Study On Low Temperature Cured Silver Paste Used In Membrane Switch

With the rapid development of science and technology, many researches are putting more emphasis on the low temperature cured silver paste. Silver paste is kind of significant functional conducting material which is usually used in membrane switch and printed circuit board. Silver paste has excellent electrical conductivity and mechanical properties, including hardness, adhesiveness and bend resistance capability. The conductive phase and resin binder phase are the most influential ingredients in the paste.The preparation and manufacturing of silver paste was studied in this paper and the effect of the content of silver powder, the shape of silver, diameter of silver powder was studied and the curing conditions and resin matrix on electrical property has been studied at the same time. It can be seen from the experiments that the proper addition of spherical silver powders in the flaky silver would improve the electrical conductivity and enhance bend resistance capability.The effect of different resin binder phase on electrical conductivity and mechanical properties of silver paste was studied in the paper. The bending strength of silver paste using polyurethane as resin phase was studied. Results show that the electrical conductivity of silver paste which used mixture of flaky silver and spherical silver as conductive phase is better than that of flaky silver and spherical silver. It also showed that the bending property of silver paste and the surface wettability of silver powder was improved dramatically if polyurethane was used as the resin matrix. In addition, the solvent-evaporation of paste was researched by DSC and TG, the curing temperature and time was optimized.