Date of Award
Summer 1993
Document Type
Dissertation - Restricted
Degree Name
Doctor of Philosophy (PhD)
Department
Mechanical Engineering
Abstract
An analytical solution to the joint formation problem in surface mount technology is obtained treating upright reflow soldering, inverted reflow soldering and wave soldering. Two mathematical models are developed, one for upright joints and one for inverted joints, to predict two-dimensional joint shape given the solder properties, the height of the joint, and the contact angles between the joint surface and the metallizations. These models are unique in that they contain explicit integral expressions for the joint profile and are solved both numerically and using elliptic integrals. For the first time known to the author, an analytical method is proposed for predicting the amount of solder contained in a joint formed by a wave soldering process. An approximation to the models, useful for predicting the shapes of "small" joints, is also presented. All of the above are incorporated into algorithms which predict joint shape given solder properties, tinning geometry, and, in the case of reflow soldering, the amount of available solder. Results are presented in the form of dimensionless plots showing the relationship between the final joint geometry and the solder properties, the tinning geometry, and the amount of available solder. These should be useful in the design and manufacture of solder joints in surface-mount applications.