Wiring board and a process of producing a wiring board

• US 20020045394A1
• Filed: 10/25/2001
• Published: 04/18/2002
• Est. Priority Date: 07/16/1997
• Status: Active Grant

• Current Assignee: Hideo Hatanaka, Kazunori Sakamoto, Masanaru Hasegawa, Osamu Noda
• Original Assignee: Hideo Hatanaka, Kazunori Sakamoto, Masanaru Hasegawa, Osamu Noda
• Inventors: Sakamoto, Kazunori, Hatanaka, Hideo, Hasegawa, Masanaru, Noda, Osamu
• Granted Patent: US 6,780,493 B2
• Time in Patent Office: Days
• US Class Current: 442/180
• CPC Class Codes: B32B 27/04 as impregnant, bonding, or embedding substance not used
• CPC Class Codes: B32B 3/10 characterised by a discontinuous layer, i.e. formed of separate pieces of material
• CPC Class Codes: B32B 5/02 characterised by structural features of a fibrous or filamentary layer layer formed of metallic wires B32B15/02; layer formed of natural mineral fibres B32B19/02; layer formed of wood fibres B32B21/02
• CPC Class Codes: B32B 7/12 using interposed adhesives or interposed materials with bonding properties
• CPC Class Codes: H01L 23/49822 Multilayer substrates multilayer metallisation on monolayer substrate H01L23/498
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H05K 1/036 Multilayers with layers of different types
• CPC Class Codes: H05K 1/0366 reinforced, e.g. by fibres, fabrics H05K1/036 takes precedence
• CPC Class Codes: H05K 2201/015 Fluoropolymer, e.g. polytetrafluoroethylene [PTFE]
• CPC Class Codes: H05K 2201/0154 Polyimide
• CPC Class Codes: H05K 2201/0355 Metal foils
• CPC Class Codes: H05K 2201/10378 Interposers
• CPC Class Codes: H05K 2203/0191 Using tape or non-metallic foil in a process, e.g. during filling of a hole with conductive paste
• CPC Class Codes: H05K 2203/1461 Applying or finishing the circuit pattern after another process, e.g. after filling of vias with conductive paste, after making printed resistors
• CPC Class Codes: H05K 3/20 by affixing prefabricated conductor pattern H05K1/187, H05K3/046, H05K3/4658, H05K3/4682 takes precedence
• CPC Class Codes: H05K 3/386 by the use of an organic polymeric bonding layer, e.g. adhesive
• CPC Class Codes: H05K 3/4069 for via connections in organic insulating substrates
• CPC Class Codes: H05K 3/462 characterized by laminating only or mainly similar double-sided circuit boards
• CPC Class Codes: H05K 3/4623 the circuit boards having internal via connections between two or more circuit layers before lamination, e.g. double-sided circuit boards H05K3/462 takes precedence
• CPC Class Codes: Y10S 428/901 : Printed circuit
• CPC Class Codes: Y10T 428/24273 : including aperture
• CPC Class Codes: Y10T 428/24917 : including metal layer
• CPC Class Codes: Y10T 442/2418 : Coating or impregnation increases electrical conductivity or anti-static quality
• CPC Class Codes: Y10T 442/2992 : Coated or impregnated glass fiber fabric
• CPC Class Codes: Y10T 442/674 : Nonwoven fabric with a preformed polymeric film or sheet

Abstract

In a wiring board, predetermined wiring patterns which are formed on both sides of an insulation substrate are electrically connected by an electrically conductive material provided in through holes formed through the insulation substrate. The insulation substrate is composed of a resin impregnated fibrous sheet and a heat resistant film. The present invention solves the problems of the wiring board which are caused by irregularities on the surface of the resin impregnated fibrous sheet. The problems include insufficient adhesion strength between the wiring pattern and the insulation substrate or the limitation of fineness of the wiring pattern due to the irregularities on the surface of the printed wiring board which are formed upon the thermocompression bonding process.

Claims

1. A wiring board comprising:

an insulation substrate comprising a resin impregnated fibrous sheet, and a heat resistant film provided on at least one side of said resin impregnated fibrous sheet, wherein at least one through hole is formed through said heat resistant film and said resin impregnated fibrous sheet, and said at least one through hole is filled with an electrically conductive material;

a first wiring pattern formed on a first side of said insulation substrate;

a second wiring pattern formed on a second side of said insulation substrate and being electrically connected to said first wiring pattern by said electrically conductive material; and

an adhesive layer provided between said heat resistant film and one of said first and second wiring patterns.

2. The wiring board as claimed in claim 1, wherein said heat resistant film has a breaking strength of not less than 10 kg/mm².

3. The wiring board as claimed in claim 1, wherein said heat resistant film is selected from the group consisting of films of an aromatic polyamide, a polyimide, an aromatic polyester, a polycarbonate, a polysulfone, a polytetrafluoroethylene, a polyhexafluoropropylene, a polyetherketone and a polyphenylene ether.

4. The wiring board as claimed in claim 1, wherein said resin impregnated fibrous sheet is at least one selected from the group consisting of a glass fiber-epoxy resin composite, a glass fiber-bismaleimide triazine resin composite, an aramid fiber-epoxy resin composite and an aramid fiber-bismaleimide triazine resin composite.

5. A multi-layer wiring board comprising an intermediate connector, a first two-sided wiring board laminated on a first side of said intermediate connector, and a second two-sided wiring board laminated on a second side of said intermediate connector,

said intermediate connector having a resin impregnated fibrous sheet formed with at least one through hole that is filled with a conductive material, and p1 of said first and second two-sided wiring boards comprising:

an insulation substrate comprising a resin impregnated fibrous sheet, and a heat resistant film provided on at least one side of said resin impregnated fibrous sheet, wherein at least one through hole is formed through said heat resistant film and said resin impregnated fibrous sheet, and said at least one through hole is filled with an electrically conductive material;

a first wiring pattern formed on an inner side of said insulation substrate;

a second wiring pattern formed on an outer side of said insulation substrate and being electrically connected to said first wiring pattern by said electrically conductive material; and

an adhesive layer provided between said heat resistant film and one of said first and second wiring patterns, and

wherein said first wiring patterns of said first and second two-sided wiring boards are electrically connected by said electrically conductive material of said intermediate connector.

6. The wiring board as claimed in claim 5, wherein said heat resistant film has a breaking strength of not less than 10 kg/mm².

7. The wiring board as claimed in claim 5, wherein said heat resistant film is selected from the group consisting of films of an aromatic polyamide, a polyimide, an aromatic polyester, a polycarbonate, a polysulfone, a polytetrafluoroethylene, a polyhexafluoropropylene, a polyetherketone and a polyphenylene ether.

8. The wiring board as claimed in claim 5, wherein said resin impregnated fibrous sheet is at least one selected from the group consisting of a glass fiber-epoxy resin composite, a glass fiber-bismaleimide triazine resin composite, an aramid fiber-epoxy resin composite and an aramid fiber-bismaleimide triazine resin composite.

9. A multi-layer wiring board comprising a two-sided wiring board, a first intermediate connector provided on a first side of said two-sided wiring board, and a second connector provided on a second side of said two-sided wiring board, said two-sided wiring board comprising:

an insulation substrate comprising a resin impregnated fibrous sheet,

a heat resistant film provided on at least one side of said resin impregnated fibrous sheet, and at least one through hole formed through said heat resistant film and said resin impregnated fibrous sheet, wherein said at least one through hole is filled with an electrically conductive material;

a wiring pattern provided on a first side of said insulation substrate;

a wiring pattern provided on a second side of said insulation substrate, said wiring patterns being electrically connected by said electrically conductive material; and

an adhesive layer provided between one of said wiring patterns and said heat resistant film,

each of said first and second intermediate connectors comprising;

a resin impregnated fibrous sheet having at least one through hole formed at a predetermined position of said resin impregnated fibrous sheet;

a conductive material provided in said through hole; and

a predetermined wiring pattern provided on a surface of said resin impregnated fibrous sheet that is remote from said wiring board,

wherein said predetermined wiring pattern of said first intermediate connector is electrically connected to one of said wiring patterns of said two-sided wiring board by said electrically conductive material of said first intermediate connector, and said wiring pattern of said second intermediate connector is electrically connected to the other of said wiring patterns of said two-sided wiring board by said electrically conductive material of said second intermediate connector.

10. The wiring board as claimed in claim 9, wherein said heat resistant film has a breaking strength of not less than 10 kg/mm².

11. The wiring board as claimed in claim 9, wherein said heat resistant film is selected from the group consisting of films of an aromatic polyamide, a polyimide, an aromatic polyester, a polycarbonate, a polysulfone, a polytetrafluoroethylene, a polyhexafluoropropylene, a polyetherketone and a polyphenylene ether.

12. The wiring board as claimed in claim 9, wherein said resin impregnated fibrous sheet is at least one selected from the group consisting of a glass fiber-epoxy resin composite, a glass fiber-bismaleimide triazine resin composite, an aramid fiber-epoxy resin composite and an aramid fiber-bismaleimide triazine resin composite.

14. The multi-layer wiring board as claimed in claim 13, wherein the multi-layer wiring board has outermost members, and the number of said wiring boards is larger by one than the number of said intermediate connectors so that said wiring boards form the outermost members of the multi-layer wiring board, and at least one of said outermost members includes said heat resistant film.

15. The multi-layer wiring board as claimed in claim 13, wherein the multi-layer wiring board has outermost members, and the number of said wiring boards is smaller by one than the number of said intermediate connectors so that said outermost members are defined by said intermediate connectors, and one of said wiring boards that are disposed adjacent to said outermost members includes said heat resistant film.

13. A multi-layer wiring board comprising:

a plurality of wiring boards, wherein each of said wiring boards includes predetermined wiring patterns provided on both sides of a resin impregnated fibrous sheet, at least one through hole extending through said resin impregnated fibrous sheet, and an electrically conductive material provided in said through hole,

said wiring patterns on both sides of said resin impregnated fibrous sheet being electrically connected by said electrically conductive material,

wherein at least one of said wiring boards has a heat resistant film disposed between one of said wiring patterns thereof and said resin impregnated sheet, and an adhesive layer provided on a side of said heat resistant film that opposes said one wiring pattern such that said heat resistant film and said one wiring pattern are bonded together by said adhesive layer; and

at least one intermediate connector comprising a resin impregnated fibrous sheet having at least one through hole filled with an electrically conductive material, and wiring patterns provided on both sides of said resin impregnated fibrous sheet, said wiring patterns being electrically connected by said electrically conductive material,

wherein said wiring boards and said intermediate connector are alternately arranged so that said wiring patterns directly opposing opposite sides of said intermediate connector are electrically connected by said electrically conductive material provided in said through hole of said intermediate connector.

16. A multi-layer wiring board comprising:

at least three wiring pattern layers, each of said wiring patterns having a wiring pattern on both sides thereof;

at least two resin impregnated fibrous sheets, each of said resin impregnated fibrous sheets being interposed between two of said at least three wiring patterns, wherein each of said resin impregnated fibrous sheets has at least one through hole, which is filled with an electrically conductive material;

a heat resistant film provided between at least one of said wiring patterns of said wiring pattern layers and one of said resin impregnated fibrous sheets; and

an adhesive layer provided between said heat resistant film and said wiring pattern, wherein said wiring patterns of adjacent wiring pattern layers are electrically connected by said electrically conductive material of said resin impregnated fibrous sheet that is disposed between said adjacent wiring pattern layers.

17. An intermediate connector for connecting wiring boards, said intermediate connector comprising:

a resin impregnated fibrous sheet;

a heat resistant film provided on at least one side of said resin impregnated fibrous sheet;

an adhesive layer provided on said heat resistant film for forming a bond between said heat resistant film and a wiring pattern of one of the wiring boards;

at least one through holes extending through said resin impregnated fibrous sheet and said heat resistant film at a predetermined location; and

an electrically conductive material provided in said through hole for electrically connecting the wiring boards.

18. A wiring board comprising:

an insulation substrate comprising a thermosetting resin impregnated fibrous sheet, and a heat resistant film provided on at least one side of said resin impregnated fibrous sheet, wherein at least one through hole is formed through said heat resistant film and said resin impregnated fibrous sheet, and said at least one through hole is filled with an electrically conductive material;

a first wiring pattern formed on a first side of said insulation substrate; and

a second wiring pattern formed on a second side of said insulation substrate and being electrically connected to said first wiring pattern by said electrically conductive material,

wherein said heat resistant film is selected so as to not melt when said insulation substrate is heated and pressed in order to cure the thermosetting resin which is contained in said insulation substrate.

19. A multi-layer wiring board comprising an intermediate connector, a first two-sided wiring board laminated on a first side of said intermediate connector, and a second two-sided wiring board laminated on a second side of said intermediate connector,

said intermediate connector having a thermosetting resin impregnated fibrous sheet formed with at least one through hole that is filled with an electrically conductive material, and

each of said first and second two-sided wiring boards comprising:

an insulation substrate comprising a thermosetting resin impregnated fibrous sheet, and a heat resistant film provided on at least one side of said resin impregnated fibrous sheet, wherein at least one through hole is formed through said heat resistant film and said resin impregnated fibrous sheet, and said at least one through hole is filled with an electrically conductive material;

a first wiring pattern formed on an inner side of said insulation substrate; and

a second wiring pattern formed on an outer side of said insulation substrate and being electrically connected to said first wiring pattern by said electrically conductive material,

wherein said heat resistant films are not melted when said first and second two-sided wiring boards and said intermediate connector are heated and pressed so as to cure the thermosetting resins which are contained in said first and second two-sided wiring boards and said intermediate connector, and

wherein said first wiring patterns of said first and second two-sided wiring boards are electrically connected by said electrically conductive material of said intermediate connector.

20. A multi-layer wiring board comprising a two-sided wiring board, a first intermediate connector provided on a first side of said two-sided wiring board, and a second connector provided on a second side of said two-sided wiring board,

said two-sided wiring board comprising:

an insulation substrate comprising a thermosetting resin impregnated fibrous sheet, a heat resistant film provided on at least one side of said resin impregnated fibrous sheet, and at least one through hole formed through said heat resistant film and said resin impregnated fibrous sheet, wherein said at least one through hole is filled with an electrically conductive material;

a wiring pattern provided on a first side of said insulation substrate; and

a wiring pattern provided on a second side of said insulation substrate, said wiring patterns being electrically connected by said electrically conductive material;

each of said first and second intermediate connectors comprising;

a thermosetting resin impregnated fibrous sheet having at least one through hole formed at a predetermined position of said resin impregnated fibrous sheet;

a conductive material provided in said through hole; and

a predetermined wiring pattern provided on a surface of said thermosetting resin impregnated fibrous sheet that is remote from said wiring board,

wherein said heat resistant film is not melted when said two-sided wiring board and said first and second intermediate connectors are heated and pressed so as to cure the thermosetting resins which are contained in said two-sided wiring board and said first and second intermediate connectors, and

wherein said predetermined wiring pattern of said first intermediate connector is electrically connected to one of said wiring patterns of said two-sided wiring board by said electrically conductive material of said first intermediate connector, and said wiring pattern of said second intermediate connector is electrically connected to the other of said wiring patterns of said two-sided wiring board by said electrically conductive material of said second intermediate connector.

21. A multi-layer wiring board comprising:

a plurality of wiring boards, wherein each of said wiring boards includes predetermined wiring patterns provided on both sides of a thermosetting resin impregnated fibrous sheet, at least one through hole extending through said resin impregnated fibrous sheet, and an electrically conductive material provided in said through hole,

said wiring patterns on both sides of said resin impregnated fibrous sheet being electrically connected by said electrically conductive material,

wherein at least one of said wiring boards has a heat resistant film disposed between one of said wiring patterns thereof and said thermosetting resin impregnated sheet,

at least one intermediate connector comprising a thermosetting resin impregnated fibrous sheet having at least one through hole filled with an electrically conductive material,

wherein said heat resistant film is not melted when said wiring patterns and said intermediate connector are heated and pressed so as to cure the thermosetting resins which are contained in said wiring patterns and said intermediate connector; and

wherein said wiring boards and said intermediate connector are alternately arranged so that said wiring patterns directly opposing opposite sides of said intermediate connector are electrically connected by said electrically conductive material provided in said through hole of said intermediate connector.

22. A multi-layer wiring board comprising:

at least three wiring pattern layers, each of said wiring patterns having a wiring pattern on both sides thereof;

at least two thermosetting resin impregnated fibrous sheets, each of said resin impregnated fibrous sheets being interposed between two of said at least three wiring patterns, wherein each of said resin impregnated fibrous sheets has at least one through hole, which is filled with an electrically conductive material;

a heat resistant film provided between at least one of said wiring patterns of said wiring pattern layers and one of said resin impregnated fibrous sheets;

said heat resistant films being formed of a material that does not melt when said wiring pattern layers and said resin impregnated fibrous sheets are heated and pressed so as to cure the thermosetting resins which are contained in said wiring pattern layers and said resin impregnated fibrous sheets,

wherein said wiring patterns of adjacent wiring pattern layers are electrically connected by said electrically conductive material of said resin impregnated fibrous sheet that is disposed between said adjacent wiring pattern layers.

23. An intermediate connector for connecting wiring boards, said intermediate connector comprising:

a thermosetting resin impregnated fibrous sheet;

a heat resistant film provided on at least one side of said resin impregnated fibrous sheet, said heat resistant film is formed of a material that does not melt when said intermediate connector is heated and pressed to cure the thermosetting resin contained in said intermediate connector;

at least one through holes extending through said resin impregnated fibrous sheet and said heat resistant film at a predetermined location; and

an electrically conductive material provided in said through hole for electrically connecting the wiring boards.