Method for making multilayer printed wiring board

Claim 1

A method of making a multilayer printed wiring board including a plurality of printed wiring boards, said method comprising the steps of providing a copper clad laminate with buried lands on a basic material consisting of glass fiber impregnated with resin and arranging copper foil with lands projecting in correspondence with land forming positions at a first side and a flat surface second side so that the projecting lands face the basic material side; laminating copper foil and said basic material to provide a copper clad laminate; etching said copper clad laminate to provide an intermediate layer substrate having a desired circuit including a land pattern and circuit conductors; laminating a plurality of said intermediate layer substrates by thermal bonding with said basic material and applying pressure to the layers to provide a multilayer laminate; boring through holes to specified lands of each layer of said multilayer laminate; and plating the through holes bored in said multilayer laminate upon completion of said boring.

Claim 2

A method of making a multilayer printed wiring board including a plurality of printed wiring boards, said method comprising the steps of providing a copper clad laminate with buried lands on a basic material consisting of glass fiber impregnated with resin and arranging copper foil with lands projecting in correspondence with land forming positions at a first side and a flat surface second side so that the projecting lands face the basic material side; laminating copper foil and said basic material to provide a copper clad laminate; etching said copper clad laminate to provide an intermediate layer substrate having a desired circuit including a land pattern and circuit conductors; laminating a plurality of said intermediate layer substrates by thermal bonding with said basic material and applying pressure to the layers to provide a multilayer laminate; boring through holes to specified lands of each layer of said multilayer laminate; and plating the through holes bored in said multilayer laminate upon completion of said boring.

Claim 6

A method of making a printed wiring board for forming a multilayer printed wiring board, said method comprising the steps of impregnating a fibrous material with resin to form a resinous base; forming a copper foil on a temporary substrate; covering said foil with a photo resist; primarily exposing the photo resist via a mask film having common land patterns which are regularly arranged in the form of a matrix; secondarily exposing the photo resist via a mask film having intrinsic circuit patterns including specified land patterns and circuit conductor patterns; developing the twice-exposed photo resist other than specified land forming areas; etching uniformly to a predetermined depth in areas other than the land forming areas of said foil; placing a pre-preg over the copper foil upon completion of the etching; printing the copper foil on the pre-preg by thermally bonding the temporary substrate and the pre-preg; removing the temporary substrate thereby forming a copper clad foil in a pattern for forming a wiring circuit with a pair of major surface areas opposite each other; and laminating said foil to said base with each of said major surface areas having a first level at a first distance from said base and a second level at a second distance from said base different from said first distance, the second levels of said major surface areas being at areas for forming lands where through holes are to be formed.

Claim 7

A method of making a printed wiring board for forming a multilayer printed wiring board, said method comprising the steps of impregnating a fibrous material with resin to form a resinous base; forming a copper foil on a temporary substrate; covering said foil with a photo resist; primarily exposing the photo resist via a mask film having common land patterns which are regularly arranged in the form of a matrix; secondarily exposing the photo resist via a mask film having intrinsic circuit patterns including specified land patterns and circuit conductor patterns; developing the twice-exposed photo resist other than specified land forming areas; etching uniformly to a predetermined depth in areas other than the land forming areas of said foil; placing a pre-preg over the copper foil upon completion of the etching; printing the copper foil on the pre-preg by thermally bonding the temporary substrate and the pre-preg; removing the temporary substrate thereby forming a copper clad foil in a pattern for forming a wiring circuit with a pair of major surface areas opposite each other; and laminating said foil to said base with each of said major surface areas having a first level at a first distance from said base and a second level at a second distance from said base different from said first distance, the second levels of said major surface areas being at areas for forming lands where through holes are to be formed.

Claim 9

A method of making a printed wiring board for forming a multilayer printed wiring board, said method comprising the steps of impregnating a fibrous material with resin to form a resinous base; forming a copper foil on a temporary substrate; covering said foil with a photo resist; primarily exposing the photo resist via a mask film having common land patterns which are regularly arranged in the form of a matrix; secondarily exposing the photo resist via a mask film having intrinsic circuit patterns including specified land patterns and circuit conductor patterns; developing the twice-exposed photo resist other than specified land forming areas of said foil; removing the resist at the specified land forming areas; plating only the land forming areas of said foil; placing a pre-preg over the copper foil upon completion of the plating; printing the copper foil on the pre-preg by thermally bonding the temporary substrate and the pre-preg; removing the temporary substrate thereby forming a copper clad foil in a pattern for forming a wiring circuit with a pair of major surface areas opposite each other; and laminating said foil to said base with each of said major surface areas having a first level at a first distance from said base and a second level at a second distance from said base different from said first distance, the second levels of said major surface areas being at areas for forming lands where through holes are to be formed.

Claim 10

A method of making a printed wiring board for forming a multilayer printed wiring board, said method comprising the steps of impregnating a fibrous material with resin to form a resinous base; forming a copper foil on a temporary substrate; covering said foil with a photo resist; primarily exposing the photo resist via a mask film having common land patterns which are regularly arranged in the form of a matrix; secondarily exposing the photo resist via a mask film having intrinsic circuit patterns including specified land patterns and circuit conductor patterns; developing the twice-exposed photo resist other than specified land forming areas of said foil; removing the resist at the specified land forming areas; plating only the land forming areas of said foil; placing a pre-preg over the copper foil upon completion of the plating; printing the copper foil on the pre-preg by thermally bonding the temporary substrate and the pre-preg; removing the temporary substrate thereby forming a copper clad foil in a pattern for forming a wiring circuit with a pair of major surface areas opposite each other; and laminating said foil to said base with each of said major surface areas having a first level at a first distance from said base and a second level at a second distance from said base different from said first distance, the second levels of said major surface areas being at areas for forming lands where through holes are to be formed.