Common Plastic Based Packaging Materials

1. Epoxy molding compound

Epoxy molding compound (EMC) is composed of phenolic epoxy resin, phenol resin and filler (SiO) It is composed of release agent, curing agent, dye, etc. It has excellent adhesion, excellent electrical insulation, high strength, good heat resistance and chemical corrosion resistance, low water absorption, and good molding process. Plastic packaging dominated by EMC accounts for more than 90% of the packaging industry. It is reported that by mixing the negative thermal expansion material powder with E-51 epoxy resin in a certain proportion, the powder can be uniformly dispersed in the epoxy resin matrix through ultrasonic treatment. As the mass fraction of the powder increases, the thermal expansion coefficient of the packaging material decreases, the glass transition temperature increases, and the tensile and bending strength increases.

Epoxy resin is the most widely used material in plastic packaging, accounting for about 90%. Epoxy resin is so important in the manufacturing of electronic devices that it is said that "without epoxy resin, there is no IC".

2. Silicone rubber

Silicone rubber has good heat aging resistance, ultraviolet aging resistance and insulation performance, which is mainly used in semiconductor chip coating and LED packaging adhesive. It is reported that the colorless transparent silicone packaging material obtained by mixing composite silicone resin and organic silicone oil and conducting addition reaction under catalyst conditions can be used on high-power white LED, with the light transmittance of 98% and the light flux of white LED of 42.65lm. As a lens material, epoxy resin has obviously insufficient aging resistance, and is incompatible with the interface of inner packaging material, resulting in a sharp reduction in the life of LED. Silicone rubber shows good interface compatibility and aging resistance with inner packaging materials.

3. Polyimide

Polyimide (PI) is a kind of polymer material with aromatic ring and imine ring on the main chain. Polyimide has a dielectric constant of 3.1 and a dielectric loss of less than 0.0012. It has excellent micromachining characteristics and is widely used in the high-frequency microwave field. Polyimide can withstand the high temperature of 350~450 ℃, and has the advantages of good insulation, dielectric property, resistance to organic solvent and moisture. It has been widely used in semiconductor and microelectronic industries.

Polyimide, as an insulating material, can be directly photolithographed into fine patterns if it has photosensitive properties at the same time. Photosensitive polyimides can be developed by direct photolithography, eliminating the fabrication and etching of mask layers, simplifying the entire complex micro processing process. Especially in the manufacturing of multi chip modules and multi-layer boards, the processing accuracy and yield can be greatly improved and the cost can be greatly reduced.

Polyimide is mainly used for passivation layer, stress buffer and protective coating of chips, interlayer dielectric materials, liquid crystal alignment films, etc., especially for the substrate of flexible circuit boards. Materials can be modified through molecular design, such as improving adhesion, introducing hydroxyl or epoxy groups; Silicon oxygen bond can be introduced to improve flexibility and reduce curing stress.