Is the blackening of the LED light source caused by sulfuration, chlorination, bromination, oxidation, carbonization, or chemical incompatibility? BBIER lighting experts will tell you the answer!

The blackening of LED light sources is a problem often encountered by major LED companies. However, the blackening of the light source is only an appearance. Reasons such as sulfidation, chlorination, bromination, oxidation, carbonization, and chemical incompatibility will all lead to the blackening of the LED light source. Due to the lack of professional testing equipment and personnel, most LED companies usually rely on experience and guesswork when doing blackening failure analysis, lacking scientific testing data. In response to this phenomenon, BBIER lighting experts launched the preliminary diagnosis of LED light source blackening, aiming to help customers quickly, low-cost, and accurately characterize the cause of LED light source blackening (whether it is vulcanization, chlorination, bromination or not) within 2 days. , oxidation, carbonization, or chemical incompatibility?), and at the same time provide customers with further solutions to find out the problem according to the LED light source blackening failure analysis route.

Sulfurization, chlorination, bromination

The silver-plated layer on the LED bracket will generate silver sulfide when it contacts sulfur-containing gas, and it will generate light-sensitive silver halide when it contacts acidic nitrogen-containing chlorine and bromine gases, which will cause the light source to turn black and fail. Sulfur/chlorine/bromination of light sources may occur in every link of production, storage, aging, and use of LED light sources and lamps. After the blackening of the light source is diagnosed as sulfur/chlorine/bromination, the customer should choose a specific sulfur removal plan according to the process of sulfur/chlorine/bromination. At present, the sulfur/chlorine/bromine detection items launched by BBIER lighting experts include: sulfur/chlorine/bromine exhaust from lamps (including built-in power supply), sulfur/chlorine/bromine exhaust from lamps (except external power supply), sulfur/chlorine/bromine exhaust from power supply, Sulfur/chlorine/bromine exhaust from auxiliary materials, sulfur/chlorine/bromine exhaust from packaging workshop, sulfur/chlorine/bromine exhaust from lighting workshop, sulfur/chlorine/bromine exhaust from reflow soldering workshop. Since sulfur/chlorine/bromine-containing gases will permeate into the light source through the gaps in the silica gel or the bracket, BBIER lighting experts have also launched an air tightness inspection program to further help customers improve the requirements for incoming light sources.

2. Oxidation

Silver reacts easily with oxygen in a high-temperature and high-humidity environment to form black silver oxide. After BBIER lighting experts confirm that the reason for the blackening of the light source is the oxidation of the silver plating layer, they will advise the customer to further check the air tightness of the light source and lamps to eradicate the way of moisture penetration.

3. Carbonization

Based on experience, the material defects of the six raw materials of LED light sources (chips, brackets, die-bonding glue, bonding wires, phosphor powder, and packaging glue) and the process defects of the three major packaging processes (die-bonding, wire bonding, and glue potting) All of them may cause the light source to generate extremely high temperature, resulting in partial or overall blackening of the light source and carbonization of the light source. Unreasonable heat dissipation design of LED lamps, low thermal conductivity of heat dissipation materials, unreasonable power supply design, and too many reflow soldering defects will also cause carbonization of the light source. Therefore, when BBIER lighting experts preliminarily diagnose that the cause of the blackening of the light source is carbonization, they will advise customers to take the LED light source or lamp failure analysis route, dissect the light source/lamp, and find out the source of defects or high thermal resistance.

4. Chemical incompatibility

Blackening of LED light sources can also be caused by chemical contamination, which often occurs in sealed luminaires with little or no air flow. When BBIER lighting experts confirm that the blackening of the light source is caused by chemical compatibility issues, they will advise customers to conduct chemical incompatibility investigations on the materials used in the lamps to find out materials that are incompatible with the light source.