The reason is nothing more than the two cases:
First, the LED leakage current caused by the PN junction failure, so the point of LED light does not shine, this generally does not affect the work of other LED lights;
Second, disconnect the internal connection lead of the LED lights, resulting in LED current through produce dead lights, this will affect the other LED lights work properly, because of low operating voltage of the LED lights (red, yellow, orange LED operating voltage 1.8V-2.2V, blue, green and white LED Operating voltage 2.8-3.2V), are generally required to use the string and parallel connections, to adapt to different working voltage series LED lights are more affected, including an LED light internal wiring open circuit, will result in the series circuit of a whole string of LED lights are not bright, visible circumstances of this case than the first serious.
high power led dead lights affect product quality, reliability of the key, how to reduce and eliminate the dead lights, and improve product quality and reliability, is packaged applications enterprises need to address the key issues. The following are some of the reasons causing the dead lights, for some analysts explore:
Electrostatic damage the LED chip, LED chips of the PN junction failure, leakage current, into a resistor
Static electricity is a pernicious devil, the world countless electrostatic damage to electronic components, resulting in tens of millions of dollars in economic losses. So to prevent electrostatic damage to electronic components, is a very important task of the electronics industry, LED packaging, application of the enterprise do not take it lightly. Any link problems, will result in damage to the LED, the LED performance deterioration and even failure.
We know that the human body static electricity (ESD) can reach about three kV, enough for the LED Blue 150W chip to breakdown damage in the LED packaging production line, the grounding resistance of various types of equipment to meet the requirements, it is also important, general requirements for the grounding resistance of 4 Ohm, some of the occasions the grounding resistance even to achieve ≤ 2 ohms. These requirements are for the electronics industry, people familiar with the key is in the actual implementation is in place, whether there is record.
Not doing far as I understand private enterprise, anti-static measures in place, this is the most finding out grounding resistance test records, even if the ground resistance testing is also a once a year or a few years time, or have a problem check the grounding resistance, not knowing that the grounding resistance test is a very important task, at least four times a year (the test once each quarter), some of the requirements, the monthly for a ground resistance testing.
Soil resistivity changes with the seasons and different spring and summer days of rain, the soil wet ground resistance is easier to achieve, the dry soil moisture in autumn and winter, the grounding resistance is likely to exceed the prescribed value, for the record in order to save the raw data, so that future well documented. Compliance with ISO2000 quality management system. Test grounding resistance can design their own forms, ground resistance testing packaging companies, LED applications, enterprises have to do, as long as all kinds of device names to fill in the form, measure the grounding resistance of the device records documented test signatures can be archived.
Human body electrostatic damage to the LED 200W http://www.ledwt.com/led-blue-150w.html is a lot of work should wear anti-static clothing, equipped with electrostatic rings and electrostatic ring should be grounded, there is a need to ground the static ring of anti-static effect is not good, it is recommended not to use the strap of the product, if the staff violation of rules, you should receive the appropriate warning education, but also played the role of the notices of others. Body with static electricity, wear different fabrics and clothes, and the people's physique, autumn and winter night, we undress it is easy to see the clothes between the discharge phenomenon, and this electrostatic discharge voltage, there kV.
The silicon carbide substrate chip ESD only 1100 volts, the sapphire substrate chip ESD value is even lower, only 500-600 volts. A good chip or LED, if we hand-pick (the body without any protective measures), the results can imagine, chip or LED will be varying degrees of damage, and sometimes a good device through our hands inexplicable bad, this is the electrostatic blame.
Packaging companies in strict accordance with the grounding procedures act at the expense of the enterprise itself, will result in lower rate of qualified products to reduce the economic efficiency of enterprises, the enterprise of the same application of LED equipment and personnel is poorly grounded, can also cause damage to the LED, and rework unavoidable.
In accordance with the requirements of the LED standard manual, the LED leads from the colloid should not be less than 3-5 mm, clubfoot, or welding, but most applications, companies have not done that, but only separated by the thickness of a PCB board (≤ 2 mm) soldered directly, this will cause harm or damage to the LED, because too high welding temperature will chip an impact, make chip features deterioration, reduce the luminous efficiency, or even damage the LED 400W, this phenomenon is not uncommon. Some small businesses to use hand soldering, the use of 40 watt ordinary iron, beyond the control of soldering temperature, soldering iron temperature above 300-400 ℃, high welding temperatures can also cause the dead lights, LED lead at a high temperature coefficient of expansion than about 150 ° C the expansion coefficient is several times higher inside the gold solder joints because of the large thermal expansion and contraction of the welding point opened, resulting in the phenomenon of dead lights.
2 LED lights internal wiring of the solder joint to open causing the phenomenon of dead lights Cause Analysis
2.1 package production process does not build incoming inspection methods are backward, is caused by the direct cause of the LED die light
Commonly used stent row LED package, the stent row of copper or iron metal materials made by the precision die stamping, copper is more expensive, the cost naturally, by the fierce market competition factors, in order to reduce manufacturing costs, the market mostly cold-rolled low carbon steel stamping LED bracket irresolute stent row of iron to go through a silver-plated, silver has two roles, first in order to prevent the oxidation of rust, is to facilitate the welding, the stent row plating quality is critical it relates to the life of the LED in the plating before processing should strictly follow the rules, rust, oil, phosphate, and other processes should be meticulous, to control current in the plating, silver plating thickness control, the coating is too the high cost of thick, too thin to affect the quality.
LED strip lights packaging companies do not have the ability to test stent row plating quality, which gives a number of electroplating enterprises can take advantage of the silver layer thinning of the bracket of the plating row, reduce costs, and general packaging companies IQC stent row inspection means lacking, not detected stent row of coating thickness and the fastness of the instrument, and was easier to muddle through. I have seen some bracket emissions in a warehouse a few months after the rust, Do not say, we can see how bad the plating quality. Row of the products made out of this bracket is certainly not last long, not to mention the 30,000 to 50,000 hours, 10,000 hours is a problem. The simple reason that every year a period of southerly days, the weather in the air humidity can easily lead to poor plating metal rust, so that the failure of LED components. Even if the package of the LED will be the silver layer is too thin adhesion is not strong, the solder joint and stand out, resulting in the phenomenon of dead lights.