Original Publication Date: 1988-Oct-01
Included in the Prior Art Database: 2005-Feb-15
Prepreg, used in the manufacture of multilayered printed circuit boards, consists of continuous glass fiber cloth impregnated with liquid epoxy resin which is then dried to remove residual solvents. Rolls of prepreg are cut into rectangular sheets, stacked and interleaved with copper sheets to form a layup which is placed under pressure, heat, and vacuum to cure the epoxy to a rigid laminate. Because the laminate must maintain good bonding between layers, particular attention has to be paid to environmental conditions and to the accuracy of the stacking operation which requires the inversion of alternate sheets to ensure neutralization of inherent stresses of the glass cloth during subsequent lamination operations. Problems caused by improper handling pose additional problems.