Abstract: Separators with direct heating medium and method for manufacturing thermally curable laminates thereof. Metal separators used in a book to separate board from board after lamination are engineered to incorporate a thin metal layer or multiple circuits as an electrical heating medium. The electrically heatable separators can then heat the boards directly in contact with individual boards, so that the temperature differences among the boards in a book as well as in an individual board are minimized. This reduction of the difference in temperature minimizes the characteristic difference in chemorheology of the thermally curable bonding sheets. Laminates manufactured by this process exhibit low levels of variation in physical properties, making it suitable for printed circuit board of high density integration.