Abstract: An IC-mounting flexible circuit board and the process of producing the same in which the process comprises the steps of forming bump protrusions passing through a flexible circuit board to be electrically conductive with a circuit wiring pattern in such a way that the bump protrusions are allowed to protrude from the back surface of the flexible circuit board, and arranging to have the surface of each bump protrusion coated with junction metal in accordance with the structure of the protrusion, so that a bare IC chip is simply bonded to the bump protrusions of the flexible circuit board by means of heat fusion or ultrasonic bonding.An excimer laser means is preferably used for boring small holes in an insulating base to form bump protrusions, i.e., IC pad junction protrusions on the flexible circuit board. Such an IC pad junction protrusion is formed by a plating means such as soldering or the filling of a conductive member.

Abstract: A method for the manufacture of a multilayer printed circuit board on which integrated circuit chips may be directly mounted includes producing holes at predetermined locations to enable electrical connections between a chip and conductive layers of the circuit board to be established via the holes. Electrically conductive bump members, which protrude outwardly from the circuit board, are formed in registration with the holes. The bump members cooperate with an electrically conductive plating layer or filler that is deposited so as to be in intimate contact with a conductive layer(s) exposed during the production of each hole.

Abstract: A multilayer printed circuit board on which integrated circuit chips may be directly mounted has holes at predetermined locations, electrical connections between a chip and conductive layers of the circuit board being accomplished via the holes. The electrical connections are in the form of bump members which protrude outwardly from the circuit board. The bump members cooperate with an electrically conductive plating layer or filler that is in intimate contact with a conductive layer(s) exposed in the formation of each hole.

Abstract: Herein disclosed is an IC mounting circuit substrate which comprises: a predetermined circuit conductor pattern formed on one face of an insulating layer; IC pad junctioning bumps junctioned electrically to predetermined portions of said circuit conductor pattern and projecting to the outside of a circuit substrate through said insulating layer; and a transparent insulating coating formed at the side of said circuit conductor pattern for transmitting an irradiation beam for heating and melting said bumps. As a fundamental process for mounting an IC on the IC mounting circuit substrate thus constructed, there is adopted a process for connecting the pads of said IC chip and said bumps electrically while heating and melting said bumps by the action of the irradiation beam supplied concentratedly from the side of said transparent insulating coating to said bump portions with said IC chip being arranged over said bumps.