Application of chemo-rheology to establish a process window for a new solventless system to manufacture pre-pregs and laminates for electronic applications

The most common commercial processes for manufacturing pre-pregs for electr onic applications use solvent-based epoxy systems. Solvents are environment ally unfriendly and contribute to voids in the pre-preg and laminate. Voids cause product variability, which is a major source of scrap in board shops . In this paper, we use chemo-rheological and kinetic measurements to ident ify a potential epoxy-based resin system for a solventless process that is based on injection pultrusion. Differential scanning calorimetry and rheolo gical data show that the candidate system does not react appreciably withou t catalyst up to temperatures of 170 degreesC or with catalyst at temperatu res < 110 degreesC. The system solidifies at temperatures < 105 degreesC. T he overall viscosity of the resin system is dependent on the temperature, d egree of cure, and filler content. Kinetic rate and viscosity rise expressi ons to be used in process modeling and optimization have been developed. A preliminary process window for the process is established. (C) 2001 John Wi ley & Sons, Inc.