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A 9-year-old packaging industry practitioner's insight into the causes of LED dead lights

Jun 17, 2017


In this year's March 1, there was an article named "Led Dead light" heard so much this beam teacher analysis of the most complete! "The explosive article, obtained the 32000 reading volume, and by the other dozens of enterprise media reprint, has caused the profession to discuss hotly."

Recently, there are enthusiastic fans in the background message, published their personal views on the causes of LED death. Because the content is more detailed, so today's small part of the fan's point of view sorted out for your reference.

The following is the original fan view (slightly modified):

Causes the direct cause of LED dead light:

1. Solid Crystal: Less gum chip substrate around the low heat conductivity coefficient of the bottom, lamp bead use process heat dissipation conditions are not good cause dead lights. (Its own heat dissipation is to do led the biggest technical difficulties)

2. Welding line: One or two welding gold ball too flat tensile force is not enough or pull enough, but the contact point is very fragile or too round, adhesion is not enough. In the use process with the lamp bead internal temperature gradually rises easily to break off the dead lamp or appears the false expiration Dead lamp question (hand press the chip or the lamp bead on the Light)

3. Driving power: The current voltage value is not stable, the impact load of the current is too large to exceed the scope of the chip, causing the chip to burn the black line of electricity, performance failure or gold wire disconnect caused by lamp bead dead lamp.

4. Encapsulation of silicone or epoxy: Light beads in the use of the process with the increase in the internal temperature, silicone thermal expansion coefficient and stress index in the use of the time to reach a peak, there will be a silicone thermal expansion cracking phenomenon, and will directly affect the internal conduction wire break, resulting in lamp bead dead lamp. (The elongation coefficient of the gold line and the thermal expansion coefficient of the silica gel are critical when selected)

5. Chip: Chip leakage, process manufacturing caused by leakage and chip itself from the factory leakage. Test time is normal, and small amplitude leakage sometimes can not be measured (do high-power lamp bead to find these problems), the application process will cause electrical overload, a small portion of the current distribution uneven, transmission to the lamp board or bracket, after a period of time after the use of brightness is not enough, light deterioration serious, lamp bead failure, the internal structure blackened burn caused by the death lamp.

6. Heat dissipation: Application of thermal silica gel, radiator and heat dissipation conditions or equipment in the process of gap, the screws are not matter, thermal silica gel coating uneven, radiator and lamp bead total wattage mismatch, heat condition environment is poor, after a period of time after use will cause the lamp bead failure Light deterioration serious Black Death lamp.

7. Uncovered problems dead lights: material, technology, heat dissipation conditions, all normal, but there is still a dead light phenomenon and generally can not find the cause of the death of the problem point, this point of the older generation of people to do led for a long time, also have a special testing center and their own technical laboratory stripping detection, but the answer is vague (generally not very senior led enthusiasts will not say these days, the first condition of defects) so far can not find the specific reasons may be outside the appearance of this kind of testing equipment now.

The above is the 8, 9 years in the packaging industry engineering team's most common customer complaints experience, and the text mentioned similar. Because before I included in the engineering team is also at the Hong Kong Hkust led Research Center in Foshan, with the Dayang Research Center analysis of the failure of light beads and our own team analysis of the results are basically consistent, I hope that this is helpful.

Let's look at other fans ' comments and comments on the original text:

@ Indifferent: analysis is correct.

@ Spyker: solid-crystal wire welding is very important.

Liede: It is not always the problem of welding line, the relationship between glue is quite big.

@ Next moment, goodbye: Static electricity also causes dead lights.

@ Gansu Zhong Lian Photoelectric-snow view blue landscape LED lighting: the spirit of exploration.

@ Shell: Analysis is correct, many will encounter such a situation.

@ Small white: Welding line determines the quality of the bead.

@ Hua Huachun: for 1. 2 Case 2, personal opinion of the external force caused by: because the text mentioned mainly concentrated in the fourth solder joint, it seems that there is a law to follow, that the position of the welding line loss, may be welded wire when the loss of gold wire, or a patch of suction nozzle extruded to the lamp bead, or reflow after welding placement, board, assembly process extrusion to the lamp bead. Still need to be a troubleshooting.

Woind Flower: Weld line determines quality, glue determines reliability.

With the original author beam teacher said, led dead lights are many reasons, from the packaging, application, to use the various links are likely to appear dead lights. How to reduce and eliminate dead lights, improve product quality and reliability, is the key problem that every led enterprise needs to face.

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