JP4407471B2 - Flexible wiring board, electronic device using the same, and manufacturing method thereof - Google Patents

Description

  The present invention relates to a flexible wiring board used for wiring or the like of an electronic device, and more particularly to a flexible wiring substrate provided with a terminal reinforcing portion or a reinforcing portion, an electronic device using the same, and a manufacturing method thereof.

  In recent years, as various electronic devices have become highly accurate and highly dense, flexible wiring boards having flexibility are often used for connection between electronic circuits in these electronic devices.

  A conventional flexible wiring board will be described with reference to FIGS.

  As shown in the perspective view of FIG. 18, the conventional flexible wiring board 500 is formed by etching copper foil that is pasted on the surface of a thin and thin insulating substrate 510 having flexibility such as polyethylene terephthalate or polyimide. Alternatively, a conductive pattern 520 is formed along the longitudinal direction of the insulating substrate 510 by printing a flexible conductive resin such as polyester or epoxy resin in which silver or copper is dispersed. The upper surface is covered with a thin insulating layer 540 except for the terminal portion 530.

  Then, as shown in the cross-sectional view of FIG. 19, by inserting the terminal portion 530 of the flexible wiring board 500 into the connector 550, the exposed conductive pattern 520 comes into contact with and electrically connects to the contact 560 having elasticity of the connector 550. Is done.

  However, since the flexible wiring board 500 has flexibility, for example, when the terminal portion 530 is inserted into the connector 550, it may be bent or deformed. In particular, in the case of a flexible wiring board using a thinner insulating substrate 510 in order to enhance flexibility, care must be taken in handling.

  In addition, if the flexible wiring board 500 is positioned when the flexible wiring board 500 is attached to another member or a part on which an electronic component such as an IC chip is easily bent, the reliability and the like are lowered. For this reason, usually, reinforcing portions are also provided in these portions to increase the rigidity.

  As a method for increasing the rigidity, as shown in the sectional view of FIG. 20, a reinforcing plate 580 made of a resin film and having a size corresponding to the portion to be reinforced and having an adhesive layer 570 on one side is used. It was affixed on the back surface etc. of the terminal part 530.

  However, when reinforcing with the reinforcing plate 580, bubbles remain between the adhesive layer 570 of the reinforcing plate 580 and the insulating substrate 510, so that continuous bonding by, for example, a roll-to-roll method or the like cannot be performed, and the reinforcing plate 580 Were attached individually one by one.

  For this reason, it takes time to manufacture the flexible wiring board 500 and causes a high cost.

  In recent years, in order to solve such problems, it has been proposed to continuously form the reinforcing portion of the flexible insulating substrate 510 by a roll-to-roll method by printing resin instead of a resin film. ing.

  For example, as shown in a cross-sectional view in a direction perpendicular to the conductive pattern in FIG. 21, a flexible insulating substrate 590 having a conductive pattern 600 formed on one surface is irradiated with ultraviolet light at a predetermined position on the other surface. A method of forming a reinforcing layer 610 by printing a photocurable resin ink such as UV light and then curing it by irradiation with light such as ultraviolet rays is disclosed (for example, Patent Document 1).

Further, as shown in the perspective view of FIG. 22, positioning at the time of attachment to another member of the insulating substrate 620 provided at a predetermined position of the flexible insulating substrate 620 on which the conductive pattern 630 is formed. A method of forming a reinforcing layer 650 with a resin around a through hole 640A or a notch 640B is shown (for example, Patent Document 2).
JP-A-5-175618 JP 2000-153103 A

  However, in a conventional flexible wiring board, when a reinforcing plate is attached to a flexible insulating substrate or a reinforcing layer is formed by printing / curing resin ink to reinforce, a portion provided with these reinforcing portions The rigidity is improved and it is difficult to bend, and the insertion into the connector and the positioning at the time of mounting are in a good state, but other parts remain easy to bend. That is, the difference in rigidity between the portion where the reinforcing portion is provided on the insulating substrate and the portion where the reinforcing portion is not provided is large, and the rigidity is discontinuous. In particular, this state is remarkable in the case of a flexible wiring board using a thin insulating substrate.

  Therefore, when inserting the terminal part of the flexible wiring board into the connector, or during handling, for example, when a force to bend in the thickness direction of the insulating board is applied, the insulating board is caused by the difference in rigidity at the end of the reinforcing board. The end portion is bent at an acute angle, and the bending stress is concentrated on the end portion. Then, when the conductive pattern is bent at an acute angle, the conductive pattern is cracked, and the conductive resistance of the conductive pattern is increased. In particular, there is a problem that this phenomenon is likely to occur at the end portion of the reinforcing plate of the terminal portion.

  The present invention has been made in order to solve the above-described problems, and a reinforcing portion for a terminal portion or the like to be inserted into a connector can be efficiently formed by resin printing. Furthermore, when a force to bend the insulating substrate of the flexible wiring board in the plate thickness direction is applied, a flexible wiring board capable of dispersing bending stress at the end of the reinforcing portion of the insulating substrate, an electronic device using the flexible wiring board, and It aims at providing the manufacturing method.

In order to solve the problems as described above, the flexible wiring board of the present invention includes a flexible insulating substrate, a conductive pattern formed on one surface of the insulating substrate, and the other surface of the insulating substrate. and a terminal reinforcing portion whose surface is formed by printing a resin roughened comprising a filler comprising an inorganic material on the rear surface of the terminal portion at least the conductive pattern is exposed, insulation around the terminal reinforcing portion It has a configuration in which a bending stress dispersion portion is provided at an end portion not located on the outer periphery of the substrate.

According to such a structure, the terminal reinforcement part with respect to the terminal part inserted in a connector can be formed efficiently by resin printing. Furthermore, even when a force to bend in the thickness direction of the flexible wiring board is applied, it is possible to disperse the bending stress at the end portion of the terminal reinforcing portion of the insulating substrate, so that the insulating substrate is bent, such as a discontinuous deformation or A flexible wiring board with excellent reliability that does not cause deformation with a small bending radius can be realized. In addition, the terminal reinforcing part is formed by printing a resin containing a filler made of an inorganic material, and its surface is roughened, so the frictional resistance with the connector can be increased, and it is difficult to pull out from the connector. A wiring board can be realized.

  Moreover, the flexible wiring board of this invention is good also considering the shape of the edge part of the terminal reinforcement part which is not located in the outer periphery of an insulated substrate as a bending stress dispersion | distribution part to a waveform shape.

  According to such a configuration, the portion of the corrugated shape as the bending stress dispersion portion at the end of the terminal reinforcing portion is wide in the portion close to the terminal reinforcing portion and gradually becomes narrower as the distance increases. There is no portion in which the rigidity changes abruptly at the end of. Therefore, even when a force that bends the insulating substrate of the flexible wiring board in the thickness direction is applied, the bending stress at the end of the terminal reinforcing portion of the insulating substrate can be dispersed, so that the insulating substrate is not bent. A flexible wiring board excellent in reliability that does not cause continuous deformation or deformation with a small bending radius can be realized.

  Moreover, the flexible wiring board of this invention may provide a taper in the thickness direction in the edge part of the terminal reinforcement part which is not located in the outer periphery of an insulated substrate as a bending stress dispersion | distribution part.

  According to such a configuration, the taper as the bending stress dispersion portion at the end portion of the terminal reinforcing portion of the insulating substrate is thinned away from the terminal reinforcing portion, so that the rigidity at the end portion of the terminal reinforcing portion is rapidly increased. There is no change. Therefore, even when a force that bends the insulating substrate of the flexible wiring board in the thickness direction is applied, the bending stress at the end of the terminal reinforcing portion of the insulating substrate can be dispersed, so that the insulating substrate is not bent. A flexible wiring board with excellent reliability that does not cause continuous deformation can be realized.

  In the flexible wiring board of the present invention, the terminal reinforcing portion may be formed by laminating a plurality of resin layers.

  According to such a configuration, the elastic modulus of the terminal reinforcing portion can be freely changed.

  In the flexible wiring board of the present invention, among the terminal reinforcing portions formed by laminating a plurality of resin layers, the elastic modulus of the outermost resin layer may be higher than the elastic modulus of the other resin layers. .

  According to such a structure, a bending stress dispersion | distribution part can be provided also in the resin layer with a low elasticity modulus.

  In addition, the flexible wiring board of the present invention is formed so as to overlap the resin layer on the insulating substrate side at an end portion that is not located on the outer periphery of the insulating substrate around the terminal reinforcing portion that is printed and formed by overlapping a plurality of resin layers. The bending stress dispersion portion may be formed by sequentially reducing the resin layer.

  According to such a configuration, the end portion of the terminal reinforcing portion of the insulating substrate printed and formed so that the resin layer formed on the resin layer on the insulating substrate side is sequentially reduced becomes thinner from the end portion. Since it changes stepwise in the direction of the terminal portion, the rigidity changes step by step, and there is no portion that changes suddenly. Therefore, even when a force that bends the insulating substrate of the flexible wiring board in the thickness direction is applied, the bending stress at the end of the terminal reinforcing portion of the insulating substrate can be dispersed, so that the insulating substrate is not bent. A flexible wiring board with excellent reliability that does not cause continuous deformation can be realized.

  In the flexible wiring board of the present invention, the terminal reinforcing portion may be divided into a plurality of strips by grooves.

  According to such a configuration, the rigidity of the terminal reinforcing portion can be adjusted by changing the number and dimensions of the strip-like portions divided into a plurality of portions by the grooves with respect to the terminal reinforcing portion formed on the entire terminal portion. It becomes easy.

  In the flexible wiring board of the present invention, the surface of the terminal reinforcing portion may be roughened.

  According to such a configuration, since the frictional resistance with the connector can be increased by roughening the surface, it is possible to realize a highly reliable flexible wiring board that is difficult to be removed from the connector.

  Further, the flexible wiring board of the present invention is provided on the other surface of the insulating substrate with a positioning portion when fixed to another member, a mounting portion of an electronic component, a bent portion when bent and used, or a bent portion of a conductive pattern. Of these, a reinforcing portion having a bending stress distribution portion at an end portion not located on the outer periphery of the insulating substrate may be provided for at least one location.

  Further, the flexible wiring board of the present invention is formed on the insulating layer formed by printing an insulating resin on the conductive pattern formed on one surface of the insulating substrate so as to cover the portion excluding the terminal portion. Bending stress distribution portion at the end not located on the outer periphery of the insulating substrate with respect to at least one of the positioning portion at the time of fixing to the member, the bent portion when bent and used, or the bent portion of the conductive pattern You may provide the reinforcement part which has these.

  According to such a configuration, even when a thin insulating substrate is used in order to increase the flexibility of the flexible wiring substrate, it is possible to reinforce a portion that is easily bent other than the terminal portion. Furthermore, since the reinforcing portions of these portions also have bending stress dispersion portions at the end portions, even when a force that bends the insulating substrate of the flexible wiring board in the thickness direction is applied, the end of the reinforcing portion of the insulating substrate is added. Since the bending stress at the portion can be dispersed, it is possible to realize a flexible wiring substrate with excellent reliability that does not cause discontinuous deformation such as bending of the insulating substrate.

  In the flexible wiring board of the present invention, the reinforcing portion provided on the insulating substrate may be formed by printing the same resin as the terminal reinforcing portion.

  According to such a configuration, since the terminal reinforcing portion and the other reinforcing portions can be printed using the same resin with the same printing equipment, the flexible wiring board can be formed efficiently and inexpensively.

  Moreover, the flexible wiring board of this invention may be formed by printing the reinforcing portion provided on the insulating substrate to a thickness different from that of the terminal reinforcing portion.

  According to such a configuration, the terminal reinforcing portion and the other reinforcing portions are formed by printing the same resin with the same printing equipment, for example, by changing the number of meshes of the screen mask for screen printing or the wire diameter of the mesh. A flexible wiring board having rigidity according to the location and being inexpensive can be formed.

  Further, the flexible wiring board of the present invention includes a terminal portion of an insulating layer formed by printing an insulating resin so as to cover a portion excluding the terminal portion on a conductive pattern formed on one surface of the insulating substrate. The bending stress distribution part is provided at the boundary part.

  According to such a configuration, the rigidity of the overlapping portion of the insulating layer on the conductive pattern and the terminal reinforcing portion is reduced by providing the insulating layer with the bending stress dispersion portion, so that the flexible wiring board is more reliable. Can be realized.

  Moreover, the flexible wiring board of this invention may form a conductive pattern, an insulating layer, a terminal reinforcement part, or a reinforcement part with the same base resin.

  According to such a configuration, characteristics such as uniform adhesion strength with the insulating substrate and expansion coefficient can be matched, so that a flexible wiring substrate with excellent reliability can be realized.

  Further, the flexible wiring board of the present invention includes a flexible insulating substrate, a conductive pattern formed on one surface of the insulating substrate, and a terminal having at least a conductive pattern exposed on the other surface of the insulating substrate. A terminal reinforcing portion formed by printing a plurality of resin layers on the back surface of the portion and laminating, and the elasticity of the outermost resin layer among the terminal reinforcing portions formed by laminating the plurality of resin layers The modulus is higher than the elastic modulus of other resin layers.

  According to such a configuration, since the resin layer having a low elastic modulus becomes a bending stress dispersion portion, a flexible wiring board having a terminal reinforcing portion with a simple shape can be realized.

  Moreover, the manufacturing method of the flexible wiring board of the present invention includes a step of forming a conductive pattern of a plurality of flexible wiring boards on one surface of a flexible insulating sheet, and a plurality of steps on the other surface of the insulating sheet. A step of forming a terminal reinforcing portion having a bending stress dispersion portion by printing resin on the back surface of the terminal portion where the conductive pattern of the flexible wiring substrate is exposed, and a plurality of flexible wiring substrates formed on the insulating sheet are individually provided. And a step of separating.

  According to such a manufacturing method, even when a force that bends the insulating substrate of the flexible wiring board in the thickness direction is applied, the flexible device having the terminal reinforcing portion having the bending stress dispersion portion that can disperse the bending stress. The wiring board can be efficiently produced continuously from the insulating sheet by, for example, a roll-to-roll method.

According to the flexible wiring board of the present invention, it is possible to efficiently form the terminal reinforcing portion and the reinforcing portion for the terminal portion inserted into the connector by resin printing. Furthermore, even when a force is applied to bend the insulating substrate of the flexible wiring board in the thickness direction, the bending stress at the end of the terminal reinforcing portion of the insulating substrate can be dispersed, so that the insulating substrate is bent. It has a great effect that it is possible to realize a flexible wiring board excellent in reliability that does not cause continuous deformation or deformation with a small bending radius.
In addition, the terminal reinforcing part is formed by printing a resin containing a filler made of an inorganic material, and its surface is roughened, so the frictional resistance with the connector can be increased, and it is difficult to pull out from the connector. A wiring board can be realized.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In each drawing, in order to make the configuration easy to understand, the conductive pattern surface is on the lower side and the dimension in the thickness direction is enlarged.

(First embodiment)
A flexible wiring board according to a first embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a perspective view of a flexible wiring board provided with a terminal reinforcing portion having a bending stress distribution portion having a wave shape, and FIG. 2 is a cross-sectional view of a principal portion of the flexible wiring board as seen from line AA in FIG.

  As shown in FIG. 1, the flexible wiring board 10 is a copper foil attached on one surface of an insulating board 20 having a thickness of, for example, about 50 μm to 200 μm having flexibility such as polyethylene terephthalate or polyimide. The conductive pattern 30 is formed on the insulating substrate 20 by etching, or printing a conductive resin such as a polyester resin or an epoxy resin in which silver or copper is dispersed, and then curing. An insulating layer 50 such as an acrylic resin or an epoxy resin is formed with a thickness of, for example, 50 μm so as to cover at least the conductive pattern 30. Further, on the other surface of the insulating substrate 20, a terminal reinforcing portion 60 is formed with a thickness of, for example, about 50 μm to 200 μm with a resin such as polyester or epoxy at the back surface position of the terminal portion 40 where the conductive pattern 30 is exposed. ing. And the waveform shape part 70 of a waveform which has a some peak and trough, for example is formed in the edge part which is not located in the outer periphery of the insulated substrate 20 of the terminal reinforcement part 60. FIG. Here, the end portion not located on the outer periphery of the insulating substrate 20 means a position in the vicinity of the end face portion where the conductive pattern 30 of the terminal portion 40 is covered with the insulating layer 50.

  As described above, the corrugated portion 70 formed at the end portion of the terminal reinforcing portion 60 that becomes the boundary between the portion where the terminal reinforcing portion 60 is provided and the portion where the terminal reinforcing portion 60 is not provided has a shape whose width becomes narrower as the distance from the terminal portion 40 increases. Have For this reason, the rigidity of the corrugated portion 70 also changes from a large rigidity on the terminal reinforcing portion 60 side to a small rigidity on the insulating substrate 20 side in accordance with the change in the shape of the width. , The longitudinal direction) changes rapidly.

  Hereinafter, the region portion where the bending stiffness sequentially changes is referred to as a bending stress dispersion portion. That is, in the first embodiment, the corrugated portion 70 corresponds to a bending stress dispersion portion.

  The effect will be described with reference to a sectional view of the state in which the flexible wiring board of FIG. 3 is connected to the connector.

  FIG. 3 shows that when the flexible wiring board 10 is inserted into the connector 80 and the conductive pattern 30 of the terminal portion 40 is connected to the contact 90 or when the both are combined and handled, the flexible wiring board 10 is bent in the thickness direction. A state in which force (for example, an arrow direction) is applied is shown. Even in such a state, discontinuous deformation or deformation with a small bending radius with the end portion of the terminal reinforcing portion 60 of the insulating substrate 20 as shown by a two-dot chain line in FIG. It does not occur by providing 70.

  This is because, as shown by the solid line in FIG. 3, the corrugated portion 70 at the end of the terminal reinforcing portion 60 acts as a bending stress dispersion portion that disperses the bending stress and eliminates the inflection point 100, and is continuously deformed. Alternatively, it is for deformation with a large bending radius. As a result, damage such as cracks and breaks of the conductive pattern 30 is less likely to occur.

  In addition, in the terminal part 40, you may coat | cover with the conductive resin containing carbon so that the conductive pattern 30 may be covered separately. Thereby, for example, when the conductive pattern 30 is formed of a conductive resin containing silver, it is effective in preventing silver migration due to moisture absorption or moisture.

  Moreover, although the flexible wiring board 10 which has the insulating layer 50 was demonstrated to the above as an example, this invention is not limited to this. The insulating layer 50 may be omitted as long as migration does not occur and a short circuit between the conductive patterns 30 and other devices does not occur.

  Moreover, although the flexible wiring board 10 which has the terminal part 40 at the both ends of the insulated substrate 20 was demonstrated to the example, this invention is not limited to this. For example, the terminal portion may be provided on one side and an electronic component or the like may be mounted on the conductive pattern. Further, one terminal portion may be configured to be electrically connected to another electronic device or the like, for example, with solder or the like.

  Below, the manufacturing method of the flexible wiring board 10 provided with the terminal reinforcement part 60 mentioned above is demonstrated using FIG.

  First, as shown in FIG. 4A, a flexible layer having an insulating layer 50 covering the conductive patterns 30 other than the plurality of conductive patterns 30 and the terminal portions 40 on one surface of a flexible insulating sheet 110 having a predetermined size. A plurality of wiring boards 10 are formed at a predetermined pitch, for example, by screen printing or the like. And the terminal reinforcement part 60 which has a waveform-shaped part 70 in alignment with the back surface of the part used as the terminal part 40 which the conductive pattern 30 of each flexible wiring board 10 exposed to the other surface of the flexible insulating sheet 110. Is formed by printing polyester, epoxy or the like, resin, or UV curable resin by screen printing or the like. At this time, of the outer periphery of the terminal reinforcing portion 60, the corrugated portion 70 is not formed on the outer periphery of the flexible wiring substrate 10, but is formed at the end portion of the flexible wiring substrate 10 facing the insulating layer 50. Here, the thickness of the terminal reinforcing portion 60 can be adjusted by, for example, the number of times of screen printing according to the required rigidity. Usually, the thickness per printing is 15 μm to 80 μm by adjusting the thickness of the screen mask and the viscosity of the resin. Therefore, for example, when the required thickness of the terminal reinforcing portion 60 is 200 μm, the terminal reinforcing portion 60 can be formed with a number of printing times of about 2 to 14.

  In addition, although the terminal reinforcement part 60 which has the waveform shape part 70 can be formed with a screen mask or a metal mask, it is not restricted to this. For example, after forming the terminal reinforcing portion 60 having the corrugated portion into a rectangular shape, the corrugated portion 70 may be formed using, for example, laser processing or sand blast processing.

  In general, it is preferable that the portion corresponding to the outer periphery of the flexible wiring board 10 is formed with the terminal reinforcing portion 60 having a shape slightly larger than the outer shape of the flexible wiring board 10. However, if the rigidity of the terminal reinforcing portion 60 is sufficient, the shape other than the bending stress dispersion portion is not particularly limited, and may be an arbitrary shape.

  Next, as shown in FIG. 4B, a plurality of flexible wiring boards formed on the flexible insulating sheet 110 after the terminal reinforcing portion 60 is printed and cured by drying or heating or ultraviolet irradiation. 10 are individually separated by, for example, a punching method or a laser processing method. In addition, you may harden the terminal reinforcement part 60 after isolation | separation.

  According to such a manufacturing method, the flexible wiring board 10 including the terminal reinforcing portion 60 having the corrugated portion 70 serving as a bending stress dispersion portion is continuously and efficiently produced by, for example, a roll-to-roll method. can do.

  A flexible wiring board according to another example of the first embodiment of the present invention will be described below with reference to FIGS.

  FIG. 5 is a perspective view of a flexible wiring board provided with a terminal reinforcing portion having a taper-shaped bending stress dispersion portion, and FIG. 6 is a cross-sectional view of the main part of the flexible wiring board as seen from the line AA in FIG.

  As shown in FIG. 5, like the flexible wiring board 10 shown in FIG. 1, the flexible wiring board 120 has a conductive pattern 30 including a terminal portion 40 and an insulating layer 50 on one surface of the insulating board 20. Yes. Then, on the other surface of the insulating substrate 20, as a bending stress dispersion portion provided at the end of the terminal reinforcing portion 130 formed of a resin such as polyester, epoxy, or acrylic, as shown in FIG. The taper-shaped part 140 which provided the taper is formed. For example, in the case of the screen printing method, the terminal reinforcing portion 130 having the tapered portion 140 can be formed by changing the mesh size of the screen mask little by little in the tapered portion 140. Further, after the terminal reinforcing portion 130 is formed to have a uniform thickness, the tapered portion 140 may be formed at the end portion thereof by using, for example, laser processing or sand blast processing. These can be realized by changing the laser irradiation energy and the sandblast collision energy step by step so as to have a tapered shape.

  That is, by reducing the thickness of the taper-shaped portion 140 as the distance from the terminal portion 40 decreases, there is no portion where the rigidity in the longitudinal direction changes abruptly at the end portion of the terminal reinforcing portion 130. Therefore, even when a force for bending the flexible wiring board 120 in the plate thickness direction is applied, the conductive pattern is continuously deformed without inflection points due to the distribution of bending stress, as in the case of the flexible wiring board 10. Occurrence of 30 cracks and breaks can be prevented. Moreover, since the rigidity in the width direction of the terminal reinforcing portion 130 is uniform, it can be continuously deformed in the width direction.

  In particular, if the terminal portion 40 does not require a uniform rigid portion, the tapered portion 140 may be formed over the entire terminal reinforcing portion 130.

  Further, a flexible wiring board according to another example of the first embodiment of the present invention will be described below with reference to FIGS.

  FIG. 7 is a perspective view of a flexible wiring board provided with a terminal reinforcing part having a bending stress distribution part by multi-layer printing, and FIG. 8 is a cross-sectional view of the main part of the flexible wiring board as seen from line AA in FIG.

  As shown in FIG. 7, like the flexible wiring board 10 shown in FIG. 1, the flexible wiring board 150 has a conductive pattern 30 including a terminal portion 40 and an insulating layer 50 on one surface of the insulating board 20. Yes. And the bending stress dispersion | distribution part provided in the edge part of the terminal reinforcement part 160 formed with resin, such as polyester and an epoxy, on the other surface of the insulating substrate 20, as shown in FIG. By stacking and printing, the multi-stage printing unit 170 is provided with a step-like taper in the thickness direction. The terminal reinforcing portion 160 having the multi-step printed portion 170 is an upper portion that overlaps the lower resin layer 160A on the insulating substrate 20 side at the end when the terminal reinforcing portion 160 is formed by overlapping a plurality of resin layers. The resin layer 160B and a resin layer 160C (not shown) that overlaps the resin layer 160B are formed by gradually decreasing the size.

  The terminal reinforcing portion 160 printed and formed in this way has a portion where the rigidity is rapidly changed by reducing the thickness of the multi-step printing portion 170 at the end portion as the distance from the terminal portion 40 decreases. As a result, the same effect as the first embodiment can be obtained.

  As described above, according to the first embodiment of the present invention, the terminal reinforcing portion that reinforces the terminal portion to be inserted into the connector can be efficiently formed by resin printing. Furthermore, even when a force is applied to bend the flexible wiring board in the plate thickness direction in the longitudinal direction, the end of the terminal reinforcing part is discontinuous due to the bending stress distribution part formed at the end of the terminal reinforcing part of the insulating substrate. It does not become an inflection point that causes bending deformation. Therefore, since the end portion of the terminal reinforcing portion is continuously deformed without inflection points due to the dispersion of bending stress, it is possible to prevent the conductive pattern from cracking or breaking.

  In the description of the first embodiment, the shape of the bending stress distribution portion at the end of the terminal reinforcing portion has been described as the corrugated portion, but the present invention is not limited to this, and is shown in FIG. It is good also as such a sawtooth-shaped part 180A. Further, the shape of the bending stress dispersion portion at the end of the terminal reinforcing portion may be an uneven comb tooth shape 180B as shown in FIG. 9B, and the concave portion is U as shown in FIG. 9C. Even if it is character shape 180C, a convex part may be U-shaped. Furthermore, the same effect can be obtained even if the waveform shape portion, the sawtooth shape portion, or the comb shape is formed in combination with the configuration of the taper shape portion or the multistage printing portion. The same applies to the following embodiments.

  Furthermore, a flexible wiring board according to another example of the first embodiment of the present invention will be described below with reference to FIGS.

  10 is a perspective view of the flexible wiring board, and FIG. 11 is a cross-sectional view of the main part of the flexible wiring board as seen from the line AA in FIG.

  In FIG. 11, the terminal reinforcing portion 190 has a configuration in which a plurality of resin layers made of different resins are screen-printed and laminated. For example, in the terminal reinforcing portion 190, the outermost resin layer 190A that comes into contact with the connector is formed of a resin having a high elastic modulus (high rigidity), such as polyester, epoxy, or acrylic, and the other resin layers 190B are: It is formed of a resin having a low elasticity such as styrene, nitrile or acrylic rubber having a low elasticity (low rigidity). As a result, the resin layer 190A ensures the mechanical strength with the connector, and the resin layer 190B not only causes the bending stress dispersion portion by the corrugated shape portion 70, for example, but also the terminal reinforcing portion 190 as a whole to distribute the bending stress. Can be further enhanced. Here, the other resin layer 190B may have a multilayer structure instead of a single layer structure. In the case of a multilayer structure, the rigidity of the terminal reinforcing portion can be easily changed by adjusting the elastic modulus of each resin layer. The same applies to the following embodiments.

Further, in the embodiment of the present invention, the surface of the terminal reinforcing portion is formed by, for example, sandblasting or printing resin, for example, SiO ₂ , AlN or Al ₂ O having a size of about 1 μm to several tens μm. _The surface may be roughened by containing a filler made of an inorganic material such as ₃ and printing.

  With this configuration, when the flexible wiring board is inserted into the connector, the terminal portion is not easily removed from the connector due to the rough surface of the terminal reinforcing portion, and the connection reliability is improved.

  Furthermore, it is good also as a terminal reinforcement part structure which included electroconductive particles, such as a metal, in resin, or provided the metal layer in the resin layer of the laminated structure, or the surface. With this configuration, heat due to contact resistance generated at the terminal portion of the flexible wiring board can be dissipated, and external noise and radiation of electromagnetic waves from the terminal portion can be shielded. Therefore, connection with a high frequency apparatus etc. is attained. The present invention can also be applied to the following embodiments.

(Second Embodiment)
A flexible wiring board according to a second embodiment of the present invention will be described with reference to FIGS.

  FIG. 12 is a plan view of a flexible wiring board provided with a terminal reinforcing portion having a corrugated bending stress distribution portion. FIG. 13 is a cross-sectional view taken along the line PP in FIG.

  As shown in FIG. 12, the flexible wiring board 200 has a configuration of a terminal reinforcing portion 220 including a belt-shaped portion obtained by dividing the terminal reinforcing portion 60 of the flexible wiring substrate 10 of the first embodiment into a plurality of belt shapes by grooves 210. It is a thing. The configuration of other parts is the same as that of the flexible wiring board 10, and the description thereof is omitted.

  In FIG. 12, the terminal reinforcing portion 220 has a configuration in which two types of belt-like portions 230 and 240 having different lengths are alternately arranged, and at the inner end portion 250 that is not located on the outer periphery of the insulating substrate 20, The waveform has a plurality of peaks and valleys. Here, for example, a mountain corresponds to the belt-like portion 230, and a valley corresponds to the belt-like portion 240.

  With this configuration, the rigidity of the inner end portion 250 changes according to the shape change of the terminal reinforcing portion 220 from the large rigidity on the terminal portion 40 side to the small rigidity of the insulating substrate 20. Therefore, even if a force for bending the flexible wiring board 200 in the thickness direction is applied, discontinuous bending deformation does not occur. That is, there is an effect as a bending stress dispersion portion similar to the waveform shape portion 70 of the terminal reinforcing portion 60 of the flexible wiring board 10 of the first embodiment, in which continuous deformation occurs due to the dispersion of bending stress.

  Furthermore, in the terminal reinforcement part 220 consisting of a plurality of band-like parts 230, 240, the rigidity of the terminal reinforcement part 220 is adjusted by changing the number of divisions and dimensions (width, length, thickness) of the band-like parts 230, 240. You can also.

  Further, when the rigidity of the terminal reinforcing portion is kept at a predetermined size, the terminal reinforcing portion 220, that is, the entire terminal portion 40 can be equivalently increased in thickness, so that the contact pressure of the conductive pattern 30 against the contact of the connector is increased and stable. Contact can also be achieved.

  For example, when the thickness of the belt-like portions 230 and 240 is made constant, the rigidity can be increased by increasing the width of the individual belt-like portions 230 and 240, and conversely, the rigidity can be reduced by reducing the width. In addition, when the rigidity is made constant, it can be arbitrarily coped with, for example, increasing the thickness by reducing the width of each of the strips 230 and 240 and decreasing the thickness by increasing the width.

  In addition, in FIG. 12, although the front-end | tip of the strip | belt-shaped parts 230 and 240 was made into the round shape in the inner side edge part 250 of the terminal reinforcement part 220, this is not necessarily required, for example, sawtooth shape, a semicircle, and linear shape. There may be.

  Moreover, in the above description, the terminal reinforcement part 220 which divided | segmented the terminal reinforcement part 60 which has the waveform shape part 70 as a bending stress dispersion | distribution part of the flexible wiring board 10 shown in FIG. 1 in 1st Embodiment in strip | belt shape is described. However, it is not limited to this. For example, the terminal reinforcing portion 130 having the tapered portion 140 as the bending stress distribution portion of the flexible wiring board 120 shown in FIG. 5 and the terminal having the multi-stage printing portion 170 as the bending stress distribution portion of the flexible wiring substrate 150 shown in FIG. The reinforcing portion 160 can also be divided into strips so as to have the same function.

  Moreover, although the strip | belt-shaped parts 230 and 240 which comprise the terminal reinforcement part 220 were divided | segmented by the linear groove | channel 210, this invention is not limited to this. As long as it has an action of a bending stress dispersion portion at the end of the terminal reinforcing portion, it may be divided into arbitrary groove shapes such as a curved shape.

(Third embodiment)
A flexible wiring board according to a third embodiment of the present invention will be described below with reference to FIG.

  FIG. 14 is a plan view of a flexible wiring board provided with a terminal reinforcing portion having a corrugated bending stress dispersion portion and a reinforcing portion.

  As shown in FIG. 14, the flexible wiring board 300 needs to be reinforced in addition to the terminal reinforcing portion provided on the back surface of the terminal portion to be inserted and connected to the connector of the flexible wiring substrate 10 described in the first embodiment. The reinforcement part which has a bending stress dispersion | distribution part is provided also with respect to the other part.

  Specifically, the reinforcing portion is formed at the position indicated by hatching in FIG. 14 on the other surface of the flexible insulating substrate 310 having the conductive pattern 320 (only the main portion is indicated by a dotted line) formed on one surface. Is. For example, the terminal reinforcing portions 330 and 340 at both ends, the positioning reinforcing portion 350 for the positioning portion when fixed to other members, the mounting reinforcing portion 360 for the mounting portion of the electronic component, etc. When used, there is a bending reinforcement portion 370 for the bending portion and a bending reinforcement portion 380 for the bending portion of the conductive pattern 320. In these reinforcing portions, a corrugated portion 390 as a bending stress dispersion portion is provided at an end portion that is not located on the outer periphery of the insulating substrate 310.

  In addition, for example, the terminal reinforcing portions 330 and 340 at both ends, the positioning reinforcing portion 350 and the mounting reinforcing portion 360 are thick, and the bending reinforcing portion 370 and the bending reinforcing portion 380 are formed thin. It can be formed with a thickness. Needless to say, the same thickness may be used.

  As a result, even when the thin insulating substrate 310 is used to increase the flexibility of the flexible wiring substrate 300, it is possible to reinforce portions other than the terminal portions that are easily bent and unstable.

  In addition, these reinforcing portions 350, 360, 370, and 380 also have a corrugated portion 390 that serves as a bending stress dispersion portion at an end portion that is not located on the outer periphery of the insulating substrate 310. Therefore, when a force that bends the flexible wiring board 300 in the thickness direction is applied, the insulating substrate 310 does not discontinuously deform with the end portions of the reinforcing portions 350, 360, 370, and 380 as inflection points, so that bending stress is applied. Can be dispersed.

  In addition, for example, in the case of screen printing, these reinforcing portions 350, 360, 370, and 380 are made of the same printing device as the terminal reinforcing portions 330 and 340 by changing the number of meshes of the screen mask, the wire diameter of the mesh, etc. And the same resin such as epoxy can be printed at the same time.

  Thereby, while the mutual positional accuracy of the terminal reinforcement parts 330 and 340 and the reinforcement parts 350, 360, 370, and 380 becomes favorable, these reinforcement parts can be formed efficiently and inexpensively.

  In addition, if there exists a part which needs reinforcement other than said reinforcement part 350, 360, 370, 380, a reinforcement part can be provided similarly.

  Further, the above description is about the case where the bending stress distribution portion at the end portions of the terminal reinforcing portions 330 and 340 and the reinforcing portions 350, 360, 370, and 380 that are not located on the outer periphery of the insulating substrate 310 is the corrugated portion 390. As described above, it may be constituted by a tapered portion or a multi-stage printing portion.

  In the above description, the reinforcing portions 350, 360, 370, and 380 are formed on the other surface of the insulating substrate 310, but the present invention is not limited to this. For example, the insulating substrate 310 may be formed on one surface (the conductive pattern 320 forming surface). Furthermore, the conductive patterns 320 other than the terminal portions may be covered with an insulating layer made of acrylic resin, epoxy resin, or the like, and reinforcing portions 350, 370, and 380 may be formed thereon. With this configuration, since the portion other than the terminal reinforcing portion can be continuously formed on the same surface, productivity is improved.

  Further, the terminal reinforcing portion and the reinforcing portion may be configured by laminating resin layers made of different resins. For example, the outermost resin layer is formed of a resin having a high elastic modulus (high rigidity) such as polyester, epoxy, or acrylic, and the other resin layers are excellent in elasticity such as styrene, nitrile, or acrylic. You may form with low elastic modulus (small rigidity) resin, such as the rubber | gum of a type | system | group. Thereby, while ensuring the mechanical strength of the part which contacts a connector or another member, not only a bending stress dispersion | distribution part but the terminal reinforcement part and the whole reinforcement part can further raise the dispersion | distribution effect of a bending stress.

  Moreover, especially a reinforcement part etc. are good also as a structure which forms with resin with high adhesiveness, for example, and uses it for fixation with another member.

(Fourth embodiment)
A flexible wiring board according to a fourth embodiment of the present invention will be described with reference to FIG.

  FIG. 15 is a perspective view of a flexible wiring board provided with an insulating layer having a corrugated bending stress dispersion portion. In FIG. 15, the conductive pattern formation surface is shown on the upper side.

  As shown in FIG. 15, the flexible wiring board 400 includes a terminal reinforcing portion 60 having a corrugated portion 70 (not shown) on the other surface of the insulating substrate 20 described in the first embodiment. On the substrate, a corrugated portion 420 having a plurality of peaks and valleys is provided at a boundary portion with the terminal portion 40 of the insulating layer 410 made of an acrylic resin, an epoxy resin, or the like covering the conductive pattern 30 excluding the terminal portion 40. Is.

  The purpose of this is that the flexible wiring board 400 usually has a portion where the insulating layer 410 on the conductive pattern 30 and the terminal reinforcing portion 60 overlap, and the rigidity increases by becoming thicker than the other portions. It is to reduce the increase. That is, the corrugated portion 420 is provided as a bending stress dispersion portion at the boundary portion between the portion where the conductive pattern 30 is exposed as the terminal portion 40 and the insulating layer 410 in this way.

  As a result, when a force is applied to bend the flexible wiring board 400 in the thickness direction, the insulating substrate 20 is not discontinuously deformed with the boundary portion as an inflection point, and the bending stress is dispersed, so that the conductive pattern 30 The flexible wiring board 400 is less prone to cracks and breaks.

  In the above description, the flexible wiring board including the terminal reinforcing portion 60 having the wave shape portion 70 as the bending stress dispersion portion has been described. However, in this configuration, the bending stress dispersion portion is a flexible portion in which the taper shape portion 140 is provided. You may apply to the flexible wiring board 150 which is the wiring board 120 or the multistage printing part 170. FIG. Further, the corrugated portion 420 of the insulating layer 410 may be similarly formed with a tapered portion or a multistage printed portion configuration. In addition, each reinforcing portion shown in the third embodiment may be formed on the insulating layer 410.

(Fifth embodiment)
A flexible wiring board according to a fifth embodiment of the present invention will be described with reference to FIGS.

  16 is a perspective view of the flexible wiring board, and FIG. 17 is a cross-sectional view of the main part of the flexible wiring board as seen from the line AA in FIG.

  As shown in FIG. 16, the flexible wiring board 450 is a copper foil pasted on one surface of an insulating substrate 20 having a thickness of, for example, about 50 μm to 200 μm having flexibility such as polyethylene terephthalate and polyimide. The conductive pattern 30 is formed on the insulating substrate 20 by printing a conductive resin such as a polyester resin or an epoxy resin in which silver or copper is dispersed. An insulating layer 50 such as an acrylic resin or an epoxy resin is formed with a thickness of, for example, 50 μm so as to cover at least the conductive pattern 30. Furthermore, on the other surface of the insulating substrate 20, the terminal reinforcing portion 460 is formed with a plurality of resin layers having a laminated structure on the back surface position of the terminal portion 40 where the conductive pattern 30 is exposed, for example, with a thickness of about 50 μm to 200 μm. Is formed.

  Then, as shown in FIG. 17, the terminal reinforcing portion 460 is excellent in elasticity of the resin layer 460A on the insulating substrate 20 side, and has an elastic modulus (small rigidity) such as styrene, nitrile or acrylic rubber. The resin layer 460B, which is a low resin, is formed by printing a resin such as polyester, epoxy, or acrylic with a high elastic modulus (high rigidity) by screen printing or the like.

  With this configuration, the resin layer 460B can ensure mechanical strength with the connector, and the bending stress can be dispersed throughout the terminal reinforcing portion 460 due to the displacement deformation of the resin layer 460A. Here, the resin layer 460A may have a multilayer structure instead of a single layer structure. In the case of a multilayer configuration, the rigidity of the terminal reinforcing portion 460 can be easily changed by adjusting the elastic modulus of each resin layer.

  Needless to say, the configurations of the first to fourth embodiments can be applied to the present embodiment.

  Moreover, in each embodiment mentioned above, you may form a flexible wiring board with the conductive pattern which has the same base resin, a terminal reinforcement part, a reinforcement part, and an insulating layer. For example, as the base resin, resins such as polyester, epoxy, and acrylic can be used. Thereby, the adhesion strength with the insulating substrate can be made uniform. Furthermore, by reducing the difference in the expansion coefficient or the like, it is possible to improve the warp of the flexible wiring board due to thermal history.

  By using the flexible wiring board described above for a portable terminal, an electronic device, or the like, an electronic device with excellent reliability can be realized.

  The flexible wiring board according to the present invention is reliable because the insulating substrate does not undergo discontinuous deformation or deformation with a small bending radius with the end of the terminal reinforcing portion as the inflection point even when a force to bend in the thickness direction is applied. Excellent. Therefore, it is useful in a small-sized and high-density electronic device that uses a thin and highly flexible flexible wiring board.

The perspective view of the flexible wiring board which concerns on the 1st Embodiment of this invention Sectional drawing of the principal part of the flexible wiring board seen from the AA line of FIG. Sectional drawing of the state which connected the flexible wiring board which concerns on the 1st Embodiment of this invention to the connector The perspective view explaining the manufacturing method of the flexible wiring board based on the 1st Embodiment of this invention The perspective view of the flexible wiring board which concerns on another example of the 1st Embodiment of this invention. Sectional drawing of the principal part of the flexible wiring board seen from the AA line of FIG. The perspective view of the flexible wiring board which concerns on another example of the 1st Embodiment of this invention. Sectional drawing of the principal part of the flexible wiring board seen from the AA line of FIG. The perspective view of the flexible wiring board which concerns on another example of the 1st Embodiment of this invention. The perspective view of the flexible wiring board which concerns on another example of the 1st Embodiment of this invention. Sectional drawing of the principal part of the flexible wiring board seen from the AA line of FIG. The top view of the flexible wiring board which concerns on the 2nd Embodiment of this invention Sectional drawing in the PP line of FIG. The top view of the flexible wiring board which concerns on the 3rd Embodiment of this invention The perspective view of the flexible wiring board based on the 4th Embodiment of this invention. The perspective view of the flexible wiring board which concerns on the 5th Embodiment of this invention Sectional drawing of the principal part of a flexible wiring board seen from the AA line of FIG. Perspective view of a conventional flexible wiring board Sectional drawing explaining the state which connects the conventional flexible wiring board to a connector Sectional view of a flexible wiring board with a conventional reinforcing plate Sectional view of a flexible wiring board with a conventional reinforcing layer The perspective view of the other flexible wiring board which formed the conventional reinforcement layer

Explanation of symbols

10, 120, 150, 200, 300, 400, 450 Flexible wiring board 20, 310 Insulating board 30, 320 Conductive pattern 40 Terminal part 50, 410 Insulating layer 60, 130, 160, 190, 220, 330, 340, 460 Terminal Reinforcing part 70, 390, 420 Corrugated part 80 Connector 90 Contact 100 Inflection point 110 Flexible insulating sheet 140 Tapered part 160A, 160B, 160C, 190A, 190B, 460A, 460B Resin layer 170 Multi-stage printing part 180A Serrated shape Part 180B comb tooth shape 180C U-shaped 210 groove 230, 240 band-like part 250 inner end part 350 (positioning) reinforcing part 360 (attachment) reinforcing part 370 (bending) reinforcing part 380 (bending) reinforcing part

Claims (15)

An insulating substrate having flexibility;
A conductive pattern formed on one surface of the insulating substrate;
On the other surface of the insulating substrate, a terminal reinforcing portion formed by printing a resin containing a filler made of an inorganic material on at least the back surface of the terminal portion where the conductive pattern is exposed and having a roughened surface. A flexible wiring board having a bending stress distribution portion at an end portion of the insulating substrate around the terminal reinforcing portion that is not located on the outer periphery of the insulating substrate. The flexible wiring board according to claim 1, wherein as the bending stress dispersion portion, the shape of the end portion of the terminal reinforcing portion that is not located on the outer periphery of the insulating substrate is a wave shape. The flexible wiring board according to claim 1, wherein a taper is provided in the thickness direction at the end portion of the terminal reinforcing portion that is not located on the outer periphery of the insulating substrate as the bending stress dispersion portion. The flexible wiring board according to claim 1, wherein the terminal reinforcing portion is formed by laminating a plurality of resin layers. 5. The elastic modulus of the resin layer of the outermost layer among the terminal reinforcing portions formed by stacking a plurality of the resin layers is higher than the elastic modulus of the other resin layers. Flexible wiring board. The resin layer formed to overlap the resin layer on the insulating substrate side at the end portion that is not positioned on the outer periphery of the insulating substrate around the terminal reinforcing portion formed by printing a plurality of resin layers. The flexible wiring board according to claim 1, wherein the bending stress dispersion portion is formed by sequentially decreasing the size. The flexible wiring board according to claim 1, wherein the terminal reinforcing portion is divided into a plurality of strips by a groove. On the other surface of the insulating substrate, at least one of a positioning part at the time of fixing to another member, a mounting part of an electronic component, a bent part when bent and used, or a bent part of the conductive pattern On the other hand, the flexible wiring board according to claim 1, wherein a reinforcing portion having the bending stress dispersion portion is provided at the end portion not located on the outer periphery of the insulating substrate. Positioning at the time of fixing to another member on an insulating layer formed by printing an insulating resin on the conductive pattern formed on one surface of the insulating substrate so as to cover a portion excluding the terminal portion The bending stress dispersion portion at the end portion that is not located on the outer periphery of the insulating substrate with respect to at least one of the bent portion when bent and used, or the bent portion of the conductive pattern, The flexible wiring board according to claim 1, further comprising a reinforcing portion. The flexible wiring board according to claim 8 or 9 , wherein the reinforcing portion provided on the insulating substrate is formed by printing the same resin as the terminal reinforcing portion. The flexible wiring board according to claim 10 , wherein the reinforcing portion provided on the insulating substrate is printed and formed with a thickness different from that of the terminal reinforcing portion. On the conductive pattern formed on one surface of the insulating substrate, the bent portion is formed at a boundary portion between the terminal portion of the insulating layer formed by printing an insulating resin so as to cover a portion excluding the terminal portion. the flexible wiring board according to claim 1 or claim 9, characterized in that a stress dispersion portion. The flexible wiring substrate according to item 1 one of claims 1 to 12, wherein the terminal reinforcing portion or the reinforcing portion and the insulating layer and the conductive pattern, characterized by comprising the same base resin. Forming a conductive pattern of a plurality of flexible wiring boards on one surface of an insulating sheet having flexibility; and
On the other side of the insulating sheet, on the back surface of the terminal portion where the conductive pattern of the plurality of flexible wiring boards is exposed , a resin containing a filler made of an inorganic material is printed to have a bending stress dispersion portion and the surface Forming a roughened terminal reinforcing portion,
A step of individually separating the plurality of flexible wiring boards formed on the insulating sheet. An electronic apparatus characterized by using a flexible wiring board according to any one of claims 1 to 13.

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