The failure reasons of LED lamp bead
LED die light phenomenon often occurs in the LED lighting professional, seriously affected the product quality and reliability, is also a problem concerned by the manufacturer. LED lamp is death caused by what reason? How to avoid the LED die light phenomenon is the focus of this paper.
the reason LED to death light
LED die light has been blamed on two conditions: first, the internal connection wire cut off of the LED lights form the LED lamp, no current produced by the survival this situation will affect the normal operation of other LED lamp, the reason is due to the low voltage LED lights work ( 1 red yellow orange LED operation voltage. 8 v - 2. 2 v, blue, green, white LED voltage 2 homework. 8 - 3. 2V) , is typically used in series, in parallel to join, to used to different operating voltage, the more LED lights series impact, the greater the as long as one of the LED lights inside the attachment open circuit, will form the series circuit of the whole series of LED lamp is not bright, visible this situation more serious condition than the first one.
second, LED the leakage through the formation of p-n junction failure, the LED lamp is not bright, this situation general will not affect other LED lights work;
analyzes the status of the LED die light
LED die light is the key to influence the reliability of product quality, and how to reduce and eradicate death lamp, advance the product quality and reliability, is the key to the packaging, using the enterprise needs to solve problems. Here are some reasons of forming die lamp some analysis.
static electricity on the LED chip formation damage
electrostatic hazards for the LED chip, the LED chip of p-n junction failure, leakage current increase, become a great harm electrostatic resistance is a devil, countless RMB due to electrostatic damage electronic equipment all over the world, tens of millions of dollars in economic losses. So to avoid electrostatic damage to electronic equipment, is a very important job, electronic professional LED encapsulation, the use of enterprise don't careless. Any link problems and will form the harm of the LED, the LED function deterioration and even failure. We know that the human body, ESD) Can arrive at about 3 kv, electrostatic breakdown damage to the LED chip, the LED packaging production line, the grounding resistance whether fit the requirements of all kinds of equipment, it is also very important, the general requirement for grounding resistance of 4 ohms, some occasions with higher requirements the grounding resistance and even to reach & le; 2 ohm. These requirements are for the professional people are familiar with, whether the key is in the actual execution time in place, whether there are recorded.
human body static electricity is also a big to the harm of leds, homework should wear antistatic clothing, equipped with electrostatic ring and static ring were good, there is a kind of don't need ground electrostatic ring anti-static role owe good, no use equipped with this kind of product, if workers violate operational procedures, should accept the corresponding warning education, also have the effect of notice other people together. How much the body with electrostatic, fabrics and people wear different clothes, and every man's constitution, fall and winter night let's take off your clothes is easy to see clothes between discharge phenomenon, this kind of electrostatic discharge voltage 3 kv.
according to the general private enterprises, anti-static measures do not reach the designated position, do not check this is the most enterprises of the grounding resistance test records, even if the grounding resistance test was also once a year, or a few years time, have a problem or check the grounding resistance, little imagine earth resistance test this is a very important job, at least four times a year, Once every quarter test) , some of the local high, will be once a month grounding resistance test. Soil resistance will follow the change of seasons, spring and summer much rain, soil wet ground resistance is easy to reach, autumn and winter dry soil moisture, grounding resistance is likely beyond the specified value, as a record is to save raw materials, do well documented in the future. Went well quality control system. Test grounding resistance can design form, packaging enterprises, LED using grounding resistance test are to be done, as long as all sorts of equipment name fill in the table, measured grounding resistance recorded in the equipment, test signatures can save.
and silicon carbide substrate of the chip ESD value as long as 1100 v, the sapphire substrate of the chip ESD value is lower, as long as 500 - 600 v. A good chip or LED, if we use hand to pick up ( The body without any protection measures), The all too clear, or LED chip will encounter different degrees of harm, sometimes a good equipment through our hands are broken, this is the fault of the static electricity of. Packaging companies if not strictly according to the grounding procedures will, who is the enterprise oneself, will form the product percent of pass down, cut enterprise economic benefits, also using the LED enterprise if poor equipment and personnel grounding also LED the damage of formation, rework is inevitable. Manual requirements in accordance with the LED specification, LED the lead from the colloid should not less than 3 - 5 mm, curved foot or welded, but most using the enterprise do not do this, just a piece of PCB thickness (apart ≤ 2 mm) Direct welding, it also LED to form harm or damage, due to the high welding temperature will affect the chip, can make the chip characteristics deteriorate, reduce the luminous efficiency, and even damage the LED, this kind of phenomenon common occurance. Some small businesses use manual welding, using 40-watt ordinary iron, the welding temperature control, solder iron temperature - in 300 Above 400 ℃, the welding of high temperature will form dead lamp, LED lead expansion coefficient at high temperature is higher than about 150 ℃ the expansion coefficient of the several times,'s internal gold solder joints due to excessive heat bilges cold shrink to will spread out the welding points, forming die modulation phenomenon.