Preparation And Performances Of Nano-Silver Pastes

Electronic paste belongs to the high and new technology products, which is widely applied in electronic, chemical engineering, biological engineering field. With the rapid development of integrated circuits,the traditional conductive pastes in which the sizes of the functional phase are in the range of micros can not meet the demands for low-temperature sintering, narrow line widths and multi-layer boards. The nano conductive paste has become more and more important for electronic industry. The technique seems developing very rapidly for the researchers abroad, and several kinds of nano paste have become commercial products in the past years. However, the contents seem empty in China.In this dissertation, the preparation techniques of the silver nano paste have been studied systematically and their performances have been characterized. Following are the main research contents and results:Firstly, we have studied how to mix the nano silver particles with the organical materials and the ceramic particles. The conductive silver pastes with the average sizes of around 400 nm have been prepared well by stirring the mixture in a can with the high speed at the temperature of 90℃. Different morphologies of the nano particles have been used to prepare the nano silver pastes, and it was found that the plate nano particles have better performances, which can form a network structure after sintering.Next, the nano silver paste prepared by us and purchased from abroad have been characterized by the laser particle size analyzer and scanning electron microscopy (SEM). The average particle sizes of the nano paste prepared by us were 100nm less than that of South Korea, while both showed the network structure.Finally, the processing performances of the nano silver pastes were tested by three methods: spinning coating plus laser treatment (i.e. laser micro cladding ), direct writing by micropen and microjet. The conductive lines with the width less than 200μm and thickness 10μm can be fabricated on different substrate with the resistance of 5mΩ. The Sintering temperature of nano silver paste developed by us is about 520℃, which is far lower than that of the commercial paste.