The reason why the LED light source is black

Release date: 2017-11-02 Source: Foreign station sharing:

Sulfation, chlorination, bromination

The silver-plated layer on the LED holder contacts the sulfur-containing gas to form silver sulfide. Contact with acidic nitrogen-containing chlorine or bromine gas generates light-sensitive silver halide, which causes the source to black out. Source sulfur/chlorine/bromination is likely to occur at every stage of the production, storage, aging, and use of LED light sources and luminaires. After the blackening of the light source has been diagnosed as sulfur/chlorine/bromination, the customer has to select a specific sulfur removal scheme based on the stage of sulfur/chlorine/bromination. At present, the sulfur emission/chlorine/bromine detection projects launched by Jinjian include: sulfur emission/chlorine/bromine (including built-in power supply), sulfur emission/chlorine/bromine (except for power supply), sulfur emission/chlorine/bromine, and auxiliary materials. Sulfur removal / chlorine / bromine, sulfur / chlorine / bromine in the packaging workshop, sulfur / chlorine / bromine in the lighting workshop, sulfur / chlorine / bromine in the reflow shop. Since the sulfur/chlorine/bromine-containing gas penetrates into the light source through the gap of the silica gel or the bracket, Jinjian also introduces a gas tightness inspection program to further help the customer to improve the light source incoming requirements.

2. Oxidation
Silver in the high temperature and high humidity environment will easily react with oxygen to form black silver oxide. After the blackening of the confirmed light source is caused by the oxidation of the silver plating layer, Jinjian will advise the customer to further check the airtightness of the light source and the lamp to eradicate the moisture infiltration route.

3. Carbonization
Experience to talk about the material defects of the six raw materials (chip, bracket, solid crystal glue, bonding wire, phosphor, encapsulant) of LED light source and the process defects of three major packaging processes (solid crystal, wire bonding, potting) It is possible to cause the light source to generate extremely high temperatures, causing the light source to be partially or totally black and the light source to be carbonized. Unreasonable heat dissipation design of LED lamps, low thermal conductivity of heat dissipation materials, unreasonable power supply design, and too many reflow soldering defects can cause carbonization of the light source. Therefore, when Jin Jian initially diagnoses that the cause of blackening of the light source is carbonization, it is recommended that the customer take the LED light source or the failure analysis route of the lamp, dissect the light source/light fixture, and find the source of defects or high thermal resistance.

4. Chemical incompatibility

Blackening of the LED source may also be caused by chemical contamination, which often occurs in sealed luminaires with little or no air flow. When the blackening of the light source of Jinjian is caused by chemical compatibility problems, customers are advised to conduct chemical incompatibility investigations on the materials used in the lamps to find materials that are incompatible with the light source. Frequently encountered problems. However, blackening of the light source is only an appearance, and the causes of blackening of the LED light source are caused by vulcanization, chlorination, bromination, oxidation, carbonization, and chemical incompatibility. Due to the lack of professional testing equipment and personnel, most LED companies often rely on experience and guessing for blackening failure analysis, lacking scientific testing data. In response to this phenomenon, Jinjian launched the initial diagnosis of LED light source blackening, aiming to help customers to quickly, low-cost, and accurately determine the blackening of LED light sources within two days (in the end, vulcanization, chlorination, bromination, oxidation) , carbonization, or chemical incompatibility?), according to the LED light source blackening failure analysis roadmap to provide customers with further solutions to find out the problem.

Label: The reason why the LED light source is black