First, common notes in the use of LED lamp bead:
The welding conditions
Reflow welding: please preheat at 150℃ within 2 minutes, and weld once at 240℃ within 5s after heating.
Soldering iron: use the maximum 25W controllable temperature soldering iron, the tip temperature is not higher than 320℃, within 3 seconds to complete one welding.
Do not apply external force on the product during welding. Do not bend the circuit plate after welding.
Packing:
The purpose of moisture-proof packaging is to ensure the lowest moisture in the package because moisture absorption of resin during welding causes moisture evaporation and expansion, which may cause interface stripping.
The product should be used within one year from the date of packaging. Before the package is opened, the product should be stored in an environment with temperature of 5-30 ℃ and relative humidity <60%.
After unpacking bags, the products must be welded and used within 24 hours. Otherwise, the products must be stored in an environment with temperature of 5-30 ℃ and relative humidity of less than 30% for less than one week. If you have any unused products, please put them back
Moisture-proof bag sealed for preservation:
If the product exceeds the above storage requirements or becomes damp, it must be baked at 60±5℃ for 12 hours.
The electrode surface of the product is gold-plated, which is easy to be corroded or discolored, resulting in welding difficulties. It is recommended to use it as soon as possible.
Take care to avoid rapid changes in ambient temperature, especially in humid environments.
Esd protection:
High-brightness blue, green and white products are sensitive to static electricity. Pay attention to the electrostatic surge in use, which may damage or destroy the product. The workbench in contact with the product should be grounded through the resistance with a conductive pad. The tip of the soldering iron must be grounded; Ion generators are recommended.
Two, LED lamp bead welding process 7 causes of dead light
1. Common welding methods can be divided into electric iron welding, heating platform welding and reflow welding, etc. .
A. Electric iron welding is the most common, such as sample making and maintenance. In order to save cost, most of the electric iron bought back by most existing manufacturers are unqualified inferior products, and most of them are poorly grounded. There is electricity leakage. That is to say, tens of times - hundreds of times the voltage under the lamp bead added to the LED lamp bead, instantly burn it out.
Note: The situation of being connected with the electrostatic belt will be more serious, because when the human body is connected with the electrostatic belt, the resistance of the circuit to the ground will be smaller, and the current through the human body to the lamp will be larger. This is also the problem that many people say that there are still so many damage of the lamp with the electrostatic belt.
B. Dead lamps caused by welding of heating platform. Due to the continuous sample list of lamps, in order to meet the needs of small batch and sample list, most enterprises have become the best production tool due to the advantages of low equipment cost, simple structure and operation. However, due to the use environment (such as: Where there is a fan, the temperature can not be constant) and the control of the welding operator's proficiency and welding speed has become a big problem that causes the dead lamp. In addition, there is the grounding of the heating platform equipment.
C, reflow welding, generally this welding method is the most reliable production method, suitable for mass production and processing, if improper operation, will cause more serious dead light consequences, such as unreasonable temperature adjustment, machine grounding, etc..
2. Improper storage causes dead lights:
This problem is the most common: due to the opening of the package do not pay attention to moisture-proof problem, because the sealing glue of the lamp beads using silica gel material; Silica gel material has a certain water absorption characteristics, after the damp lamp bead stick board, after the high temperature welding process, silica gel will thermal expansion and contraction, gold wire, chip, support deformation caused by the gold wire displacement fracture, the phenomenon of lamp point is not bright.
Therefore, it is suggested that LED should be stored in a dry and ventilated environment, with storage temperature of -40℃- +100℃ and relative humidity below 85%. LED should be used within 3 months in its original packaging condition to avoid rust of the bracket; When the LED bag is unsealed, it should be used as soon as possible, at this time the storage temperature is 5℃-30℃, the relative humidity is below 60%.
3, Chemical cleaning:
Do not use unknown chemical liquid cleaning LED, because that may damage the LED colloidal surface, or even cause colloidal cracks, if necessary, please use alcohol cotton swab cleaning in normal temperature ventilation environment, the best time to control the wind in one minute.
4. Dead light caused by deformation:
As part of the lamp board exists deformation, the operator will go to plastic, due to the deformation of the board, the above beads also follow the deformation together, pull off the gold line, the lamp is not bright, it is recommended that this type of board had better be plastic processing before production. More often in the process of production and assembly and handling may also cause deformation pull broken gold wire phenomenon.
There is stacking, in order to facilitate the production process, the lamp board will be stacked at will, due to gravity, the lower lamp beads will be deformed by force, damage the gold line.
5, The heat dissipation structure, power supply and lamp board do not match:
Due to the improper design or selection of power supply, the power supply exceeds the maximum limit that LED can bear (overcurrent, instantaneous impact); The unreasonable heat dissipation structure of lamps and lanterns will cause dead lamps and premature light decline.
6. Factory grounding:
The factory's main grounding wire must be checked for good.
7. Static electricity:
Static electricity can cause LED function failure. It is recommended to prevent ESD damage to LED.
A. When detecting and assembling LED, operators must wear antistatic bracelets and antistatic gloves.
B. welding equipment and testing equipment, work table, storage rack, etc., must be well grounded.
C. Use ion fan to eliminate static electricity caused by friction during storage and assembly of LED.
D. the LED material box adopts anti-static material box, the bag adopts static bag.
E. do not have a fluke psychology, conveniently to touch LED.
The abnormal phenomena of LED damaged by ESD are as follows:
A. reverse leakage, light will cause brightness reduction, serious lamp does not light.
B. The forward voltage becomes smaller. Leds do not glow when driven at low current.
C. the lamp does not light due to poor welding.
