PREDICTION OF LAY-UP CONSOLIDATION DURING BOARD LAMINATION.

A model has been developed for the prediction of lay-up consolidation (i. e. , lay-up thickness, inter-spacings between prepregs and resin flow field) during the squeeze-flow lamination of circular prepreg lay-ups for the manufacture of printed circuit boards. This model allows for a time-dependent lamination temperature and pressure schedule, and the temperature non-uniformity across the thickness of the lay-up (which must be considered when a large number of prepreg layers is involved). The input parameters required by this model are both the cloth parameters (such as the yarn diameter and the pitch distances) and knowledge of resin viscosity as a function of time and temperature. While the former is usually available from the cloth manufacturer, the latter can be predicted from separate squeeze flow experiments for the neat resin using a thermomechanical analyzer. The lay-up thickness predictions provided by this model have been found to be in good agreement with experimental results obtained using a thermomechanical analyzer for the lamination of up to five epoxy prepreg layers.