LEDs often encounter product vulcanization during production and use, resulting in product failure, causing significant losses to customers and manufacturers. In particular, SMD LEDs and high-power LEDs use a large amount of polymer materials such as silica gel and silica gel modified materials in the manufacturing process, which has become the hardest hit area for product vulcanization. How to prevent LED vulcanization during manufacturing and use has become a common problem faced by various LED manufacturers. LED vulcanization refers to the process of generating black silver sulfide due to the chemical reaction of sulfur-(S) or sulfur-containing substances under certain temperature and humidity conditions, in which -2 valence sulfur reacts with +1 valence silver. LED products encapsulated in silicone materials are highly hygroscopic and oxygen permeable, so LED vulcanization leads to product failures that are particularly severe in such products. The vulcanization of LED products mainly occurs in the following links, first, in the LED production process. The raw materials and finished products are vulcanized and preventable, and the probability of occurrence is also low. Second, during the SMT process. The finished product is vulcanized, preventable, and has a high probability of occurrence; third, during use. The finished product is vulcanized, preventable, and has a high probability of occurrence. 1. Prevention of vulcanization during production The first step in preventing LED vulcanization is in the manufacturing process. The SMD packaged in silicon below illustrates the materials that the LEDs may be vulcanized during the manufacturing process: 1 The silver-plated stent is vulcanized, the stent is yellowish black and tarnished, and the solid crystal process is performed, and the reliability is lowered; 2 Silver glue is vulcanized, silver glue is black, color is dim, solid crystal process, reliability is reduced or invalid; 3 Silicon-based solid crystal glue is vulcanized, resulting in curing inhibition, unable to fully cure, solid crystal process, decreased adhesion or failure; 4 silicon properties point powder rubber is vulcanized, resulting in curing inhibition, can not be fully cured, dispensing, powder, packaging process, product failure; 5 Phosphors contain sulfur, which leads to curing inhibition, powdering process, and product failure. The vulcanization phenomenon in the production process mainly occurs in the solid crystal and dispensing process. The main causes of vulcanization are silver-containing materials and silicon film materials. In the production process, we must pay great attention to the prevention of vulcanization in these two links. The main sources of possible sulphide contamination are: Sulfur-containing gloves, finger cots, sulfur-containing masks, sulfur-containing PCBs, sulfur-containing cleaners, vulcanized ovens, vulcanized cartridges, fixtures, etc. The prevention method is to use: Desulfurization gloves, finger sleeves, sulfur-free masks, cleaning, desulfurization, use, sulfur-free cleaning agent, independent baking, set a special sulfur-free oven, separate use, distinguish between sulfur-free materials, box clamp fixture. It can be seen from the above analysis that in the LED manufacturing process, the main prevention is to prevent the vulcanized raw materials (silver material, silicon material) from being used in the production process by sulfur-containing tools, clamps, gloves, Contamination of sulfur-containing materials such as masks leads to vulcanization. The best precaution is to minimize the use of sulfur-containing materials and fixtures and other sulfur-containing auxiliary tools and materials during the production process. The production environment of LED is basically in the dust-free workshop. The isolation of sulfur in the environment is very high. As long as the isolation measures of sulfur-containing materials, fixtures and auxiliary materials in production are done, it is generally not easily vulcanized in production. 2. Prevention of vulcanization during SMT Vulcanization in the SMT process is the most serious part of the vulcanization of LED products, mainly because a large amount of sulfur-containing materials are encountered during the SMT process, and PCB boards, solder paste, wash water, and other irrigations are found during the inspection process. There is a record of sulfur in the filling. During the SMT operation, these materials will enter the reflow furnace together with the LED. After being left for a period of time after reflow, there will be blackening of the silver plating part of the stent, mainly the sulfur content during the reflow process. The medium penetrates into the LED, causing the silver to be vulcanized and the product to fail. PCB products on the market have different levels of sulfur. Although PCB manufacturers will clean the plates for desulfurization during the manufacturing process, it is difficult to completely remove them. Therefore, in the SMT operation, it is necessary to carry out quality control on the sulfur content of the PCB board, and generally the upper limit of the sulfur content of the PCB copper foil or more is not more than five thousandths. In view of the fact that sulfur is active in a high temperature environment, in the SMT operation, the PCB board can be pre-cleaned once in a high temperature reflow oven to reduce the sulfur content on the surface of the PCB. If the process does not allow, the PCB surface cleaning can be performed directly before SMT. After the reflow is completed, the surface of the product is cleaned once, and the probability of LED vulcanization is reduced by cleaning the plate surface and the solder joint. When cleaning, it is necessary to choose a cleaning agent that does not contain sulfur and does not contain other acids. During the SMT operation, it is necessary to prevent the use of sulfur-containing materials to vulcanize the LEDs, and to prevent the use of vulcanized fixtures and machines. It is best to use it separately. It is best to establish a separate sulfur-free SMT production line or production workshop to ensure that the product is not contaminated by vulcanization during the SMT process of LED products. Then study the composition of glue, generally as LED potting glue, there are two main types, one is low refractive index (usually around 1.43), methyl glue, the price is relatively low, but the permeability is strong, so this The glue has a high probability of vulcanization. The second type is phenyl glue. The refractive index is high (usually above 1.5). The price is very expensive. Because of its complicated molecular structure, water and gas are difficult to enter. Go, the ability to prevent vulcanization is very high. If the LED sealed with methyl glue is equivalent to carrying the root of the disease at the factory, when the customer encounters any condition that can cause the vulcanization of the LED, the condition will be triggered and the LED will be vulcanized. LEDs encapsulated in phenyl glue will be strong when shipped from the factory and will not carry any cause, so no vulcanization will occur during application. 3. Prevention of vulcanization during use Sulfur is a very common, odorless non-metal. Pure sulfur is a yellow crystal, also known as sulfur. Sulfur has many different valences, and the most common ones are -2,0, +4, +6, etc. In nature it often appears in the form of sulphides or sulphates, which are part of a variety of amino acids and are thus part of most proteins. It is mainly used in fertilizers and is also widely used in gunpowders, lubricants, insecticides and antifungals. It can be used to make sulfuric acid, sulfite, plastic, enamel, synthetic dyes, vulcanized rubber, bleach, drugs, paints, etc. In life and production, we are ubiquitously exposed to sulfur and sulfur-containing substances, so we need to pay special attention when using LED products in daily life to prevent LED lamps or other products from being vulcanized. LED originals and LED application products should be stored in a uniform environment with sulfur-containing substances. Semi-finished products and finished products for LED applications should be avoided in the natural environment if they are not sealed, especially to avoid exposure to acidic environments. MiFi stands for Mobile WiFi. A MiFi works in the same way as a WiFi router, with the difference that you can set up a wireless personal area network and get online where ever you are on the globe. 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