JP2005101112A - Flexible printed circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new flexible printed circuit board which is hardly reduced in durability even when it is repeatedly rotated while a flexible interconnect line member is wound thereon in spirals, easily assembled together, and more increased in the number of interconnect lines than a single-sided board. <P>SOLUTION: A pair of rectilinear flexible interconnect line members 101 and 102 which can be folded in half along a folding line VL provided at a one lengthwise end and overlap with each other when they are folded in half, a first and a third connectors 11 and 13, which are extended in the direction so as to cross the lengthwise direction from the ends of the interconnect line members 101 and 102 on the folding line VL side, and a second and a fourth connectors 12 and 14, which are extended in the opposite direction from the other ends of the interconnect lines 101 and 102, are integrally formed with a sheet of base film, and conductor interconnect lines 16a and 16b and terminals 15a to 15d are formed in the flexible printed circuit board 1. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flexible printed circuit board for connection having a novel structure.

  Recently, instead of the conventional folding type, for example, as shown in FIG. 4, a first main body HP1 having a push button HP1a and the like, and a second main body HP2 having a display screen HP2a and the like, A mobile phone HP having a structure in which an axis XL is directed in a direction orthogonal to the plane direction of the axis and connected to each other by a single-axis rotary hinge, and both main bodies HP1 and HP2 are rotated relative to each other about the axis XL. It is becoming popular.

  In order to electrically connect the two main bodies HP1 and HP2 in the mobile phone HP having such a structure, several dozens of very fine coaxial cables having a diameter of about 0.2 mm are parallel between the pair of connectors. A connection part called a boomerang type having an arranged structure is used. The boomerang type connection component can flexibly cope with the twisting of the pair of connectors due to the relative rotation of the two main bodies by not fixing the coaxial cables to each other.

  However, the boomerang type connection parts are laborious for connecting the central conductor of each coaxial cable to the corresponding individual terminal of each connector and connecting the outer shield wire to the shield terminal of the connector. There is a problem that it takes. In addition, in order to securely connect the center line of each coaxial cable to each terminal of the connector while maintaining a distance so as not to come into contact with adjacent ones or shielded wires, it is necessary in terms of workability and electrical insulation. In this respect, it is necessary to provide a certain amount of space between the terminals. Therefore, there is a limit in the range in which the connector size can be reduced, and there is a problem that further downsizing is difficult. These problems become more prominent as the number of lines to be connected between the two main bodies increases as the number of multifunctional mobile phones increases.

  Therefore, the inventor uses, for example, an electrical connection at the hinge portion between the first main body and the second main body in a conventional foldable mobile phone as described in Patent Document 1. The application of the flexible printed circuit board to the mobile phone having the above structure was examined.

  That is, as shown in FIG. 5 (a), a linear flexible wiring member 92 in which a conductor wiring 91 for connecting between a pair of circuit members in both main bodies is formed on one side thereof, and the flexible wiring member. 92, a connecting portion having a terminal portion 93 for projecting in one direction intersecting the length direction on one end side in the length direction for connecting the conductor wiring 91 to a circuit member in one main body. 94, and a connecting part 96 having a terminal part 95 for connecting the conductor wiring 91 to the circuit member in the other main body, projecting in the opposite direction to the above on the other end side of the flexible wiring member 92; Were examined using a flexible printed circuit board 9 formed integrally with a single base film.

The flexible printed circuit board 9 has a flexible wiring member 92 set in a spiral shape as shown in FIG. 5 (b), and both connecting portions 94 and 96 are bent outwardly to form circuit members in both main bodies (not shown). For example, as shown by a solid arrow in the figure, the upper connecting portion 94 and the circuit member connected thereto, and thus the upper body, the lower connecting portion 96 and the circuit member connected thereto, and With respect to the lower body, the flexible wiring member 92 can be rotated in the direction of tightening and loosening the axis XL.
JP 2002-300147 A (claims 1 to 3, columns 0011 to 0014, FIG. 1)

  However, the flexible printed circuit described in Patent Document 1 has a problem that the number of wires is not sufficient. Therefore, we considered to stack two flexible printed circuit boards, but in a limited space of the mobile phone's rotating hinge, two separate flexible printed circuit boards are neatly set in a spiral shape and accommodated. It was difficult and it took a lot of time to assemble, resulting in a new problem of reduced productivity.

  An object of the present invention is to provide a novel flexible printed circuit board that requires less time for assembly and can improve the number of wires.

The invention according to claim 1 is a linear first flexible wiring member provided with a conductor wiring for connecting two circuit members, and a length direction from one end of the first flexible wiring member. From the other end of the first flexible wiring member, the first connection portion having a terminal portion for connecting the conductor wiring, which is provided in one intersecting direction, to a circuit on one circuit member, the first flexible wiring member is provided. One base includes a connecting portion and a second connecting portion that projects in the opposite direction across the first flexible wiring member and has a terminal portion for connecting a conductor wiring to a circuit on the other circuit member. A first substrate member formed integrally with a film;
A linear second flexible wiring member having a planar shape that is substantially line symmetrical with the first substrate member and provided with a conductor wiring for connecting the two circuit members, and the second flexible wiring member A third connecting portion having a terminal portion for connecting the conductor wiring to a circuit on one circuit member, projecting in one direction intersecting the length direction from one end, and a second flexible wiring member A fourth portion having a terminal portion for connecting the conductor wiring to the circuit on the other circuit member, projecting in the opposite direction from the other end of the third connection portion and the second flexible wiring member. A second substrate member integrally formed with one base film with the connection portion,
The first connecting portion and the third connecting portion are joined to each other at the side edges, and the side edges are folded in half along the fold line, and one of the flexible wiring members is the other. It is a flexible printed circuit board characterized by being formed longer.

According to a second aspect of the present invention, the first and second substrate members are integrally formed with a single base film, and the position corresponds to a joint portion between the side edges of the first connection portion and the third connection portion. The flexible printed circuit board according to claim 1, wherein the flexible printed circuit board is folded in two along a crease line provided on the substrate.
According to a third aspect of the present invention, the conductor wiring and the terminal portion are formed on the outer surface when the pair of flexible wiring members of the base film are folded in two along the crease line and overlapped with each other. A flexible printed circuit board according to claim 1.

  Furthermore, the invention according to claim 4 is the first and second flexible in a state in which the first connection portion and the third connection portion, which are folded in two along the crease line and overlapped, are fixed to the shaft of the rotary hinge. The flexible printed circuit board according to claim 1, wherein the wiring member is used by being wound around the shaft in a spiral shape.

  According to the first aspect of the present invention, the number of wirings can be improved because two first and second substrate members each having a flexible wiring member are stacked. In addition, the individual flexible wiring members are not fixed to each other except at the joint portions of the side edges of the first connection portion and the third connection portion, and one of them is formed longer than the other, so that it has a spiral shape. It has a high degree of freedom when wound and has good flexibility. For this reason, durability of a flexible wiring member can be improved and it can prevent that a conductor wiring is disconnected early.

  In addition, since the flexible wiring members are integrally connected at the joints at the side edges as described above, the workability when spirally wound around the rotating hinge portion of a cellular phone or the like is improved. be able to. Therefore, according to the first aspect of the present invention, a novel flexible print that is excellent in durability when it is repeatedly rotated in a spiral shape, takes less time for assembly, and can improve the number of wires. A substrate can be provided.

  According to a second aspect of the present invention, the first substrate member and the second substrate member are integrally formed with a single base film, which corresponds to a joint portion between the side edges of the first connection portion and the third connection portion. Since it is folded in two along the crease line provided at the position, the labor of joining both the connecting portions can be saved and the productivity can be improved.

  According to the third aspect of the present invention, the pair of flexible wiring members are superposed on each other so that the uneven surface on which the conductor wiring is formed is on the outside, and the smooth surface as the base film is on the opposite side. The flexible wiring members can be moved more smoothly without being caught by each other when they are accommodated in a spirally wound state on a rotating hinge such as a cellular phone or when they are repeatedly rotated in this state. For this reason, there is an advantage that workability at the time of accommodation can be further improved and disconnection of the conductor wiring can be more reliably prevented.

  Furthermore, in the configuration of claim 4, the first and second flexible wiring members are fixed to the shaft of the rotary hinge while the first connecting portion and the third connecting portion folded in two along the crease line are overlapped. Can be wound around the shaft in a spiral shape, so that the workability of winding can be further improved. In addition, the bending trajectory after winding can be stabilized, and the bending resistance can be further improved.

FIG. 1 is a plan view showing an example of an embodiment of a flexible printed circuit board 1 of the present invention.
The flexible printed circuit board 1 in the above example is
A linear first flexible wiring member 101 and a first connection portion 11 projecting from one end of the first flexible wiring member 101 in one direction (downward in the figure) intersecting the length direction; A first substrate member 1a having a second connection portion 12 projecting from the other end of the first flexible wiring member 101 in a direction opposite to the first connection portion 11 (upward in the figure);
A linear second flexible wiring member 102 and a third connection portion 13 projecting from one end of the second flexible wiring member 102 in one direction (downward in the drawing) intersecting the length direction; A second substrate member 1b having a fourth connecting portion 14 projecting from the other end of the second flexible wiring member 102 in the direction opposite to the third connecting portion 13 (upward in the figure);
Are integrally formed with a single base film.

  In addition, terminal portions 15a to 15d for connecting to circuits on circuit members (not shown) are provided on the front side surfaces of the first to fourth connection portions 11 to 14 in the drawing, respectively. Conductor wirings 16a and 16b are formed on the same surface of the second flexible wiring members 101 and 102 to connect the terminal portions 15a-15b and the terminal portions 15c-15d. Further, nothing is formed on the back side (not shown), and the smooth surface of the base film is left as it is.

  That is, the entire flexible printed circuit board 1 is configured as a single-sided board. For this reason, the flexibility of the first and second flexible wiring members 101 and 102 can be further enhanced and the durability thereof can be improved. Moreover, productivity of the flexible printed circuit board 1 can also be improved by setting it as the structure of a single-sided board.

  In addition, the first and third connection portions 11 and 13 are separated by forming a slit SL along the fold line VL provided at a position corresponding to the side edge thereof. The terminal portions 15a and 15c are bent in the direction so as to be connected to the circuit on the circuit member. In the figure, the terminal portions 15a to 15d and the conductor wirings 16a and 16b are all abbreviated as a single flat plate, but in reality, the terminal portions 15a to 15d are terminals in which a plurality of terminals are regularly arranged. Consists of columns. The conductor wirings 16a and 16b are formed of a plurality of fine wirings for electrically connecting individual terminals of the terminal row between the terminal portions 15a to 15c and between the terminal portions 15b to 15d, for example, one to one. It is an aggregate.

  In order to use the flexible printed circuit board 1, first, the conductor wirings 16 a and 16 b of the first and second flexible wiring members 101 and 102, and the first to fourth connection portions 11 to 14 along the crease line VL. As shown in FIG. 2 (a), the terminal portions 15a to 15d are folded and overlapped so as to be outside. Next, as shown by the white arrow in FIG. 2 (b), the overlapped first connection portion 11 and third connection portion 13 are connected to the shaft HG1 of the rotary hinge and the flange portion integrally formed with the shaft HG1. The first and second flexible wirings overlapped as shown in FIG. 3 by rotating the shaft HG1 in the direction indicated by the thick arrow in the figure while being inserted and fixed in the slit HG3 provided in the HG2. The members 101 and 102 are wound around the shaft HG1 in a spiral shape.

In this state, although not shown, the rotary hinge is assembled, and the first to fourth connecting portions 11 to 14 are bent in arbitrary directions and connected to the circuit members in both main bodies.
Then, for example, as shown by solid line arrows in the figure, the second and fourth connecting portions 12 and 14 and the circuit members connected thereto, and thus the upper main body, are connected to the first and third connecting portions 11 and 13 and the same. The circuit member and the lower main body can be rotated in the direction in which the spirals of the flexible wiring members 101 and 102 are tightened and loosened around the axis XL that coincides with the center line of the axis HG1. .

Further, in the flexible printed circuit board 1, the second flexible wiring member 102 located outside in the spirally wound state among the two flexible wiring members 101 and 102 is the first flexible wiring located inside. It is formed longer than the wiring member. That is, L ₁ and L ₂ in FIG. 1 are set as L ₁ <L ₂ . As a result, a sufficient gap is provided between the flexible wiring members 101 and 102 in the spirally wound state as shown in FIG. 3, and the winding directions of the second and fourth connecting portions 12 and 14 are also provided. Can be eliminated as much as possible. The difference between L ₁ and L ₂ is not particularly limited. For example, when the flexible wiring members 101 and 102 are spirally wound about three times, the longer dimension L ₂ is set as follows: preferably set to 1.04 times ～1.08 times relative to the size _{L 1} of the short.

  A flexible resin film is used as the base film on which the flexible printed circuit board 1 is based. In particular, a polyimide film is preferable in consideration of dimensional stability, heat resistance, durability, flexibility, and the like. Moreover, what is necessary is just to form the terminal parts 15a-15d and the conductor wiring 16a, 16b with metal thin films, such as copper foil. As a forming method, various conventionally known methods such as a subtractive method and an additive method can be employed.

  Although not shown, a cover lay made of a resin film or the like is preferably formed on the conductor wirings 16a and 16b. Thereby, when the first and second flexible wiring members 101 and 102 are wound in a spiral shape, it is possible to prevent the conductor wirings 16a and 16b from coming into contact with each other and causing a short circuit or the like. In addition, the sliding between the first and second flexible wiring members 101 and 102 folded in two and folded can be improved and can be moved more smoothly. Moreover, it is preferable to laminate | stack the reinforcement board which consists of a resin film etc. on the surface on the opposite side to the side in which the terminal parts 15a-15d were formed of the 1st-4th connection parts 11-14. As the resin film which becomes the basis of the coverlay and the reinforcing plate, a polyimide film is preferable for the same reason as described above.

  Further, although not shown in the drawing, conductor layers 16a and 16b are preferably provided with a shield layer to prevent interference from external electromagnetic waves and noise from adjacent wirings. For example, the shield layer is formed by providing a metal thin layer on the inner surface of the cover lay, or a material containing metal powder as a part of an adhesive used for laminating and bonding a resin film to be a cover lay as described below. It can be formed by applying.

  Also, in a subtractive method or the like, a metal foil such as a copper foil that becomes the base of the terminal portions 15a to 15d and the conductor wirings 16a and 16b is laminated and bonded to the surface of the base film, or a resin that becomes a coverlay or a reinforcing plate An adhesive is used for laminating and bonding the films. As such an adhesive, a curable resin-based adhesive is preferable, and an epoxy resin-based adhesive is particularly preferable in order not to impair the properties of each layer.

  In the above description, the first substrate member 1a and the second substrate member 1b are integrally formed from a single base film. However, the first substrate member 1a and the second substrate member 1b are joined together at a portion corresponding to the crease line VL. The flexible printed board of the present invention may be formed.

Example 1
Copper foil by a subtractive method using a single-sided plate in which 18 μm thick copper foil is laminated on one side of a 12.5 μm thick polyimide film as a base film via an epoxy resin adhesive layer of 10 μm thickness The terminal portions 15a to 15d and the conductor wirings 16a and 16b having the planar shape shown in FIG. 1 were formed on one side of the base film.

  Next, a polyimide film having a thickness of 12.5 μm is laminated and bonded to a region of the base film where the conductor wirings 16 a and 16 b are formed via an epoxy resin adhesive layer having a thickness of 20 μm and the conductor wirings 16 a and 16 b are bonded. After forming a coverlay that covers the substrate, punching was performed to manufacture a flexible printed circuit board 1 having a planar shape shown in FIG. In the pair of flexible wiring members 101 and 102, the length of the second flexible wiring member 102 on the outer side of the winding is 1.05 times the length of the first flexible wiring member 101 on the inner side.

Comparative Example 1
A flexible printed circuit board was manufactured in the same manner as in Example 1 except that the lengths of the pair of flexible wiring members 101 and 102 were exactly the same.

Comparative Example 2
Copper foil by a subtractive method using a double-sided board in which a copper foil with a thickness of 18 μm is laminated on one side of a polyimide film with a thickness of 12.5 μm as a base film via an epoxy resin adhesive layer with a thickness of 10 μm As a result, a planar conductor wiring 91 and terminal portions 93 and 95 shown in FIG. 5A were formed on one side of the base film.

  Next, the conductor film 91 of the base film is formed, and a polyimide film having a thickness of 12.5 μm is laminated and bonded via an epoxy resin adhesive layer having a thickness of 30 μm to cover the conductor wiring. After forming, a flexible printed circuit board having a planar shape shown in FIG. 5A and having a single-sided plate structure was manufactured.

Total cost evaluation The total cost required from the production of the flexible printed circuit board produced in Example 1 and Comparative Examples 1 and 2 to the completion of the work accommodated in the rotary hinge portion of the mobile phone HP shown in FIG. 4 is evaluated. did. Note that the flexible printed circuit board manufactured in Example 1 and Comparative Example 1 was wound around the axis HG1 of the rotary hinge shown in FIG. 2 (b) and FIG. Housed in a rotating hinge. In addition, the same flexible printed circuit board manufactured in Comparative Example 2 was overlapped, and housed in the rotating hinge portion of the mobile phone in a state of being set in a spiral shape for the same number of times as described above. The evaluation was performed by calculating the ratio of the total cost of each comparative example when the total cost required for Example 1 was 1.0.

Durability Evaluation As described above, the rotating hinge portion of the mobile phone incorporating the flexible printed circuit board manufactured in Example 1 and Comparative Examples 1 and 2 was rotated 180 ° in the direction of vortex, and then returned to the original state. The returning operation was repeated 40,000 times. And when it broke by 40,000 times, the repetition frequency was counted and durability was evaluated.

The results are shown in Table 1.

  From the table, the flexible printed circuit board of Comparative Example 1 having the same structure as Example 1 and the same length of only a pair of flexible wiring members 101 and 102 had the same total cost as Example 1. 2. Conductor wiring was broken by repeated bending of 80,000 times. In Comparative Example 2, the conductor wiring was not broken by repeated bending of 40,000 times, but two single-sided plates were required, and it took time to assemble, so the total cost was 1.7 of Example 1. It has doubled. In contrast, the flexible printed circuit board of Example 1 had a low total cost, and the conductor wiring was not broken by repeated bending of 40,000 times, showing good durability.

It is a top view which shows an example of embodiment of the flexible printed circuit board of this invention. The figure (a) is a top view which shows the state which folded the flexible printed circuit board of the said example along the crease line, The figure (b) is the 1st connection part which overlap | superposed the folded flexible printed circuit board, and It is a perspective view which shows the state in the middle of inserting and fixing a 3rd connection part in the slit provided in the axis | shaft of the rotation hinge. It is a perspective view which shows the state which fixed the 1st connection part and the 3rd connection part to the axis | shaft of a rotation hinge, and wound the 1st and 2nd flexible wiring member around the said axis | shaft spirally. It is a perspective view which shows an example of a mobile telephone in which the flexible printed circuit board of this invention is used. FIG. 4A is a plan view showing an example of a conventional flexible printed board having a single-sided board configuration, and FIG. 4B is a perspective view showing a state in which the flexible printed board is set in a spiral shape. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flexible printed circuit board 1a 1st board | substrate member 1b 2nd board | substrate member 101 1st flexible wiring member 102 2nd flexible wiring member VL Crease line 11 1st connection part 12 2nd connection part 13 3rd connection part 14 4th connection Part 15a-15d Terminal part 16a, 16b Conductor wiring

Claims (4)

A linear first flexible wiring member provided with a conductor wiring for connecting two circuit members, and one end of the first flexible wiring member projecting in one direction intersecting the length direction. The first connection part having a terminal part for connecting the conductor wiring to a circuit on one circuit member, the first connection part and the first flexible terminal from the other end of the first flexible wiring member. A first base film integrally formed with a second connection part having a terminal part for connecting a conductor wiring to a circuit on the other circuit member, projecting in the opposite direction across the wiring member 1 substrate member;
A linear second flexible wiring member having a planar shape that is substantially line symmetrical with the first substrate member and provided with a conductor wiring for connecting the two circuit members, and the second flexible wiring member A third connecting portion having a terminal portion for connecting the conductor wiring to a circuit on one circuit member, projecting in one direction intersecting the length direction from one end, and a second flexible wiring member A fourth portion having a terminal portion for connecting the conductor wiring to the circuit on the other circuit member, projecting in the opposite direction from the other end of the third connection portion and the second flexible wiring member. A second substrate member integrally formed with one base film with the connection portion,
The first connecting portion and the third connecting portion are joined to each other at the side edges, and the side edges are folded in half along the fold line, and one of the flexible wiring members is the other. A flexible printed board characterized in that it is formed longer.   The first and second substrate members are integrally formed with a single base film, and are formed along a crease line provided at a position corresponding to a joint between the side edges of the first connection portion and the third connection portion. The flexible printed circuit board according to claim 1, which is folded.   The flexible printed circuit board according to claim 1, wherein the conductor wiring and the terminal portion are formed on a surface that becomes the outer side when the pair of flexible wiring members of the base film are folded in two along the crease line and overlapped with each other.   The first and second flexible wiring members are fixed around the shaft in a state where the first connection portion and the third connection portion, which are folded in two along the crease line, are superposed on the shaft of the rotary hinge. 2. The flexible printed circuit board according to claim 1, wherein the flexible printed circuit board is used by being wound in a spiral shape.

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