Soldering Process for Molded Interconnect Devices in Three Dimensions

Estimated reading time: 4 minutes

When vacuum is used, the Galden Vapor is distributed uniformly throughout the process chamber instead of forming an ascending vapor front during preheating and soldering. In this way, the disadvantages of the temperature gradient associated with conventional vapor phase systems (the closer to the source of heat the sooner heat up takes place) and with convection systems (the closer to the source of heat the sooner heat up takes place and the hotter it gets) are avoided. This is due to the fact that there are not any large masses of air which have to be displaced, thus permitting quick distribution of the gas molecules into the "empty room". This effect has a positive influence on the profiling of the soldering process and the temperature homogeneity during heat up, and finally on the quality of the soldering result.

Summary

By using vapor phase soldering in combination with in-situ vacuum, geometry-related deviations in the temperature profiles can also be eliminated in addition to reducing void content and void count. As revealed by temperature profile measurements on a MID housing, it was possible to level out the heat gradients at all measurement points to a significant extent with the help of pre-vacuum, and the small temperature difference at peak temperatures which is associated with vapor phase soldering was retained as well. Furthermore, pre-vacuum can be used to assure quicker and more uniform heat-up of components with large thermal masses.

In summary it can be concluded that vacuum during vapor phase soldering provides an additional, highly flexible influencing parameter for the evaluation of an ideal soldering profile and, beyond this, prevents the drag-out of Galden in the case of cup-shaped components.

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