The high-power LED lamp bead is a kind of LED lamp bead . Compared with the low-power LED lamp bead, the high-power LED lamp bead has higher power, brighter brightness and higher price. The low-power LED lamp bead rated current is 20mA, and the rated current higher than 20mA can basically be counted as high power. The general power numbers are: 0.25w, 0.5w, 1w, 3w, 5w, 8w, 10w, and so on. The main brightness unit is lm (lumen), and the unit of brightness of low power is generally mcd (millicandela, 1cd=1000mcd), which is the luminous intensity I. 1cd=1 lm/sr (lumen/stereoargon)=1 candlelight. It is interpreted as: the luminous flux emitted by the light source within the solid angle dΩ in the specified direction or the luminous flux dΦ transmitted by the obtained light source, the quotient of which is the luminous intensity I (in candela, cd). The outer cover can be made of PC tube, and the high temperature resistance is up to 135 degrees. The PC tube is made of LED cover, the internal temperature can reach 135 degrees, and the external temperature can resist -45 degrees without cracking.
High power lamp bead classification
At present, it is widely used in automobile lights, flashlights, lamps and other places as an emerging green, environmentally friendly and energy-saving light source. The reason why LED high power is so called, mainly for low-power LEDs, I have summarized three types of classification standards:
The first type is divided into 0.5W, 1W, 3W, 5W, 10W...100W depending on the power, depending on the total power of the molded product after packaging.
The first type is divided into 0.5W, 1W, 3W, 5W, 10W...100W depending on the power, depending on the total power of the molded product after packaging.
The second can be divided into different sizes according to the packaging process: large-size epoxy resin package, mermaid-type epoxy resin package, aluminum substrate (MCPCB) package, TO package, power SMD package, MCPCB integrated package, etc.
The third type can be classified into low light decay high power products and non-low light decay high power products according to the degree of light decay.
Of course, since the parameters of the high-power LED itself are relatively large, there are different classification standards according to different parameters, which are not described here.
Precautions
Precautions
LED high power is still one of the LED packaging products, which is the most important part of the semiconductor lighting industry. Due to the limitations of current semiconductor light-emitting diode chip technology, the photoelectric conversion efficiency of LEDs needs to be improved, especially for high-power LEDs. Because of its high power, about 60% of the electrical energy will become thermal energy release (with the development of semiconductor technology). The photoelectric conversion efficiency will gradually increase), which requires the end customer to do the heat dissipation work when applying high-power LED products to ensure the high-power LED products work normally.
1. Heat sink requirements.
Appearance and material: If the sealing requirements of the finished product are not high, it can directly convect with the outside air environment. It is recommended to use aluminum or copper fins with fins.
2. Effective heat dissipation surface area:
For 1W high power LED white light (other colors are basically the same), we recommend the total heat dissipation surface area of ​​the heat sink ≥ 50-60 square centimeters. For 3W products, it is recommended that the total heat dissipation surface area of ​​the heat sink be ≥150 square centimeters. The higher power depends on the situation and the test results. Try to ensure that the heat sink temperature does not exceed 60 °C.
3. connection method:
When connecting the high-power LED substrate to the heat sink, please make sure that the two contact surfaces are flat and the contact is good. To strengthen the bonding degree between the two contact surfaces, it is recommended to apply a layer of thermal grease on the bottom of the LED substrate or the surface of the heat sink (thermal conductivity of thermal grease) ≥3.0W/mk), the thermal grease should be applied evenly and in an appropriate amount, and then fixed by screws.
Static Protection
LED is a semiconductor device, which is sensitive to static electricity. Especially for white, green, blue and purple LEDs, it is necessary to prevent static electricity generation and eliminate static electricity.
1. The generation of static electricity:
1 Friction: In daily life, any two objects of different materials are separated and contacted to generate static electricity. The most common method of generating static electricity is to generate electricity by friction. The better the insulation of the material, the easier it is to rub the electricity. In addition, static electricity can also be generated by the separation of any two different substances after contact.
2 Induction: For conductive materials, because electrons can flow freely on its surface, such as placing it in an electric field, due to the same-sex repellent, the opposite sex attracts, positive and negative ions will transfer, and charges will be generated on the surface. .
3 Conduction: For conductive materials, charge transfer occurs due to the free flow of electrons on its surface, such as contact with charged objects.
2. The harm of static electricity to LED:
1 The heat generated by the instantaneous electric field or current causes the LED to be partially injured. It shows that the leakage current increases rapidly and still works, but the brightness is lowered and the life is damaged.
2 The electric field or current destroys the insulation layer of the LED, making the device inoperable (completely destroyed), which is a dead light.
3. Electrostatic protection and elimination measures:
For the entire process (production, testing, packaging, etc.) all employees who are in direct contact with the LED must take measures to prevent and eliminate static electricity, mainly
1. Lay the anti-static floor and ground the workshop.
2. The workbench is an anti-static workbench, and the production machine is well grounded.
3. The operator wears an antistatic suit with an anti-static wrist strap, gloves or an ankle ring.
4. Apply an ion fan.
5. Soldering the soldering iron to make grounding measures.
6, the packaging uses anti-static materials.
Welding precautions
1. When soldering, please pay attention to the best choice of constant temperature soldering iron. The soldering temperature is below 260 °C. The time for the soldering iron to contact the LED pad once does not exceed 3S.
2. For high-power LEDs encapsulated in silicone, the highest heat-resistant temperature of silica gel is 180 °C, so the soldering temperature of LEDs must not exceed 170 °C. Soldering with low-temperature soldering iron and low-temperature solder paste (wire), the soldering iron and LED pads are in one contact. The time does not exceed 3S.
How to test high power LED lamp beads
How to test high power LED lamp beads
Faced with the chaos of the high-power LED lamp bead market, the forestry and mixed-use accessories market has indeed made many new generations of high-power LED lamp bead technicians very confused. Here are a few quick and easy ways to test fluorescent glue, phosphors, and chips for your reference.
1. How to test the stability of the chip
The chips of different chip manufacturers were tested with the same batch of silica gel, the same batch of phosphors, and the same process technology was used to encapsulate the initial luminous flux. It was then aged with a current of 700 mA for 96 hours, after 192 hours, the resulting luminous flux, and the drift of the color coordinates. The final test parameters can be quickly determined, the quality of the chip manufacturer.
2. How to test fluorescent glue
The method is the same as above, using the same batch of chips, the same batch of phosphors, and two different fluorescent glues. After the same process is used to encapsulate the test, the initial luminous flux is tested. It was then aged with a current of 700 mA for 96 hours, after 192 hours, the resulting luminous flux, and the drift of the color coordinates. The final test parameters can be quickly determined, the quality of different fluorescent glue manufacturers.
3. How to test phosphors
The method is the same as above, using the same batch of chips, the same batch of fluorescent glue, and then using two different phosphors. After the same process is used to encapsulate the test, the initial luminous flux is tested. It was then aged with a current of 700 mA for 96 hours, after 192 hours, the resulting luminous flux, and the drift of the color coordinates. The final tested parameters can be quickly determined by the quality of different phosphor manufacturers.
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