Preparation And Characterization Of Silver Powder And Its Photosensitive Paste

Photosensitive silver paste is a kind of widely used conductive materials in industry, such asthe application in making the electrode part of plasma TV. In this article, a methodology to makephotosensitive silver paste has been developed, during which course the factors affecting theformation and quality of silver paste have been studied and summarized. The photosensitivesilver paste generated via this method has been characterized and tested to verify the reliabilityof our methodology.The first step to make the photosensitive silver paste is to prepare ultrafine silver powdervia chemical reduction of silver nitrate. Generally, ultrafine silver powder of decent qualityshould consist of spherical shaped silver particles with a narrow diameter distribution. Toachieve this goal, different reductants and dispersants were screened and ascorbic acid, oleic acidwere identified to be the optimal reductant and dispersant respectively. In addition, thecorresponding reaction mechanism was proposed. To optimize the reaction condition, differentfactors such as silver nitrate concentration, reducing agent concentration, system pH value,stirring rate and reaction temperature were carefully monitored to see how they influence silverparticle shape and diameter distribution. Under the optimized condition, ultra fine silver powderwas prepared and fully characterized. Our results indicate the formation of highly pure silverpowder with the particle diameters between 0.3 m and 1.0 m adjustable by adjusting thereaction condition.The second step is to make ultrafine glass powder which acts as a binding material in thepreparation of silver paste. The combination of PbO - SiO2 - B2O3 was sintered at hightemperature twice and then grinded to yield ultrafine glass powder. The composition, shape,diameter and heat performance of the glass powder were characterized by a series ofinstrumentation method.The photosensitive silver paste was prepared by integrating the ultrafine silver powder,glass powder and photosensitive monomer together with some additives. The influence of theamount of silver glass powder, defoamer, photosensitive monomer and methylacrylic ester...