JP2008235595A - Multilayer printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer printed wiring board in which desired wiring patterns can be formed. <P>SOLUTION: The multilayer printed wiring board 1 includes: two flexible substrates 10 for outer layers; two flexible printed wiring board 20 for inner layers; adhesive layers 30 which bond the two flexible substrates 10 for outer layers and the flexible printed wiring boards 20 for inner layers, respectively; and a bonded and layered part 50 which is formed by bonding the flexible substrates 10 for outer layers and flexible printed wiring boards 20 by the adhesive layers 30. Further, the multilayer printed wiring board 1 includes a bend section 60 which is arranged adjacent to the bonded and layered part 50 and has spaces 61, 62 and 63 which are formed in the flexible substrates 10 for outer layers and the flexible printed wiring boards 20 for inner layers. The end 33a of one adhesive layer 33 of the adhesive layers 30 is extended from the bonded and layered part 50 toward the bend section 60 farther than the ends 31a, 32a of the other adhesive layers 31 and 32. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a multilayer printed wiring board in which a mask having an opening is placed on a conductor of an outer layer flexible substrate, and the opening is exposed to form a wiring pattern.

  In recent years, in the electronic equipment field, with the increase in the density of electronic equipment, multilayered printed wiring boards used as parts of electronic equipment have progressed. As such a multilayer printed wiring board, a flexible printed wiring board having a multilayer structure, a rigid flex printed wiring board that is a composite substrate of a flexible printed wiring board and a rigid printed wiring board, and the like are used.

  For example, as shown in FIG. 10, the multilayer printed wiring board 101 is provided between two outer-layer flexible boards 110 in which a conductor 112 is provided on a board 111, and the two outer-layer flexible boards 110. Two inner-layer flexible printed wiring boards 120 provided with another conductor 122 having a wiring pattern on a substrate 121 are provided. Furthermore, the multilayer printed wiring board 101 includes a plurality of adhesive layers 131, 132, and 133 (hereinafter referred to as “a plurality of adhesive layers 131, 132, 133 "is referred to as" adhesive layer 130 "). In addition, the multilayer printed wiring board 101 includes an adhesive laminated portion 150 in which two outer layer flexible substrates 110 and two inner layer flexible printed wiring boards 120 are bonded together by an adhesive layer 130. The multilayer printed wiring board 101 is provided adjacent to the adhesive laminated portion 150 and has spaces 161, 162, and 163 formed in the two outer layer flexible boards 110 and the two inner layer flexible printed wiring boards 120. A bent portion 160 is provided. Since the adhesive layer is not provided in the bent portion 160, the bent portion 160 can have high flexibility (see, for example, Patent Document 1).

In addition, in order to manufacture a multilayer printed wiring board, a mask having an opening is placed on a conductor of an outer layer flexible substrate in a state where a flexible substrate provided with a conductor is laminated on the substrate, and a wiring pattern is formed. It is known to expose the opening to form. More specifically, a photosensitive film is laminated on the surface of the conductor of the flexible substrate for the outer layer, and a mask having an opening having a wiring pattern shape is placed on the conductor and laminated to the conductor. Adhere to the photosensitive film. Then, by exposing the opening, the photosensitive film is cured on the conductor, and a resist having a wiring pattern shape is formed on the conductor. It is known that a wiring pattern is formed by performing processing such as development and etching (see, for example, Patent Document 2).
JP 2004-281734 A JP-A-11-154788

  However, a desired wiring pattern can be formed when a mask having an opening is placed on the conductor 112 of the above-described flexible substrate 110 for outer layer and the opening is exposed to form a wiring pattern. There was a problem that it might not be possible. That is, the bent portion 160 of the multilayer printed wiring board 101 has space portions 161, 162, and 163 formed in the outer layer flexible substrate 110 and the inner layer flexible printed wiring board 120. Therefore, as shown in FIG. 11, when the mask 70 having an opening (not shown) is brought into close contact with the photosensitive film 80 laminated on the conductor 112, the outer layer flexible substrate 110 and the inner layer flexible printed wiring board 120. Are in close contact. At the bent portion 160, the thickness of the multilayer printed wiring board 101 (that is, the length in the direction of the arrow W in FIG. 11) is reduced by the thickness of the adhesive layer 130. Therefore, even if the mask 70 is moved in the direction of the arrow X so that the mask 70 and the photosensitive film 80 are in close contact with each other, there is a problem that the mask 70 and the photosensitive film 80 are not sufficiently in close contact with each other. In particular, when the inner layer flexible printed wiring board 120 constituting the multilayer printed wiring board 101 is large, when the adhesive layer 130 is thick, or when the mask 70 is formed of non-flexible glass, the mask 70 and the photosensitive film 80 are difficult to adhere. As a result, the gap between the opening of the mask 70 and the photosensitive film 80 becomes large, so that there is a problem that correct exposure cannot be performed and a desired wiring pattern may not be formed.

  The present invention has been made in view of such circumstances, and can easily adhere a mask having an opening and a photosensitive film laminated to a conductor, and a desired wiring pattern can be formed. An object is to provide a multilayer printed wiring board.

  In order to achieve the above object, according to the first aspect of the present invention, there is provided between the two outer-layer flexible boards provided with the conductor on the board and the two outer-layer flexible boards, and is provided on the other board. At least one inner layer flexible printed wiring board provided with another conductor having a wiring pattern, a plurality of adhesive layers for bonding the outer layer flexible printed circuit board and the inner layer flexible printed wiring board, and two outer layer flexible printed circuit boards A substrate and at least one flexible printed wiring board for inner layer are bonded by a plurality of adhesive layers and are provided adjacent to each other, two adjacent flexible substrates for outer layers, and at least one A bent portion having a space formed in the flexible printed wiring board for the inner layer, and among the plurality of adhesive layers, Both ends of the one adhesive layer is, from the end portion of the other adhesive layer, characterized in that it extends toward the adhesive lamination unit to bend.

  According to the configuration, among the plurality of adhesive layers, at least one of the adhesive layers has an end portion extending from the adhesive laminated portion toward the bent portion rather than the end portions of the other adhesive layers. Therefore, the thickness of the multilayer printed wiring board can be gradually reduced at the bent portion. More specifically, since the end of the at least one adhesive layer extends from the adhesive laminated portion toward the bent portion rather than the end of the other adhesive layer, the at least one adhesive The volume of the space part adjacent to the edge part of an agent layer and the space part adjacent to the edge part of said other adhesive bond layer can be changed. For this reason, in the extending direction of the at least one adhesive layer, an end portion of the at least one adhesive layer and an end portion of the other adhesive layer are arranged at intervals, so that the outer layer When the flexible printed circuit board and the inner layer flexible printed wiring board are in close contact with each other, the thickness of the multilayer printed wiring board can be gradually reduced at the bent portion. Therefore, since the mask having the opening and the photosensitive film laminated on the conductor can be easily adhered, a desired wiring pattern can be formed.

  Invention of Claim 2 is the multilayer printed wiring board of Claim 1, Comprising: The edge part of the at least 1 adhesive layer in the extending direction of an at least 1 adhesive layer, and another adhesive agent The distance from the end of the layer is 0.15 mm or more and 0.4 mm or less.

  According to the same configuration, since the distance between the end of at least one adhesive layer and the end of the other adhesive layer in the extending direction of at least one adhesive layer is 0.15 mm or more, The end portion of the at least one adhesive layer can be extended with a sufficient length from the adhesive layer toward the bent portion, rather than the end portion of the other adhesive layer. Therefore, when the outer layer flexible substrate and the inner layer flexible printed wiring board are in close contact with each other, it is possible to ensure that the thickness of the multilayer printed wiring board is gradually reduced at the bent portion. Further, since the distance between the end of the at least one adhesive layer and the end of the other adhesive layer in the extending direction of the at least one adhesive layer is 0.4 mm or less, the at least one of the above It can suppress extending the edge part of an adhesive bond layer from the edge part of an adhesive layer toward the bending part rather than the edge part of said other adhesive bond layer. Therefore, the flexibility at the bent portion can be prevented from being impaired.

  Invention of Claim 3 is a multilayer printed wiring board of Claim 1 or Claim 2, Comprising: A several adhesive layer is symmetrical in the center plane orthogonal to the thickness direction of a multilayer printed wiring board. It is characterized by being. The central plane perpendicular to the thickness direction of the multilayer printed wiring board is a plane orthogonal to the thickness direction of the multilayer printed wiring board and passing through the center of the multilayer printed wiring board.

  According to this configuration, since the plurality of adhesive layers are symmetrical on the center plane perpendicular to the thickness direction of the multilayer printed wiring board, the photosensitive film laminated on the conductors of the two outer-layer flexible boards and The mask having the opening can be easily adhered.

  ADVANTAGE OF THE INVENTION According to this invention, the mask which has an opening part and the photosensitive film laminated | stacked on a conductor can be made easy to closely_contact | adhere, and a desired wiring pattern can be formed.

  Hereinafter, a preferred embodiment of the present invention will be described. FIG. 1 is a cross-sectional view for explaining a method for producing a multilayer printed wiring board in an embodiment of the present invention, and more particularly, a diagram for explaining an outer layer flexible substrate of the multilayer printed wiring board of the present invention. FIG. 2 is a cross-sectional view for explaining a method for producing a multilayer printed wiring board according to an embodiment of the present invention. In particular, a flexible printed wiring board for an inner layer of the multilayer printed wiring board according to the present invention and a method for producing the same. It is a figure for demonstrating. 3 and 4 are cross-sectional views for explaining a method for manufacturing a multilayer printed wiring board in the embodiment of the present invention.

  As a manufacturing method of the multilayer printed wiring board of the present invention, as shown in FIG. 1, first, an outer layer flexible substrate 10 in which a conductor 12 is provided on a substrate 11 formed of a flexible resin film is prepared. The conductor 12 may be provided via an adhesive (not shown). However, in consideration of the flexibility and flexibility of the outer layer flexible substrate 10, the surface of the substrate 11 may be used without using an adhesive. Preferably, the conductor 12 is provided.

  As a resin film which comprises the board | substrate 11, what consists of a resin material excellent in the softness | flexibility is used. As such a resin, for example, any resin film having versatility for a flexible printed wiring board, such as a polyester film, can be used. In particular, in consideration of the pressurization and heating process described later, it is preferable that the resin film has high heat resistance in addition to flexibility, and examples of such a resin film include a polyamide-based resin film. Also, polyimide resin films such as polyimide and polyamideimide are preferably used. Further, as the metal foil constituting the conductor 12, a copper foil is suitably used.

  Next, a flexible printed wiring board for the inner layer is manufactured. That is, as shown in FIG. 2A, similarly to the outer layer flexible substrate 10 described above, a conductor 22 as another conductor is provided on a substrate 21 as another substrate formed of a flexible resin film. Prepare a single-sided plate. Furthermore, the conductor 22 which has a wiring pattern is formed by etching by a conventional method. Next, as shown in FIG. 2B, a cover lay film 23 constituted by an adhesive layer 24 and a resin film 25 laminated thereon is provided so as to cover the conductor 22. That is, the inner layer flexible printed wiring board 20 is manufactured by laminating the resin film 25 with the adhesive layer 24 and laminating the cover lay film 23 on the surface on which the conductor 22 of the single-sided board is provided.

  As the resin film constituting the substrate 21 and the resin film 25 constituting the cover lay film 23, the same resin film as that constituting the substrate 11 described above can be used. Further, as the metal foil constituting the conductor 22, a copper foil is preferably used. The adhesive layer 24 constituting the cover lay film 23 is preferably made of an adhesive having excellent flexibility and heat resistance. Examples of such an adhesive include nylon, epoxy resin, and butyral. Various adhesives such as resin-based and acrylic resin-based are listed.

  Through the above steps, the outer layer flexible substrate 10 and the inner layer flexible printed wiring board 20 are manufactured. Next, the outer layer flexible substrate 10 and the inner layer flexible printed wiring board 20 are laminated to produce a multilayer printed wiring board.

  In addition, as a multilayer printed wiring board provided with the flexible printed wiring board for inner layers in which the other conductor which has a wiring pattern was provided on the other board | substrate, here a multilayer printed wiring board provided with two flexible printed wiring boards 20 for inner layers is used. An example will be described.

  First, as shown in FIG. 3A, an adhesive layer 31 is sandwiched between the outer layer flexible substrate 10 and the inner layer flexible printed wiring board 20, and then, as shown in FIG. By performing the pressure, the outer layer flexible substrate 10 and the inner layer flexible printed wiring board 20 are laminated via the adhesive layer 31 to form a laminate 40a. Similarly, the outer layer flexible substrate 10 and the inner layer flexible printed wiring board 20 are laminated via the adhesive layer 32 to form a laminate 40b. And as shown in FIG.3 (c), the adhesive bond layer 33 is pinched | interposed between the two laminated bodies 40a and 40b. As the adhesive layers 31, 32, and 33 (hereinafter referred to as “adhesive layer 30”), the same adhesive layer 24 that constitutes the above-described coverlay film 23 can be used.

  And as shown in FIG. 4, the multilayer printed wiring board 1 can be manufactured by heating and pressurizing. This multilayer printed wiring board 1 includes two outer layer flexible boards 10, two inner layer flexible printed wiring boards 20, and an adhesive layer 30 that bonds the outer layer flexible board 10 and the inner layer flexible printed wiring board 20. And. Furthermore, the multilayer printed wiring board 1 includes an adhesive laminated portion 50 in which two outer layer flexible boards 10 and two inner layer flexible printed wiring boards 20 are bonded together by an adhesive layer 30. The multilayer printed wiring board 1 is provided adjacent to the adhesive laminated portion 50 and has space portions 61, 62, 63 formed in the two outer layer flexible boards 10 and the two inner layer flexible printed wiring boards 20. A bent portion 60 is provided.

  Here, in the present embodiment, as shown in FIG. 4, the end portion 33 a of one adhesive layer 33 of the adhesive layer 30 is more than the end portions 31 a and 32 a of the other adhesive layers 31 and 32. Also, it is characterized in that it extends from the adhesive laminated portion 50 toward the bent portion 60. With such a configuration, the volume of the space 63 adjacent to the end portion 33a of the adhesive layer 33 and the space portions 61 and 62 adjacent to the end portions 31a and 32a of the other adhesive layers 31 and 32 are changed. be able to. For this reason, in the extending direction of the adhesive layer 33, the end portion 33 a of the adhesive layer 33 and the end portions 31 a and 32 a of the other adhesive layers 31 and 32 are arranged with a space therebetween. Therefore, as shown in FIG. 5, when the outer layer flexible substrate 10 and the inner layer flexible printed wiring board 20 are in close contact with each other, the thickness of the multilayer printed wiring board 1 is gradually reduced at the bent portion 60. be able to. In addition, thickness is the length in the arrow W in a figure.

  The distance D between the end portion 33a of the adhesive layer 33 and the end portions 31a and 32a of the other adhesive layers 31 and 32 in the extending direction of the adhesive layer 33 is 0.15 mm or more and 0.4 mm or less. It is preferable that According to such a configuration, the distance between the end portion 33a of the adhesive layer 33 and the end portions 31a and 32a of the other adhesive layers 31 and 32 in the extending direction of the adhesive layer 33 is 0.15 mm. As described above, the end portion 33a of the adhesive layer 33 is extended with a sufficient length from the adhesive laminated portion 50 to the bent portion 60 as compared with the end portions 31a and 32a of the other adhesive layers 31 and 32. can do. Further, since the distance between the end portion 33a of the adhesive layer 33 and the end portions 31a and 32a of the other adhesive layers 31 and 32 in the extending direction of the adhesive layer 33 is 0.4 mm or less, It is possible to prevent the end portion 33a of the agent layer 33 from extending beyond the end portions 31a and 32a of the other adhesive layers 31 and 32 from the adhesive laminated portion 50 toward the bent portion 60 by an unnecessary length. Can do.

  In the present embodiment, as shown in FIG. 4, the adhesive layer 30 is symmetrical on the center plane S perpendicular to the thickness direction W of the multilayer printed wiring board 1. According to such a configuration, the photosensitive film 80 laminated on each conductor 12 of the two outer-layer flexible substrates 10 and the mask 70 having an opening can be easily adhered.

According to the above embodiment, the following effects can be obtained.
(1) In the present embodiment, in the adhesive layer 30, the end portion 33 a of one adhesive layer 33 is closer to the adhesive laminate portion 50 than the end portions 31 a and 32 a of the other adhesive layers 31 and 32. It extends toward the bent portion 60. For this reason, when each of the outer layer flexible substrate 10 and the inner layer flexible printed wiring board 20 is brought into close contact, the thickness of the multilayer printed wiring board 1 can be gradually reduced at the bent portion 60. Therefore, the mask 70 having an opening (not shown) as shown in FIG. 5 and the photosensitive film 80 laminated on the conductor 12 can be easily adhered, so that a desired wiring pattern is formed. be able to.

  (2) In the present embodiment, the distance D between the end portion 33a of the adhesive layer 33 and the end portions 31a and 32a of the other adhesive layers 31 and 32 in the extending direction of the adhesive layer 33 is 0. .15 mm or more and 0.4 mm or less. Therefore, the end portion 33a of the adhesive layer 33 is extended from the end portion 31a, 32a of the other adhesive layers 31, 32 to the bent portion 60 with a sufficient length. In addition, it is possible to suppress the extension with an unnecessary length. Therefore, when the outer layer flexible substrate 10 and the inner layer flexible printed wiring board 20 are in close contact with each other, it is possible to reliably reduce the thickness of the multilayer printed wiring board 1 at the bent portion 60, and It is possible to prevent the bendability at the bent portion 60 from being impaired.

  (3) In the present embodiment, the adhesive layer 30 is symmetric with respect to the center plane S orthogonal to the thickness direction W of the multilayer printed wiring board 1. Therefore, the photosensitive film 80 laminated on the respective conductors 12 of the two outer layer flexible substrates 10 and the mask 70 having the opening can be easily adhered.

  In addition, this invention is not limited to the said embodiment, A various design change is possible based on the meaning of this invention, and they are not excluded from the scope of the present invention. Even if the above embodiment is changed as follows, for example, the above-described effect (1) can be obtained.

  In the above embodiment, the adhesive layer 30 is symmetric on the center plane S orthogonal to the thickness direction W of the multilayer printed wiring board 101, but the adhesive layer 30 may not be symmetric on the center plane S. Good. That is, as shown in FIG. 6, among the plurality of adhesive layers 31, 32, 33, the end portion 32 a of the adhesive layer 32 is bonded more than the end portions 31 a, 33 a of the other adhesive layers 31, 33. The laminated part 50 may extend toward the bent part 60.

  In the above embodiment, among the plurality of adhesive layers 31, 32, 33, the end portion 33 a of one adhesive layer 33 is bonded more than the end portions 31 a, 32 a of the other adhesive layers 31, 32. Although it extended from the lamination | stacking part toward the bending part 60, two or more adhesive bond layers are extended toward the bending part 60 from the adhesion lamination | stacking part 50 rather than the edge part of another adhesive bond layer. It may be. That is, as shown in FIG. 7, the end portions 32 a and 33 a of the two adhesive layers 32 and 33 extend from the adhesive laminated portion 50 toward the bent portion 60 rather than the end portions 31 a of the other adhesive layers 31. It may be provided.

  In the above embodiment, the number of the inner layer flexible printed wiring boards 20 is two, but may be one or three or more. That is, as shown in FIG. 8, the multilayer printed wiring board includes two outer layer flexible boards 10, one inner layer flexible printed wiring board 20, outer layer flexible board 10, and inner layer flexible printed wiring board 20. Adhesive layers 31 and 32 may be provided. Further, as shown in FIG. 9, the multilayer printed wiring board includes two outer layer flexible boards 10, three inner layer flexible printed wiring boards 20, outer layer flexible boards 10, and inner layer flexible printed wiring boards 20. May be provided with adhesive layers 31, 32, 33, and 34.

  As an application example of the present invention, there is a multilayer printed wiring board in which a mask having an opening is placed on a conductor of an outer layer flexible substrate, and the opening is exposed to form a wiring pattern.

It is sectional drawing for demonstrating the manufacturing method of the multilayer printed wiring board in embodiment of this invention, and the figure for demonstrating the flexible substrate for outer layers of the multilayer printed wiring board of this invention especially. (A) (b) It is sectional drawing for demonstrating the manufacturing method of the multilayer printed wiring board in embodiment of this invention, Especially the flexible printed wiring board for inner layers of the multilayer printed wiring board of this invention, and its manufacturing method The figure for demonstrating. (A) (b) (c) Sectional drawing for demonstrating the manufacturing method of the multilayer printed wiring board in embodiment of this invention. Sectional drawing for demonstrating the multilayer printed wiring board and its manufacturing method in embodiment of this invention. Sectional drawing for demonstrating the multilayer printed wiring board in embodiment of this invention. Sectional drawing of the multilayer printed wiring board which shows another example of this invention. Sectional drawing of the multilayer printed wiring board which shows another example of this invention. Sectional drawing of the multilayer printed wiring board which shows another example of this invention. Sectional drawing of the multilayer printed wiring board which shows another example of this invention. Sectional drawing which shows the conventional multilayer printed wiring board. Sectional drawing for demonstrating the conventional multilayer printed wiring board.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Multilayer printed wiring board, 10 ... Flexible substrate for outer layers, 11 ... Substrate, 12 ... Conductor, 20 ... Flexible printed wiring board for inner layer, 21 ... Substrate (other substrate), 22 ... Conductor (other conductor), 31 , 32, 33 ... adhesive layer, 50 ... adhesive laminated part, 60 ... bent part, 61, 62, 63 ... space part.

Claims (3)

Two flexible substrates for outer layers in which a conductor is provided on the substrate;
At least one inner layer flexible printed wiring board provided between the two outer layer flexible boards and provided with another conductor having a wiring pattern on another board;
A plurality of adhesive layers for bonding the outer layer flexible substrate and the inner layer flexible printed wiring board;
The two outer layer flexible boards and the at least one inner layer flexible printed wiring board are bonded and stacked by the plurality of adhesive layers; and
A bent portion provided adjacent to the adhesive laminate portion, and having a space portion formed in the two outer-layer flexible boards and the at least one inner-layer flexible printed wiring board;
Of the plurality of adhesive layers, an end portion of at least one adhesive layer extends from the adhesive laminate portion toward the bent portion, rather than an end portion of another adhesive layer. Multi-layer printed wiring board.   The distance between the end of the at least one adhesive layer and the end of the other adhesive layer in the extending direction of the at least one adhesive layer is 0.15 mm or more and 0.4 mm or less. The multilayer printed wiring board according to claim 1.   3. The multilayer printed wiring board according to claim 1, wherein the plurality of adhesive layers are symmetrical on a center plane orthogonal to a thickness direction of the multilayer printed wiring board.

Images