Research progress on polymer materials for LED packaging

Since the 1990s, with the rise of third-generation semiconductors represented by gallium nitride, blue, green, and white LEDs have been mass-produced. China has a good technology and industrial base in the field of LED lighting, and has formed an industrial chain from the production of epitaxial wafers, chip preparation, and device packaging integration. At present, there are more than 400 large-scale enterprises engaged in the production of semiconductor LED devices and lighting systems in China. The annual output of ultra-high brightness LED dies of red, orange and yellow has exceeded 1 billion, accounting for about 12% of the world total. It is estimated that by the end of 2010, the global LED market demand will be about 210 billion, the sales will reach 85 billion US dollars, and the value of China's LED industry will exceed 150 billion yuan. At present, LED products have occupied a considerable share in the international market, and packaging materials have also been widely used in LEDs, and their performance has a very important role in the application of LED products.

The LED is composed of a chip, a wire, a bracket, a conductive adhesive, a packaging material, etc., and the package is filled, potted or molded to fill the liquid glue into the device containing the electronic component and the line, at room temperature or heating. Under conditions, it is cured into a thermosetting polymer insulation material having high light transmittance (transmission of a sample having a thickness of 1 mm at a wavelength of 450 nm at a wavelength of more than 99%), high refractive index, high weather resistance, and ultraviolet radiation resistance. It can enhance the integrity of electronic devices, improve the resistance to external shocks and vibrations, improve the insulation between internal components and circuits, avoid linear exposure of components and lines, and improve the waterproof and moisture-proof performance of devices.

The packaging materials currently used mainly include high transparency materials such as epoxy resin, polycarbonate, polymethyl methacrylate, glass, silicone, etc., in which polycarbonate, polymethyl methacrylate and glass are used as outer lens. Materials, epoxy resins and silicones are mainly used as packaging materials and as lens materials.