Polyimide multilayer wiring board and method of producing same

Claim 1

A multilayer wiring board, comprising: an electrically insulating substrate; a plurality of laminated blocks which are laid on top of another on said substrate and bonded to each other, each of said laminated blocks comprising a plurality of wiring layers and a plurality of polyimide resin layers in an alternately laminated arrangement; and connection means for electrically connecting two adjacently positioned laminated blocks to each other.

Claim 17

A method of producing a multilayer wiring board, comprising the steps of: (i) making a laminated base block which comprises an electrically insulating substrate, a combination of a plurality of wiring layers and a plurality of polyimide resin layers in an alternately laminated arrangement and a plurality of electrical terminals exposed in the surface opposite from said substrate; (ii) separately making a plurality of laminated temporary blocks each of which comprises a temporary substrate, a combination of a plurality of wiring layers and a plurality of polyimide resin layers in an alternately laminated arrangement and a plurality of electrical terminals on the surface opposite from said temporary substrate; (iii) bonding one of said temporary blocks to said base block such that said electrical terminals of the temporary block come into alignment with said electrical terminals of the base block, respectively, and electrically connecting said electrical terminals of the temporary block to said electrical terminals of the base block, respectively; (iv) removing said temporary substrate; (v) providing a plurality of electrical terminals on the surface exposed by the removal of said temporary substrate; and (vi) bonding another temporary block to the laminate obtained by the steps (i) to (v) and electrically connecting the electrical terminals of said another temporary block to the electrical terminals provided at the step (v); and (vii) removing the temporary substrate of said another temporary block.

Claim 21

A method according to any one of Claims 17 to 20, wherein one of (A) said electrical terminals in the step (i) and said electrical terminals in the step (v) and (B) said electrical terminals in the step (ii) are conductor pools and the other are metal bumps, said conductor pools being formed of a dispersion of fine particles of a metal in a polyimide resin.

Claim 23

A method according to any one of Claims 17 to 22, wherein said electrical terminal of said base block and said electrical terminals of each temporary block are all metal bumps.

Claim 25

A method according to any one of Claims 17 to 24, wherein at least one of (A) said electrical terminals in the step (i) and said electrical terminals in the step (v) and (B) said electrical terminals in the step (ii) are metal bumps, both the step (iii) and the step (vi) comprising interposing an anisotropically conductive film, which is a resin film comprising fine particles of a metal, between the two blocks to be bonded to each other such that the anisotropically conductive film is squeezed by said metal bumps of one of the two blocks against the electrical terminals of the other block.

Claim 26

A method according to any one of Claims 17 to 25, wherein said surface of each temporary block in the step (ii) is formed of a polyimide resin which has a glass transition temperature and serves as an adhesive when heated to a temperature above the glass transition temperature.

Claim 27

A method according to any one of Claims 17 to 26, wherein both the step (iii) and the step (vi) comprise interposing a thermosetting adhesive resin between the two blocks to be bonded to each other.

Claim 29

A method according to any one of Claims 17 to 28, wherein both the step (iii) and the step (vi) comprise interposing a thermoplastic adhesive resin between the two blocks to be bonded to each other.

Claim 31

A method according to any one of Claims 17 to 30, wherein said temporary substrate is made of alumina, both the step (iv) and the step (vii) comprising dissolving the temporary substrate in an acid solution.

Claim 32

A method according to any one of Claims 17 to 31, wherein said temporary substrate is made larger in surface area than said wiring layers in each temporary block, the step (ii) comprising the sub-steps of bonding only a peripheral region of the temporary substrate to the bottom layer of said combination with a polyimide resin and providing the temporary substrate with an adhesion restricting means for preventing the remaining major region of the temporary substrate from firmly adhering to said bottom layer, both the step (iv) and the step (vii) comprising the sub-steps of cutting away said peripheral region of the temporary substrate together with the polyimide resin adhering to said peripheral region and peeling the remaining major region of the temporary substrate.

Claim 36

A method according to any one of Claims 32 to 35, wherein the material of said temporary substrate is selected from the group consisting of aluminum, silicon and alumina, said adhesion restricting means comprises a nickel plating layer formed on the temporary substrate so as to leave only said peripheral region exposed and a polyimide layer of a polyimide resin having a glass transition temperature formed on said nickel plating layer so as to cover said peripheral region of the temporary substrate too.