Answer: A. Silicone, B. Epoxy resin, D. Silicone resin
Answer analysis: When discussing the types of lamp bead encapsulation glue, we need to understand the key role of encapsulation glue in LED lamp bead manufacturing, that is, protecting the lamp bead chip, improving the light efficiency, and enhancing heat dissipation. Now let's analyze each option one by one:
A. Silicone: Silicone is a commonly used encapsulation material. It is widely used in the encapsulation of LED lamp beads due to its good high and low temperature resistance, excellent insulation, tear resistance and good light transmittance. Silicone encapsulation can protect the inside of the lamp bead from the influence of the external environment, while improving the light efficiency and heat dissipation performance.
B. Epoxy resin: Epoxy resin is also a common encapsulation material with excellent physical and mechanical properties, electrical insulation, chemical corrosion resistance, and bonding performance to a variety of materials. In LED encapsulation, epoxy resin can effectively protect the lamp bead chip and improve the light efficiency through its light transmittance.
C. 502 glue: 502 glue is mainly α-cyanoacrylate ethyl, which belongs to the instant glue category. It is mainly used for rapid bonding between porous and absorbent materials, such as steel, non-ferrous metals, rubber, leather, plastic, ceramics, wood, non-metallic ceramics, glass and flexible rubber products, leather shoes, soft and hard plastics, etc., or bonding between each other. However, due to its rapid curing characteristics and possible brittleness, it is not suitable as a long-term encapsulation material for LED lamp beads.
D. Silicone resin: Silicone resin generally has excellent heat resistance, cold resistance, weather resistance, electrical insulation performance and good dielectric properties, as well as excellent oxidation stability and water resistance. In some LED packaging applications, silicone resin can also be used as a packaging material, but its application may not be as extensive as silicone and epoxy resin.
E. Epoxy lens: In fact, "epoxy lens" is not a type of encapsulation glue, but refers to a lens made of materials such as epoxy resin, which is used in LED packaging to change the distribution of light. Although it is related to packaging, it is not directly used as an encapsulation glue.
In summary, the types of lamp bead encapsulation glue mainly include A (silicone), B (epoxy resin) and D (silicone resin). Although C (502 glue) is a kind of glue, it is not suitable as a long-term encapsulation material for LED lamp beads; E (epoxy lens) is a description of an optical component made of epoxy resin, not a type of encapsulation glue.
Therefore, the correct answer is A, B, D.