We often encounter LEDs that don't shine. Package companies, application companies, and the units and individuals that use them are likely to come across. This is the phenomenon of dead lights in the industry. The reason is nothing more than two situations:
First, the leakage current of the LED is too large, causing the PN junction to fail, so that the LED light is not bright. This situation generally does not affect the operation of other LED lights;
Second, the internal connection leads of the LED lamp are disconnected, causing no current to pass through the LED and generating a dead light. This situation will affect the normal operation of other LED lamps, because the operating voltage of the LED lamp is low (red, yellow and orange LED operating voltage) 1.8V-2.2V, blue green white LED working voltage 2.8-3.2V), generally have to be connected in series and parallel to adapt to different working voltages. The more LED lights in series, the greater the impact, as long as there is one LED The internal wiring of the lamp is open, which will cause the entire LED of the series circuit to be off, which is more serious than the first case.
LED dead lights are the key to affect product quality and reliability. How to reduce and eliminate dead lights and improve product quality and reliability is a key issue for packaging and application companies. The following is some analysis of some of the causes of the dead lights.
1, the LED chip damage caused by static electricity, so that the PN junction of the LED chip failure, leakage current increases to become a resistor
Static electricity is a very harmful devil. The world's electronic components damaged by static electricity are countless, resulting in tens of millions of dollars in economic losses. Therefore, it is an important task in the electronics industry to prevent static electricity from damaging electronic components. LED packaging and application companies should not be taken lightly. Any problem in one link will cause damage to the LED, making the LED performance deteriorate or even fail. We know that the human body (ESD) static electricity can reach about three kilovolts, which can damage the LED chip. In the LED packaging production line, the grounding resistance of all kinds of equipment meets the requirements. This is also very important. Generally, the grounding resistance is 4 Ohm, in some cases where the requirements are high, the grounding resistance should even reach ≤ 2 ohms.
These requirements are familiar to people in the electronics industry. Whether the key is in place during actual execution and whether there is a record. According to the author's understanding of the general private enterprise, the anti-static measures are not in place. This is the test record that most enterprises can't find the grounding resistance. Even if the grounding resistance test is done once a year, or once a few years, or there is a problem. When checking the grounding resistance, it is a very important task to test the grounding resistance test. At least 4 times a year (tested every quarter), some places with high requirements should be grounded once a month.
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