JP2007281132A - Printed wiring board and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of connecting rigid boards together through the intermediary of a flexible board, in a case in which the rigid boards are not provided in the shape of an individual piece but in the shape of sheet. <P>SOLUTION: A printed wiring board has a configuration in which two rigid boards 2 and 3 are fixed to a connection frame 1a separating from each other by an interval D, connecting terminals 5a and 6a are provided on the rigid boards 2 and 3, respectively, and the connecting terminals 5a and 6a provided on the rigid boards 2 and 3 are connected to connection terminals located at both the sides of a flexible board 4, respectively. A curvature 12 is curved into the shape of a letter U in the planar direction of the board, and is provided on the middle part of the flexible board 4. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a technique for connecting printed wiring boards to each other, and in particular, when connecting rigid boards to each other via a flexible board, a connection method when the rigid boards are not in pieces but in a sheet form. It is an improvement.

  A printed wiring board having a structure in which rigid boards are connected to each other by a flexible board is used as a printed wiring board used for information equipment such as a personal computer, a foldable mobile phone or portable information equipment, and precision equipment such as a DVD player. . The printed wiring board having such a structure is configured such that a flexible substrate that connects two rigid substrates can be freely bent (for example, see Patent Document 1).

  In the production of a printed wiring board composed of such a rigid substrate and a flexible substrate, between the rigid substrate and the flexible substrate, individual connections for connecting after making each substrate an independent shape, In a sheet state in which a plurality of rigid substrate portions are connected by a single sheet, two types of sheet connection in which the rigid substrate portions are connected by a flexible printed circuit board are conceivable.

  In the case of individual connection, each board is independent, so there is no restriction on the alignment work to correctly superimpose the connection conductors at the time of connection, and the boards can be aligned freely for optimal alignment On the other hand, since the board after the connection is, for example, a rigid board-flexible board-rigid board is connected and the shape of the flexible printed board can be deformed, one rigid board and the other rigid board When the positional relationship of the board is not determined and component mounting is performed thereafter, there is a problem that it is difficult to define the mounting position of the component and mounting work becomes difficult. In order to solve this, it is conceivable that a carrier board for determining the position of the rigid board is separately made and mounted on the carrier board. However, since it is necessary to design a carrier board for every design of the substrate, and a process of mounting on the carrier board before the mounting is added, it is disadvantageous in terms of mounting cost.

  On the other hand, in the case of sheet connection, since the rigid board is formed in a sheet shape in advance, the relative positions of the plurality of rigid boards are determined, and positioning in component mounting is easy. This can be easily understood in view of the fact that mounting is usually performed in the form of a sheet even when mounting a rigid board that does not have a flexible printed circuit board portion. The rigid flex structure on a sheet-like substrate in which a plurality of rigid substrate portions are arranged on one sheet is connected by a substrate connection method as described below.

  That is, as shown in FIG. 8, when the two rigid substrates 101 and 102 are not separated from the rigid substrate sheet 100 and are connected to the connection frame 100a via the connection piece 100b, The rigid substrates 101 and 102 are connected by a flexible substrate 103. The rigid board sheet 100 includes a connecting frame body 100a that is a rectangular frame-shaped connecting member, and at least a pair of rigid boards 101 and 102 that are arranged in the connecting frame body 100a and connected via a connecting piece portion 100b. It is configured. Each of the rigid substrates 101 and 102 is formed such that a plurality of connection terminal portions 101a and 102a are exposed at end edges facing each other. The flexible substrate 103 has a plurality of connection terminal portions (not shown) formed at both ends thereof.

  Then, the flexible substrate 103 is positioned and arranged at a position where the two rigid substrates 101 and 102 are connected to the rigid substrate sheet 100. Specifically, the connection terminal portions at both ends of the flexible substrate 103 and the connection terminal portions 101a and 102a of the rigid substrates 101 and 102 are aligned with each other, and the corresponding connection terminal portions of both are connected. Join by soldering. After this substrate connection step, the two rigid substrates 101 and 102 are separated from the connecting frame 100a to obtain a rigid-flex printed wiring board.

In the state of the rigid substrate sheet 100, the relative positional relationship between the two rigid substrates 101 and 102 is set via the connecting frame 100a. Further, the positions of the group of connection terminal portions 101a and the group of connection terminal portions 102a in the two rigid substrates 101 and 102 are also set. Further, the distance D between the rigid substrates 101 and 102 is also set to a predetermined dimension. As described above, if the relative positional relationship between the two rigid substrates 101 and 102 is constant, the flexible substrate 103 can be easily aligned and connected. That is, when the two rigid substrates 101 and 102 are a part of one rigid substrate sheet 100, the positions of one connection terminal portion of the flexible substrate 103 and the connection terminal portion 101a of the one rigid substrate 101 are the same. After matching and connecting, the other connecting terminal portion of the flexible substrate 103 and the connecting terminal portion 102a of the other rigid substrate 102 are aligned and connected.
Japanese Patent Application Laid-Open No. 2005-217030

  However, as described above, since the two rigid substrates 101 and 102 are integrally provided on the single rigid substrate sheet 100, if the distance D between the rigid substrates 101 and 102 is short, FIG. As shown, it is difficult to deform the flexible substrate 103 in the x direction (width direction). For this reason, if there is a displacement in at least one of the connection terminal portions 101 a and 102 a of the two rigid substrates 101 and 102, the connection terminal portion 101 a of one rigid substrate 101 and one end side of the flexible substrate 103 are connected. After the terminal portions are aligned and connected, the flexible substrate 103 is deformed even if the connection terminal portion 102a of the other rigid substrate 102 and the connection terminal portions on the other end of the flexible substrate 103 are aligned together. Therefore, there is a problem that the positioning cannot be performed and the connecting terminal portions on the other end side cannot be connected to an appropriate position.

  If the distance D between the two rigid substrates 101 and 102 is larger than a predetermined dimension, the connection terminal portions of the flexible substrate 103 are sufficiently overlapped with the connection terminal portions 101a and 102a of the rigid substrates 101 and 102. Can not be aligned with holding. Therefore, there is a problem that an appropriate joining state between the corresponding connecting terminal portions cannot be obtained.

  Therefore, an object of the present invention is to provide a print that can join the rigid board and the flexible printed circuit board in a proper joined state even when a positional deviation occurs in the relative positional relationship between the two rigid boards. It is to provide a wiring board and a manufacturing method thereof.

  The invention according to the first aspect of the present invention is a printed wiring board, wherein a plurality of rigid boards whose positions are relatively fixed, and the rigid board are electrically connected to each other, and the bent part is formed in an intermediate part. And a flexible substrate on which is formed. The thing of the form integrally formed in one board | substrate sheet | seat is applicable to a some rigid board | substrate. Moreover, as a bending | flexion shape part, the planar shape can be made into the part currently formed in U shape, crank shape, or L shape. The flexible substrate is connected to both rigid substrates while being bent between the rigid substrates.

  The invention according to the second aspect of the present invention is a method for manufacturing a printed wiring board, wherein a plurality of rigid boards each provided with a connected portion where a connecting terminal portion is exposed are arranged at intervals. A step of preparing a single substrate sheet, a step of preparing a flexible substrate in which a pair of connection portions are provided, and a bent portion is formed at an intermediate portion between the connection portions, and a pair of adjacent rigid substrates The connected portion of one of the rigid substrates and the one connected portion of the flexible substrate are aligned and joined, and then the flexible substrate is bent and the other rigid substrate is bent. And a step of aligning and joining the connected portion and the other connecting portion of the flexible substrate.

  According to the present invention, in the state where the positions of the rigid substrates are relatively fixed, the flexible substrate has the bent shape portion, so that there is a displacement in the center line of each connection terminal portion of the plurality of rigid substrates. When the intervals between the plurality of rigid substrates are longer than a predetermined dimension, the connecting terminal portions at both ends of the flexible substrate are made to be two rigid substrates by flexing and deforming the bent shape portion of the flexible substrate or widening the bent shape portion. Both can be properly aligned with each of the connection terminals. Even when a positional shift occurs in the relative positional relationship between the plurality of rigid substrates, the corresponding connecting terminal portions of the rigid substrate and the flexible substrate can be bonded in an appropriate bonded state. In particular, by setting the arrangement distance between the flexible substrates connected by the flexible substrate short, for example, the rigid substrate sheet that holds the rigid substrates whose positions are relatively fixed can be made compact, and waste can be suppressed.

  Hereinafter, details of a printed wiring board and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to the drawings.

(Configuration of printed wiring board)
1 to 5 show a printed wiring board and a manufacturing method thereof according to an embodiment of the present invention. FIG. 1 is a perspective view showing a board connection process in a method for manufacturing a printed wiring board, FIG. 2 is a plan view of the printed wiring board, and FIG. 3 is a positional shift of the center line of a terminal portion for connection of a pair of rigid boards on a rigid board sheet. FIG. 4 is a plan view of a flexible substrate, and FIG. 5 is a plan view of a finished printed wiring board showing a state where the rigid substrate is separated from the rigid substrate sheet.

  As shown in FIGS. 1 and 2, a printed wiring board 20 according to the present embodiment includes a pair of rigid boards 2 and 3 integrally formed on a rigid board sheet 1 and these rigid boards in a bent state. The flexible substrate 4 is joined to the sheets 2 and 3.

  The rigid substrate sheet 1 is formed of an insulating substrate made of a prepreg such as glass epoxy resin by a method such as press punching. Specifically, the rigid substrate sheet 1 is, for example, a frame-shaped connecting frame 1a, and two rigid pieces arranged in the connecting frame 1a and fixed to the connecting frame 1a via a connecting piece 1b. It consists of substrates 2 and 3.

The rigid substrates 2 and 3 include the insulating substrate described above, a plurality of wiring patterns 5 and 6 patterned on one surface of the insulating substrate, and one surface of the insulating substrate on which the wiring patterns 5 and 6 are formed. And a resist layer 7 that covers the substrate. 1 and 3, the wiring patterns 5 and 6 are partially exposed for convenience of explanation.

  The two rigid substrates 2 and 3 are arranged at a predetermined interval D. The interval D is set shorter than the longest interval when the flexible substrate 4 is actually connected.

  The wiring patterns 5 and 6 are formed by patterning a copper foil attached on an insulating substrate by, for example, a subtractive method. The plurality of wiring patterns 5 and 6 are exposed as connecting terminal portions 5a and 6a at the connected portions 8 and 9 that are not covered with the resist layer, at the edge positions of the rigid substrates 2 and 3 facing each other. . In these connected portions 8 and 9, the groups of connecting terminal portions 5a and 6a are formed so as to be parallel to each other (side by side). In addition, pad portions for mounting electronic components such as semiconductor packages are appropriately formed at desired positions of the rigid substrates 2 and 3.

  As shown in FIG. 4, the flexible substrate 4 is roughly composed of a flexible insulating substrate 10, a plurality of wiring patterns 11 disposed on one surface thereof, and a cover layer 13 covering the wiring pattern 11. It is configured. The intermediate portion of the flexible substrate 4 is formed as a bent portion 12 that is curved in a substantially U shape along the substrate surface direction. The bent portion 12 extends in parallel to the pair of first extension portions 12a and 12b orthogonal to the center line O connecting the connection portions 14 and 15 located at both ends of the flexible substrate 4, and is parallel to the center line O. The first extension portions 12a and 12b are formed in a substantially U shape from the second extension portion 12c connecting the first extension portions 12a and 12b. The wiring pattern 11 is wired along the U shape in the bent portion 12. Further, the wiring pattern 11 is exposed as connection terminal portions 11 a and 11 b at the connection portions 14 and 15 of the flexible substrate 4 without being covered with the resist layer. These connection terminal portions 11a and 11b are formed so as to be parallel to each other (side by side).

  As shown in FIGS. 1 and 2, the flexible substrate 4 is bent at the intermediate portion (particularly, the second extension portion 12c), and the connection portions 14 and 15 are respectively connected to the corresponding rigid substrates 2 and 3, respectively. Are soldered to the connected parts 8 and 9.

  In the printed wiring board 20 according to the present embodiment, the position is fixed to the rigid substrate sheet 1 in a state where the flexible substrate 4 is bent, that is, in a state where the distance D between the rigid substrates 2 and 3 is reduced. The overall size of the printed wiring board 20 can be reduced. Moreover, in the rigid board | substrate sheet | seat 1, since the space | interval D of the rigid board | substrates 2 and 3 can also be set short, the part which is wasted by press punching etc. can be reduced, for example, and the cost of the rigid board | substrate sheet | seat 1 can be reduced.

  In the printed wiring board 20 according to the present embodiment, since the flexible substrate 4 is bent and joined to the rigid substrates 2 and 3, the connecting portions 14 and 15 of the flexible substrate 4 are connected to the rigid substrate 2 and 3, respectively. 3 has a structure that can secure a degree of freedom when positioning with respect to the three connected portions 8 and 9. For this reason, the printed wiring board 20 in which the flexible substrate 4 is bonded to the rigid substrates 2 and 3 with high positioning accuracy can be obtained.

  In practice, the printed wiring board 20 is used as a printed wiring board 20A as shown in FIG. 5 by separating the two rigid boards 2 and 3 from the connecting frame 1a. That is, when the two rigid substrates 2 and 3 are separated from the connecting frame 1a, the bending deformation portion of the bent shape portion 12 of the flexible substrate 4 indicated by symbol a in FIG. Therefore, the printed wiring board 20A is not stressed. Accordingly, the interval D2 between the rigid substrates 2 and 3 is longer than the interval D1 when the rigid substrates 2 and 3 are provided integrally with the connecting frame 1a. The positions of the rigid substrates 2 and 3 can be arbitrarily changed within the range of the length of the flexible substrate 4 due to the flexibility of the flexible substrate 4.

  In the state of the printed wiring board 20 according to the present embodiment, an electronic component such as a semiconductor package may be mounted on each of the rigid boards 2 and 3, or the rigid boards 2 and 3 are attached from the connecting frame 1a. Although it is possible to mount electronic components in a separated state, when mounting components on multiple rigid boards, it is better to use a single sheet connected by a connecting frame to ensure positional accuracy of component mounting. It is easy and there is no waste in the process.

  Further, in the printed wiring board 20 according to the present embodiment, the planar shape is a U-shape as the bent portion, but if it can be bent and deformed, it can be a crank shape or an L-shape. There may be.

(Printed wiring board manufacturing method)
The printed wiring board 20 according to the present embodiment has been described above. Next, a method for manufacturing the printed wiring board 20 will be described.

  As shown in FIG. 1, the flexible substrate 4 is positioned and positioned at a position where the two rigid substrates 2 and 3 are connected to the rigid substrate sheet 1. In this case, first, one connecting portion 14 of the flexible substrate 4 is aligned and fixed to the connected portion 8 of one rigid substrate 2. Next, the connecting portion 15 on the other side of the flexible substrate 4 is aligned with the connected portion 9 of the other rigid substrate 3.

  Here, as shown in FIG. 3, the center lines C1 and C2 of the connected portions 8 and 9 of the two rigid boards 2 and 3 are the processing accuracy, temperature and humidity environment resulting from the board manufacturing process. For example, in the case of a fine pitch connection of 0.1 mm pitch, this deviation cannot be ignored. When this positional deviation exists, the connection of the connection portion 15 on the other side is caused. The terminal part 11b for connection and the terminal part 6a for connection of the to-be-connected part 9 are in the state which caused the position shift. In this case, with the position of the connecting portion 14 on one side of the aligned flexible substrate 4 fixed, the connecting portion 15 on the other end side of the flexible substrate 4 is moved in the displacement direction S as shown in FIG. Force move. Then, since the U-shaped bent portion 12 of the flexible substrate 4 can be easily bent and deformed in that direction, this bending deformation (location indicated by symbol a in FIG. 2) causes the other end side of the flexible substrate 4 to be bent. The position of the connecting portion 15 can be easily changed. By this bending deformation, the connecting terminal portion 11 b of the connecting portion 15 on the other end side of the flexible substrate 4 can be properly aligned with the 9 connecting terminal portion 6 a of the connected portion of the other rigid substrate 3. As described above, after the connection terminal portions 11a, 5a, 11b, and 6a are aligned with each other without misalignment and with a sufficient overlap length d (see FIG. 5), the corresponding connections are made. What is necessary is just to join the terminal parts 11a, 5a, 11b, and 6a for use by soldering.

  Actually, in a step after the substrate connecting step, the two rigid substrates 2 and 3 are separated from the connecting frame 1a and used as a printed wiring board 20A as shown in FIG. That is, when the two rigid substrates 2 and 3 are separated from the connecting frame 1a, the bending deformation portion of the bent shape portion 12 of the flexible substrate 4 indicated by symbol a in FIG. As a result, the printed wiring board 20A becomes stress-free.

  As described above, in the method for manufacturing the printed wiring board 20 according to this embodiment, since the flexible substrate 4 has the bent portion 12, the center lines C 1 of the connected portions 8 and 9 of the two rigid substrates 2 and 3. Even when there is a positional shift in C2, the corresponding connecting terminal portions of the rigid substrates 2, 3 and the flexible substrate 4 can be joined in an appropriate joined state.

(Modification)
FIG. 6 is an explanatory side view schematically showing Modification 1 of the bending deformation (the portion indicated by symbol a in FIG. 2) of the intermediate portion of the printed wiring board 20 according to the above-described embodiment. As shown in FIG. 6, in the first modification, a bending deformation portion 16 that is bent so as to be bent downward is formed in an intermediate portion of the flexible substrate 4. Other configurations are the same as those of the above-described embodiment.

  FIG. 7 is an explanatory side view schematically showing Modification 2 of the bending deformation (the portion indicated by reference numeral a in FIG. 2) of the intermediate portion of the printed wiring board 20 according to the above-described embodiment. As shown in FIG. 7, in the first modification, a bending deformation portion 17 that is bent up and down and curved in an S shape is formed in an intermediate portion of the flexible substrate 4. Other configurations are the same as those of the above-described embodiment.

(Other embodiments)
It should not be understood that the descriptions and drawings which form part of the disclosure of the above-described embodiments limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  In the above-described embodiment, the case where the two rigid boards 2 and 3 are connected by the flexible board 4 has been described, but the same applies to the case where three or more rigid boards are connected by two or more flexible boards. Of course, the present invention can be applied.

  The printed wiring board 20 according to the above-described embodiment is an example in which the center lines of the connected portions 8 and 9 of the pair of rigid boards 2 and 3 connected by the flexible board 4 are set so as to coincide with each other by design. However, the positions of the connected parts 8 and 9 can be changed as appropriate. In addition, the flexible substrate 4 may have a U-shaped bent portion 12 as long as the center lines of the connecting portions 14 and 15 do not coincide with each other as in the above-described embodiment. Needless to say, the positions of the portions 14 and 15 can be appropriately changed.

(Example)
Hereinafter, specific materials and dimensional examples of embodiments of the method of connecting the rigid substrates 2 and 3 and the flexible substrate 4 will be described below.

  For example, 0.4 mm, 0.6 mm, 0.8 mm, 1.0 mm, 1.2 mm, 1.6 mm, 2.0 mm, 2.4 mm, etc. are adopted as the thickness of the insulating substrates of the rigid substrates 2 and 3. be able to. In recent years, many insulating substrates have a thickness of 1.6 mm or less. The material of this insulating substrate is mainly glass epoxy, and SEM3, paper epoxy, etc. can be used for others. In addition, the thickness of the insulating substrate of the flexible substrate 4 is, for example, 25 μm, and 1/2, 1/3, and 1/4 thereof can be used. The material of the insulating substrate is mainly polyimide, and other materials such as polyethylene naphthalate (PEN) and polyethylene terephthalate (PET) can be used.

  For example, the thickness of the wiring patterns 5, 6, and 11 can be ½, １／２, ¼, etc. based on 35 μm, for example. For the wiring patterns 5, 6, and 11, rolled copper foil or electrolytic copper foil can be used. The connection terminal portions 5a, 6a, 11a, and 11b have a width of 10 to 500 μm, and the connection terminal portions 5a, 6a, 11a, and 11b have a pitch of 10 to 500 μm.

  In the case of solder bonding, the bonding material may be lead-containing solder paste, lead-free solder paste, solder plating, or tin plating. These are applied or plated on one or both of the rigid substrates 2 and 3 and the flexible substrate 4. In addition, when ultrasonic bonding is performed, Au plating can be used as a bonding material with Au plating or Ni plating as a base.

It is a perspective view which shows the board | substrate connection process of the printed wiring board which concerns on embodiment of this invention. It is a top view of the printed wiring board concerning an embodiment of the invention. It is a top view which shows a mode that the centerline of the terminal part for a connection of the two rigid boards in the printed wiring board which concerns on embodiment of this invention has shifted. It is a top view which shows the flexible substrate of the printed wiring board which concerns on embodiment of this invention. It is a top view which shows the state which cut | disconnected the printed wiring board which concerns on embodiment of this invention from the connection frame. It is side surface explanatory drawing which shows the modification 1 of the curved deformation part of the flexible substrate in the printed wiring board which concerns on embodiment of this invention. It is side surface explanatory drawing which shows the modification 2 of the curved deformation part of the flexible substrate in the printed wiring board which concerns on embodiment of this invention. It is a perspective view which shows the board | substrate connection process of the conventional printed wiring board.

Explanation of symbols

1a Connecting frame (connecting member)
2,3 Rigid board 5a, 6a Connection terminal part 4 Flexible board 8, 9 Connected part 11a, 11b Connection terminal part 12 Bent shape part 14, 15 Connection part 16, 17 Deflection part 20 Printed wiring board 20A Printed wiring Board

Claims (7)

A plurality of rigid substrates whose positions are relatively fixed;
A flexible substrate in which a bent shape portion is formed in an intermediate portion, electrically connecting the rigid substrates;
A printed wiring board comprising:   The printed wiring board according to claim 1, wherein the plurality of rigid boards are integrally formed on a single board sheet.   3. The printed wiring board according to claim 1, wherein the bent shape portion is formed in a U shape in a planar shape. 4.   The printed wiring board according to claim 1, wherein the bent shape portion is formed in a crank shape in a planar shape.   The printed wiring board according to claim 1, wherein the bent shape portion is formed in an L shape in a planar shape.   The printed wiring board according to any one of claims 1 to 5, wherein the flexible substrate is connected between the rigid substrates in a bent state. A step of preparing a single substrate sheet in which a plurality of rigid substrates each provided with a connected portion where a connection terminal portion is exposed are arranged at intervals;
A step of preparing a flexible substrate in which a pair of connection portions are provided and a bent shape portion is formed in an intermediate portion between the connection portions;
In a state where the connected portion of one of the rigid substrates of the pair of adjacent rigid substrates and the one connected portion of the flexible substrate are aligned and joined, and then the flexible substrate is bent. A step of aligning and joining the connected portion of the other rigid substrate and the other connecting portion of the flexible substrate;
A method for manufacturing a printed wiring board, comprising:

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