In the production and application of LED beads, we will encounter some “dead lights” phenomenon. The dead light is that the LED light does not illuminate.
Whether it is the dead lights generated in production or application, it is a headache for manufacturers. It has to face the loss caused by product defects and the confidence of consumers in LED products.
Therefore, research and analysis of some common LED dead lights causes us to reduce and prevent the recurrence of LED product failures.
Guarantee product quality and enhance product competitiveness, and also provide a reference for enterprise technology improvement and improvement, thus creating greater economic benefits for enterprises.
Below we analyze the cause of the dead light and how to choose the right LEDs.
8 Reasons why LED dead
We collected 8 common reasons why LED dead, below are the details.
1. Welding method is not used correctly
Common welding methods can be divided into electric soldering iron welding, heating platform welding, and reflow soldering, etc.:
1.1 Soldering iron welding is the most common, such as sample preparation and maintenance
Due to the cost savings of most existing manufacturers, most of the soldering irons purchased are unqualified products, most of which are poorly grounded, there is leakage.
The welding process This is equivalent to the tip of the electric iron in the leakage – the LED is welded – the human body – the earth forms a loop, that is to say, tens of times – hundreds of times the voltage of the lamp bead is applied to the LED lamp bead, instantaneously Burn it out.
Note: The situation of connecting the static electricity belt will be more serious, because when the human body is connected to the static electricity belt, the resistance to the ground forming circuit is smaller, and the current through the human body to the lamp bead will be larger, which is also said to be electrostatically charged by many people. There are still so many problems with lamp bead damage.
1.2 The dead light caused by heating platform welding
Due to the continuous sample of the lamps, most enterprises have become the best production tools in order to meet the needs of small batches and sample sheets.
Due to the low cost of equipment, simple structure, and operation, etc.
However, due to the use environment (for example, the temperature of the fan cannot be constant) and the control of the welding operator’s proficiency and welding speed has become a major problem causing the dead light, in addition to heating Grounding of equipment on the platform.
1.3 Reflow soldering
Generally, this welding method is the most reliable production method, suitable for mass production and processing.
If the improper operation, it will cause more serious dead light consequences, such as unreasonable temperature adjustment, poor machine grounding.
2. Improper storage caused by dead lights
Improper storage is mainly due to the lack of attention to moisture.
Since the sealing of the lamp bead is mostly made of the silica gel material, it has a certain water absorption property.
After the damp lamp post is attached, after the high-temperature welding process, the silica gel will expand and contract, and the gold wire, the chip, and the bracket will be deformed, causing the gold wire to be displaced and broken, and the lamp spot will not be bright.
- LEDs should be stored in a dry and ventilated environment, storage temperature is -40 ° C – +100 ° C, relative humidity is below 85%.
- The LED is preferably used within 3 months of its original packaging conditions to avoid rusting the bracket.
- When the LED packaging bag is opened, it should be used as soon as possible. At this time, the storage temperature is 5°C-30°C, and the relative humidity is below 60%.
3 Incorrect cleaning method
Do not use an unknown chemical liquid to clean the LED, as it may damage the surface of the LED colloid and even cause colloidal cracks.
If it is necessary to clean, please use an alcohol swab for cleaning in a normal temperature and ventilation environment. The time is best controlled to complete in one minute.
4 Dead LED caused by deformation
Due to the deformation of some of the lamp panels, the operator will deform the shape, causing the board to deform.
The lamp beads on the top are also deformed together at the same time. The gold wire is broken and the light is not bright. It is recommended that this type of board be the best. Shaping is done before production.
Longer production and assembly and handling may also cause deformation to break the gold wire.
There is also the stacking, the production process for the convenience of the hand, the light board is randomly stacked, due to gravity, the lower layer of the lamp bead will be deformed by force, damage the gold line.
5. The heat dissipation structure, power supply, and lamp board do not match.
Because the power supply design or selection is unreasonable, the power supply exceeds the maximum limit that the LED can withstand (super current, instantaneous impact).
The heat dissipation structure of the lamp is unreasonable, which will cause dead lights and premature light decay.
6. Factory ground wire
The factory’s total ground wire must be checked for goodness.
7. Static electricity
Static electricity can cause LED function failure. It is recommended to prevent ESD from damaging the LED.
- 7.1 The operator must bring an anti-static wrist strap and anti-static gloves when testing and assembling LEDs.
- 7.2 Welding equipment and test equipment, work tables, storage racks, etc. must be well grounded.
- 7.3 Use an ion fan to eliminate static electricity generated by the LED during storage and assembly due to friction.
- 7.4 The box containing LED is made of anti-static material box, and the packaging bag is made of the electrostatic bag.
- 7.5 Do not have the luck, touch the LED.
The anomalies that occur with LEDs damaged by ESD are:
- Reverse leakage, the light will cause the brightness to decrease, and the light will not light.
- The forward voltage value becomes smaller. The LED does not emit light when driven at low current.
8. Poor soldering causes LED lights to failure
Some of the LED beads are poorly soldered, causing poor contact during use and cannot be lit.
How to buy LED lamp beads correctly
LED beads are the light source of LED products, and need to work a long time. If the LED lights price too high or the quality is too bad, it can’t meet people’s needs. So how should we choose the right LED lights?
Below we summarize 6 points about the purchase of LED light beads:
1. Pay attention to the service life of LED light beads – long life. The temperature of the light source base does not exceed 60 degrees Celsius.
2. Pay attention to the LED chip used by the LED light bead. The expansion of optoelectronic LEDs uses wafer chips and uses a unique packaged light source design.
3. Pay attention to the brightness of the LED light bead. The imported high-brightness semiconductor wafer has the characteristics of high thermal conductivity, small light decay, pure light color, and no ghosting; the overall illumination and uniform brightness.
4. Pay attention to the warranty time of LED light beads.
5. Pay attention to the light color of the LED light beads. The color rendering is good, the color of the real object is more realistic, can meet the needs of different environments, and eliminates the depressed emotion caused by the high or low color temperature of the traditional lights, which makes the visual comfort.
6. Start with constant current, fast response, no preheating, and quick start.