Abstract: A method for easily making a barrier for preventing overflow of interlayer insulating resin in a cable-fitted multi-layer FPC that uses bumps for connecting the layers, and a barrier having a structure that can easily be made. In a method for manufacturing a multi-layer flexible printed circuit board including a circuit section, a cable section that is connected to the circuit section, the circuit section having a multi-layer structure of insulating resin arranged between multiple layers of metal foil, a barrier, that stops the insulating resin from overflowing, has a two-row configuration and is formed on a metal foil that constitutes an outermost conductive layer in the multi-layer flexible printed circuit board, and the metal foil and the insulating resin are laminated to form the multi-layer flexible printed circuit board.

Abstract: A multilayered circuit board has good imbedding properties for circuit patterns, and an interlayer insulating material having superior adhesive force and interlayer insulating properties. In a multilayered circuit board wherein interlayer connection is achieved by the contact of minute pointed protrusions, provided on a first conductive circuit layer, with a second conductive circuit layer, interlayer insulation is achieved by a film having a three-layer structure, comprising a thermoplastic film inserted between a pair of thermosetting adhesive layers.

Abstract: This invention provides a method for easily making a barrier for preventing overflow of interlayer insulating resin in a cable-fitted multi-layer FPC that uses bumps for connecting the layers, and a barrier having a structure that can easily be made. In a method for manufacturing a multi-layer flexible printed circuit board comprising a circuit section, a cable section that is connected to the circuit section, the circuit section having a multi-layer structure of insulating resin arranged between multiple layers of metal foil, a barrier, that stops the insulating resin from overflowing, has a two-row configuration and is formed on a metal foil that constitutes an outermost conductive layer in the multi-layer flexible printed circuit board, and the metal foil and the insulating resin are laminated to form the multi-layer flexible printed circuit board.

Abstract: A multilayered circuit board has good imbedding properties for circuit patterns, and an interlayer insulating material having superior adhesive force and interlayer insulating properties. In a multilayered circuit board wherein interlayer connection is achieved by the contact of minute pointed protrusions, provided on a first conductive circuit layer, with a second conductive circuit layer, interlayer insulation is achieved by a film having a three-layer structure, comprising a thermoplastic film inserted between a pair of thermosetting adhesive layers.

Abstract: A photosensitive insulation bonding layer is formed on a conducting layer. The photosensitive insulation bonding layer is subjected to exposure treatment to produce an exposed area and an unexposed area. Another conducting layer is formed on the outer surface of the photosensitive insulation bonding layer which has undergone the exposure treatment, then both conducting layers are photoetched to produce desired wiring patterns. In the next step, the unexposed area is removed from the photosensitive insulation bonding layer by development so as to form an access opening for connecting a circuit component to the wiring patterns. Then, the exposed area of the photosensitive insulation bonding layer is turned into an insulating layer by curing.