Volumetric Characterization of Reservoir Printing In Deep Cavities
Authors: Phani Vallabhajosyula, Ph.D., William Coleman, Ph.D., Karl Pfluke and Mark Reece, Brook Sandy-Smith Company: Photo Stencil and Indium Corporation Date Published: 2/6/2017
Pan Pacific Symposium
Abstract: With the advancements in board designs, and widespread application of stencils into the solar/optics fields, new challenges arise leading to new solution stencils. Extensive work has been done in the past to print glue¹, solder paste², &sup4, &sup5 , and/or flux³ into cavities using reservoir printing. The reservoir depth for these applications ranged from 75 microns to 355 microns, with aperture sizes from 65 microns to 200 microns. This paper deals with printing solder paste into multiple cavities of depths ranging from 355 microns to 450 microns, with varying cavity wall angles and various stencil thicknesses ranging from 50 microns to 150 microns. Apertures varying in shape and area ratio were placed in these cavities and experimentation was conducted to analyze the print performance of the stencils and hence, infer guidelines for future stencil designs and aperture placement in cavities. Solder paste designed for best printing on fine features with different powder sizes were recommended to assess printing in deep cavities and to obtain good print volume. Solder paste inspection was used to characterize deposit volumes and compare results numerically. Details on stencil design, paste material selection, experimentation, and print results will be presented in the paper.