Solder Powder Characteristics and Their Impact on Rheological Behavior of Solder Pastes
Authors: Amir H. Nobari, Ph.D., Arslane Bouchemit, Ana Da Silva Marques, Sylvain St-Laurent, Ph.D. and Gilles L’Espérance, Ph.D. Company: 5N Plus Micro Powders, 5N Plus Inc., Center for Characterization and Microscopy of Materials, École Polytechnique de Date Published: 10/14/2018
Abstract: Solder paste is a key material being widely used in electronics assembly lines of surface mount and semiconductor packaging. To assemble miniature components, advanced solder pastes with fine particles sizes (Type 5, 6, 7, and 8) are required. An in-depth understanding of different properties of solder pastes is essential to develop these solder pastes. Among different properties, the rheology of solder paste is the one that controls the quality of paste deposition for various paste deposition techniques i.e. stencil printing, needle dispensing, and jet printing. This paper describes our latest results on the characterization of solder powders. More specifically, the surface oxide layer is characterized using Auger Electron Spectroscopy (AES) and Transmission Electron Microscopy (TEM). Also, powders were admixed with fluxes and the rheological behaviour of pastes was studied. In addition to the initial viscosity of the pastes, the stability of the viscosity was also evaluated. The relation between powder characteristics and the rheological behaviour of the pastes is described. The knowledge obtained in this paper can be applied to design advanced solder pastes with fine powders.