Method of LED vulcanization failure analysis

Reading Volume：【 2914 】

Time：【 2018-09-01 】

Method of LED vulcanization failure analysis
The vulcanization of the LED refers to the process in which the silver ions in the coating react with sulfide ions to produce black silver sulfide after the LED lamp beads are exposed to sulfur-containing substances in the external environment. High temperature and humidity will accelerate the reaction rate.
The impact of LED vulcanization:
1. The functional area of the lamp bead becomes black, the luminous flux decreases, and the color temperature drifts.
2. After the silver layer in the functional area turns into silver sulfide, the contact force between the golden ball and the functional area decreases, and the lamp is likely to die.
Method of LED vulcanization failure analysis:
1. Although it is easy to observe the vulcanization phenomenon, every subtle link in the production and application of LED lamp beads may cause sulfur pollution; the source of sulfur is diversified and the determination process is complicated, and the influence of each factor needs to be eliminated.
2. Scanning electron microscope-energy spectrum analyzer (SEM-EDS) has accurate results of element analysis of materials, which can effectively eliminate irrelevant factors and determine the source of sulfur pollution.
case analysis:
A lighting factory sent a batch of LED vulcanized lamp beads and commissioned Jinjian to find out the cause of the failure.
In order to find the source of sulfur, Jinjian uses SEM-EDS equipment to trace all links that may cause vulcanization
Packaging factory: bracket, phosphor, packaging glue and other materials, packaging, transportation, etc.
Application factory: circuit board, soldering agent, wire, coating glue, potting glue, rubber pad, adhesive and other materials, packaging, transportation, etc.
Others: auxiliary supplies (rubber gloves, cleaning agent), workshop environment, etc.
End customer use conditions and environment
Sample two
Sample two
SEM-EDS inspection points:
Sample one
Sample one
Package application process
Package application process inspection data
The energy spectrum analysis results show that the lamp beads do not contain sulfur before reflow soldering; the plastic foam used for circuit boards and packaging contains high sulfur content, and the sulfur element lines in defective products may come from circuit boards and plastic foam.

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