JP2018174201A - Wiring board, structure including the wiring board, and method for mounting wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board and a method for mounting a wiring board, capable of easily avoiding a situation where current cannot be carried due to the disconnection of a circuit pattern when mounting work is performed while the wiring board is extended.SOLUTION: A wiring board of the present invention is a wiring board including a circuit pattern 1 formed of a linear metal foil 10 on at least one surface of a resin substrate. A part or the all of the circuit pattern 1 has a structure where the metal foil 10 is folded in a zigzag shape. In a folded portion 15 of a metal foil folded in a zigzag shape, the metal foil is branched on an outer peripheral side and an inner peripheral side along a folded shape.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wiring board, a structure including the wiring board, and a method for attaching the wiring board.

  Conventionally, various substrates such as a glass epoxy substrate, a polyimide flexible printed circuit board, a card type antenna substrate represented by RFID, and the like are known as circuit wiring boards, and components for forming electronic components, etc. It is an indispensable member. These wiring boards are formed in a planar shape such as a sheet shape, and are used by being incorporated into a member such as a board type or a card type stored in a housing, for example.

  In recent years, electronic devices, various machines, various devices, and the like have complicated shapes and remarkable miniaturization, and therefore, development of a wiring board that can be adapted to such various structures is required. . In particular, it is difficult to apply a conventionally used wiring board for a planar shape to a member having a curved surface shape and a three-dimensional shape. From this viewpoint, various wiring boards that can be attached in a complicated shape have been proposed.

  For example, Patent Document 1 discloses a highly reliable flexible circuit body that can be flexibly deformed and can prevent wear of a flexible wiring board even if it is rubbed. This flexible circuit body includes a wiring and a thermoplastic elastomer on an insulating film, and is formed into a three-dimensional shape by molding at a temperature below the melting point.

JP 2012-231018 A

  However, in the technique disclosed in Patent Document 1, when the wiring board is used for application to a solid body having a curved surface while being stretched, the circuit board may be stretched too much and the circuit pattern may be disconnected without notice. When a wiring board is attached to a base material having a curved surface or the like, it is necessary to extend the wiring board as much as possible to prevent sagging. However, if the circuit pattern is broken due to excessive stretching of the wiring board, the circuit pattern formed on the wiring board becomes non-conductive, and the substrate on which such a circuit pattern is attached is discarded as a defective product. There was a problem that the yield decreased.

  The present invention has been made in view of the above, and a wiring board and a wiring board mounting method that can easily prevent disconnection of a circuit pattern and easily avoid electrical connection when performing installation work while stretching. The purpose is to provide.

  As a result of intensive research to achieve the above object, the present inventor achieved the above object by forming a folded portion of a metal foil folded in a zigzag shape in a branched structure and providing a so-called sacrificial pattern. The present inventors have found that this can be done and have completed the present invention.

That is, the present invention includes, for example, the subject matters described in the following sections.
Item 1. A wiring board provided with a circuit pattern formed of a linear metal foil on at least one side of a resin board,
A part or all of the circuit pattern has a structure in which the metal foil is folded in a zigzag shape,
The wiring board in which the folded portion of the metal foil folded in a zigzag shape is branched along the folded shape into the outer peripheral side and the inner week side.
Item 2. Item 2. The wiring board according to Item 1, wherein a length of the metal foil on the outer peripheral side is longer than a length of the metal foil on the inner week side.
Item 3. Item 3. The wiring board according to Item 1 or 2, wherein the number of branches is 3 or more.
Item 4. Item 4. The wiring board according to any one of Items 1 to 3, wherein the metal foil includes at least one of an aluminum foil and a copper foil.
Item 5. Item 5. The wiring substrate according to any one of Items 1 to 4, wherein the resin substrate includes one or more selected from the group consisting of polyethylene, polypropylene, polyester, acrylic resin, and polycarbonate.
Item 6. Item 6. A structure including the wiring board according to any one of Items 1 to 5.
Item 7. The wiring board attachment method which attaches the wiring board of any one of Claims 1-5 to a base material.

  When the wiring board according to the present invention is used, it is easy to prevent disconnection of the circuit pattern when performing the attaching operation to the target base material while being stretched, and it is possible to easily avoid a situation in which electrical connection is disabled.

  Since the wiring board mounting method according to the present invention uses the wiring board, it is easy to prevent disconnection of the circuit pattern when the mounting work is performed on the target base material while extending the wiring board, and it is easy to prevent a situation where electrical connection is disabled. Can be avoided.

An example of the circuit pattern with which the wiring board of this invention is provided is shown, (a) is the top view of the whole circuit pattern, (b) is the top view which expanded a part of circuit pattern. It is sectional drawing which shows the outline of the layer structure of the wiring board obtained by each Example and the comparative example. It is a reference figure explaining the method of measuring the extension rate of a circuit pattern. It is an image which shows a mode that the wiring board was extended to the longitudinal direction, and the state after extending.

  Hereinafter, embodiments of the present invention will be described in detail.

  The wiring board of the present invention includes a circuit pattern formed of a linear metal foil on at least one surface of a resin substrate. In particular, the wiring board of the present invention has a structure in which a part or all of the circuit pattern is folded in a zigzag shape, and the folded portion of the zigzag folded metal foil is a folded shape. The metal foil branches along the outer peripheral side and the inner week side.

  In the wiring board of the present invention, the circuit pattern has a specific structure, so that it is possible to easily avoid the situation where the circuit pattern is disconnected due to the disconnection of the circuit pattern when the wiring board is stretched and attached to the target base material. it can.

<Resin substrate>
The resin substrate is a material that becomes a base material of the wiring substrate. The type of the resin substrate is not particularly limited, and a wide variety of resin substrates that are applied to known wiring substrates can be used. The resin substrate is preferably formed of a material that has an insulating property and is extensible in at least one direction. In particular, it is preferable that the resin substrate easily stretches in the longitudinal direction. In this case, the effect of the present invention is more easily exhibited.

  For example, the resin forming the resin substrate is vinyl chloride, EVA, polyethylene, polypropylene, natural rubber, styrene butadiene rubber, isoprene rubber, butadiene rubber, chloroprene rubber, acrylonitrile-butadiene rubber, isobutylene-isoprene rubber, ethylene-propylene rubber. , Ethylene-propylene-diene rubber (EPDM), urethane rubber, silicone rubber, fluorine rubber and the like.

  Among them, the resin forming the resin substrate preferably contains one or more selected from the group consisting of polyethylene, polypropylene, polyester, acrylic resin, and polycarbonate. In this case, the resin substrate has excellent insulating properties and stretchability. Therefore, the obtained wiring board is more easily extended and flexible. These resins may be modified or may be copolymers with other resins.

  The resin substrate can be formed of only one kind of resin, or can be formed of only two or more kinds of resins. The resin substrate may contain additives such as a dispersion stabilizer and a light stabilizer as necessary.

  The shape of the resin substrate can be, for example, the same shape as a resin substrate used for a known wiring substrate, and can be a long sheet shape, a long film shape, or the like. The resin substrate may be either a single layer or a multilayer.

  The resin substrate can be obtained by, for example, a known production method, and a commercially available resin substrate can also be adopted.

  The thickness of the resin substrate is not particularly limited, and can be set to any thickness depending on the desired wiring substrate. For example, the thickness of the resin substrate can be set to 30 to 500 μm. In this case, it is easy to prevent a decrease in strength, to suppress deformation, and to improve moldability. The thickness of the resin substrate is more preferably 100 to 300 μm.

  The resin substrate can also have an adhesive layer on one or both sides. In this case, the adhesion between the resin substrate and another layer such as a metal foil is good.

  For example, the pressure-sensitive adhesive layer can be the same as the pressure-sensitive adhesive layer used in a known wiring board. For example, the pressure-sensitive adhesive layer can be formed of an acrylic resin, a urethane resin, a silicon resin, a vinyl chloride resin, or the like. The method for forming the pressure-sensitive adhesive layer is not particularly limited, and a wide variety of known forming methods can be employed.

<Circuit pattern>
1A and 1B show an example of a circuit pattern 1 provided in a wiring board of the present invention. FIG. 1A is a plan view of the entire circuit pattern 1 and FIG. 1B is an enlarged plan view of a part of the circuit pattern 1.

  As shown in FIG. 1, the circuit pattern 1 has a structure in which a linear metal foil 10 (metal foil line) is folded in a zigzag manner. The linear metal foil 10 (metal foil line) folded in a zigzag manner can be formed by, for example, one straight metal foil line (however, it has a plurality of points that are branched off and merged again). In FIG. 1, only the circuit pattern 1 is shown, and the resin base material and the like are not shown.

  A portion 15 surrounded by a broken line in FIG. 1 indicates a portion where the metal foil 10 is folded in a structure folded in a zigzag manner. In the present specification, the folded portion of the metal foil 10 is referred to as a “folded portion 15”.

  The circuit pattern 1 is formed to be long, for example. The circuit pattern 1 formed in a long shape is elongated while being repeatedly folded back in the longitudinal direction, and thus can have a structure that is folded in the longitudinal direction.

  The circuit pattern 1 can have a structure in which only part of the circuit pattern 1 is folded in a zigzag shape, or can have a structure in which the entire circuit pattern 1 is folded in a zigzag shape. That is, the circuit pattern 1 may have a structure in which the circuit pattern 1 is continuously folded in a zigzag shape from one end to the other end, or may have a structure in which the circuit pattern 1 is zigzag-folded in a piecewise manner.

  As long as the circuit pattern 1 has a structure folded in a zigzag manner, the shape of the folded portion 15 is not particularly limited. For example, the circuit pattern 1 has a structure folded while being bent as in the embodiment shown in FIG. Can do. Moreover, the folding | returning part 15 can also be made into the structure bent. As described above, the circuit pattern 1 can form various zigzag shapes, and can take various meandering shapes such as a wave shape, a zigzag shape, and a hairpin shape.

  As shown in FIGS. 1A and 1B, in the folded portion 15, the metal foil is branched into the outer peripheral side and the inner week side along the folded shape. In the present specification, a branch on the outer peripheral side in the folded portion 15 is referred to as a first branch 11, and a branch on the inner peripheral side in the folded portion 15 is referred to as a second branch 12. As used herein, the inner periphery of the folded portion 15 refers to the inner side of the folding. For example, if the folded portion 15 is curved, it refers to the inside of a region surrounded by the curved metal foil 10.

  As shown in FIG. 1B, both the first branch 11 and the second branch 12 of the folded portion 15 are formed from one branch point 2a to the other branch point 2b. For example, the linear metal foil 10 branches to the first branch 11 and the second branch 12 with one branch point 2a as the starting point, and the first branch 11 and the second branch 12 have the other branch point 2b as the end point. Join again. As described above, the folded portion 15 is a portion formed with at least the first branch 11 and the second branch 12.

  In the folded portion 15 branched to the outer peripheral side and the inner week side, the length of the outer peripheral side metal foil 10 can be longer than the length of the inner week side metal foil 10. That is, the length of the first branch 11 can be made longer than the length of the second branch 12.

  The length of the 1st branch 11 here and the length of the 2nd branch 12 are the distance along each shape from one branch point 2a to the other branch point 2b. In other words, the length of the first branch 11 and the length of the second branch 12 are the distance from the branch point 2a to the branch point 2b when the curved or bent metal foil 10 is stretched and regarded as a straight line. it can. In this way, the first branch 11 is longer than the second branch 12 by branching into the first branch 11 on the outer peripheral side and the second branch 12 on the inner peripheral side at the turn-back portion 15.

  When the wiring board is extended in the longitudinal direction, the first branch 11 and the second branch 12 of the folded portion 15 also extend in the same direction. In the wiring board of the present invention, since the circuit pattern 1 is formed as described above, when the wiring board extends in the longitudinal direction, the second branch 12 shorter than the length of the first branch 11 is cut first. Is done. Even if the second branch 12 is cut by extending the wiring board, the circuit pattern 1 formed on the wiring board can be electrically connected as long as the first branch 11 is not cut. Therefore, the second branch 12 can serve as a “sacrificial pattern” in the circuit pattern 1. On the other hand, the first branch 11 can be called a “main line” in the circuit pattern 1.

  In attaching the wiring board to the base material while extending the wiring board, the extension of the wiring board can be adjusted by using the presence or absence of disconnection as an index while visually checking the second branch 12. That is, when the wiring board is extended and attached to the base material, if the second branch 12 that is the sacrificial pattern is cut by the extension, the first branch 11 may also be cut if the extension is further extended. The presence or absence of cutting can be used as one guideline for the extension of the wiring board.

  Therefore, when the wiring board of the present invention is used, when the wiring board is attached to the base material while being stretched, it is easy to attach the circuit pattern to the base material without making the circuit pattern non-conductive. Moreover, since the wiring board is extended while visually confirming whether or not the sacrificial pattern is cut, the wiring board can be attached to the base material in a fully extended state, and the wiring board can be more closely attached to the base material. As described above, when the wiring board according to the present invention is used, it is possible to easily avoid a situation in which electrical connection is not possible due to the disconnection of the circuit pattern when performing the attaching operation to the target base material while stretching, and it is easy to suppress the decrease in the yield of the product. .

  Even if the second branch 12 that is the sacrificial pattern is cut in a state in which the wiring board is attached to the target base material, the circuit pattern 1 is as long as the first branch 11 that is the main line is not cut. Dentsu is possible.

  All of the folded portions 15 formed in the circuit pattern 1 may have the first branch 11 and the second branch 12, or a part of the folded portions 15 formed in the circuit pattern 1. Only the first branch 11 and the second branch 12 may be included. From the viewpoint of easily confirming the disconnection state of the sacrificial pattern, it is preferable that all the folded portions 15 have the first branch 11 and the second branch 12.

  It is also preferable that the second branch 12 has a structure that is easier to cut than the first branch 11. For example, the line width of the second branch 12 as the sacrificial pattern may be made thinner than the line width of the first branch 11 as the main line. Or the thickness of the 2nd branch 12 as a sacrificial pattern is made thinner than the thickness of the 1st branch 11 as a main line. In these cases, since the second branch 12 is more likely to be cut than the first branch 11, the possibility that the first branch 11 is cut by extending the wiring board can be further reduced.

  The line width of the linear metal foil 10 is not particularly limited. For example, the line width of the metal foil 10 can be 0.1 mm or more and 3 mm or less. In this case, when the wiring substrate is stretched and attached to the target substrate, the metal foil is immediately opened when the folded portion 15 is opened. The wiring substrate 10 can be extended without being cut. The line width of the metal foil 10 is particularly preferably 0.5 mm or more and 2 mm or less.

  In the folded portion 15, the number of branches is preferably 3 or more. In this case, in the folded-back portion 15, the outermost metal foil line can be a main line, and the rest can be a sacrificial pattern. If the circuit pattern has this structure, it is more reliable if the wiring board is stretched until the sacrificial pattern closest to the main line is cut and attached so that one or all of the remaining sacrificial patterns are not disconnected. It is possible to prevent the main line from being cut.

  In the structure folded in a zigzag shape, the folding width D and the amplitude H (see FIG. 1) are not particularly limited, and can be appropriately selected according to the required shape of the circuit pattern 1. The folding width D can be a linear distance from one branch point 2a to the other branch point 2b. The amplitude H can be regarded as a distance between a tangent line passing through the apex of one folded portion 15 of the circuit pattern 1 and a tangent line passing through the apex of the folded portion 15 protruding in the opposite direction to the folded portion 15.

  The kind of metal foil for forming the circuit pattern is not particularly limited, and various metals for forming a circuit pattern of a known wiring board can be widely used, for example.

  The metal foil preferably includes at least one of an aluminum foil and a copper foil. In this case, the circuit pattern can be easily formed. The metal foil may be formed of only an aluminum foil or may be formed of only a copper foil. The metal foil may be formed of only aluminum and copper.

  As the aluminum foil, soft materials or hard materials such as 1030, 1N30, 1050, 1100, 8021, and 8079 defined by JIS (AA) can be used. The thickness of the aluminum foil is, for example, 5 to 140 μm. From the viewpoint of workability, it is more preferable to use an aluminum foil that is a soft material of 1N30, 8021, and 8079 and has a thickness of 20 to 50 μm.

  The circuit pattern can be formed in a desired shape by etching the metal foil. When the etching process is employed, for example, it can be performed under the same conditions as the etching process employed for forming a circuit pattern of a known wiring board.

  The circuit pattern is formed on at least one side of the resin substrate. The circuit pattern can be formed only on one side of the resin substrate, or can be formed on both sides of the resin substrate. When the circuit pattern is formed on both surfaces of the resin substrate, the circuit pattern can have the same shape. That is, the line width, the folding width D, the amplitude H, the total length of the circuit pattern, and the like forming the circuit pattern can all be made the same. In this case, it is preferable that the circuit patterns formed on the one surface and the other surface are overlapped without being shifted from each other in the thickness direction of the resin substrate. That is, the circuit patterns formed on one surface and the other surface can be in a plane-symmetrical relationship with respect to the resin substrate.

  When the circuit pattern is formed on both sides, the operator can confirm whether the sacrificial pattern is disconnected while looking at the front and back surfaces of the wiring board, which makes the work easier. .

  An adhesive layer may be formed on the surface of the circuit pattern opposite to the resin substrate. This pressure-sensitive adhesive layer has the same configuration as described above, and the formation method can also be the same as described above. Since the adhesive layer is formed on the surface opposite to the resin substrate side of the circuit pattern, the circuit board can be easily attached to the object even if the adhesive is not applied to the object to which the wiring board is attached. Can be attached.

<Separator>
The other configuration of the wiring board is not limited as long as the circuit pattern is provided on the resin substrate. For example, the wiring board can have the same configuration as a known wiring board. For example, when a pressure-sensitive adhesive layer is formed on a resin substrate or a circuit pattern, the wiring board can have a separator that protects the pressure-sensitive adhesive layer.

  As the separator, for example, a peelable sheet, a film, or the like can be adopted. For example, a known separator can be widely used. Examples of the separator include paper, PET, and aluminum foil.

  The separator is removed when the wiring board is attached to the target base material.

<Wiring board>
The wiring board of the present invention can be formed, for example, by laminating the resin base material, the pressure-sensitive adhesive layer, and the circuit pattern in this order. Moreover, a separator can be provided on the surface opposite to the circuit pattern side of the resin substrate via an adhesive layer.

  The wiring board of the present invention is formed, for example, by laminating the resin base material, the pressure-sensitive adhesive layer, and the circuit pattern in this order, and on the surface opposite to the resin base material side of the circuit pattern. A separator can be provided via the pressure-sensitive adhesive layer. In this case, a pressure-sensitive adhesive layer can be further provided on the surface of the resin substrate opposite to the circuit pattern side.

  When the wiring board is provided with circuit patterns on both sides, for example, the resin base material, the pressure-sensitive adhesive layer, and the first circuit pattern are laminated in this order, and further, the first circuit pattern of the resin base material and The second circuit pattern is formed on the opposite surface through an adhesive layer, and a separator is provided on the surface opposite to the resin substrate of the second circuit pattern through the adhesive layer. Can do.

  The wiring board of the present invention can be formed in a shape such as a long sheet. The wiring board is extensible in the longitudinal direction, and can be attached to the target base material while extending the wiring board in the longitudinal direction. In this case, the wiring board can be bonded while being stretched so that the pressure-sensitive adhesive layer side adheres to the target base material. In extending the wiring board in the longitudinal direction, the wiring board can be heated.

  Since the wiring board includes the circuit pattern having the above-described structure, it can be easily attached to the target substrate without cutting the main line of the circuit pattern.

  The method for manufacturing the wiring board is not particularly limited, and for example, a well-known method for manufacturing a wiring board can be widely adopted. For example, an adhesive layer is formed on a resin base material, and a metal foil is formed on the adhesive layer. Thereafter, the metal foil is etched to form a metal foil having a desired shape, which can be obtained as a circuit pattern. As a method for forming the metal foil on the resin substrate, for example, a known heat laminating method, vacuum laminating method or the like can be employed.

  The wiring board can be attached to a target substrate having various shapes, and even if it is attached to a substrate having a complicated shape, such as a substrate having a curved shape or a substrate having a three-dimensional shape, a circuit pattern It is possible to prevent a situation in which the main line is disconnected and the circuit pattern becomes inoperable. Moreover, since the wiring substrate can be bonded to the target substrate while being stretched as strongly as possible, it can be more closely attached.

  For this reason, the structure including the wiring board of the present invention is less likely to be unable to conduct electricity, and the circuit pattern is less likely to be disconnected even after the wiring boards are bonded together, so that stable performance can be maintained over a long period of time.

  In the method of attaching the wiring board of the present invention to the target base material, for example, the sacrificial pattern (inner circumference side branch) is disconnected and the wiring board is extended in the longitudinal direction so that the main line (outer side branch) is not disconnected. In this state, the wiring board is attached to the target base material. Thereby, the operator can easily attach the wiring board to the target base material without disconnecting the main line of the circuit pattern when attaching the wiring board.

  The wiring board of the present invention can be suitably used for various base materials such as handle members for automobiles, constituent members for robots, and other flexible base materials.

  EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to the aspect of these Examples.

Example 1
A long aluminum foil (1N30, manufactured by Toyo Aluminum Co., Ltd.) having a thickness of 30 μm, an adhesive (PC18, manufactured by Reader Co., Ltd.), and a long resin substrate (EPDM, manufactured by Kureha Elastomer Co., Ltd.) having a thickness of 300 μm are used. A laminate was obtained by sequentially stacking by a known method.

  Next, the aluminum foil of this laminate was etched to form a circuit pattern having a structure folded in a zigzag manner, thereby obtaining a wiring board. The line width of the circuit pattern was 1 mm. The folded portion of the circuit pattern has a curved shape, and the aluminum foil was branched into the outer peripheral side and the inner week side along the folded shape (see FIG. 1). The outer peripheral side was the main line of the circuit pattern, and the inner peripheral side was the sacrificial pattern. The extension rate of the main line was 1.58, and the extension rate of the sacrificial pattern was 1.12. In addition, the separator was provided in the surface on the opposite side to the circuit pattern of a resin base material through the adhesive layer (7021, Teraoka Seisakusho).

(Example 2)
A long first aluminum foil (1N30, manufactured by Toyo Aluminum Co., Ltd.) having a thickness of 30 μm, an adhesive (PC18, manufactured by Reader Co., Ltd.), and a long resin substrate (EPDM, manufactured by Kureha Elastomer Co., Ltd.) having a thickness of 300 μm. Were laminated in this order by a known method. Further, a long second aluminum foil (1N30, manufactured by Toyo Aluminum) having a thickness of 30 μm on the surface opposite to the first aluminum foil of the resin base material is used as an adhesive (PC18, manufactured by Leader Co., Ltd.). It laminated | stacked through the layer and obtained the laminated body.

  Next, the aluminum foil of the laminate was etched to form a circuit pattern having a structure folded in a zigzag manner on both sides to obtain a wiring board. The circuit patterns formed from the first aluminum foil and the second aluminum foil were used as a first circuit pattern and a second circuit pattern, respectively. The line widths of the first circuit pattern and the second circuit pattern were both 1 mm. The folded portions of the circuit patterns on both sides were in a curved shape, and the aluminum foil was branched into the outer peripheral side and the inner week side along the folded shape (see FIG. 1). The outer peripheral side was the main line of the circuit pattern, and the inner peripheral side was the sacrificial pattern. Both the first circuit pattern and the second circuit pattern had the main line extension rate of 1.47 and the sacrificial pattern extension rate of 1.22. In addition, the separator was provided in the surface on the opposite side to the circuit pattern of a resin base material through the adhesive layer (7021, Teraoka Seisakusho).

(Example 3)
The circuit pattern is formed so that the extension rate of the main line is 1.77, the extension rate of the sacrificial pattern is 1.33, and only the adhesive layer is provided on the surface opposite to the circuit pattern of the resin substrate. A wiring board was obtained in the same manner as in Example 1 except that a separator was provided on the surface of the circuit pattern opposite to the resin base via an adhesive layer.

Example 4
The circuit pattern is formed so that the extension rate of the main line is 1.58 and the extension rate of the sacrificial pattern is 1.12. Further, the line width of the main line is 1 mm and the line width of the sacrificial pattern is 0.5 mm. A wiring board was obtained in the same manner as in Example 3 except that the circuit pattern was formed.

(Comparative Example 1)
A wiring board was obtained in the same manner as in Example 1 except that the circuit pattern having only the main line was formed without providing the sacrificial pattern.

(Comparative Example 2)
A wiring board was obtained in the same manner as in Example 3 except that the circuit pattern having only the main line was formed without providing the sacrificial pattern.

  FIG. 2 is a cross-sectional view of the layer structure of the wiring board obtained in each example and comparative example. 2A shows the layer configuration of Example 1 and Comparative Example 1, FIG. 2B shows the layer configuration of Example 2, and FIG. 2C shows the layer configuration of Examples 3, 4 and Comparative Example 2. FIG.

<Measurement method of extension rate>
FIG. 3 shows a reference diagram for explaining a method of measuring the extension rate of the circuit pattern. The extension rate of the metal foil on the outer periphery (main line) and inner periphery (sacrificial pattern) of the folded portion in the circuit pattern formed on the wiring board is expressed by the following formula (1).
Extension rate = B / A (1)
Calculated from

  Here, A is a linear distance between the bending points 2a and 2b in the curved portion of the folded portion. B is the total length of the curved portion of the folded portion in the main line or the sacrificial pattern. The value of B was calculated from r and θ by measuring the radius r and the angle θ as shown in FIG. Since the main line or the sacrificial pattern has a constant line width, the value of B varies depending on the measurement location, but here, the innermost length of the curved main line or the sacrificial pattern was measured (FIG. 3). reference).

<Evaluation method>
50 wiring boards for each of the examples and comparative examples were prepared, and for one worker, the longitudinal direction was adjusted so that the degree of expansion / contraction of the wiring board was in the range of 5 to 10% at the handle portion of the on-vehicle handle. Instructed to stretch and paste. Note that the degree of expansion / contraction is a value indicating how much the wiring board is extended with respect to the length in the longitudinal direction before the wiring board is extended. When the wiring board is stretched and extended, with respect to the example products in which the sacrificial pattern is formed, when the sacrificial pattern is visually confirmed, at least one point is disconnected and the handle is held without being further extended. I told the worker to stick it on my hand. In addition, margins of 1.5 cm were respectively formed at both ends in the longitudinal direction of the wiring board, and the operator performed the operation while pulling the margin portions.

  For the handle to which the wiring board is bonded, the presence or absence of disconnection is confirmed by a resistor. If there is a disconnection, it is judged as rejected (NG). When the length was measured, the case where the elongation was 5 to 10% was accepted, and the other case was judged as NG.

  Table 1 shows the evaluation results. The pass rate of the wiring board of the example in which the sacrificial pattern was formed was significantly higher than that of the wiring board of the comparative example in which the sacrificial pattern was not formed.

  FIG. 4 is an image showing a state after the wiring board of the example is stretched in the longitudinal direction. From this figure, it can be seen that by extending the wiring board in the longitudinal direction, only the sacrificial pattern (inner peripheral side) is disconnected, and the main line (outer peripheral side) is not disconnected.

  Further, as an effect by the formation of the sacrificial pattern, not only the disconnection is prevented, but also the elongation rate of the wiring board tends to fall within a desired range. It was also confirmed that it would be an indicator for extending

1: Circuit pattern 10: Linear metal foil 11: First branch 12: Second branch 15: Folded part

Claims (7)

A wiring board provided with a circuit pattern formed of a linear metal foil on at least one side of a resin board,
A part or all of the circuit pattern has a structure in which the metal foil is folded in a zigzag shape,
The wiring board in which the folded portion of the metal foil folded in a zigzag shape is branched along the folded shape into the outer peripheral side and the inner week side.   The wiring board according to claim 1, wherein a length of the metal foil on the outer peripheral side is longer than a length of the metal foil on the inner week side.   The wiring board according to claim 1, wherein the number of branches is 3 or more.   The wiring board according to claim 1, wherein the metal foil includes at least one of an aluminum foil and a copper foil.   The wiring substrate according to claim 1, wherein the resin substrate includes one or more selected from the group consisting of polyethylene, polypropylene, polyester, acrylic resin, and polycarbonate.   A structure provided with the wiring board according to claim 1.   The wiring board attachment method which attaches the wiring board of any one of Claims 1-5 to a base material.