Multi-layered flexible print circuit board and manufacturing method thereof

• US 7,263,769 B2
• Filed: 10/19/2005
• Issued: 09/04/2007
• Est. Priority Date: 10/20/2004
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Yoshino, Toyokazu, Nakashima, Kouji, Okamoto, Katsuya, Morimoto, Shinji
• Primary Examiner(s): Arbes; Carl J.
• Application Number:
  US11/252,540
• Publication Number:
  US 20060102386A1
• Time in Patent Office: 685 Days
• Field of Search: 298/25, 298/30, 298/42, 298/45, 298/52, 228/180.1, 228/180.21, 228/180.22
• US Class Current: 29/852
• CPC Class Codes: H05K 1/0393 Flexible materials H05K1/038 takes precedence; specific organic compositions are classified in H05K1/0313 and subgroups
• CPC Class Codes: H05K 2201/0195 Dielectric or adhesive layers comprising a plurality of layers, e.g. in a multilayer structure
• CPC Class Codes: H05K 2201/0221 Insulating particles having an electrically conductive coating
• CPC Class Codes: H05K 2201/0379 Stacked conductors
• CPC Class Codes: H05K 2201/043 Stacked PCBs with their backs attached to each other without electrical connection
• CPC Class Codes: H05K 2201/096 Vertically aligned vias, holes or stacked vias
• CPC Class Codes: H05K 2201/10234 Metallic balls solder balls H05K2203/041
• CPC Class Codes: H05K 2201/10416 Metallic blocks or heatsinks completely inserted in a PCB metallic supports H05K3/0061
• CPC Class Codes: H05K 2203/0278 Flat pressure, e.g. for connecting terminals with anisotropic conductive adhesive
• CPC Class Codes: H05K 2203/041 Solder preforms in the shape of solder balls soldering leadless components having an array of bottom contacts H05K3/3436
• CPC Class Codes: H05K 2203/082 Suction, e.g. for holding solder balls or components
• CPC Class Codes: H05K 3/386 by the use of an organic polymeric bonding layer, e.g. adhesive
• CPC Class Codes: H05K 3/4046 using auxiliary conductive elements, e.g. metallic spheres, eyelets, pieces of wire
• CPC Class Codes: H05K 3/4084 by deforming at least one of the conductive layers
• CPC Class Codes: H05K 3/4614 the electrical connections between the circuit boards being made during lamination
• CPC Class Codes: H05K 3/4617 characterized by laminating only or mainly similar single-sided circuit boards
• 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: H05K 3/4635 laminating flexible circuit boards using additional insulating adhesive materials between the boards
• CPC Class Codes: Y10T 29/49126 Assembling bases
• CPC Class Codes: Y10T 29/49147 : Assembling terminal to base
• CPC Class Codes: Y10T 29/49153 : with shaping or forcing terminal into base aperture
• CPC Class Codes: Y10T 29/49165 : by forming conductive walled aperture in base

Abstract

A multi-layered flexible print circuit board comprising an insulating layer, a circuit layer formed on the front and back surfaces of the insulating layer and a hole connecting between the circuit layers via the insulating layer, wherein there is provided an electrically-conductive member having a metal layer formed thereon at least on the surface thereof which is press-fitted into the hole to electrically conduct the circuit layer.

Claims

1. A method of producing a multi-layered flexible print circuit board comprising:

a one-sided circuit board forming step of forming a first circuit layer on one side of a first insulating layer and insulating layer on the other side thereof to form a first one-sided circuit board and forming a second circuit layer on one side of a second insulating layer to form a second one-sided circuit board;

a through-hole forming step of forming a through-hole for connecting between the first circuit layer and the second circuit layer in the one-sided circuit board in the thickness direction;

a metal portion forming step of press-fitting a substantially spherical conductor made of a metallic material at least on the surface thereof into the through-hole to make conduction to the first circuit layer so that a metal portion extending from the surface of the first insulating layer is formed; and

a conducting step of laminating the first one-sided circuit board and the second one-sided circuit board on each other and press-deforming the metal portion such that the metal portion and the second circuit layer are electrically-conducted to each other to electrically-conduct the first circuit layer and the second circuit layer to each other via the metal portion; and

the insulating layer is an adhesive layer for laminating the first one-sided circuit board and the second one-sided circuit board on each other.

2. The method of producing a multi-layered flexible print circuit board as defined in claim 1, wherein the through-hole forming step comprises another through-hole forming step of forming a through-hole in the second one-sided circuit board in the thickness direction, the metal portion forming step comprises another metal portion forming step of press-fitting a substantially spherical conductor made of a metallic material at least on the surface thereof into the through-hole to form another metal portion electrically-conducted to the second circuit layer and extending from the surface of the second insulating layer and the conducting step is a step of laminating the first one-sided circuit board and the second one-sided circuit board on each other and press-deforming the metal portion and the other metal portion such that the metal portion and the other metal portion are electrically-conducted to each other to electrically-conduct the first circuit layer and the second circuit layer to each other via the metal portion.

3. The method of producing a multi-layered flexible print circuit board as defined in claim 1, wherein the metallic material is made of a soft metal.

4. The method of producing a multi-layered flexible print circuit board as defined in claim 3, wherein the metallic material comprises at least one of solder alloy, copper and copper alloy.

5. The method of producing a multi-layered flexible print circuit board as defined in claim 1, wherein the substantially spherical conductor is made of a resin ball having a smaller diameter than the diameter of the hole and a metal layer covering the resin ball.

6. The method of producing a multi-layered flexible print circuit board as defined in claim 1, wherein the substantially spherical conductor comprises a solder material coat layer provided on the surface thereof.

7. A method of producing a multi-layered flexible print circuit board comprising:

a one-sided circuit board forming step of forming a first circuit layer on one side of a first insulating layer to form a first one-sided circuit board and forming a second circuit layer on one side of a second insulating layer to form a second one-sided circuit board;

a through-hole forming step of forming a through-hole for connecting between the first circuit layer and the second circuit layer in the first one-sided circuit board in the thickness direction;

a laminating step of laminating the first one-sided circuit board and the second one-sided circuit board on each other with an adhesive layer interposed therebetween in such an arrangement that the first insulating layer and the second circuit layer are disposed opposed to each other to form a blind via hole by the through-hole and the second circuit layer; and

a conducting step of filling the blind via hole with a substantially spherical solder member made of solder material or a particulate solder and then press-fitting a substantially spherical conductor made of a metallic material having a smaller thermal expansion coefficient than the solder material into the blind via hole to form a metal member bonded to the substantially spherical solder member or particulate solder so that the circuit layer provided on the front and back sides of the insulating layer are electrically-conducted to the substantially spherical solder member or particulate solder with the junction to the metal member.