First, the common precautions during the use of LED lamp beads:
1, welding conditions
Reflow soldering: Preheat at 150°C for 2 minutes. After heating, perform soldering at 240°C for 5 seconds.
Soldering Iron Welding: Use a controlled temperature soldering iron with a maximum of 25W, the tip temperature is not higher than 320°C, and soldering is completed within 3 seconds.
Do not apply external force to the product during welding. Do not bend the circuit board after soldering.
2, packaging
Since the moisture absorption of the resin causes the evaporation and expansion of moisture during welding, which may cause interface peeling, the purpose of the moisture-proof packaging is to ensure that the moisture in the packaging bag is the lowest.
The product should be used within one year from the date of packaging. Before the packaging bag is unpacked, it should be stored at a temperature of 5 to 30°C and a relative humidity of <60%.
After the packaging bag is unpacked, the product must be soldered and used within 24 hours. Otherwise, the product must be stored at a temperature of 5 to 30°C and a relative humidity of less than 30% for a period of no more than one week. If there is any unused product, please replace it.
Moisture-proof bag sealed
If the product exceeds the above storage requirements or is affected by moisture, it must be baked at 60±5°C for 12 hours.
The surface of the electrode of the product is gold-plated, and it is prone to corrosion or discoloration, resulting in welding difficulties. It is recommended that it be used as soon as possible.
Take care to avoid rapid changes in ambient temperature, especially in humid environments.
3, electrostatic protection
High-brightness blue, green and white products are sensitive to static electricity. When using them, it is necessary to pay attention to the fact that the static electricity surge will damage or destroy the product. The worktable that comes into contact with the product should be grounded through a resistor with a conductive table pad; the tip of the soldering iron must be Grounding; ionizers are recommended.
Second, the 7 causes of dead lights in LED lamp beads welding process
1, common welding methods can be divided into soldering iron welding, heating platform welding and reflow welding, etc.:
A. The soldering iron welding is the most common, such as sample making and maintenance. Because most of the existing manufacturers in order to save costs, the soldering irons purchased are mostly unqualified, and most of the soldering irons are poorly grounded, and there are leakage currents. The welding process This is equivalent to the leakage of the soldering iron tip - the LED is welded - the human body - the earth forms a loop, that is equal to dozens of times - hundreds of times the voltage of the lamp is added to the LED lamp beads, instantly Burn it out.
Note: The situation of connecting static belts will be more serious, because when the human body is connected to the static belt, the resistance to the circuit forming the ground is smaller, and the current flowing from the human body to the lamp beads will be greater, which is also what many people have said to have static electricity. There are still so many problems with lamp damage.
B. Dead lights caused by welding of heating platforms. Due to the constant sample list of lamps and lanterns, most companies have to meet the needs of small batches and sample orders. Due to the advantages of low equipment cost, simple structure and operation, the heating platform becomes the best production tool. , However, due to the use of the environment (such as: there is a fan temperature where the temperature can not be constant) and the welding operator's control of proficiency and welding speed has become a major problem caused by the dead lights, there is also heating Platform grounding conditions.
C, reflow, generally this welding method is the most reliable production method, suitable for mass production and processing, if not handled properly, it will cause more serious consequences of dead lights, such as unreasonable temperature adjustment, poor machine grounding.
2, caused by improper storage of dead lights:
This problem is the most common, because after opening the package does not pay attention to the issue of moisture, because the lamp beads more than the use of silicone rubber seal material, which according to a certain degree of water absorption characteristics, after the lamp beads after damp, after high temperature welding process Silicone will expand and contract due to thermal expansion, gold wire, chips, and stents will cause deformation and dislocation of the gold wire, resulting in a phenomenon that the light is not bright. Therefore, it is recommended that the LED be stored in a dry and ventilated environment with a storage temperature of -40. °C-
+100°C, relative humidity below 85%; LED is used within 3 months under its original packaging conditions to avoid rust; when the LED bag is opened, it should be used as soon as possible. The temperature is 5°C-30°C and the relative humidity is below 60%.
3, chemical cleaning:
Do not use unclear chemical liquids to clean the LED, because it may damage the surface of the LED colloid, or even cause gel cracks. If necessary, use an alcohol swab under room temperature ventilation. The time is best controlled in one minute.
4, deformation caused by dead lights:
Due to the fact that some of the lamp boards are deformed, the operator will reshape the board. Because the board is deformed, the upper lamp beads will also deform along with it. The gold wire will be pulled off and the lamp will not light. It is recommended to have this type of board. Fortunately, plastic processing before production. Longer assembly and movement in the production and may also cause deformation to break the gold wire phenomenon. There is stacking, the production process to facilitate the convenience, the lamp board will be stacked, due to gravity, the lower lamp beads will be deformed by force, damage the gold wire.
5, heat dissipation structure, power supply and light board do not match:
Due to the unreasonable power supply design or selection, the power supply exceeds the maximum limit (overcurrent, instantaneous impact) that the LED can withstand; the unreasonable heat dissipation structure of the lamp can cause dead light and premature light failure.
6, factory grounding:
It must be checked whether the plant's total grounding line is good.
7, static electricity:
Static electricity can cause malfunction of the LED. It is recommended to prevent ESD from damaging the LED.
A. When the LED is detected and assembled, the operator must wear an anti-static wristband and anti-static gloves.
B. Welding equipment and test equipment, working tables, storage racks, etc. must be well grounded.
C. Use an ion fan to eliminate the static electricity generated by the LED during storage and assembly.
D. The anti-static material box is used for the LED-filled cartridges, and electrostatic bags are used for the packaging bags.
E. Don't be lucky. Touch the LED.
The abnormal phenomena that LED damage by ESD are:
A, reverse leakage, light will cause the brightness to decrease, serious lights do not shine.
B, the forward voltage value becomes smaller. The LED does not emit light when driven at low current.
C. Bad soldering causes the lamp to be off.
