A Novel Solvent-Less Approach to Manufacture Pre-Pregs and Laminates with Improved Dimensional Consistency for Electronic Applications

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This research project will investigate a new solvent-less process, based on the concept of continuous Resin Transfer Molding or Injection Pultrusion. Current processes used to manufacture electronic pre-pregs and laminates use solvent-based systems. Solvents are environmentally unfriendly, pose potential hazards to workers and add no value to the final product. Solvents are being increasingly regulated with permit costs expected to double by the year 2000. Solvents can also be the source of defects, with voids forming if the pre-preg is dried too rapidly. In this closed-system, the heart of the process is the impregnation/B-staging die, where high pressures can be used to promote resin impregnation into the glass fabric. In more traditional approaches, where the laminate is constructed from copper foils and multiple layers of pre-preg materials, the batch process can induce variability through temperature differences during curing. The injection pultrusion process will be a continuous in-line lamination process that allows vacuum techniques as well as flooding of the die chamber with gases other than air in order to minimize or eliminate voids. The introduction of fillers to improve properties will also be investigated. It is expected that with the improved impregnation and reduced defects, this process will allow the manufacture of more dimensionally consistent pre-pregs with fewer voids. Dimensional consistency is a key enabler for increased densification of printer circuit boards and is critical to decreasing internal registration scrap at the board shops, thus reducing costs and avoiding waste.