JP2008112879A - Rigid flexible printed wiring board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rigid flexible printed wiring board where a bending part is not necessary to be prolonged and a fixing part does not become thin, and to provide a manufacturing method of the board. <P>SOLUTION: The rigid flexible printed wiring board has the rigid fixing part for mounting a component and the bending part that can be bent. In the rigid flexible printed wiring board, the bending part is protected and insulated by a resin layer formed of resin which flows out from prepreg and has a bending characteristic. The manufacturing method of the rigid flexible printed wiring board has a process for gouging out a part becoming the bending part in prepreg where resin having the bending characteristic is immersed, a process for laminating prepreg after the gouging process on the resin layer having a flexible circuit, a process for pressing the prepreg after lamination and protecting and insulating the bending part by resin which flows out from prepreg and a process for forming a circuit and forming a wiring pattern. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a rigid flex printed wiring board and a manufacturing method thereof, and more particularly, to a rigid flex printed wiring board whose bent portion is protected and insulated by a resin flowing out from a prepreg and a manufacturing method thereof.

  In a rigid flex printed wiring board used for a small device such as a module substrate, a bent portion having a length of 5 mm or less is usually required.

Conventionally, such a rigid flex printed wiring board has been manufactured by punching a portion that becomes a bent portion of a prepreg in advance, and then multilayering by a subsequent laminating press.
However, in the case of such a manufacturing method, since the resin of the prepreg slightly flows out to the bent portion at the time of laminating press, there is a problem that the length of the bent portion must be designed to be long to some extent.

In addition, since the resin flows out to the bent portion, the fixed portion near the bent portion becomes thinner toward the bent portion. Therefore, a wiring pattern close to the bent portion must be provided at a position slightly away from the end of the bent portion. There was also a problem of not becoming.
Hereinafter, such a conventional problem will be described more specifically with reference to the drawings.

  FIG. 3 is a schematic cross-sectional view for explaining a first conventional example of a rigid flex printed wiring board, in which A is a bent portion having flexibility and B1 and B2 are weights of components to be mounted. Rigid fixed portion having “hardness” and “strength” that can withstand the thickness and has excellent component mountability; L1 is the distance from the end of the wiring pattern 304a provided on the fixed portion B1 to the bent portion A, L2 This is the length of the portion where the resin constituting the fixing portion B2 flows out to the bent portion A (hereinafter referred to as “flowing portion”) during the manufacturing process.

  Also, 301 is a resin layer made of, for example, polyimide resin; 302a and 302b are coverlays; 303a and 303b are prepregs; 304a and 304b are wiring patterns; and 305a and 305b are flexible circuits formed on both sides of the resin layer 301.

  In the rigid flex printed wiring board of the first conventional example having such a configuration, after forming the flex circuits 305a and 305b on both sides of the resin layer 301, the cover lays 302a and 302b are laminated and the prepregs 303a and 303b are laminated. After that, it was manufactured by forming wiring patterns 304a and 304b.

  However, since the flow-out portion L2 reaches 1 mm at the maximum during the laminating press, the length of the bent portion A is required to be 5 mm or more, which is a problem. Further, there is a problem that the distance L1 from the end of the wiring pattern 304a provided on the fixed portion B1 to the bent portion A is also required to be 0.7 mm or more.

FIG. 4 is a schematic cross-sectional explanatory diagram for explaining a second conventional example of a rigid flex printed wiring board (in the figure, the same symbols as those in FIG. 3 are used with the same meaning, so here The duplicate explanation of was omitted.)
In the figure, 401 is a resin layer made of, for example, polyimide resin; 402a and 402b are prepregs with glass cloth; 403a and 403b are wiring patterns; 404a and 404b are flex circuits formed on both sides of the resin layer 401.

  The rigid flex printed wiring board of the second conventional example having such a structure is impregnated with a resin (for example, polyimide resin) having excellent characteristics of bending to the prepregs 402a and 402b, but glass cloth is also included. As a result of the presence of the glass cloth in the bent portion A, there is a problem that the bent portion A cannot withstand bending with a large degree of bending (that is, a curvature radius R is small).

FIG. 5 is a schematic cross-sectional view for explaining a third conventional example of a rigid flex printed wiring board (in the figure, the same symbols as those in FIG. 3 are used with the same meaning, so Duplicate explanation was omitted).
In the figure, 501 is a resin layer made of, for example, polyimide resin; 502a and 502b are insulating layers; 503a and 503b are wiring patterns; and 504a and 504b are flexible circuits formed on both sides of the resin layer 501.

  In the rigid flex printed wiring board of the third conventional example having such a configuration, a resin sheet or a resin-added copper foil (resin coated copper foil, hereinafter abbreviated as RCC) having excellent bending characteristics is used as the insulating layers 502a and 502b. Since the glass cloth was not used, the fixing parts B1 and B2 naturally had no glass cloth. As a result, there was a problem that the rigidity of the fixing parts B1 and B2 was insufficient.

  Furthermore, regarding the multilayer rigid flexible wiring board, the first flexible board is used as a core material, and a rigid board is laminated on the core material via a cover lay. A technique using a flexible insulating material having a function has already been reported (for example, see Patent Document 1).

  This multilayer rigid flexible wiring board is manufactured as follows (i) to (iii). That is, first, (i) a resin sheet with copper foil or the like is laminated on the surface of the conductor circuit formed on both surfaces of the first flexible substrate as a flexible insulating material having an adhesive function so that the copper foil is on the outside. Then, a 1st flexible substrate, a resin sheet with copper foil, etc. are cut | disconnected for every shaping | molding size. Next, (ii) the cut laminate is baked to bring the epoxy resin of the resin sheet with copper foil into a C-stage state, and then the copper foil is etched to form a conductor circuit. Next, (iii) a prepreg and a copper foil are sequentially stacked on the conductor circuit and laminated to form a conductor circuit from the surface copper foil.

However, the multilayer rigid flexible wiring board manufactured as described above has a problem that the flow-out portion is large and the bent portion needs to be lengthened as in the case of the first conventional example. In addition, there is a problem that it is necessary to increase the distance from the end of the wiring pattern provided on the fixed portion to the bent portion.
JP 2006-93647 A

  The present invention has been made in view of the above-described problems, and the problem is that the rigidity of the fixed portion can be maintained without impairing the bendability of the bent portion, and the length of the bent portion can be increased. It is another object of the present invention to provide a rigid flex printed wiring board and a method for manufacturing the same, which do not need to be performed and a fixing portion does not become thin.

  The present invention according to claim 1 is a rigid-flex printed wiring board having a rigid fixing portion for mounting components and a bendable bend portion, and the bend portion is formed of a resin having a bend characteristic that flows out of the prepreg. The above-mentioned problems are solved by a rigid flex printed wiring board characterized by being protected and insulated by a resin layer.

  As a result, a rigid flex printed wiring board having a small bent portion and high positional accuracy is realized.

  According to a second aspect of the present invention, in the rigid flex printed wiring board, the resin is made of an epoxy resin.

  According to a third aspect of the present invention, in the rigid flex printed wiring board, the epoxy resin is composed of an epoxy resin blended with a rubber component. According to the present invention, in the rigid flex printed wiring board, the rubber component is a carboxyl group-terminated butadiene-acrylonitrile copolymer.

  Further, the present invention according to claim 5 includes a step of hollowing out a portion that becomes a bent portion of a prepreg impregnated with a resin having a bending property, and the prepreg after the hollowing is formed on a resin layer having a flexible circuit. A rigid-flex printed wiring board comprising: a step of laminating; a step of protecting and insulating a bent portion by a resin that is pressed after laminating and flowing out of a prepreg; and a step of forming a circuit by forming a circuit. The above-mentioned problem is solved by this manufacturing method.

  According to a sixth aspect of the present invention, in the method for manufacturing the rigid flex printed wiring board, the pressing is performed using an autoclave press.

According to the present invention, since the entire bent portion is protected and insulated by the resin flowing out from the prepreg, it is not necessary to increase the length of the bent portion as in the prior art.
In addition, since the fixing portion does not become thin, there is an advantage that the distance from the position where the wiring pattern can be arranged to the end of the bent portion can be shortened.

  Furthermore, since the portion of the prepreg that is to be bent is cut and laminated, the bendability and flexibility of the bent portion can be ensured even if the prepreg includes a reinforcing material such as glass cloth. On the other hand, since the rigidity of the fixing portion is ensured by the reinforcing material such as the glass cloth, there is an advantage that it is easy to mount components, unlike the case of a general multilayer flexible substrate.

  Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings. In addition, this invention is not restrict | limited at all by embodiment described in full detail below, A various change is possible within the scope of the present invention.

FIG. 1 is a schematic cross-sectional explanatory view of a rigid flex printed wiring board according to the present invention.
In FIG. 1, A is a flexible bending portion that can be bent; B1 and B2 are rigid fixing portions that can withstand the weight of the mounted component and have hardness and strength excellent in component mounting. Also, 101 is a flexible resin layer; 102a and 102b are flex circuits formed on both sides of the resin layer 101; 103a and 103b are prepregs disposed on the fixing portions B1 and B2, and 104a and 104b are prepregs 103a, Resin layers having bending characteristics formed in the bent portion A by the resin flowing out from 103b; 105a and 105b are wiring patterns formed in the outer layer.

  As the resin layers 104a and 104b having the bending property, for example, an epoxy resin, in particular, an epoxy resin blended with a rubber component such as a carboxyl group-terminated butadiene-acrylonitrile copolymer (CTBN) is preferably used as one having excellent bending properties. used.

  In addition, as the resin layers 104a and 104b having the bending characteristics, it is possible to use a resin made of polyimide. In addition, when a softness | flexibility is required, you may add an elastomer component suitably, As such an elastomer component, acrylonitrile butadiene rubber (NBR) etc. are used suitably, for example.

  According to the rigid flex printed wiring board having such a configuration, the entire bent portion A including the flexible circuits 102a and 102b is protected and insulated by the resin layers 104a and 104b formed of the resin flowing out from the prepregs 103a and 103b. Therefore, the length of the bent portion A does not need to be increased because it is not affected unlike the conventional case in which a part of the resin flows out. Further, since the fixing portion is not thinned, the distance from the position where the wiring pattern can be arranged to the end of the bent portion can be shortened.

On the other hand, FIG. 2 is a schematic cross-sectional process explanatory diagram showing a method for producing a printed wiring board according to the present invention.
In FIG. 2, 201 is a resin layer made of, for example, an epoxy resin; 202a and 202b are flexible circuits formed on both sides of the resin layer 201; 203a and 203b are prepregs in which a glass cloth is impregnated with an epoxy resin; 204a and 204b are Copper foils; 205a and 205b are hollow portions formed in the prepregs 203a and 203b; 206a and 206b are resin layers formed of resin flowing out of the prepregs 203a and 203b; and 207a and 207b are wiring patterns formed in the outer layer. .
As in FIG. 1, A is a bendable portion; B1 and B2 are rigid fixing portions.

Hereinafter, the manufacturing method of the printed wiring board of this invention is demonstrated using FIG.
First, the prepregs 203a and 203b are cut into portions to be bent portions A to form the cut portions 205a and 205b. Next, the prepregs 203a and 203b after the punching process are laminated on the upper and lower surfaces of the resin layer 201, and at the same time, the copper foils 204a and 204b are laminated (see FIG. 2 (a)).

  Next, if pressing is performed in this state, the resin flows out from the prepregs 203a and 203b to the cutout portions 205a and 205b to cover the flexible circuits 202a and 202b, and finally the entire bent portion A is protected and insulated (see FIG. 2 (b)).

  Thereafter, circuit formation is performed to form outer layer wiring patterns 207a and 207b (see FIG. 2C).

  In this way, a rigid-flex printed wiring board having resin layers 206a and 206b that both protect and insulate the bent portion A is produced by the resin having bending characteristics impregnated in the prepreg flowing into the cut-out portions 205a and 205b. Is done.

The schematic cross-section explanatory drawing of this invention printed wiring board. BRIEF DESCRIPTION OF THE DRAWINGS The schematic cross-sectional process explanatory drawing which shows the manufacturing method of this invention printed wiring board. The schematic cross-section explanatory drawing which shows the 1st prior art example of a rigid flex printed wiring board. Schematic cross-sectional explanatory drawing which shows the 2nd prior art example of a rigid flex printed wiring board. The schematic cross-section explanatory drawing which shows the 3rd prior art example of a rigid flex printed wiring board.

Explanation of symbols

101: resin layers 102a, 102b: flexible circuits 103a, 103b: prepregs 104a, 104b: resin layers 105a, 105b: wiring patterns 201: resin layers 202a, 202b: flexible circuits 203a, 203b: prepregs 204a, 204b: copper foil 205a, 205b: Cut-out portions 206a, 206b: Resin layers 207a, 207b: Wiring pattern A: Bendable bending portions B1, B2: Rigid fixing portions

Claims (6)

  In a rigid flex printed wiring board having a rigid fixing portion for component mounting and a bendable bending portion, the bending portion is protected and insulated by a resin layer formed of a resin having a bending characteristic that flows out of the prepreg. Rigid flex printed wiring board.   The rigid flex printed wiring board according to claim 1, wherein the resin is an epoxy resin.   3. The rigid flex printed wiring board according to claim 2, wherein the epoxy resin is an epoxy resin blended with a rubber component.   4. The rigid flex printed wiring board according to claim 3, wherein the rubber component is a carboxyl group-terminated butadiene-acrylonitrile copolymer.   Of the prepreg impregnated with a resin having a bending characteristic, a step of punching a portion to be a bending portion, a step of laminating the prepreg after the punching processing on a resin layer having a flexible circuit, and pressing after the lamination A method of manufacturing a rigid flex printed wiring board, comprising: a step of protecting and insulating a bent portion with a resin flowing out from a prepreg; and a step of forming a circuit by forming a circuit.   6. The method of manufacturing a printed wiring board according to claim 5, wherein the pressing is performed using an autoclave press.