Masters Abstracts (1997)

SATAGOPAN, SANTHANA
(August 1997), Advanced Manufacturing Engineer, Nortel Networks, Santa Clara, CA

Email: ssatagop@nortelnetworks.com

Effect of the Filling and Release Processes on Solder Paste Volume Transferred in the Stencil Printing Process

The filling of the stencil's apertures and the release of the stencil are two critical sub-processes within stencil printing. The volume of solder paste that is actually transferred is governed by the factors that affect these two sub-processes. The filling of the stencil aperture process typically affects the volume of solder paste deposited across a pattern of apertures. The release of the stencil affects the shape of the solder paste deposit and may also affect the volume of solder paste deposited. This research focused on providing insight into the filling and the release processes with the aid of extensive experimentation. In addition, data from prior (related) experiments was also used. Periodic variations were found in the amount of solder paste deposited across rows within a full array pattern of circular apertures for boards with pads and for bare laminates. The frequency of variation within a pattern was determined using time series analysis. Autoregressive models were developed in order to determine the period of variation. The significance of the release process on the volume transferred was determined through extensive experimentation using different aperture sizes, shapes and solder pastes. In order to isolate the effect of the release process, other print parameters were kept constant throughout all the experiments conducted in this research. Therefore, traditional experimental design techniques were not adopted to conduct the experiments. However, a statistically valid sample size was collected in each of the experiments to arrive at the appropriate conclusions. The results obtained from different experiments provide input that can be used in the development of a generic mechanistic model of the print process.