With the popularity of LED lighting, the advantages of integrated LED light sources in the application of lamps are gradually recognized by people in the industry and gradually become the trend of lamp applications. Integrated LED light source We usually refer to the CHIP on Board package form, which is a package form that integrates several LED chips on the same bracket and realizes high-power LED through internal connection. The volume is large and the power is generally 10W the above.
LED integrated light source and its application, improper use can also cause the phenomenon of dead lights. After using the LED end-users for a period of time, they may encounter the situation that the light source is not bright (dead light). The causes of dead lights can be divided into the following types:
- The static electricity damages the LED chip: the static electricity makes the LED chip invalid, the leakage current becomes larger, and the short circuit forms a resistance. The other chips of the integrated light source can continue to light, including chips of the same series of circuits, but the chips of the same series will be slightly brighter. Lighting for a long time uses light decay to accelerate and the service life becomes shorter; 2. Observe obvious traces of static loss on the chip through a microscope. If the light source is tested again, the leakage current parameter will be exceeded.
Reason: Electrostatic damage (human body, environment, equipment and other factors) during LED integrated light source storage, packaging and welding applications.
Improvement: ESD protection includes storage/operation environment, instrument/equipment grounding, human body static electricity protection, etc.
- The LED integrated light source is abnormally matched with the power supply or the drive power output is out of control, which causes damage to the internal chip and gold wire of the LED integrated light source. This undesirable phenomenon is: the chip and the gold wire are obviously blackened, and the gold wire is carbonized or the chip is found through microscope observation. Burnt state. Lighting for a long time will affect the heat dissipation of the light source, so the light decay is serious until the dead light.
Reason: abnormal output of the driving power supply (including factors such as parameter mismatch, poor power supply performance and abnormal output).
Improvement: The technical personnel’s evaluation of the electrical performance of the LED light source and drive, the feasibility of structural safety; the improvement of the reliability of the drive power performance, etc.
- The surface of the LED integrated light source is damaged or cracked, which causes the light source to fail to light and die.
Reason: The working temperature of the LED light source reaches the endurance limit, causing the colloid to fail and harden, or the light source is wet to cause welding or use. During the thermal expansion and contraction of the colloid, the gold wire is broken and the dead light is caused. In addition, the colloid is damaged during the use (external stress When applied to the surface of the colloid, the internal gold wire is broken and the lamp is broken (one of the points B/C/D is broken as shown in the figure). Occasionally, other substances adhere to the surface of the colloid during the welding process and damage the colloid. The use of time will eventually lead to a dead light.
Improvement: The feasibility experiment verification of packaging glue parameters by packaging manufacturers; LED application manufacturers evaluate the feasibility of heat dissipation structure according to the use temperature limits provided by packaging manufacturers; pay attention to protect the colloid surface from damage during use and handling.
- the black LED internal light source causes a dead light.
Reasons: There are chemical substances (sulfur, halogen, etc.) that cause vulcanization in the environment of the packaging workshop; there are sulfur and halogen components in LED application structural parts, glue, and environment, especially high temperature links such as welding will accelerate the volatilization of such substances and affect the LED The integrated light source causes the internal bracket to vulcanize. The vulcanized bracket will affect the heat dissipation and light parameters of the product. The final result is that the LED dead light does not turn on.
Improvement: Both the packaging plant and the application plant should strictly control the chemical composition of the materials, and eliminate the use of sulfur-containing auxiliary materials (glue, washing water, packaging bags, gloves, etc.) and the control of sulfur in the environment. At the same time, the packaging plant must LED integrated light source for anti-vulcanization test.