Back to news

News & Events

LED dead lights in the end how many?

Today we LED death light, for example, to analyze how many kinds of reasons:
To failure analysis of big data, LED dead lights may be hundreds of reasons, limited to time, today we only LED light source, for example, from the LED light source of the five raw materials (chips, stents, phosphors, solid crystal plastic, plastic packaging And gold line) to start, introduce some of the reasons may lead to dead lights.
01, chip antistatic ability is poor
LED lamp beads antistatic index level depends on the LED light-emitting chip itself, and the packaging material is expected to have little or no impact on the packaging process, the impact is very small, very subtle; LED lamp is more susceptible to electrostatic damage, which with two pin spacing Relationship, LED chip nude two electrodes spacing is very small, usually less than one hundred microns, while the LED pin is about two millimeters, when the electrostatic charge to transfer, the greater the spacing, the more likely to form a large potential difference , That is, high voltage. Therefore, sealed LED lights are often more prone to electrostatic damage accident.
02, chip epitaxial defects
LED epitaxial wafers in the process of high temperature crystal growth, the substrate, MOCVD reaction chamber residual deposits, peripheral gases and Mo sources will introduce impurities, these impurities will penetrate the epitaxial layer to prevent gallium nitride crystal nucleation, the formation of various Various epitaxial defects finally form tiny pits on the surface of the epitaxial layer, which will also seriously affect the crystal quality and performance of the epitaxial wafer thin film material.
03, chip chemical residue
Electrode processing is the key process of LED chips, including cleaning, evaporation, yellow, chemical etching, fusion, grinding, will come into contact with many chemical cleaning agents, if the chip is not clean enough clean, harmful chemicals will remain. These harmful chemicals in the LED power, electrochemical reaction with the electrode, leading to dead lights, light fades, dark, dark and so on. Therefore, the identification of chip chemical residue LED packaging plant is crucial.
04, chip damage
LED chip damage will directly lead to LED failure, so to improve the reliability of LED chips is essential. Vapor deposition process sometimes need to use the spring clip to fix the chip, it will have a nick. Yellow work if the development is not complete and the mask has a hole in the light emitting area will have more residual metal. Grains in the first stage of the process, the process such as cleaning, evaporation, yellow, chemical etching, fusion, grinding and other operations must use tweezers and flower baskets, carriers, etc., there will be scratched the grain electrode occurs.
Chip electrode on the impact of solder joints: the chip electrode evaporation itself is not reliable, resulting in wire after the electrode off or damage; chip electrode itself solderability will lead to solder ball Weld; chip storage improper will lead to electrode surface oxidation, surface contamination Etc., slight contamination of the bonding surfaces may affect the diffusion of metal atoms between the two, resulting in failure or Weld.
05, the new structure of the chip and light source material is not compatible
The new structure of the LED chip electrode layer of aluminum, the role of the electrode in the formation of a layer of mirror to improve chip light efficiency, and secondly to a certain extent reduce the amount of gold deposited on the electrode to reduce costs. However, aluminum is a kind of more lively metal. Once the packaging factory is in charge of material control, the aluminum reflective layer in the gold electrode will react with the chlorine in the glue by using glue containing excessive chlorine to cause corrosion.
LED bracket
06, silver-plated layer is too thin
Existing LED light sources on the market choose copper as the lead frame substrate material. In order to prevent oxidation of copper, the general surface of the stent to be plated with a layer of silver. If the silver coating is too thin, under high temperature conditions, the stent easily yellowing. The yellowing of the silver coating is not caused by the silver plating itself but by the copper layer under the silver coating. At high temperatures, copper atoms can diffuse and penetrate into the surface of the silver layer, causing the silver layer to yellow. Copper oxidizability is the biggest drawback of copper itself. Once the oxidation state of copper appears, the thermal conductivity and thermal performance will be greatly reduced. So the thickness of the silver coating is crucial. At the same time, copper and silver are susceptible to various volatile air pollutants such as sulfides and halides, causing dark discoloration on their surfaces. Some studies have shown that discoloration increases the surface resistance of about 20 ~ 80%, power loss increases, so that the LED's stability, reliability greatly reduced, and even lead to serious accidents.
07, silver-plated layer curing
LED light source is afraid of sulfur, which is because the sulfur-containing gas will vulcanize with the silvered layer of light source through the porous structure of silica gel or bracket gap. After the curing reaction of the LED light source, the functional area of ​​the product will be blackened, the luminous flux will be gradually decreased, and the color temperature will obviously drift. After vulcanized silver sulfide increases in conductivity with increasing temperature, leakage phenomenon will occur easily during use; more serious The condition is that the silver layer is completely eroded and the copper layer is exposed. As the gold wire two solder joints attached to the surface of the silver layer, when the silver layer is fully cured sulfide corrosion, the ball appears off, resulting in dead lights.
08, silver plating oxidation
Gold Kam Detection In contact with the LED black diagnosis of the initial business found sulfur / chlorine / bromine more difficult to find the more difficult, but LED light silver signs of obvious signs of silver, which may be related to the oxidation of silver. However, pure elemental analysis such as EDS is not easy to determine the oxidation of the determination of oxidation, because the existence of the air environment, the sample surface adsorption and encapsulation of organic matter such as oxygen will interfere with the determination of test results, so determine the conclusion of oxidation black need to use SEM, EDS, FTIR, XPS and other professional testing as well as light, electricity, chemistry, environmental aging and a series of reliability comparison experiments, combined with professional testing knowledge and knowledge of electroplating comprehensive analysis.
09, poor quality plating
The quality of the coating is mainly determined by the quality of the metal deposited layer of the crystalline structure, in general, the smaller the crystalline structure, the more dense coating, smooth, protective performance is also higher. This small crystalline coating is called "micro-crystal deposition layer." Golden Kam pointed out that good plating should be plated crystal fine, smooth, uniform, continuous, do not allow pollutants, chemical residues, spots, black spots, charred, rough, pinholes, pitting, cracks, Blistering, wrinkling, peeling, yellowing, crystalline coating, partial uncoated defects.
In the electroplating production practice, the thickness of the metal coating and coating uniformity and integrity of the coating quality is an important indicator of inspection, because the coating's protective properties, porosity and coating thickness are directly related. Special change is the cathode coating, with the increase of the thickness, the protection of the coating also increases. If the thickness of the coating is not uniform, it is often the thinnest area first destroyed, then the rest of the coating and then thick will lose protection.
Coating porosity, oxygen and other corrosive gases through the pores into the corrosive copper matrix.
10, organic pollution
Jinjian also pointed out that because the plating process will use a variety of organic-containing potion, silver-plated layer if the cleaning is not clean or use poor quality and deterioration of the potion, the residual organic matter once the light source in the light environment, Light, heat and electricity, the organic matter may occur redox chemical reactions lead to discoloration of the surface of the silver coating.
11, outlet material
The material of the plastic is the key to the heat conduction of the LED package bracket. If the PPA bracket is the material of the water outlet, the plastic performance of the PPA will be reduced, resulting in the following problems: high temperature tolerance, easy deformation, yellowing and low reflectivity ; High water absorption, scaffold due to water absorption caused by the dimensional changes and mechanical strength; poor adhesion with metal and silica gel, pick plastic, and a lot of silicone do not match. These potential problems make the lamp beads difficult to use at slightly larger power. Once out of range, the initial brightness is high, but the attenuation is very fast, leaving the lamp a few months dark.
12, phosphor hydrolysis
Nitride phosphor easy hydrolysis, failure.
13, phosphor self-heating mechanism
Phosphor self-heating mechanism, making the phosphor layer temperature is often higher than the LED chip p-n junction. The reason is that the conversion efficiency of the phosphor does not reach 100%, so a portion of the blue light that the phosphor absorbs converts into yellow light, and another part of the light energy absorbed by the phosphor in the high light energy density LED package becomes the heat. Because phosphors are usually blended with silica gel and silica gel has a very low thermal conductivity of 0.16 W / mK, the heat generated by the phosphor accumulates in smaller localized areas, causing localized high temperatures, LED optical density The larger the phosphor the greater the heat. When the temperature of the phosphor is above 450 degrees Celsius, the silica gel near the phosphor particles will be carbonized. Once there is a certain place of silica gel carbonized black, its light conversion efficiency is lower, the region will absorb more light emitted by the LED and convert more heat, the temperature continues to increase, making the area of ​​carbonation more and more.
Solid crystal glue
14, silver peel off
Conductive silver plastic substrate is an epoxy resin material, thermal expansion coefficient than the chip and the stent are much larger, in the light of the impact of hot and cold use of the environment, the problem will be due to heat stress, temperature changes in the environment will be more dramatic effect To exacerbate, the colloid itself has tensile strength and elongation at break, when the tension exceeds, then the gel cracked. Solid crystal peel off at the interface, the heat rapidly worsened, the heat generated by the chip can not be exported, the junction temperature rapidly increased greatly accelerated the process of light failure.
15, silver plastic layering
Silver particles dispersed in slurry state in the suspension system, due to the silver powder and the matrix due to the density difference, charge, cohesion, force and the structure of the dispersion system and many other factors, often appear stratification of silver deposition, sedimentation Fast will make the product sag hanging when the coating thickness is uneven, and even affect the physical and chemical properties of the coating, delamination will also affect the device's heat dissipation, bonding strength and electrical conductivity.
16, silver ion migration
A customer with silicone encapsulation, conductive silver adhesive vertical flip light source leakage phenomenon, commissioned Kam Kam reason. Gold Kam through the poor lamp bead analysis, abnormal silver element was detected in the side of the chip, and silver particles can be observed from the bottom of the positive silver glue area dendritic extended morphology gradually spread to the chip near the top of the P-N junction side, so Golden Kam determine the poor lamp bead leakage failure is most likely caused by silver ions from the crystal silver plastic ion migration in the side of the chip. Silver ion migration phenomenon is gradually formed during the use of the product, with the migration of the phenomenon of aggravating, the final silver ions will lead the chip P-N junction, resulting in low resistance side of the chip path, leading to the chip leakage current abnormalities, serious The case even caused a chip short circuit. There are many reasons for the migration of silver, but the main reason is that the silver-based material is damp. After the silver glue is wetted, the invaded water molecules ionize the silver and migrate along the side of the chip under the vertical electric field from bottom to top. Therefore, the detection of gold Kam recommend customers with caution in silicone packaging, silver glue vertical flip chip beads, the choice of gold tin eutectic soldering the chip fixed on the bracket, and enhance the waterproof testing of lamps.
17, solid crystal glue quit
Silicon-based curing agents for LED packages contain platinum (platinum) complexes, which are extremely toxic and poisoning agents are any of nitrogen (N), phosphorus (P), and sulfur Compounds, once the curing agent poisoning, the silicone curing incomplete, it will result in high linear expansion coefficient, stress increases.
Plastic packaging
18, glue heat resistance is poor
According to our test shows that pure silica gel to 400 degrees began to crack, but the epoxy resin modified silicone heat resistance is pulled down to the level of epoxy resin, when the modified silica gel used to high-power LED Or high-temperature environment, there will be colloidal hair black hair cracking dead lights and other phenomena.
19, do not glue
Silicon-based curing agents for LED packages contain platinum (platinum) complexes, which are extremely toxic and poisoning agents are any of nitrogen (N), phosphorus (P), and sulfur Compounds, once the curing agent poisoning, the silicone curing incomplete, it will result in high linear expansion coefficient, stress increases.
Silicone prone to "poisoning" substances are: containing N, P, S and other organic compounds; Sn, Pb, Hg, Sb, Bi, As and other heavy metal ion compounds; containing ethinyl and other unsaturated groups of organic compounds. Pay attention to the following materials:
Organic Rubber: Sulfur Vulcanized rubber such as gloves
Epoxy resin, polyurethane resin: Amine, Isocyanate curing agent
Synthetic silicone RTV rubber: In particular, the use of Sn-based catalyst
Soft Polyethylene: plasticizers, stabilizers
Engineering Plastics: Flame Retardants, Heat Resistant Agents, UV Absorbers and more
Silver, gold-plated surface (the manufacture of the plating solution is the main reason)
Degassing caused by Solder register (caused by silicone heat curing)
20, package plastic expansion coefficient is too large
In the hot and cold impact of the lamp beads using the environment, because of the heat stress, the effect of temperature changes in the environment will be more exacerbated, the colloid itself has tensile strength and elongation at break, when the pull over, then the colloid Cracked
21, glue chlorine
However, the current domestic epoxy resin production enterprises generally small-scale production, management and backward production technology, operating machinery automation is not high, resulting in the parameters of epoxy resin is difficult to protect. The production of low quality epoxy resin is related to the status quo of the industry in our country, and the industry urgently needs upgrading.
Chlorine in epoxy resins not only chlorides the stent silver plating, alloy wires or other active metals and chip electrodes (aluminum reflective layer), but also affects the curing of the resin by complexing with amine curing agents. Chlorine content is an important physical property of epoxy resin. It refers to the mass fraction of chlorine contained in epoxy resin, including organic chlorine and inorganic chlorine. Inorganic chlorine can affect the electrical properties of the cured resin. The content of organic chlorine indicates the content of the part of the chlorohydrin group in the molecule that has not closed-loop reaction, and its content should be reduced as much as possible. Otherwise, the curing of the resin and the properties of the cured product will also be affected.
In order to more effectively prevent the phenomenon of corrosion of the electrode chlorine, reduce the quality risk of the entire industry, Golden Kam exclusive to the world's LED manufacturers to launch "Kam Kam-free certification" testing services. "Kam Kam chlorine-free certification" is designed to confirm LED glue and chips contain excessive levels of chlorine, PPM level of detection accuracy. The content of the certification report can be found on the website of Jinjian Inspection Website. gmatg. com query. With the "Kam Kam chlorine-free certification" service, LED buyers can rest assured purchase of raw materials with "Kam Kam-chlorine-free certification", greatly reducing the risk of raw materials procurement.
Gold Line
22, copper alloy, gold clad silver alloy wire, silver alloy wire instead of gold wire
Gold wire has the advantages of large conductivity, good thermal conductivity, corrosion resistance, good toughness and excellent chemical stability, but the expensive gold wire leads to high packaging cost. In the periodic table, the transition metal elements of gold, silver, copper and aluminum four kinds of metal elements have a higher conductivity. Many LED manufacturers try to develop such as copper alloy, gold clad silver alloy wire, silver alloy wire instead of expensive gold wire. Although these alternatives are superior to gold wire in certain properties, they are much less chemically stable. For example, silver wire and gold-coated silver alloy wire are susceptible to sulfur / chlorine / brominated corrosion and copper wire is easily oxidized. These alternative solutions make the bonding wire susceptible to chemical attack, reducing the reliability of the light source and prolonging the life of the encapsulated silicone similar to a water-absorbing breathable sponge.
23, the diameter deviation
1g gold, you can pull a length of 26.37m, 50μm (2 mil) diameter gold wire, you can also draw a length of 105.49m, diameter 25μm (1 mil) of gold wire. If you hit the gold wire length are fixed, if the incoming wire diameter is half the original, then hit the gold wire measured resistance of the normal one-fourth.
Golden Kam test pointed out that for suppliers, the smaller the diameter of the gold wire, the lower the cost, in the case of the same price, the higher the profit. For LED customers using gold wire, the purchase of gold wire diameter cut corners, there will be increased gold wire resistance, reducing the risk of fusing current will greatly reduce the life of LED light source. The 1.0 mil gold wire life is bound to be shorter than the 1.2 mil gold wire, but the simple test at the packaging plant is not tested, where the gold can provide incoming wire diameter testing.
24, surface defects
(1) There shall be no scratches, pits, scratches, cracks, protrusions, discounts and other defects on the surface of the wire exceeding 5% of the wire diameter to reduce the service life of the device. The gold wire in the drawing process, the surface of the wire surface defects, will lead to increased current density, the damaged parts easily burned, while reducing the ability to resist mechanical stress, resulting in damage at the inner lead fracture.
(2) Gold wire surface should be free of oil, rust, dust and other adhesion, which will reduce the bonding strength between gold wire and LED chip, gold wire and bracket.
25, pull off the load and elongation is too low
A good gold wire that can withstand the impact of resin encapsulation must have the specified tensile load and elongation. At the same time, the breaking force and elongation of the gold wire play a key role in the quality of the wire bonding, and bonding wires with high breaking rates and elongations are more conducive to bonding. Too soft gold wire will lead to the following undesirable: (1) arch drooping; (2) spherical instability; (3) the neck of the ball is easy to shrink; (4) the gold wire easy to break. Too hard gold leads to the following defects: (1) puncturing the chip electrodes or epitaxy; (2) cracking the neck of the gold ball; (3) difficulty in forming the alloy; and (4) difficulty in controlling the arc of the arch wire.
After enumerating so many reasons, we can conclude that the simple appearance of a dead LED lamp may be caused by several reasons. In the past, most of LED industry encountered problems and could not see the essence of the problem , Fundamentally solve the problem, the company focused on the detection of LED materials such as Kam came out, put a lot of theoretical theorization, through the division of labor from different professional teams, high-precision testing equipment, the collection of data on the basis of the failure of the industry , Come to more precise conclusions.


  • Win the market with faith ,own the market share with brand

    LUX Lighting always aimed at becoming the global respected high-class LED supplier

    Superior quality Leading production equipment
    Rigorous production process
    Strict quality testing
    High efficiency Efficient implementation team
    Automated production processes
    Years of production experience
    High service 3-5 year warranty
    Professional service team
    Perfect after-sales service policy

    Our excellent sales and after-sales team are always at your service and will take good care of you, our valued customer