Method of forming stacked circuit boards

Claim 1

A method of forming a circuit board arrangement having at least two conducting layers separated by an interposed insulating layer, the conducting layers having at least one connection through the insulating layer for electrically interconnecting portions of the conducting layers, the method comprising the steps of providing at least one insulating layer and at least two metal conducting layers, at least one of the conducting layers being a deformable metal foil and at least one of said insulating layers having at least one opening extending therethrough: applying a layer of filler material to selected areas of a surface of the conducting layers to facilitate the forming of the surface-to-surface bond, and simultaneously applying to the opposite surface of said layers, a masking coating of etch resistant material in a predetermined pattern to provide exposed areas; arranging the layers in a superimposed stack with an insulating layer interposed between adjacent conducting layers to separate adjacent conducting layers and with the filler material disposed at each of said openings; applying pressure and heat to the stack to press the superimposed layers together to form a core, to force a portion of the metal foil into the openings of the interposed insulating layer to contact the adjacent conducting layer and to melt the filler material to form a surface-to-surface bond between the conducting layers for the connection; etching the exposed areas of the conducting layers to form the desired electrical circuit patterns from each masked conducting layer; providing an additional insulating layer and outer conducting layer of a deformable metal foil, said insulating layer having at least one opening formed therein; overlying said additional insulating layer and the deformable metal foil on one of the etched circuit patterns of the core with the opening of the additional insulating layer overlying a portion of the circuit pattern to form a second stack; and applying heat and pressure to said second stack to cause the second stack to adhere together and to force a portion of the outer conducting layer into the opening of the additional insulating layer and into contact with the etched circuit pattern for forming an electrical connection having a surfaceto-surface bond therebetween.

Claim 2

A method of forming a circuit board arrangement having at least two conducting layers separated by an interposed insulating layer, the conducting layers having at least one connection through the insulating layer for electrically interconnecting portions of the conducting layers, the method comprising the steps of providing at least one insulating layer and at least two metal conducting layers, at least one of the conducting layers being a deformable metal foil and at least one of said insulating layers having at least one opening extending therethrough: applying a layer of filler material to selected areas of a surface of the conducting layers to facilitate the forming of the surface-to-surface bond, and simultaneously applying to the opposite surface of said layers, a masking coating of etch resistant material in a predetermined pattern to provide exposed areas; arranging the layers in a superimposed stack with an insulating layer interposed between adjacent conducting layers to separate adjacent conducting layers and with the filler material disposed at each of said openings; applying pressure and heat to the stack to press the superimposed layers together to form a core, to force a portion of the metal foil into the openings of the interposed insulating layer to contact the adjacent conducting layer and to melt the filler material to form a surface-to-surface bond between the conducting layers for the connection; etching the exposed areas of the conducting layers to form the desired electrical circuit patterns from each masked conducting layer; providing an additional insulating layer and outer conducting layer of a deformable metal foil, said insulating layer having at least one opening formed therein; overlying said additional insulating layer and the deformable metal foil on one of the etched circuit patterns of the core with the opening of the additional insulating layer overlying a portion of the circuit pattern to form a second stack; and applying heat and pressure to said second stack to cause the second stack to adhere together and to force a portion of the outer conducting layer into the opening of the additional insulating layer and into contact with the etched circuit pattern for forming an electrical connection having a surfaceto-surface bond therebetween.

Claim 3

A method of forming a circuit board arrangement having a plurality of conducting layers with an interposed insulating layer disposed between each adjacent conducting layer to electrically separate said conducting layers, said circuit board having electrical connections for interconnecting various conducting layers together through the interposed insulating layers, said method comprising the steps of: providing at least two metal conducting layers and at least one insulating layer, said metal conducting layers being a deformable metal foil and said interposed insulating layer having at least one opening therethrough, arranging the layers into a stack with an insulating layer disposed between adjacent conducting layers and with filler material located at each opening; applying heat and pressure to the stack to press the layers together to form a core of the layers, to force a portion of each metal layer into the openings in the insulating layer and to melt the filler material to form the surface-to-surface bond between the conducting layers to form an electrical connection; etching the conducting layers to provide the desired electrical circuit paths; providing additional electrical conducting layers and insulating layers, some of said conducting layers being deformable metal foil and the insulating layers having openings in predetermined patterns thereon; arranging the additional layers on either side of the coRe to form a second stack, with the insulating layers interposed between conducting layers to electrically separate them, and applying heat and pressure to the second stack to press the core and layers together to form the circuit board and to cause the surface-to-surface bonding of the conducting layers through the openings in the additional insulating layers to the conducting layers of the core to provide a circuit board having a plurality of conducting layers separated by insulating layers with electrical connections between conducting layers.

Claim 4

A method of forming a circuit board arrangement having a plurality of conducting layers with an interposed insulating layer disposed between each adjacent conducting layer to electrically separate said conducting layers, said circuit board having electrical connections for interconnecting various conducting layers together through the interposed insulating layers, said method comprising the steps of: providing at least two metal conducting layers and at least one insulating layer, said metal conducting layers being a deformable metal foil and said interposed insulating layer having at least one opening therethrough, arranging the layers into a stack with an insulating layer disposed between adjacent conducting layers and with filler material located at each opening; applying heat and pressure to the stack to press the layers together to form a core of the layers, to force a portion of each metal layer into the openings in the insulating layer and to melt the filler material to form the surface-to-surface bond between the conducting layers to form an electrical connection; etching the conducting layers to provide the desired electrical circuit paths; providing additional electrical conducting layers and insulating layers, some of said conducting layers being deformable metal foil and the insulating layers having openings in predetermined patterns thereon; arranging the additional layers on either side of the coRe to form a second stack, with the insulating layers interposed between conducting layers to electrically separate them, and applying heat and pressure to the second stack to press the core and layers together to form the circuit board and to cause the surface-to-surface bonding of the conducting layers through the openings in the additional insulating layers to the conducting layers of the core to provide a circuit board having a plurality of conducting layers separated by insulating layers with electrical connections between conducting layers.

Claim 11

A method of forming a circuit board arrangement having at least three conducting layers separated by interposed insulating layers the conducting layers having at least two connections through the insulating layers for electrically connecting at least two conducting layers together, said method comprising the step of: providing metal conducting layers and insulating layers, at least one of the metal conducting layers being an intermediate conducting layer having an opening formed therein, at least two of the conducting layers being of a deformable metal foil, and said insulating layers having openings formed therein in a predetermined pattern; arranging the layers in a superimposed stack with the opening in the intermediate layer being in overlying alignment with openings in each of the adjacent insulating layers, said stack being arranged with an insulating layer interposed between adjacent conducting layers; and applying heat and pressure to press the layers of the stack together to form a core and to deform a portion of the foil on the outer layers through the aligned openings of the insulating layer and the intermediate conducting layer to form an electrical connection having a surface-to-surface bond between the outer two conducting layers with the deforming of the foil causing molding of the insulating layer to electrically insulate the connection from said intermediate conducting layer.

Claim 12

A method of forming a circuit board arrangement having at least three conducting layers separated by interposed insulating layers the conducting layers having at least two connections through the insulating layers for electrically connecting at least two conducting layers together, said method comprising the step of: providing metal conducting layers and insulating layers, at least one of the metal conducting layers being an intermediate conducting layer having an opening formed therein, at least two of the conducting layers being of a deformable metal foil, and said insulating layers having openings formed therein in a predetermined pattern; arranging the layers in a superimposed stack with the opening in the intermediate layer being in overlying alignment with openings in each of the adjacent insulating layers, said stack being arranged with an insulating layer interposed between adjacent conducting layers; and applying heat and pressure to press the layers of the stack together to form a core and to deform a portion of the foil on the outer layers through the aligned openings of the insulating layer and the intermediate conducting layer to form an electrical connection having a surface-to-surface bond between the outer two conducting layers with the deforming of the foil causing molding of the insulating layer to electrically insulate the connection from said intermediate conducting layer.