the pressure should be moderate, easy to crush the chip under pressure, too small, easy to weld. Welding temperature adjustment for good in 280 ℃, generally refers to the regulation of power ultrasonic power regulation, have poor is too big, too small, with moderate degree, in a word, the adjustment of the gold ball welding parameters, with good welding material, spring torque tester is used to inspect or 6 grams, is qualified.
2.3 Tell virtual welding die of lamp
Use lighter to heat leading wire of death lamp to 200-300 ℃, then remove the lighter, with 3 v button cell according to the positive and negative connecting the LED, if the LED lamp can light up, but as the temperature lead to reduce the LED lamp by the light is not bright, it is proved that the LED lamp is virtual welding. Heating can light up the reason is that by using the principle of the metal heat bilges cold shrink, the LED wire heating expansion elongation and internal solder joints connected, then the power switch on, the LED can normal light, LED as the temperature decreases shrinkage lead back to normal state, with the internal welds disconnect, leds dot not bright, this approach attempts are efficacious.
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Contacts:
Office: + 86-021-61993536
Mobile: + 86-13918891309(WeChat)
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