Recently, according to experts from China Epoxy Resin Industry Association, LED epoxy resin packaging technology was introduced. The expert first stated that the epoxy used in the LED production process is one of the key points in the LED industry. Epoxy resin is a kind of organic polymer compound which contains two or more epoxy groups in a molecule, and their relative molecular qualities are not high except for a few. The molecular structure of the epoxy resin is characterized by the presence of an active epoxy group in the molecular chain, and the epoxy group may be located at the end, in the middle or in a ring structure of the molecular chain. Since the molecular structure contains an active epoxy group, they can be cross-linked with various types of curing agents to form an insoluble, infusible polymer having a three-dimensional network structure. In order to maintain its own airtightness, the LED IC protects the die from external corrosion, prevents moisture from entering the outside, mechanically supports the wires, effectively discharges heat generated inside, and prevents electronic components from being mechanically vibrated. The impact is damaged, resulting in changes in the characteristics of the component, using different shapes and material properties (with or without a colorant), functioning as a lens or a diffusing lens to provide a hand-held body.
The curing temperature and time of LED sealing resin is a very important issue. The main points include the following aspects: the general LED sealing resin hardener is acid anhydride, the hardening temperature is about 120-130 ° C; the hardening time is shortened after the accelerator is added. Regarding the hardening time and the phenomenon of hardening and hardening, the expert further stated that the thermal conductivity of the resin is small, the internal hardening heat accumulation affects the hardening rate (reaction rate), and the inner (hardening heat) outside (oven) high heat disply case is easily deformed. . The expert said that one must pay attention to another point - the blending ratio and characteristics of the resin and hardener: the amount of hardener used depends on the required properties; when the blending ratio of the hardener is small, the hardness of the hardened material is hard and yellow; When the compounding ratio is large, the cured product becomes brittle and the coloring is small. For tg - glass transfer point - and hdt (heat distortion temperature), the experts continue to introduce three technical points - test method: tma, dsc.b: the temperature difference between the two is 2 ~ 3 ° C; add filler After tg becomes higher; the electrical properties of the epoxy resin (insulation resistance rate and loss rate of induced electric loss) are lower than the heat distortion temperature.
The epoxy resin used to form the envelope must have moisture resistance, insulation, and mechanical strength, and has a high refractive index and transmittance for emitting light to the LED. The choice of packaging materials with different refractive indices, the influence of package geometry on photon and escape efficiency is different. The angular division of luminous intensity is also related to the structure of the die, the way of light output, and the material and shape of the package lens. If a pointed resin lens is used, the light can be concentrated in the axial direction of the LED, and the corresponding viewing angle is small; if the resin lens at the top is circular or planar, the corresponding viewing angle will increase. As a kind of light-emitting device with small power, long service life and low energy loss, LED has been in the country for 20 years. Due to its special performance superiority, it is gradually replacing the original light-emitting device and used in industrial and civil use. All corners. Especially with the shortage of human energy, the market prospects are very impressive. In recent years, LEDs have become more and more widely used in urban lighting engineering, industrial, and civil construction industries. According to CCTV News Broadcasting, the lighting project of Shanghai Oriental Pearl TV Tower has been replaced by LED display, which not only saves energy but also enhances the appearance. Experts said that the domestic LED chip has been successfully developed abroad, and it is expected that in the near future, home decoration will also be illuminated by LEDs.
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