고온 소결형 Ag Paste의 Packing density 향상을 위한 Ag 조성 최적화 연구

Abstract

Printing electronic technology refers to the manufacture of electronic materials at a low price using the printing process of conductive paste on various substrates. Electrical conductivity paste technology is growing with the growth of printing electronics technology, and many research and development are underway. Electrical conductivity paste is made from metal fillers, glass frits, adhesives, solvents, additives, etc. It has excellent conductivity, uniform printing properties and high adhesion to the substrate. In electrical conductivity paste, conductivity is determined by the generation of conductive paths resulting from the coupling of metal fillers. The low temperature curing type paste shows conductivity by maintaining the metal filler in the adhesive in the paste and forming a network to each other. In addition, because the high temperature sintering type paste is sintering at high temperature, the metal filler melts and forms a conductive path while connecting to each other. High conductivity must be ensured in order to have excellent conductivity. Generally, the higher the temperature, the better the conductive path of the metal filler. In order to form a high conductive path at low temperatures, metal fillers with small particle sizes must be used. However, nanoparticles are not only more difficult to synthesize and operate than large particle-sized powder, but also interfere with particle densification due to aggregation of nanoparticles during sintering. In order to improve the conductive path at low temperatures, there is a method to improve the charging rate between metal filler particles. In other words, large particles and small particles are mixed to make paste. If the charging rate increases by filling the empty space between large particles with small particles, the packing properties after sintering will also increase. In general, it is said that mixing metal fillers can ensure higher packing properties than using metal fillers alone to manufacture paste. In this study, Ag paste with excellent packing and conductivity at 600℃ was studied. To ensure the excellent packing properties of Ag paste, the particle size of Ag power was changed and the two Ag power were mixed. First, the conductivity and packing property of the coating film were compared with different Ag powder particle sizes. When SEM and conductivity were measured and observed, the packing property and conductivity of the sample having a particle size of 2.8 ± 0.8 μm were the best, but pinholes on the surface and inside were generated. In the second experiment, Ag powder was mixed and the conductivity and packing property of the coating film were compared. The packing property and conductivity of the sample having a mixture of 2.8 ± 0.8 μm: 1.04 μm were the best. Further, it was found that the packing property is excellent when the Ag powder is mixed and used rather than used alone.