JP2008034702A - Rigid flex circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rigid flex circuit board enabling various connection systems, and a manufacturing method of the rigid flex circuit board. <P>SOLUTION: A flexible part 54 includes a first flexible circuit 20 composed of a first base member 121, and of a first circuit 125 provided on the first base member 121; and a second flexible circuit 21 composed of a second base member 141, and a second circuit 145 provided on the second base member 141. In first and second rigid parts 56, 58, both are disposed in superposition. The first and second base members 121 and 141 extend to the rigid part to constitute the rigid parts 56, 58. The first and second rigid parts 56, 58 include on both surface sides thereof base members 33 or the like laminated and bonded. In the first rigid part 58, the first base member 121 and the second base member 141 are separated; and in the second rigid part 56, the first base member 121 and the second base member 141 are joined with each other. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rigid flex circuit board and a manufacturing method thereof.

  With recent increases in the density of electronic devices, multilayers, thinning, and densification of flexible circuit boards and the like used for these have been advanced.

  The flexible circuit board is roughly classified into a rigid flex circuit board, which is a composite board having both a flexible circuit portion and a rigid circuit portion, and a multilayer flexible wiring board in which flexible circuit boards are stacked to be multilayered.

  In the conventional rigid flex circuit board, the flexible part is composed of a plurality of flexible circuit parts, and the rigid part has a structure in which a plurality of flexible circuit parts and rigid circuit parts are laminated and bonded (for example, Patent Document 1, Patent Document 1). 2).

The amount of information and specifications required for rigid flex circuit boards are changing year by year. As for the flexible circuit portion that connects the rigid circuit portions, the flexible portion has a single-sided structure or a double-sided structure from the viewpoint of flexibility. However, as the amount of information increases, wiring has become difficult with a single-sided structure, and therefore a plurality of single-sided flexible circuits are used when the double-sided structure or multilayer structure is not sufficiently flexible. However, since both ends are connected to the rigid circuit part, when wound spirally at the hinge part, the inner diameter side is wrinkled due to the difference in circumference between the inner diameter and the outer diameter, or a plurality of circuit boards are connected. There were problems such as being unable to do so. For example, as a method of changing the length of each flexible part, when creating a rigid flex circuit board in advance, the length of the flexible circuit part corresponding to the inner volume is shortened and manufactured, but the process is This is very complicated and causes a decrease in product yield.
Japanese Patent Laid-Open No. 2001-024297 JP-A-6-021653

  The present invention has been made in view of the above circumstances, and enables various connection methods such as connection with a plurality of circuit boards and spiral winding that does not wrinkle at the hinge without reducing the product yield. It is an object of the present invention to provide a rigid flex circuit board and a manufacturing method of the rigid flex circuit board.

  A rigid flex circuit board according to the present invention is a rigid flex circuit board including a flexible portion and first and second rigid portions, wherein the flexible portion is provided on the first base material and the first base material. A configuration in which a first flexible circuit portion including the first circuit formed, a second base material, and a second flexible circuit portion including a second circuit provided on the second base material are arranged to overlap each other. The first and second rigid parts are configured such that the first base material and the second base material respectively extend to the rigid part to form a rigid part, and the first and second rigid parts of the first rigid part The second rigid body has a structure in which another base material is laminated and bonded to the outer surface of each of the two base materials and the outer surface of each of the first and second base materials of the second rigid portion, and the first rigid In the part, the first base material and the second base material Wood is separated, in the second rigid section, the a first substrate, the second substrate and having a configuration that is joined.

  In the rigid flex circuit board, the first base material and the second base material of the flexible portion are separated by the first rigid portion. As a result, connection with a plurality of circuit boards becomes possible, and when incorporated in a spiral winding, by adjusting the attachment position to the first base material or the second base material to the first rigid part, A rigid flex circuit board without wrinkles can be realized.

  A method for manufacturing a rigid flex circuit board is a method for manufacturing a rigid flex circuit board including a flexible portion and first and second rigid portions, the first base material, and the first base material being provided on the first base material. Preparing a first flexible circuit portion including the first circuit, preparing a second flexible circuit portion including a second base material, and a second circuit provided on the second base material; A step of laminating and arranging the first flexible circuit portion and the second flexible circuit portion, a base material is disposed opposite to both surfaces of the laminated and arranged flexible circuit portion, and the second flexible portion is formed at the first flexible portion. An interlayer adhesive is disposed between the circuit portion and the second flexible circuit portion, and the first rigid circuit portion and the second flexible circuit portion are disposed at the first rigid portion forming position. Pressed in a state where between the adhesive is selectively removed, characterized in that it and a step of thermocompression bonding the rigid portion forming portion.

  Accordingly, it is possible to provide a method that does not significantly change the manufacturing method of the rigid flex circuit board and does not reduce the product yield.

  According to the present invention, a rigid flex circuit board and a rigid flex that enable various connection methods such as connection with a plurality of circuit boards and spiral winding without wrinkles at the hinge part without reducing the product yield. A circuit board manufacturing method can be provided.

  Hereinafter, a rigid flex circuit board and a manufacturing method thereof according to the present invention will be described in detail based on preferred embodiments attached.

  As shown in FIG. 1, the rigid flex circuit board 52 of the present invention is a rigid flex circuit board 52 including a flexible portion 54 and first and second rigid portions 56 and 58. The flexible part 54 is provided on the first flexible circuit part 20 including the first base 121 and the first circuit 125 provided on the first base 121, the second base 141, and the second base 141. The second flexible circuit portion 21 including the second circuit 145 formed is arranged so as to overlap with each other, and the first and second rigid portions 56 and 58 include the first base material and the second base material 121. 141 extend to the rigid portions 56, 58 to form the rigid portions 56, 58, respectively, and the outermost layers of the first and second rigid portions 56, 58 are formed on the base materials 33, 35, 37, 39, respectively. In the first rigid portion 58, the first base material 121 and the second base material 141 are separated, and in the second rigid portion 56, the first base material 121 and the second base material 121 are separated. It has a configuration in which the base material 141 is joined. .

  When the first rigid portion 58 is separated, the flexible portion 54 is spirally wound around the hinge portion when the rigid flex circuit board 52 is incorporated into a folding portable terminal, for example, as shown in FIG. In addition, since the first rigid portion 58 side is separated, the peripheral lengths of the inner winding and the outer winding can be appropriately adjusted and incorporated. In addition, as shown in FIG. 6, each separated rigid portion can be connected to a different circuit board 84, so that a rigid flex circuit board corresponding to various connection methods can be obtained.

  The second rigid portion 56 is bonded to the first and second flexible circuit portions 20 and 21 via the interlayer adhesive 30. A through hole 80 penetrating all the layers is provided for electrical connection with each layer. A plurality of second rigid portions 56 may be provided as necessary. The flexible portion 54 includes the first and second flexible circuit portions 20 and 21 and is not bonded with an interlayer adhesive at the location of the first rigid portion 58 as illustrated. And each circuit part may be in contact and may be spaced apart. Moreover, you may provide a flexible part 3 or more base materials as needed. Here, the first and second flexible circuit sections 20 and 21 are provided with the same circuit, but may be provided with different circuits.

  As shown in FIG. 2, the first and second flexible circuit portions 20 and 21 are the first and second substrates 12 and 14 on one side, and the first base 121 and the second base 141 are disposed inside. May be arranged. By using a single-sided substrate, a rigid flex circuit board with better flexibility can be obtained. Further, the first and second flexible circuit portions 20 and 21 may be separated at the flexible portion 54.

  In the first and second flexible circuit sections 20 and 20, the surfaces of the first circuit 125 and the second circuit 145 may be covered with the surface coating layers 200 and 210. The surface coating layers 200 and 210 may be a coverlay film composed of resin films 203 and 213 and adhesives 201 and 211, or a liquid resin composition containing a thermosetting resin is formed by a screen printing method or the like. Heat curing may be performed. It is preferable to use a coverlay film from the viewpoint of bending characteristics.

  In addition, the first base material 121 and the second base material 141 extend to the rigid portions 56 and 58, respectively, constitute the rigid portions 56 and 58, and the rigid circuit portions are provided on both sides of the rigid portions 56 and 58, respectively. 33, 35, 37, and 39 are stacked and the second rigid portion 56 is laminated and bonded with the interlayer adhesive 30 disposed between the second rigid portion 56 and the base material.

  Next, a method for manufacturing a rigid flex circuit board will be described.

The manufacturing method of the rigid flex circuit board 52 of the present invention is a manufacturing method of the rigid flex circuit board 52 including the flexible portion 54 and the first and second rigid portions 56 and 58, and is performed in the following order of steps. Can do.
(Step A)
As shown in FIG. 2, a step of preparing a first flexible circuit unit 20 including a first base 121 and a first circuit 125 provided on the first base 121, a second base 141, 2 a step of preparing a second flexible circuit portion 21 including a second circuit 145 provided on the base material 141, and a step of laminating and arranging the first flexible circuit portion 20 and the second flexible circuit portion 21.
(Step B)
As shown in FIG. 3, the interlayer adhesive 30 is disposed between the first flexible circuit portion 20 and the second flexible circuit portion 21 at the formation position of the second rigid portion 56 of the flexible circuit portions 20 and 21 that are stacked. In the place where the first rigid portion 58 is formed, the pressure is applied in a state where the interlayer adhesive 30 between the first flexible circuit portion 20 and the second flexible circuit portion 21 is selectively removed, and the place where the second rigid portion 56 is formed is heated. Crimp.
(Step C)
As shown in FIGS. 1 and 4, a 6-layer rigid flex circuit board 52 is manufactured.

Hereinafter, each step will be described.
(Step A)
In step A, first and second flexible circuit portions 20 and 21 are first manufactured (FIG. 2B). For example, etching is performed on the copper foil on one side of the double-sided copper-clad laminate in which the copper foil is formed on both surfaces of the base materials 121 and 141, thereby forming desired conductor circuits 125 and 145. Two substrates are obtained (FIG. 2 (a)).

  As a material which comprises the base materials 121 and 141, a resin film base material etc. are mentioned, for example. Examples of the resin film substrate include polyimide resin films such as polyimide resin films, polyetherimide resin films, polyamideimide resin films, polyamide resin films such as polyamide resin films, and polyester resin films such as polyester resin films. Can be mentioned. Among these, a polyimide resin film is mainly preferable. Thereby, especially an elasticity modulus and heat resistance can be improved.

  Although the thickness of the base materials 121 and 141 is not specifically limited, 5-50 micrometers is preferable and 12.5-25 micrometers is especially preferable. When the thickness is within the above range, the flexibility is particularly excellent.

  Next, the surface coating layers 200 and 210 are formed on the conductor circuits 125 and 145 (FIG. 2B). The surface coating layers 200 and 210 may be formed by, for example, attaching a cover lay film in which an adhesive is applied to an insulating film substrate, or printing ink directly on the substrate. In the configuration shown in FIG. 2, the surface coating layers 200 and 210 indicate the coverlay films 200 and 210 in which the adhesives 201 and 211 are applied to the insulating film base materials 203 and 213.

  The conditions for laminating the cover lay films 200 and 210 on the base materials 12 and 14 on which the conductor circuits 125 and 145 are formed are preferably pressure-bonded by a hot press molding apparatus having a temperature of 80 to 220 ° C. and a pressure of 0.2 to 10 MPa. .

  As the insulating film base materials 203 and 213, for example, a polyimide resin film such as a polyimide resin film, a polyetherimide resin film, a polyamideimide resin film, a polyamide resin film such as a polyamide resin film, a polyester, etc. Examples thereof include polyester resin-based films such as resin films. Among these, a polyimide resin film is mainly preferable. Thereby, especially an elasticity modulus and heat resistance can be improved. The surface coating layers 200 and 210 preferably cover the entire surface of the conductor circuits 125 and 145.

  The adhesives 201 and 211 are made of, for example, a resin composition containing a thermosetting resin such as an epoxy resin, a polyester resin, a polyimide resin, a polyamide resin, a polyamideimide resin, a polyurethane resin, or an epoxy resin. It is preferable. Among these, an epoxy resin is preferable. Thereby, adhesiveness can be improved. Furthermore, heat resistance can also be improved.

In addition, although the 1st flexible circuit part 20 and the 2nd flexible circuit part 21 used the same thing here, you may use a different thing.
(Step B)
In Step B, a four-layer circuit board 42 is manufactured (FIG. 3B).

  First, the interlayer adhesive 30 is prepared. Examples of the material constituting the interlayer adhesive 30 include thermosetting resins such as epoxy resins, polyimide resins, polyamideimide resins, acrylic resins, polyurethane resins, and polyester resins. Among these, an epoxy resin is preferable. Thereby, adhesiveness and heat resistance can be improved. Moreover, as a material which comprises the interlayer adhesive 30, the prepreg which impregnated the said thermosetting resin in the glass fiber base material etc. may be sufficient.

  The thickness of the interlayer adhesive 30 is preferably 10 to 200 μm, and particularly preferably 60 to 120 μm when a prepreg is used. Moreover, when using a bonding sheet, the thickness of 15-100 micrometers is preferable.

  As shown in FIG. 5, the prepared interlayer adhesive 30 is punched out with a mold or the like to form a separated rigid portion, and the interlayer between the flexible portion 54 of the rigid flex circuit board 52 and the first rigid portion 58 is formed. The adhesive agent is removed to prepare an interlayer adhesive 30 having an opening 301. At this time, in consideration of workability at the time of manufacture, it is preferable to leave an interlayer adhesive so as to bridge the separated portion outside the product (FIG. 3A).

  Next, using the interlayer adhesive 30 as a core, the first flexible circuit portion 20 and the second flexible circuit portion 21 are arranged so that the surface coating layers 200 and 210 face each other, and then heated under pressure and laminated and bonded to form four layers. An intermediate substrate 40 is obtained. The conditions for obtaining the four-layer intermediate substrate 40 are preferably integrally molded by a hot-pressure molding apparatus having a pressure of 110 to 220 ° C. and a pressure of 0.2 to 10 MPa.

  In the four-layer intermediate substrate 40, metal layers 123 and 143 that form circuits are formed on the outermost layers. For example, the four-layer circuit board 42 is obtained by etching the metal layer. During the etching process, a through hole 80 may be formed to penetrate all the layers and be electrically connected. An NC drill machine, a laser, etc. can be used for formation of a through-hole. Moreover, in order to electrically connect via the conductor circuits 125 and 145 and the base materials 121 and 141, you may carry out by a filled via etc.

Note that when the conductor circuits 125 and 145 are processed by, for example, etching, the metal layers 123 and 143 in the region to be the flexible portion 54 are preferably removed. As a result, the rigid portions 56 and 58 have a double-sided plate structure, and the flexible portion 54 has a so-called pseudo-single-sided structure having only one conductor circuit. can do.
(Step C)
In Step C, a six-layer rigid flex circuit board 52 is manufactured (FIG. 1).

  Using the four-layer circuit board 42 manufactured in Step B as a core, an interlayer adhesive 31 and a metal foil are overlapped on both sides from a position close to the four-layer circuit board 42 (FIG. 4). At this time, the interlayer adhesive 31 is removed by previously punching the flexible portion 54 with a mold or the like. Copper, iron, aluminum or the like is used as the conductor foil. Among these, it is preferable to use copper.

  The thickness of the metal foil 4 is not particularly limited, but is preferably 1 μm to 50 μm, and more preferably 5 μm to 35 μm. Examples of the material constituting the interlayer adhesives 31 and 32 include thermosetting resins such as epoxy resins, polyimide resins, polyamideimide resins, acrylic resins, polyurethane resins, and polyester resins. Among these, an epoxy resin is preferable. Thereby, adhesiveness and heat resistance can be improved. Moreover, as a material which comprises the interlayer adhesives 31 and 32, the prepreg which impregnated the said thermosetting resin in the glass fiber base material etc. may be sufficient.

  The thickness of the interlayer adhesives 31 and 32 is preferably 10 to 200 μm, and particularly preferably 60 to 120 μm when a prepreg is used. Moreover, when using a bonding sheet, the thickness of 15-100 micrometers is preferable. If the thickness is within the above range, a rigid flex circuit board having excellent insulating properties can be obtained.

  The conditions for obtaining the six-layer rigid flex intermediate board 51 by laminating the metal foil 4 and the four-layer circuit board 42 via the interlayer adhesives 31 and 32 at the positions where the rigid parts 56 and 58 are formed are 110 to 220 ° C. It is preferable to perform integral molding with a hot press molding apparatus having a pressure of 0.2 to 10 MPa.

  Through holes 80 are formed in the six-layer rigid flex intermediate substrate 51 using a drill or the like, and through-hole plating is performed to electrically connect the metal foil 4 and the rigid flex intermediate substrate 51 (FIG. 4).

  Then, for example, a desired conductor circuit is formed on the outer metal foil 4 by etching or the like, and rigid circuit portions 33, 35, 37, and 39 are formed. At that time, it is preferable to remove the portion of the metal foil of the flexible portion 54 that is not bonded with the interlayer adhesive by etching or the like.

  As described above, the rigid flex circuit board 52 from which the first rigid portion 58 is separated is obtained (FIG. 1).

  The rigid flex circuit board of the present invention can be suitably used in the periphery of electric devices such as mobile phones and personal computers.

It is sectional drawing which shows the rigid flex circuit board of this invention. It is sectional drawing which shows the process of manufacturing a 1st and 2nd flexible circuit part. It is sectional drawing which shows the process of manufacturing a 4-layer circuit board. It is sectional drawing which shows the process of manufacturing a rigid flex intermediate board. It is a top view which shows the process which laminated | stacked the circuit board and the interlayer adhesive. It is one Example which shows mounting of the separated 2nd rigid part. It is the schematic which shows the state attached to the hinge part.

Explanation of symbols

12: 1st board | substrate 121: 1st base material 123, 143: Metal foil 125: 1st circuit (conductor circuit)
14: 2nd board | substrate 141: 2nd base material 145: 2nd circuit (conductor circuit)
20: 1st flexible circuit part 200: Surface coating layer 201: Adhesive 203: Resin film 21: 2nd flexible circuit part 210: Surface coating layer 211: Adhesive 213: Resin film 30, 31, 32: Interlayer adhesive 301 : Opening 33, 35, 37, 39: Base material (rigid circuit part)
4: Metal foil 40: Four-layer intermediate board 42: Four-layer circuit board 51: Rigid flex intermediate board 52: Rigid flex circuit board 54: Flexible part 56: Second rigid part 58: First rigid part 80: Through hole 84: Circuit Board

Claims (4)

A rigid flex circuit board comprising a flexible part and first and second rigid parts,
The flexible part is
A first flexible circuit portion including a first base, a first circuit provided on the first base, a second base, and a second circuit provided on the second base. 2 flexible circuit portions, and a configuration in which the flexible circuit portions are arranged in an overlapping manner,
The first and second rigid parts are
Each of the first base material and the second base material extends to the rigid portion to form a rigid portion, and on each outer surface of the first and second base materials of the first rigid portion, and On the outer surface of each of the first and second substrates of the second rigid part, another substrate is laminated and adhered,
In the first rigid portion, the first base material and the second base material are separated,
The rigid circuit board according to claim 1, wherein the second rigid portion has a configuration in which the first base material and the second base material are joined.   The rigid flex circuit board according to claim 1, wherein the first and second flexible circuit portions are separated in the flexible portion. A manufacturing method of a rigid flex circuit board comprising a flexible part and first and second rigid parts,
Preparing a first flexible circuit portion including a first base material and a first circuit provided on the first base material;
Preparing a second flexible circuit portion including a second base material and a second circuit provided on the second base material;
Stacking and arranging the first flexible circuit portion and the second flexible circuit portion;
While opposingly arranging the base material on both sides of the flexible circuit portion arranged in a stacked manner,
An interlayer adhesive is disposed between the first flexible circuit portion and the second flexible circuit portion at the second rigid portion forming portion, and the first flexible circuit portion and the second flexible portion are disposed at the first rigid portion forming portion. Pressurizing in a state where the interlayer adhesive between the circuit portions is selectively removed, and thermocompression bonding the rigid portion forming portion; and
A method of manufacturing a rigid flex circuit board, comprising: A method for producing a rigid flex circuit board, comprising the step of removing the base material of the flexible circuit portion of the rigid flex circuit board produced by the method according to claim 3.

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