JPWO2020175476A1 - Manufacturing method of printed wiring board and printed wiring board - Google Patents

Abstract

The printed wiring board according to the present disclosure includes a base film having an insulating property, a conductive pattern including a plurality of wires arranged in parallel, and an insulating layer, and the insulating layer is a region where the conductive pattern is formed in a plan view. It has a first region that overlaps with the first region and a second region that does not overlap with the formation region of the conductive pattern in a plan view. The second region is continuous from the first region, and the thickness from the surface of the base film gradually decreases. It has an inclined portion, and in the cross section in the thickness direction perpendicular to the boundary surface of the first region and the second region, the length of the foot of the perpendicular line drawn from the top of the inclined portion to the surface of the base film is h1 and from the bottom of the inclined portion. When the length of the foot of the perpendicular line drawn on the surface of the base film is h2 and the distance in the plane direction of the base film between the top and the bottom is W, the average value of the change rate of the thickness shown by (h1-h2) / W. Is 0.01 or more and 1.0 or less.

Description

The present disclosure relates to a printed wiring board and a method for manufacturing a printed wiring board.

A printed wiring board including a base film having an insulating property, a conductive pattern laminated on the base film, and an insulating layer laminated on the base film and the conductive pattern is known.

As the insulating layer forming material for forming the insulating layer, for example, a dry film having a curable resin layer is used. Specifically, the insulating layer is formed by heating and pressing the dry film from the surface side on which the conductive pattern of the base film is laminated in a state where the conductive pattern is laminated on one surface of the base film. (See JP-A-2015-229734).

JP-A-2015-229734

However, the printed wiring board may have a problem that a part of the conductive pattern is exposed on the outer surface side of the insulating layer. Further, this defect is likely to occur at the outer end of the conductive pattern forming region where the conductive pattern is formed (near the boundary between the conductive pattern forming region and the region where the conductive pattern is not formed in the conductive pattern forming region).

Specifically, the above-mentioned defect is that the insulating layer forming material flows to the base film side (the side where the conductive pattern is not formed) due to the step between the conductive pattern and the surface of the base film at the outer end of the conductive pattern forming region. It is easy to occur by doing.

The present disclosure has been made based on such circumstances, and an object of the present invention is to provide a printed wiring board and a method for manufacturing a printed wiring board capable of preventing exposure of a conductive pattern to the outer surface side of an insulating layer. ..

The printed wiring board according to the present disclosure, which has been made to solve the above problems, has an insulating base film, a conductive pattern including a plurality of wires laminated on the base film and arranged in parallel, and the base. A printed wiring board including a film and an insulating layer laminated on a conductive pattern, the first region in which the insulating layer overlaps the conductive pattern forming region in a plan view, and the conductive pattern forming region in a plan view. The second region has a second region that does not overlap with the first region, and the second region has an inclined portion that is continuous from the first region and the thickness from the surface of the base film gradually decreases, and the first region and the second region. In the cross section in the thickness direction perpendicular to the boundary surface of the region, the length of the foot of the perpendicular line drawn from the top of the inclined portion to the surface of the base film is h1, and the length of the perpendicular line drawn from the bottom of the inclined portion to the surface of the base film. When the length of the foot is h2 and the plane distance of the base film between the top and bottom is W, the average value of the change rate of the thickness represented by (h1-h2) / W is 0.01 or more. It is less than or equal to 0.0.

Further, the method for manufacturing a printed wiring board according to the present disclosure, which has been made to solve the above problems, is a first lamination in which a conductive pattern including a plurality of wires arranged in parallel is laminated on a base film having an insulating property. A method for manufacturing a printed wiring board including a step and a second laminating step of laminating an insulating layer on the base film and the conductive pattern after the first laminating step, wherein the insulating layer is the conductive pattern in a plan view. It has a first region that overlaps with the formation region of the above and a second region that does not overlap with the formation region of the conductive pattern in a plan view, and the second region is continuous from the first region and from the surface of the base film. Has an inclined portion in which the thickness of the inclined portion gradually decreases, and in a cross section in the thickness direction perpendicular to the boundary surface of the first region and the second region, the length of the foot of a perpendicular line drawn from the top of the inclined portion to the surface of the base film. When the length of the foot of the perpendicular line drawn from the bottom of the inclined portion to the surface of the base film is h2, and the plane distance of the base film between the top and the bottom is W, the second laminating step is performed. The average value of the rate of change in thickness represented by (h1-h2) / W is controlled to be 0.01 or more and 1.0 or less.

The printed wiring board according to the present disclosure can prevent the conductive pattern from being exposed to the outer surface side of the insulating layer. According to the method for manufacturing a printed wiring board according to the present disclosure, it is possible to manufacture a printed wiring board in which the conductive pattern is prevented from being exposed to the outer surface side of the insulating layer.

FIG. 1 is a schematic plan view showing a printed wiring board according to an embodiment of the present disclosure. FIG. 2 is a partial cross-sectional view taken along line AA of the printed wiring board of FIG. FIG. 3 is a partially enlarged view of the printed wiring board of FIG. FIG. 4 is a flow chart showing a method of manufacturing the printed wiring board of FIG. FIG. 5 is a schematic plan view showing a printed wiring board according to an embodiment different from that of the printed wiring board of FIG. FIG. 6 is a partial cross-sectional view taken along the line BB of the printed wiring board of FIG. FIG. 7 is a partially enlarged view of the printed wiring board of FIG. FIG. 8 is a schematic plan view showing a printed wiring board according to an embodiment different from the printed wiring boards of FIGS. 1 and 5. FIG. 9 is a partial cross-sectional view taken along the line CC of the printed wiring board of FIG. FIG. 10 is a partially enlarged view of the printed wiring board of FIG. FIG. 11 is a schematic plan view showing a printed wiring board according to an embodiment different from the printed wiring boards of FIGS. 1, 5, and 8. FIG. 12 is a partial cross-sectional view taken along the line DD of the printed wiring board of FIG. FIG. 13 is a partially enlarged view of the printed wiring board of FIG. FIG. 14 is a schematic plan view showing a printed wiring board according to an embodiment different from the printed wiring boards of FIGS. 1, 5, 8 and 11. FIG. 15 is a partially enlarged view of the printed wiring board of FIG. FIG. 16 is an end view of the EE line portion of the printed wiring board of FIG.

[Explanation of Embodiments of the present disclosure]
First, embodiments of the present disclosure will be listed and described.

The printed wiring board according to the present disclosure includes an insulating base film, a conductive pattern including a plurality of wires laminated on the base film and arranged in parallel, and insulation laminated on the base film and the conductive pattern. A printed wiring board including a layer, the first region in which the insulating layer overlaps the formation region of the conductive pattern in a plan view, and the second region in which the insulating layer does not overlap the formation region of the conductive pattern in a plan view. The second region has an inclined portion that is continuous from the first region and the thickness from the surface of the base film gradually decreases, and has a thickness perpendicular to the boundary surface between the first region and the second region. In the directional cross section, the length of the foot of the perpendicular line drawn from the top of the inclined portion to the surface of the base film is h1, the length of the foot of the perpendicular line drawn from the bottom of the inclined portion to the surface of the base film is h2, and the length of the foot of the perpendicular line is h2. When the plane distance of the base film between the bottom and the bottom is W, the average value of the change rate of the thickness represented by (h1-h2) / W is 0.01 or more and 1.0 or less.

In the printed wiring board, the length of the foot of the perpendicular line drawn from the top of the inclined portion to the surface of the base film in the cross section in the thickness direction perpendicular to the boundary surface of the first region and the second region is h1, and the inclined portion. When the length of the foot of the perpendicular line drawn from the bottom of the base film to the surface of the base film is h2 and the plane distance of the base film between the top and the bottom is W, the thickness indicated by (h1-h2) / W. Since the average value of the rate of change is within the above range, it is possible to prevent the insulating pattern from being exposed to the outer surface side of the insulating layer.

It is preferable to further provide one or a plurality of dummy wirings which are electrically insulated from these wirings and are arranged in parallel with these wirings on the outside in the width direction of the plurality of wirings. As described above, the inclination is further provided outside the width direction of the plurality of wirings by further providing one or a plurality of dummy wirings which are electrically insulated from these wirings and are arranged in parallel with these wirings. The rate of change in the thickness of the portion can be easily controlled within the above range, and the exposure of the conductive pattern to the outer surface side of the insulating layer can be more reliably prevented.

Of the plurality of wirings, the thickness of one or a plurality of wirings arranged on the second region side is smaller than the thickness of the one or a plurality of wirings arranged on the center side of the first region. good. As described above, among the plurality of wirings, the thickness of the one or a plurality of wirings arranged on the second region side is the thickness of the one or a plurality of wirings arranged on the center side of the first region. If it is smaller than that, the rate of change in the thickness of the inclined portion can be easily controlled within the above range, and the exposure of the conductive pattern to the outer surface side of the insulating layer can be more reliably prevented.

The plurality of wirings are arranged on the second region side of the one or more first wirings having the first thickness and the one or more first wirings, and are smaller than the first thickness. It may include one or more second wires having a second thickness. In this way, the plurality of wirings are arranged on the second region side of the one or more first wirings having the first thickness and the one or more first wirings, and the first wiring is described. By including one or a plurality of second wirings having a second thickness smaller than the thickness, the rate of change in the thickness of the inclined portion can be easily and surely controlled within the above range.

It is preferable that the conductive pattern has a plated lead wire, and further includes one or a plurality of dummy lead wires arranged in parallel with the plated lead wire in an electrically insulated state from the plated lead wire. As described above, the conductive pattern has a plated lead wire, and is further provided with one or a plurality of dummy lead wires arranged in parallel with the plated lead wire in an electrically insulated state from the plated lead wire. , The exposure of the plated lead wire to the outer surface side of the insulating layer can be easily prevented.

It is preferable that the conductive pattern has a land portion, and is electrically insulated from the land portion, and further includes one or a plurality of dummy wirings arranged so as to surround the land portion. As described above, the conductive pattern has a land portion, and is electrically insulated from the land portion, and further includes one or a plurality of dummy wirings arranged so as to surround the land portion. Can be easily prevented from being exposed to the outer surface side of the insulating layer.

The conductive pattern has a connection wiring connected in a T shape to the end of at least one of the plurality of wirings, and is connected to the wiring of the connection wiring at the connection portion of the wiring and the connection wiring. It is preferable that the width of the side edge opposite to the side to be sided and the side edge facing the side edge is uniform. As described above, the conductive pattern has a connection wiring connected in a T shape to the end of at least one of the plurality of wirings, and the connection portion of the wiring and the connection wiring has the connection wiring. Since the width of the side edge opposite to the side connected to the wiring and the side edge facing the side edge is uniform, the thickness of the connecting portion of the wiring and the connecting wiring is the thickness of the other portion. It is possible to prevent the wiring from becoming larger than that. This makes it possible to prevent the connection portion from being exposed to the outer surface side of the insulating layer due to the step between the connection portion and the surface of the base film.

The method for manufacturing a printed wiring board according to the present disclosure includes a first laminating step of laminating a conductive pattern including a plurality of wires arranged in parallel on an insulating base film, and after the first laminating step, the above. A method for manufacturing a printed wiring board including a second laminating step of laminating an insulating layer on a base film and a conductive pattern, wherein the insulating layer overlaps with a forming region of the conductive pattern in a plan view and a plane surface. It has a second region that does not overlap with the formation region of the conductive pattern visually, and the second region is continuous from the first region and has an inclined portion in which the thickness from the surface of the base film gradually decreases. In the cross section in the thickness direction perpendicular to the boundary surface of the first region and the second region, the length of the foot of the perpendicular line drawn from the top of the inclined portion to the surface of the base film is h1, and from the bottom of the inclined portion to the above. When the length of the foot of the perpendicular line drawn on the surface of the base film is h2 and the plane distance of the base film between the top and bottom is W, it is indicated by (h1-h2) / W in the second laminating step. The average value of the rate of change in thickness is controlled to be 0.01 or more and 1.0 or less.

In the method for manufacturing the printed wiring board, in the second laminating step, the average value of the rate of change in the thickness of the inclined portion represented by (h1-h2) / W is controlled within the above range, so that the insulating pattern of the conductive pattern is insulated. It is possible to prevent the layer from being exposed to the outer surface side.

In the second laminating step, the insulating layer may be laminated by curing the photosensitive dry film. In this way, by laminating the insulating layer by curing the photosensitive dry film in the second laminating step, it is easy and reliable to prevent the insulating pattern from being exposed to the outer surface side of the conductive pattern. Can be manufactured to.

In the present disclosure, "parallel" means that the angle between the two is 5 ° or less, preferably 3 ° or less. The “region for forming a conductive pattern” means a region in which conductors constituting the conductive pattern are densely arranged, and specifically, adjacent conductors are arranged at intervals of 50 μm or less, preferably 30 μm or less. Refers to an area. The "average value of the rate of change in thickness" means the average value of the rate of change in thickness at any 10 points. "The connection wiring is connected to the end of the wiring in a T shape" means that the end of the wiring is connected so as not to protrude from the other side (opposite side to the connection side) of the connection wiring. "Uniform width" means that the difference between the maximum width and the minimum width is 4 μm or less, preferably 2 μm or less.

[Details of Embodiments of the present disclosure]
Hereinafter, the printed wiring board and the method for manufacturing the printed wiring board according to each embodiment of the present disclosure will be described in detail with reference to the drawings.

[First Embodiment]
<Printed wiring board>
The printed wiring boards 1 of FIGS. 1 and 2 have an insulating base film 2, a conductive pattern 3 including a plurality of wirings 3a laminated on the base film 2 and arranged in parallel, and the base film 2 and conductivity. It includes an insulating layer 4 laminated on the pattern 3. The insulating layer 4 has a first region 4a that overlaps the forming region of the conductive pattern 3 in a plan view, and a second region 4b that does not overlap the forming region of the conductive pattern 3 in a plan view. The second region 4b has an inclined portion 4c that is continuous from the first region 4a and whose thickness from the surface of the base film 2 gradually decreases.

The printed wiring board 1 is provided with a plurality of dummy wirings (hereinafter, "No. 1") arranged on the outside of the plurality of wirings 3a in the width direction in an electrically insulated state from the wirings 3a and in parallel with the wirings 3a. 1 Dummy wiring 5a ”) is provided. The plurality of first dummy wirings 5a are arranged outside the forming region of the conductive pattern 3 and adjacent to the forming region of the conductive pattern 3. The term "outside in the width direction of a plurality of wirings" means the outside in the parallel direction of a plurality of wiring groups arranged in parallel, regardless of whether it is the outer edge side or the center side of the printed wiring board. good.

As shown in FIGS. 2 and 3, the printed wiring board 1 has a top portion 4e of the inclined portion 4c, that is, an inclined portion 4c in a cross section in the thickness direction perpendicular to the boundary surface X of the first region 4a and the second region 4b. The length of the foot of the perpendicular line drawn from the upper end of the base film 2 to the surface of the base film 2 is h1, and the length of the foot of the perpendicular line drawn from the bottom 4f of the inclined portion 4c, that is, the lower end of the inclined portion 4c is h2. When the plane distance of the base film 2 between the top 4e and the bottom 4f is W, the average value of the thickness change rate represented by (h1-h2) / W is 0.01 or more and 1.0 or less. ..

The printed wiring board 1 has the length of the foot of a perpendicular line drawn from the top 4e of the inclined portion 4c to the surface of the base film 2 in the cross section in the thickness direction perpendicular to the boundary surface X of the first region 4a and the second region 4b. When h1, the length of the foot of the perpendicular line drawn from the bottom 4f of the inclined portion 4c to the surface of the base film 2 is h2, and the plane distance of the base film 2 between the top 4e and the bottom 4f is W, (h1-h2). The average value of the rate of change in thickness indicated by / W is within the above range, and the inclination of the inclined portion 4c is sufficiently gentle. Therefore, in the printed wiring board 1, the edge of the outer end portion of the conductive pattern 3 forming region is appropriately covered with the insulating layer 4, and the conductive pattern 3 is exposed to the outer surface side of the insulating layer 4. Can be prevented.

The printed wiring board 1 includes a plurality of first dummy wirings 5a arranged outside the width direction of the plurality of wirings 3a in an electrically insulated state from the plurality of wirings 3a and in parallel with the plurality of wirings 3a. Therefore, for example, when the insulating layer 4 is formed by using the photosensitive dry film, it is easy to dam the flow of the molten photosensitive dry film from the plurality of wirings 3a side to the second region 4b side. As a result, the rate of change in the thickness of the inclined portion 4c can be easily controlled within the above range, and the exposure of the plurality of wirings 3a to the outer surface side of the insulating layer 4 can be more reliably prevented.

(Base film)
The base film 2 contains a synthetic resin as a main component and has electrical insulating properties. The base film 2 is a base material layer for forming the conductive pattern 3. The base film 2 may have flexibility. When the base film 2 has flexibility, the printed wiring board 1 is configured as a flexible printed wiring board. The "main component" refers to a component having the largest content ratio in terms of mass, for example, a component having a content of 50% by mass or more.

Examples of the synthetic resin include polyimide, polyethylene terephthalate, liquid crystal polymer, fluororesin and the like.

When the printed wiring board 1 is a flexible printed wiring board, the lower limit of the average thickness of the base film 2 is preferably 5 μm, more preferably 10 μm. On the other hand, the upper limit of the average thickness of the base film 2 is preferably 50 μm, more preferably 40 μm. If the average thickness of the base film 2 does not reach the above lower limit, the dielectric strength of the base film 2 may be insufficient. On the contrary, if the average thickness of the base film 2 exceeds the above upper limit, the printed wiring board 1 may become unnecessarily thick or the flexibility may be insufficient. In addition, in this specification, "average thickness" means the average value of the thickness of arbitrary 10 points.

(Conductive pattern)
The conductive pattern 3 is a layer made of a conductor having conductivity, and includes a plurality of wirings 3a arranged in parallel. The plurality of wirings 3a form, for example, a coil pattern. Further, the conductive pattern 3 may include a pattern such as a land portion 3b other than the plurality of wirings 3a.

The plurality of wirings 3a are, for example, a laminate of a seed layer laminated on the base film 2 and an electroplating layer laminated on the seed layer. Further, the plurality of wirings 3a may have a core body composed of the seed layer and the electroplating layer, and a coating layer laminated on the outer surface of the core body by plating. Examples of the main component of the seed layer include copper, nickel, silver and the like. The seed layer is formed by, for example, electroless plating. Further, the seed layer may be a sintered body layer of metal particles obtained by applying an ink containing metal particles to the surface of the base film 2 and sintering the metal particles, and the sintered body layer and electroless electrolysis may be used. It may be a laminate of plating layers. Further, the electroplating layer is formed by electroplating. Examples of the main component of the electroplating layer include copper, nickel, silver and the like.

The upper limit of the average thickness of the plurality of wirings 3a is preferably 90 μm, more preferably 70 μm. If the average thickness exceeds the upper limit, there is a possibility that the request for thinning of the printed wiring board 1 is violated. On the other hand, as the lower limit of the average thickness of the plurality of wirings 3a, 5 μm is preferable, and 10 μm is more preferable. If the average thickness does not reach the lower limit, the electrical resistance may increase. Further, the lower limit of the average thickness may be, for example, 30 μm or 40 μm. Generally, when the thickness of the wiring becomes thick, the wiring is easily exposed to the outer surface side of the insulating layer, but the printed wiring board 1 has a plurality of printed wiring boards 1 even when the lower limit of the average thickness of the plurality of wirings 3a is set to the above value. It is possible to sufficiently prevent the insulating layer 4 of the wiring 3a from being exposed to the outer surface side.

As the lower limit of the average width of the plurality of wirings 3a, 5 μm is preferable, and 10 μm is more preferable. On the other hand, the upper limit of the average width of the plurality of wirings 3a is preferably 50 μm, more preferably 30 μm. If the average width does not reach the lower limit, it may not be easy to form the plurality of wirings 3a. Further, if the average width is not less than the lower limit, the thickness of the plurality of wirings 3a may not be sufficiently increased. On the contrary, if the average width exceeds the upper limit, it may be difficult to obtain a desired wiring density. The "mean width" means the average value of the width of any 10 points.

It is preferable that the plurality of wirings 3a are arranged at the same pitch. The lower limit of the average pitch between the adjacent wirings 3a is preferably 10 μm, more preferably 20 μm. On the other hand, the upper limit of the average pitch is preferably 100 μm, more preferably 60 μm. If the average pitch does not reach the lower limit, it may not be easy to form the plurality of wirings 3a. On the contrary, if the average pitch exceeds the upper limit, it may be difficult to obtain a desired wiring density.

As the lower limit of the average spacing between the adjacent wirings 3a, 5 μm is preferable, and 10 μm is more preferable. On the other hand, the upper limit of the average interval is preferably 50 μm, more preferably 30 μm. If the average interval does not reach the lower limit, it may not be easy to form the plurality of wirings 3a. On the contrary, if the average interval exceeds the upper limit, it may be difficult to obtain a desired wiring density. The "average interval" means the average value of the intervals of any 10 points.

(Dummy wiring)
The plurality of first dummy wirings 5a are provided on the same layer as the conductive pattern 3. The plurality of first dummy wirings 5a are arranged in parallel with the plurality of wirings 3a between the base film 2 and the insulating layer 4.

The plurality of first dummy wirings 5a are, for example, a laminate of a seed layer laminated on the base film 2 and an electroplating layer laminated on the seed layer, similarly to the plurality of wirings 3a. Further, the plurality of first dummy wirings 5a may have a core body composed of the seed layer and the electroplating layer, and a coating layer laminated on the outer surface of the core body by plating. The printed wiring board 1 is provided with a plurality of first dummy wirings 5a outside the width direction of the plurality of wirings 3a, so that the molten photosensitive dry film flows from the first region 4a to the second region 4b side. It can be dammed more reliably. When a plurality of first dummy wirings 5a are provided, the lower limit of the number of these first dummy wirings 5a is preferably two, more preferably three. Further, the upper limit of the number of the plurality of first dummy wirings 5a may be, for example, five.

The average thickness of the plurality of first dummy wirings 5a is preferably equal to or less than the average thickness of one or a plurality of wirings 3a adjacent to the plurality of first dummy wirings 5a. As a specific configuration in which the average thickness of the plurality of first dummy wirings 5a is smaller than the average thickness of the plurality of wirings 3a, for example, the plurality of wirings 3a are configured to have the core body and the covering layer, and the plurality of dummy wirings are present. It can be mentioned that 3a has a structure composed of the core body (that is, a laminated body of the seed layer and the electroplating layer). When the plurality of wirings 3a have the core body and the covering layer and the plurality of dummy wirings 3a have the core body, the width of the plurality of first dummy wirings 5a is smaller than that of the plurality of wirings 3a. .. In this case, the difference in average thickness between the plurality of wirings 3a and the plurality of first dummy wirings 5a can be, for example, 3 μm or more and 12 μm or less. The difference in average width between the plurality of wirings 3a and the plurality of first dummy wirings 5a can be, for example, 6 μm or more and 24 μm or less. The printed wiring board 1 has a plurality of first dummies by setting the average thickness of the plurality of first dummy wirings 5a to be equal to or less than the average thickness of one or a plurality of wirings 3a adjacent to the first dummy wirings 5a. It is easy to reduce the step between the wiring 5a and the surface of the base film 2 and prevent the plurality of first dummy wirings 5a from being exposed to the outer surface side of the insulating layer 4. The printed wiring board 1 is one or a plurality of first dummy wirings located on the first region 4a side from the viewpoint of surely preventing the exposure of the plurality of first dummy wirings 5a to the outer surface side. The average thickness of one or a plurality of first dummy wirings 5a located on the side opposite to the first region 4a may be smaller than the average thickness of 5a.

It is preferable that the plurality of first dummy wirings 5a are arranged at the same pitch as the plurality of wirings 3a. By arranging the plurality of first dummy wirings 5a at the same pitch as the plurality of wirings 3a in this way, the thickness of the entire insulating layer 4 can be made uniform, and the outer surface of the insulating layer 4 of the plurality of wirings 3a can be made uniform. It is easy to prevent exposure to the side. Further, the average spacing between the adjacent wirings 3a and the first dummy wiring 5a can be the same as the average spacing between the adjacent wirings 3a.

(Insulation layer)
The insulating layer 4 is laminated in a region where the conductive pattern 3, the plurality of first dummy wirings 5a, and the conductive pattern 3 of the base film 2 and the plurality of first dummy wirings 5a are not laminated. The insulating layer 4 mainly prevents damage and short circuit due to contact with other members of the conductive pattern 3. Therefore, it is preferable that the insulating layer 4 completely covers the outer surface of the conductive pattern 3 except for intentionally provided openings and notches.

The insulating layer 4 can be formed by using a solder resist, a coverlay, or the like, and it is particularly preferable that the insulating layer 4 is formed by curing a photosensitive dry film. When a photosensitive dry film is used, by pressing the photosensitive dry film while heating it from the outer surface side of the plurality of wirings 3a, the photosensitive dry film flows and covers the outer surfaces of the plurality of wirings 3a. Fill the gap between the wiring 3a. Further, the average thickness of the photosensitive dry film is preferably smaller than the average thickness of the plurality of wirings 3a. By making the average thickness of the photosensitive dry film smaller than the average thickness of the plurality of wirings 3a, it is possible to reduce the thickness of the insulating layer 4 and promote the thinning of the printed wiring board. In general, when the average thickness of the photosensitive dry film is smaller than the average thickness of the plurality of wirings, if the photosensitive dry film flows too much out of the region where the conductive pattern is formed, the outer surface of the plurality of wirings becomes the outer surface side of the insulating layer. Although there is a risk of exposure, the printed wiring board 1 can prevent the flow of the photosensitive dry film by the plurality of first dummy wirings 5a, so that the plurality of wirings 3a can be prevented from being exposed. When a photosensitive dry film having an average thickness smaller than that of the plurality of wirings 3a is used, the lower limit of the average thickness of the insulating layer 4 laminated on the surface of the plurality of wirings 3a opposite to the base film 2 is 5 μm. Preferably, 15 μm is more preferable. The upper limit of the average thickness is preferably 40 μm, more preferably 35 μm.

When a photosensitive dry film having an average thickness smaller than that of the plurality of wirings 3a is used, the average thickness of the plurality of wirings 3a and the above-mentioned photosensitive property are taken from the viewpoint of preventing the insulating layer 4 of the plurality of wirings 3a from being exposed to the outer surface side. The upper limit of the difference from the average thickness of the dry film is preferably 10 μm, more preferably 7 μm. On the other hand, from the viewpoint of reducing the thickness of the printed wiring board 1, the lower limit of the difference between the average thickness of the plurality of wirings 3a and the average thickness of the photosensitive dry film is preferably 1 μm, more preferably 3 μm.

As described above, the insulating layer 4 has a first region 4a that overlaps the forming region of the conductive pattern 3 in a plan view and a second region 4b that does not overlap the forming region of the conductive pattern 3 in a plan view. In the insulating layer 4, a region other than the first region 4a is configured as a second region 4b. Further, in a plan view, the outer edge of the first region 4a coincides with the outer edge of the formation region of the conductive pattern 3. That is, in a plan view, the boundary surface X of the first region 4a and the second region 4b coincides with the side edge of the conductor located on the outermost side of the forming region of the conductive pattern 3. Further, in the boundary surface X, the plurality of wirings 3a are not exposed on the outer surface side of the insulating layer 4 except for the intended openings and notches.

The inclined portion 4c is formed in the second region 4b with the boundary surface X with the first region 4a as an end edge. In the cross section in the thickness direction perpendicular to the boundary surface X, the inclined portion 4c has the position of the boundary surface X with the first region 4a as the top portion 4e, and the thickness is gradually reduced toward the second region 4b. In the present embodiment, the bottom portion 4f of the inclined portion 4c is formed, for example, at an intermediate position between the adjacent wiring 3a and the first dummy wiring 5a. The inclined portion 4c may include a region having a substantially uniform thickness in the middle, and for example, the thickness of a constant region from the boundary surface X toward the second region 4b may be substantially uniform. ..

In the cross section in the thickness direction perpendicular to the boundary surface X of the first region 4a and the second region 4b, the length of the foot of the perpendicular line drawn from the top 4e of the inclined portion 4c to the surface of the base film 2 is h1, and the bottom of the inclined portion 4c. When the length of the foot of the perpendicular line drawn from 4f to the surface of the base film 2 is h2 and the plane distance of the base film 2 between the top 4e and the bottom 4f is W, the thickness indicated by (h1-h2) / W. The lower limit of the average value of the rate of change of is 0.01 as described above, preferably 0.1. On the other hand, the upper limit of the average value of the rate of change is 1.0 as described above, preferably 0.5. If the rate of change is not less than the lower limit, it may not be easy to thin the insulating layer 4. On the contrary, when the rate of change exceeds the upper limit, the plurality of wirings 3a, particularly the wirings 3a located on the outermost side of the conductive pattern 3, may be exposed on the outer surface side of the insulating layer 4.

<Manufacturing method of printed wiring board>
Next, an example of the manufacturing method of the printed wiring board 1 of FIG. 1 will be described with reference to FIG. The method for manufacturing the printed wiring board includes a first laminating step of laminating a conductive pattern 3 including a plurality of wirings 3a arranged in parallel on a base film 2 having an insulating property, and a base after the first laminating step. A second laminating step of laminating the insulating layer 4 on the film 2 and the conductive pattern 3 is provided. In the method for manufacturing the printed wiring board, the insulating layer 4 has a first region 4a that overlaps the forming region of the conductive pattern 3 in a plan view and a second region 4b that does not overlap the forming region of the conductive pattern 3 in a plan view. The second region 4b has an inclined portion 4c that is continuous from the first region 4a and whose thickness from the surface of the base film 2 gradually decreases.

(First laminating process)
In the first laminating step, a plurality of first dummy wirings 5a are laminated on the surface of the base film 2 at the same time as the conductive pattern 3. In the first laminating step, for example, a conductive pattern 3 including a plurality of wirings 3a and a plurality of first dummy wirings 5a are laminated by using a semi-additive method. Specifically, the first laminating step includes a step of laminating a seed layer on the surface of the base film 2, and a conductive pattern 3 and a plurality of first dummy wirings 5a on the surface of the seed layer after the seed layer laminating step. After the step of forming the resist pattern having the inverted shape of the above, the step of electroplating the surface of the seed layer after the step of forming the resist pattern, and the step of electroplating the surface of the seed layer, and the region where the resist pattern and the resist pattern of the seed layer overlap each other. Has a step of removing. In the resist pattern forming step, a resist pattern having an inverted shape of the core may be formed for all or a part of the plurality of wirings 3a and the plurality of first dummy wirings 5a. In this case, the first laminating step further includes a step of laminating the coating layer on the core body after the removing step. The seed layer laminating step may be performed by, for example, electroless plating, or by applying an ink containing metal particles and sintering the metal particles, and the metal particles may be sintered and electroless plated. It may be done by both. Further, the coating step may be performed by, for example, electroless plating or electroplating.

(Second laminating process)
In the second laminating step, the insulating layer 4 is laminated by curing the photosensitive dry film. In the second laminating step, it is preferable to heat-laminate a photosensitive dry film having an average thickness smaller than the average thickness of the plurality of wirings 3a from the outer surface side of the conductive pattern 3 and the plurality of first dummy wirings 5a. By pressing the photosensitive dry film while heating it from the outer surface side of the conductive pattern 3 and the plurality of first dummy wirings 5a, the photosensitive dry film flows, and the outer surface of the plurality of wirings 3a and the plurality of first dummies flow. While covering the outer surface of the wiring 5a, the gap between the plurality of wirings 3a and the gap between the plurality of first dummy wirings 5a are filled. As a result, the thickness of the insulating layer 4 can be reduced to promote the thinning of the printed wiring board. In the method for manufacturing the printed wiring board, since the flow of the photosensitive dry film can be suppressed by the plurality of first dummy wirings 5a, the photosensitive dry film having an average thickness smaller than the average thickness of the plurality of wirings 3a can be produced. Even when it is used, it is possible to prevent the insulating layer 4 of the plurality of wirings 3a from being exposed to the outer surface side.

When a photosensitive dry film having an average thickness smaller than that of the plurality of wirings 3a is used, the lower limit of the difference between the average thickness of the plurality of wirings 3a and the average thickness of the photosensitive dry film is preferably 1 μm, more preferably 3 μm. preferable. On the other hand, the upper limit of the above difference is preferably 10 μm, more preferably 7 μm. If the above difference is not less than the above lower limit, it may be difficult to promote the thinning of the printed wiring board 1. On the contrary, if the above difference exceeds the above upper limit, it may be difficult to prevent the insulating layer 4 of the plurality of wirings 3a from being exposed to the outer surface side.

In the second laminating step, the length of the foot of the perpendicular line drawn from the top portion 4e of the inclined portion 4c to the surface of the base film 2 in the cross section in the thickness direction perpendicular to the boundary surface X of the first region 4a and the second region 4b is determined. When h1, the length of the foot of the perpendicular line drawn from the bottom 4f of the inclined portion 4c to the surface of the base film 2 is h2, and the plane distance of the base film 2 between the top 4e and the bottom 4f is W, (h1-h2). The average value of the rate of change in thickness indicated by / W is controlled to be 0.01 or more and 1.0 or less. The lower limit of the rate of change is preferably 0.1. The upper limit of the rate of change is preferably 0.5. If the rate of change is not less than the lower limit, it may not be easy to thin the insulating layer 4. On the contrary, when the rate of change exceeds the upper limit, the plurality of wirings 3a, particularly the wirings 3a located on the outermost side of the conductive pattern 3, may be exposed on the outer surface side of the insulating layer 4.

In the method for manufacturing the printed wiring board, in the second laminating step, the average value of the rate of change in the thickness of the inclined portion 4c represented by (h1-h2) / W is controlled within the above range, so that the conductive pattern 3 In particular, it is possible to prevent the insulating layer 4 of the plurality of wirings 3a from being exposed to the outer surface side.

In the method for manufacturing the printed wiring board, since the insulating layer 4 is laminated by curing the photosensitive dry film in the second laminating step, the printed wiring is prevented from being exposed to the outer surface side of the insulating layer 4 of the conductive pattern 3. The board can be manufactured easily and surely. Further, according to this configuration, the thickness of the insulating layer 4 can be reduced to promote the thinning of the printed wiring board 1.

[Second Embodiment]
<Printed wiring board>
The printed wiring boards 11 of FIGS. 5 and 6 have an insulating base film 2, a conductive pattern 13 including a plurality of wirings 13a laminated on the base film 2 and arranged in parallel, and the base film 2 and conductivity. The insulating layer 14 laminated on the pattern 13 is provided. The insulating layer 14 has a first region 14a that overlaps the forming region of the conductive pattern 13 in a plan view, and a second region 14b that does not overlap the forming region of the conductive pattern 13 in a plan view. The second region 14b has an inclined portion 14c that is continuous from the first region 14a and whose thickness from the surface of the base film 2 gradually decreases. Since the base film 2 of the printed wiring board 11 can have the same configuration as the base film 2 of the printed wiring board 1 of FIG. 1, the same reference numerals are given and the description thereof will be omitted.

The printed wiring board 1 has a thickness of one or a plurality of wirings 13a (in this embodiment, one wiring 13a adjacent to the second region 14b) arranged on the second region 14b side among the plurality of wirings 13a. However, it is smaller than the thickness of the plurality of wirings 13a arranged on the center side of the first region 14a. Further, the printed wiring board 11 does not have a dummy wiring outside the width direction of one or a plurality of wirings 13a having a small thickness.

As shown in FIGS. 6 and 7, the printed wiring board 11 has a thickness direction cross section perpendicular to the boundary surface X of the first region 14a and the second region 14b, from the top portion 14e of the inclined portion 14c to the surface of the base film 2. The length of the foot of the perpendicular line dropped to h1, the length of the foot of the perpendicular line dropped from the bottom 14f of the inclined portion 14c to the surface of the base film 2 is h2, and the distance in the plane direction of the base film 2 between the top portion 14e and the bottom portion 14f. When W is used, the average value of the rate of change in thickness indicated by (h1-h2) / W is 0.01 or more and 1.0 or less.

The printed wiring board 11 has a plurality of wirings in which the thickness of one or the plurality of wirings 13a arranged on the second region 14b side among the plurality of wirings 13a is arranged on the center side of the first region 14a. Since it is smaller than the thickness of 13a, the rate of change in the thickness of the inclined portion 14c can be easily controlled within the above range, and the exposure of the plurality of wirings 13a to the outer surface side of the insulating layer 14 can be more reliably prevented. More specifically, the printed wiring board 11 has a step between a plurality of wirings 13a arranged on the center side of the first region 14a and one or a plurality of wirings 13a arranged on the second region 14b side. Further, by reducing the step between one or more wirings 13a arranged on the second region 14b side and the surface of the base film 2, the plurality of wirings 13a are formed into an insulating layer due to the flow of the photosensitive dry film. It is possible to prevent the 14 from being exposed to the outer surface side.

(Conductive pattern)
The conductive pattern 13 is a layer made of a conductor having conductivity, and includes a plurality of wirings 13a arranged in parallel. The plurality of wirings 13a form, for example, a coil pattern. Further, the conductive pattern 13 may include a pattern such as a land portion 13b other than the plurality of wirings 13a.

As shown in FIG. 7, the plurality of wirings 13a are arranged on the second region 14b side of the plurality of first wirings 13c having the first thickness and the plurality of first wirings 13c, and have the first thickness. Includes one or more second wirings 13d (one second wiring 13d in this embodiment) having a second thickness smaller than that. The plurality of wirings 13a are composed of two types of wirings, a plurality of first wirings 13c and one or a plurality of second wirings 13d. The plurality of wirings 13a include a first wiring group in which a plurality of first wirings 13c are provided adjacent to each other in the width direction and a second wiring group in which one or a plurality of second wirings 13d are provided adjacent to each other in the width direction. The second wiring group is arranged on the second region 14b side of the first wiring group. Further, in the printed wiring board 11, other wiring and dummy wiring are not laminated on the surface of the base film 2 on the outside (second region 14b side) of the second wiring group. The printed wiring board 11 includes a plurality of wirings 13a, a plurality of first wirings 13c, and one or a plurality of second wirings 13d arranged on the second region 14b side of the plurality of first wirings 13c. Thereby, the rate of change in the thickness of the inclined portion 14c can be easily and surely controlled.

The plurality of first wirings 13c are laminated on, for example, a core body 13e composed of a seed layer laminated on the base film 2 and an electroplating layer laminated on the seed layer, and an outer surface of the core body 13e by plating. It has a coating layer 13f to be plated. On the other hand, the one or a plurality of second wirings 13d are composed of the core body 13e on which the seed layer and the electroplating are laminated. The specific configuration of the seed layer, the electroplating layer, and the coating layer can be the same as that of the printed wiring board 1 of FIG.

The upper limit of the average thickness of the plurality of first wirings 13c is preferably 90 μm, more preferably 70 μm. Further, as the lower limit of the average thickness of the plurality of first wirings 13c, 10 μm is preferable, and 15 μm is more preferable. If the average thickness does not reach the lower limit, the electrical resistance may increase. On the contrary, if the average thickness exceeds the upper limit, there is a possibility that the request for thinning of the printed wiring board 11 is violated.

The lower limit of the average width of the plurality of first wirings 13c is preferably 15 μm, more preferably 20 μm. On the other hand, as the upper limit of the average width of the plurality of first wirings 13c, 50 μm is preferable, and 30 μm is more preferable. If the average width does not reach the lower limit, it may not be easy to form the plurality of first wirings 13c. Further, if the average width is not less than the lower limit, the thickness of the plurality of first wirings 13c may not be sufficiently increased. On the contrary, if the average thickness exceeds the upper limit, it may be difficult to obtain a desired wiring density.

The thickness of the one or a plurality of second wirings 13d is smaller than that of the plurality of first wirings 13c by the thickness of the covering layer 13f. Further, the width of the one or a plurality of second wirings 13d is smaller than that of the plurality of first wirings 13c by twice the thickness of the covering layer 13f. As the lower limit of the average thickness of the coating layer 13f, 1 μm is preferable, and 3 μm is more preferable. On the other hand, the upper limit of the average thickness of the coating layer 13f is preferably 15 μm, more preferably 12 μm. When the average thickness of the coating layer 13f is less than the above lower limit, one or a plurality of second wirings 13d and the surface of the base film 2 are provided with respect to a step between the plurality of first wirings 13c and one or a plurality of second wirings 13d. There is a risk that the step with will become too large. On the contrary, if the average thickness of the covering layer 13f exceeds the above upper limit, the step between the plurality of first wirings 13c and the one or the plurality of second wirings 13d may become too large.

It is preferable that the plurality of wirings 13a are arranged at the same pitch. As the lower limit of the average spacing between the adjacent first wirings 13c, 5 μm is preferable, and 10 μm is more preferable. On the other hand, the upper limit of the average interval is preferably 50 μm, more preferably 30 μm. If the average interval does not reach the lower limit, it may not be easy to form the plurality of wirings 13a. On the contrary, if the average interval exceeds the upper limit, it may be difficult to obtain a desired wiring density.

(Insulation layer)
The insulating layer 14 is laminated in a region where the conductive pattern 13 and the conductive pattern 13 of the base film 2 are not laminated. The insulating layer 14 mainly prevents damage and short circuit due to contact with other members of the conductive pattern 13. Therefore, it is preferable that the insulating layer 14 completely covers the outer surface of the conductive pattern 13 except for intentionally provided openings and notches.

Like the printed wiring board 1 of FIG. 1, the insulating layer 14 can be formed of a solder resist, a coverlay, or the like, and is preferably formed by curing a photosensitive dry film. Further, the average thickness of the photosensitive dry film is preferably smaller than the average thickness of the plurality of wirings 13a. The difference between the average thickness of the plurality of wirings 13a and the average thickness of the photosensitive dry film can be the same as that of the printed wiring board 1 of FIG. Further, the average thickness of the insulating layer 14 laminated on the surface of the plurality of first wirings 13c on the side opposite to the base film 2 is the side opposite to the base film 2 of the plurality of wirings 3a in the printed wiring board 1 of FIG. It can be the same as the average thickness of the insulating layer 4 laminated on the surface of.

As described above, the insulating layer 14 has a first region 14a that overlaps the forming region of the conductive pattern 13 in a plan view and a second region 14b that does not overlap the forming region of the conductive pattern 13 in a plan view. In the insulating layer 14, a region other than the first region 14a is configured as a second region 14b. Further, in a plan view, the outer edge of the first region 14a coincides with the outer edge of the forming region of the conductive pattern 13. At the boundary surface X of the first region 14a and the second region 14b, the plurality of wirings 13a are not exposed on the outer surface side of the insulating layer 14 except for the intended openings and notches.

The inclined portion 14c is formed in the second region 14b with the boundary surface X with the first region 14a as an end edge. In the cross section in the thickness direction perpendicular to the boundary surface X, the inclined portion 14c has the position of the boundary surface X with the first region 14a as the top portion 14e, and the thickness is gradually reduced toward the second region 14b. In the present embodiment, the bottom portion 14f of the inclined portion 14c is located on the outer edge of the printed wiring board 11.

In the cross section in the thickness direction perpendicular to the boundary surface X of the first region 14a and the second region 14b, the average value of the change rate of the thickness represented by (h1-h2) / W is the printed wiring board 1 of FIG. The same can be done.

<Manufacturing method of printed wiring board>
Next, an example of the manufacturing method of the printed wiring board 11 of FIG. 5 will be described. The method for manufacturing the printed wiring board includes a first laminating step of laminating a conductive pattern 13 including a plurality of wirings 13a arranged in parallel on a base film 2 having an insulating property, and a base after the first laminating step. A second laminating step of laminating the insulating layer 14 on the film 2 and the conductive pattern 13 is provided. In the method for manufacturing the printed wiring board, the insulating layer 14 has a first region 14a that overlaps the forming region of the conductive pattern 13 in a plan view and a second region 14b that does not overlap the forming region of the conductive pattern 13 in a plan view. The second region 14b has an inclined portion 14c which is continuous from the first region 14a and whose thickness from the surface of the base film 2 gradually decreases.

(First laminating process)
In the first laminating step, for example, the conductive pattern 13 including the plurality of wirings 13a is laminated by using the semi-additive method as in the method of manufacturing the printed wiring board of FIG. In the first laminating step, among the plurality of wirings 13a, the thickness of one or the plurality of wirings 13a arranged on the second region 14b side is the thickness of the plurality of wirings arranged on the center side of the first region 14a. A plurality of wirings 13a are laminated so as to be smaller than the thickness of 13a. In the first laminating step, the covering layer 13f is laminated only on the plurality of core bodies 13e constituting the plurality of first wirings 13c in the above-mentioned covering step described in the method for manufacturing the printed wiring board of FIG. Specifically, in the coating step, plating lead wires (not shown) are connected only to the plurality of cores 13e constituting the plurality of first wirings 13c, and the coating layer 13f is provided only to these cores 13e. Stack.

(Second laminating process)
In the second laminating step, the insulating layer 14 is laminated by curing the photosensitive dry film. In the second laminating step, the insulating layer 14 is laminated in the same manner as in the method for manufacturing the printed wiring board of FIG. The method for manufacturing the printed wiring board includes a step between the plurality of first wirings 13c and one or more second wirings 13d, and a step between one or more second wirings 13d and the surface of the base film 2. By making the size smaller, it is possible to prevent the plurality of wirings 13a from being exposed to the outer surface side of the insulating layer 14 due to the flow of the photosensitive dry film.

In the second laminating step, the length of the foot of the perpendicular line drawn from the top 14e of the inclined portion 14c to the surface of the base film 2 in the cross section in the thickness direction perpendicular to the boundary surface X of the first region 14a and the second region 14b is determined. When h1, the length of the foot of the perpendicular line drawn from the bottom 14f of the inclined portion 14c to the surface of the base film 2 is h2, and the plane distance of the base film 2 between the top 14e and the bottom 14f is W, (h1-h2). The average value of the rate of change in thickness indicated by / W is controlled to be 0.01 or more and 1.0 or less. The preferable lower limit value and preferable upper limit value of the rate of change are the same as those in the method for manufacturing the printed wiring board of FIG.

[Third Embodiment]
<Printed wiring board>
The printed wiring boards 21 of FIGS. 8 and 9 have an insulating base film 2, a conductive pattern 23 including a plurality of wirings (not shown) laminated on the base film 2 and arranged in parallel, and a base film. 2 and an insulating layer 24 laminated on the conductive pattern 23 are provided. The conductive pattern 23 has a plated lead wire 23a. The insulating layer 24 has a first region 24a that overlaps the forming region of the conductive pattern 23 in a plan view, and a second region 24b that does not overlap the forming region of the conductive pattern 23 in a plan view. The second region 24b has an inclined portion 24c that is continuous from the first region 24a and whose thickness from the surface of the base film 2 gradually decreases. Since the base film 2 of the printed wiring board 21 can have the same configuration as the base film 2 of the printed wiring board 1 of FIG. 1, the same reference numerals are given and the description thereof will be omitted.

The printed wiring board 21 includes one or a plurality of dummy lead wires 25a that are electrically insulated from the plated lead wires 23a and are arranged in parallel with the plated lead wires 23a.

As shown in FIGS. 9 and 10, the printed wiring board 21 has a thickness direction cross section perpendicular to the boundary surface X of the first region 24a and the second region 24b, from the top portion 24e of the inclined portion 24c to the surface of the base film 2. The length of the foot of the perpendicular line dropped to h1, the length of the foot of the perpendicular line dropped from the bottom 24f of the inclined portion 24c to the surface of the base film 2 is h2, and the distance in the plane direction of the base film 2 between the top portion 24e and the bottom portion 24f. When W is used, the average value of the rate of change in thickness indicated by (h1-h2) / W is 0.01 or more and 1.0 or less.

The printed wiring board 21 has one or a plurality of dummy lead wires in which the conductive pattern 23 has a plated lead wire 23a, is electrically insulated from the plated lead wire 23a, and is arranged in parallel with the plated lead wire 23a. By providing 25a, for example, when the insulating layer 24 is formed by using the photosensitive dry film, it is easy to dam the flow of the molten photosensitive dry film from the plating lead wire 23a side to the second region 24b side. As a result, it is possible to easily prevent the plating lead wire 23a from being exposed to the outer surface side of the insulating layer 24.

(Conductive pattern)
The conductive pattern 23 is a layer made of a conductor having conductivity, and includes a plurality of wirings arranged in parallel. The conductive pattern 23 may have the same configuration as that of the printed wiring board 1 of FIG. 1, for example, except that the conductive pattern 23 has a plated lead wire 23a.

The plated lead wire 23a is electrically connected to one or more of the above wirings included in the conductive pattern 23, and is used, for example, to form a coating layer for these wirings. The specific configuration of the plated lead wire 23a is not particularly limited, but can be, for example, the same configuration as the core body 13e of FIG. 7. The number of the plating lead wires 23a is not particularly limited, but in the present embodiment, two parallel plating lead wires 23a are formed. The average thickness, average width, and average pitch of the two plated lead wires 23a can be the same as those of the second wiring 13d in FIG.

(Dummy lead wire)
One or a plurality of dummy lead wires 25a are arranged outside the forming region of the conductive pattern 23. The one or a plurality of dummy lead wires 25a are provided in the same layer as the conductive pattern 23. One or a plurality of dummy wirings 25a are arranged between the base film 2 and the insulating layer 24 adjacent to the plating lead wires 23a. In the present embodiment, one dummy lead wire 25a is arranged on both outer sides of the two plated lead wires 23a in the width direction. The printed wiring board 21 has two or more dummy lead wires on both outer sides of the two plated lead wires 23a in order to more reliably prevent the plated lead wires 23a from being exposed to the outer surface side of the insulating layer 24. 25a may be arranged.

The average thickness of one or a plurality of dummy lead wires 25a is preferably equal to or less than the average thickness of the plated lead wires 23a. When the average thickness of one or a plurality of dummy lead wires 25a and the average thickness of the plated lead wires 23a are made uniform, for example, one or a plurality of dummy lead wires 25a and the plated lead wires 23a are the same as the core body 13e of FIG. It may be configured as.

It is preferable that the one or a plurality of dummy lead wires 25a and the plated lead wires 23a are arranged at the same pitch. As a result, the thickness of the insulating layer 24 can be made uniform, and it is easy to prevent the plating lead wire 23a from being exposed to the outer surface side of the insulating layer 24. The average spacing between the adjacent plated lead wires 23a and the dummy lead wires 25a can be the same as the average spacing between the adjacent wirings 3a and the dummy lead wires 5a of the printed wiring board 1 of FIG.

(Insulation layer)
The insulating layer 24 is laminated in a region where the conductive patterns 23, 1 or a plurality of dummy lead wires 25a, and the conductive patterns 23 and 1 or a plurality of dummy lead wires 25a of the base film 2 are not laminated. The insulating layer 24 mainly prevents damage and short circuit due to contact with other members of the conductive pattern 23. Therefore, it is preferable that the insulating layer 24 completely covers the outer surface of the conductive pattern 3 except for intentionally provided openings and notches.

Like the printed wiring board 1 of FIG. 1, the insulating layer 24 can be formed of a solder resist, a coverlay, or the like, and is preferably formed by curing a photosensitive dry film. The average thickness of the insulating layer 24 laminated on the surface of the plated lead wire 23a opposite to the base film 2 is such that the plurality of wirings 3a in the printed wiring board 1 of FIG. 1 are laminated on the surface opposite to the base film 2. It can be the same as the average thickness of the insulating layer 4 to be formed.

As described above, the insulating layer 24 has a first region 24a that overlaps the forming region of the conductive pattern 23 in a plan view and a second region 24b that does not overlap the forming region of the conductive pattern 23 in a plan view. In the insulating layer 24, a region other than the first region 24a is configured as a second region 24b. Further, in a plan view, the outer edge of the first region 24a coincides with the outer edge of the formation region of the conductive pattern 23. At the boundary surface X of the first region 24a and the second region 24b, the plating lead wire 23a is not exposed on the outer surface side of the insulating layer 24 except for the intended opening and notch.

The inclined portion 24c is formed in the second region 24b with the boundary surface X with the first region 24a as an end edge. The thickness of the inclined portion 24c is gradually reduced toward the second region 24b with the position of the boundary surface X with the first region 24a as the top portion 24e in the cross section in the thickness direction perpendicular to the boundary surface X. In the present embodiment, the bottom portion 24f of the inclined portion 24c is formed, for example, at an intermediate position between the adjacent plating lead wires 23a and the dummy lead wires 25a.

In the cross section in the thickness direction perpendicular to the boundary surface X of the first region 24a and the second region 24b, the average value of the change rate of the thickness represented by (h1-h2) / W is the printed wiring board 1 of FIG. The same can be done.

<Manufacturing method of printed wiring board>
Next, an example of the manufacturing method of the printed wiring board 21 of FIG. 8 will be described. The method for manufacturing the printed wiring board includes a first laminating step of laminating a conductive pattern 23 including a plurality of wiring arranged in parallel on a base film 2 having an insulating property, and a base film after the first laminating step. 2 and a second laminating step of laminating the insulating layer 24 on the conductive pattern 23 are provided. In the method for manufacturing the printed wiring board, the insulating layer 24 has a first region 24a that overlaps the forming region of the conductive pattern 23 in a plan view and a second region 24b that does not overlap the forming region of the conductive pattern 23 in a plan view. The second region 24b has an inclined portion 24c that is continuous from the first region 24a and whose thickness from the surface of the base film 2 gradually decreases.

(First laminating process)
The first laminating step is a step of simultaneously laminating a plurality of wiring cores constituting the conductive pattern 23, a plated lead wire 23a, and one or a plurality of dummy lead wires 25a on the surface of the base film 2 (core laminating). Step) and a step of laminating the coating layer on the desired core body laminated in the core body laminating step (coating layer laminating step). In the first laminating step, one or a plurality of dummy lead wires 35a are laminated with the plating lead wire 23a in an electrically insulated state and in parallel with the plating lead wire 23a. The core body laminating step can be performed by using the semi-additive method as in the method for manufacturing the printed wiring board of FIG.

(Second laminating process)
In the second laminating step, the insulating layer 24 is laminated by curing the photosensitive dry film. In the second laminating step, the insulating layer 24 is laminated in the same manner as in the method for manufacturing the printed wiring board of FIG. The method for manufacturing the printed wiring board is such that when the insulating layer 24 is laminated using the photosensitive dry film, it is easy to block the flow of the molten photosensitive dry film from the plating lead wire 23a side to the second region 24b side. It is possible to prevent the plating lead wire 23a from being exposed to the outer surface side of the insulating layer 24.

In the second laminating step, the length of the foot of the perpendicular line drawn from the top portion 24e of the inclined portion 24c to the surface of the base film 2 in the cross section in the thickness direction perpendicular to the boundary surface X of the first region 24a and the second region 24b is determined. When h1, the length of the foot of the perpendicular line drawn from the bottom 24f of the inclined portion 24c to the surface of the base film 2 is h2, and the plane distance of the base film 2 between the top 24e and the bottom 24f is W, (h1-h2). The average value of the rate of change in thickness indicated by / W is controlled to be 0.01 or more and 1.0 or less. The preferable lower limit value and preferable upper limit value of the rate of change are the same as those in the method for manufacturing the printed wiring board of FIG.

[Fourth Embodiment]
<Printed wiring board>
The printed wiring boards 31 of FIGS. 11 and 12 have an insulating base film 2, a conductive pattern 33 including a plurality of wirings (not shown) laminated in parallel on the base film 2, and a base film. 2 and an insulating layer 34 laminated on the conductive pattern 33 are provided. The conductive pattern 34 has a land portion 33c. The insulating layer 34 has a first region 34a that overlaps the forming region of the conductive pattern 33 in a plan view, and a second region 34b that does not overlap the forming region of the conductive pattern 33 in a plan view. The second region 34b has an inclined portion 34c that is continuous from the first region 34a and whose thickness from the surface of the base film 2 gradually decreases. In the printed wiring board 31, the conductive pattern 33 and the insulating layer 34 are laminated on both sides of the base film 2. Since the base film 2 of the printed wiring board 31 can have the same configuration as the base film 2 of the printed wiring board 1 of FIG. 1, the same reference numerals are given and the description thereof will be omitted.

The printed wiring board 31 includes a plurality of dummy wirings (hereinafter, also referred to as “second dummy wiring 35a”) arranged so as to be electrically insulated from the land portion 33c and surround the land portion 33c.

As shown in FIGS. 12 and 13, the printed wiring board 31 has a thickness direction cross section perpendicular to the boundary surface X of the first region 34a and the second region 34b, from the top portion 34e of the inclined portion 34c to the surface of the base film 2. The length of the foot of the perpendicular line dropped to h1, the length of the foot of the perpendicular line dropped from the bottom 34f of the inclined portion 34c to the surface of the base film 2 is h2, and the distance in the plane direction of the base film 2 between the top portion 34e and the bottom portion 34f. When W is used, the average value of the rate of change in thickness indicated by (h1-h2) / W is 0.01 or more and 1.0 or less.

The printed wiring board 31 includes a plurality of second dummy wirings 35a in which the conductive pattern 33 has a land portion 33c, is electrically insulated from the land portion 33c, and is arranged so as to surround the land portion 33c. Thereby, for example, when the insulating layer 34 is formed by using the photosensitive dry film, it is easy to dam the flow of the melted photosensitive dry film from the land portion 33c side to the second region 34b side. As a result, it is possible to easily prevent the insulation layer 34 of the land portion 33c from being exposed to the outer surface side.

(Conductive pattern)
The conductive pattern 33 is a layer made of a conductor having conductivity, and includes a plurality of wirings arranged in parallel. The conductive pattern 33 may have the same configuration as that of the printed wiring board 1 of FIG. 1, for example, except that the conductive pattern 33 has a land portion 33c.

In the present embodiment, the land portion 33c is a through-hole land provided on the surface side of the base film 2 of the through-hole 33b. The land portion 33c is formed, for example, by laminating the core body 33d on both sides of the base film 2, forming a through hole penetrating the core body 33d, and applying the same plating as the above-mentioned coating layer to the through hole. Will be done. Therefore, the land portion 33c includes a plating layer provided on both side surfaces of the core body 33d and the base film 2. The land portion 33c is an annular shape in a plan view. The average thickness of the land portion 33c is not particularly limited. However, since the land portion 33c generally has a large plane area, the plating thickness tends to increase when plating is applied. Therefore, the average thickness of the land portion 33c tends to be larger than that of the first wiring 13c in FIG. 7.

(Dummy wiring)
The plurality of second dummy wirings 35a are arranged outside the forming region of the conductive pattern 33. The plurality of second dummy wirings 35a are provided on the same layer as the conductive pattern 33. In the present embodiment, the plurality of second dummy wirings 35a are arranged on both sides of the base film 2. The plurality of second dummy wirings 35a are arranged between the base film 2 and the insulating layer 34 adjacent to the land portion 33c. The second dummy wiring 35a surrounds the land portion 33c so that the distance from the land portion 33c is uniform over the entire area in the longitudinal direction. Therefore, in the present embodiment, each of the second dummy wirings 35a is formed in a C shape having an opening for passing the wiring 33a connected to the land portion 33c. The printed wiring board 31 is provided with a plurality of second dummy wirings 35a so as to surround the land portion 33c, so that the flow of the molten photosensitive dry film from the land portion 33c side to the second region 34b side is more reliable. It can be stopped. In particular, the printed wiring board 31 has a plurality of second dummy wirings 35a even when the thickness of the land portion 33c is relatively large, so that the flow of the molten photosensitive dry film is sufficiently suppressed. Can be done. When a plurality of second dummy wirings 35a are provided, the lower limit of the number of these second dummy wirings 35a is preferably two, more preferably three. On the other hand, the upper limit of the number of the plurality of second dummy wires 35a can be, for example, five.

The plurality of second dummy wirings 35a are, for example, a laminate of a seed layer laminated on the base film 2 and an electroplating layer laminated on the seed layer. Further, the plurality of second dummy wirings 35a may have a core body composed of the seed layer and the electroplating layer, and a coating layer laminated on the outer surface of the core body by plating. When the plurality of second dummy wirings 35a are made of a laminate of the seed layer and the electroplating layer, the average thickness and the average width of these second dummy wirings 35a are the same as those of the second wiring 13d in FIG. be able to. When the plurality of second dummy wirings 35a are composed of the core body and the covering layer, the average thickness and the average width of these second dummy wirings 35a may be the same as those of the first wiring 13c in FIG. can.

The average thickness of the plurality of second dummy wirings 35a is preferably equal to or less than the average thickness of the land portion 33c. When the average thickness of the plurality of second dummy wirings 35a is made smaller than the average thickness of the land portions 33c, the difference in the average thickness between the land portions 33c and the plurality of second dummy wirings 35a is, for example, 3 μm or more and 12 μm or less. Can be. In the printed wiring board 31, the average thickness of the plurality of second dummy wirings 35a is set to be equal to or less than the average thickness of the land portions 33c, so that the plurality of second dummy wirings 35a (more specifically, the farthest from the land portions 33c). It is easy to prevent the insulating layer 34 from being exposed to the outer surface side of the second dummy wiring 35a) arranged at the above position.

It is preferable that the plurality of second dummy wirings 35a are arranged at the same pitch. Further, it is preferable that the distance between the land portion 33c and the second dummy wiring 35a adjacent to the land portion 33c and the distance between the adjacent second dummy wiring 35a are the same. As a result, the thickness of the insulating layer 34 can be made uniform, and it is easy to prevent the land portion 33c from being exposed to the outer surface side of the insulating layer 34. The pitch can be the same as the average pitch between the adjacent wirings 3a of the printed wiring board 1 of FIG. Further, the distance between the land portion 33c and the second dummy wiring 35a adjacent to the land portion 33c and the distance between the adjacent second dummy wiring 35a are between the adjacent wirings 3a of the printed wiring board 1 of FIG. It can be the same as the average interval.

(Insulation layer)
The insulating layer 34 is laminated in a region where the conductive pattern 33, the plurality of second dummy wirings 35a, and the conductive pattern 33 of the base film 2 and the plurality of second dummy wirings 35a are not laminated. The insulating layer 34 mainly prevents damage and short circuit due to contact with other members of the conductive pattern 33. Therefore, it is preferable that the insulating layer 34 completely covers the outer surface of the conductive pattern 33 except for intentionally provided openings and notches.

Similar to the printed wiring board 1 of FIG. 1, the insulating layer 34 can be formed of a solder resist, a coverlay, or the like, and is preferably formed by curing a photosensitive dry film. The average thickness of the insulating layer 34 laminated on the surface of the land portion 33c opposite to the base film 2 is such that the plurality of wirings 3a in the printed wiring board 1 of FIG. 1 are laminated on the surface opposite to the base film 2. It can be the same as the average thickness of the insulating layer 4.

As described above, the insulating layer 34 has a first region 34a that overlaps the forming region of the conductive pattern 33 in a plan view and a second region 34b that does not overlap the forming region of the conductive pattern 33 in a plan view. In the insulating layer 34, a region other than the first region 34a is configured as a second region 34b. Further, in a plan view, the outer edge of the first region 34a coincides with the outer edge of the formation region of the conductive pattern 33. At the boundary surface X of the first region 34a and the second region 34b, the land portion 33c is not exposed on the outer surface side of the insulating layer 34 except for the intended opening and notch.

The inclined portion 34c is formed in the second region 34b with the boundary surface X with the first region 34a as an end edge. The thickness of the inclined portion 34c is gradually reduced toward the second region 34b with the position of the boundary surface X with the first region 34a as the top portion 34e in the cross section in the thickness direction perpendicular to the boundary surface X. In the present embodiment, the bottom portion 34f of the inclined portion 34c is formed, for example, at an intermediate position between the land portion 33c and the dummy lead wire 35a adjacent to the land portion 33c.

In the cross section in the thickness direction perpendicular to the boundary surface X of the first region 34a and the second region 34b, the average value of the change rate of the thickness represented by (h1-h2) / W is the printed wiring board 1 of FIG. The same can be done.

<Manufacturing method of printed wiring board>
Next, an example of the manufacturing method of the printed wiring board 31 of FIG. 11 will be described. The method for manufacturing the printed wiring board includes a first laminating step of laminating a conductive pattern 33 including a plurality of wiring arranged in parallel on a base film 2 having an insulating property, and a base film after the first laminating step. 2 and a second laminating step of laminating the insulating layer 34 on the conductive pattern 33 are provided. In the method for manufacturing the printed wiring board, the insulating layer 34 has a first region 34a that overlaps the forming region of the conductive pattern 33 in a plan view and a second region 34b that does not overlap the forming region of the conductive pattern 33 in a plan view. The second region 34b has an inclined portion 34c which is continuous from the first region 34a and whose thickness from the surface of the base film 2 gradually decreases.

(First laminating process)
In the first laminating step, a plurality of second dummy wirings 35a are laminated on the surface of the base film 2 at the same time as the conductive pattern 33 having the land portion 33c. In the first laminating step, a plurality of second dummy wirings 35a are laminated so as to be electrically insulated from the land portion 33c and surround the land portion 33c. The first laminating step includes a step of laminating the core body 33d of the land portion 33c and the core body of the plurality of second dummy wirings 35a by a semi-additive method, and a step of forming a through hole in the core body 33d of the land portion 33c. It also has a step of plating the through hole and, if necessary, the core body of a plurality of second dummy wirings 35a.

(Second laminating process)
In the second laminating step, the insulating layer 34 is laminated by curing the photosensitive dry film. In the second laminating step, the insulating layer 34 is laminated in the same manner as in the method for manufacturing the printed wiring board of FIG. In the method of manufacturing the printed wiring board, when the insulating layer 34 is laminated using the photosensitive dry film, it is easy to block the flow of the melted photosensitive dry film from the land portion 33c side to the second region 34b side, and the land It is possible to prevent the insulating layer 33 of the portion 33c from being exposed to the outer surface side.

In the second laminating step, the length of the foot of the perpendicular line drawn from the top portion 34e of the inclined portion 34c to the surface of the base film 2 in the cross section in the thickness direction perpendicular to the boundary surface X of the first region 34a and the second region 34b is determined. When h1, the length of the foot of the perpendicular line drawn from the bottom 34f of the inclined portion 34c to the surface of the base film 2 is h2, and the plane distance of the base film 2 between the top 34e and the bottom 34f is W, (h1-h2). The average value of the rate of change in thickness indicated by / W is controlled to be 0.01 or more and 1.0 or less. The preferable lower limit value and preferable upper limit value of the rate of change are the same as those in the method for manufacturing the printed wiring board of FIG.

[Fifth Embodiment]
<Printed wiring board>
The printed wiring boards 41 of FIGS. 14 to 16 include a base film 2 having an insulating property, a conductive pattern 43 including a plurality of wirings 43a laminated on the base film 2 and arranged in parallel, and the base film 2 and conductivity. The insulating layer 44 laminated on the pattern 43 is provided. The conductive pattern 43 has a connection wiring 43b connected in a T shape to the end of at least one of the plurality of wirings 43a. The connection wiring 43b is arranged along the outer edge of the printed wiring board 41. The insulating layer 44 has a first region 44a that overlaps the forming region of the conductive pattern 43 in a plan view, and a second region 44b that does not overlap the forming region of the conductive pattern 43 in a plan view. The second region 44b has an inclined portion 44c that is continuous from the first region 44a and whose thickness from the surface of the base film 2 gradually decreases. Since the base film 2 of the printed wiring board 41 can have the same configuration as the base film 2 of the printed wiring board 1 of FIG. 1, the same reference numerals are given and the description thereof will be omitted.

As shown in FIG. 15, the printed wiring board 41 has a side edge (hereinafter, "first side") of the connection portion C of the wiring 43a and the connection wiring 43b on the side opposite to the side connected to the wiring 43a of the connection wiring 43b. The width w between the edge 43c) and the side edge facing the first side edge 43c (hereinafter, also referred to as the “second side edge 43d”) is uniform.

As shown in FIG. 16, the printed wiring board 41 is lowered from the top 44e of the inclined portion 44c to the surface of the base film 2 in the cross section in the thickness direction perpendicular to the boundary surface X of the first region 44a and the second region 44b. The length of the foot of the perpendicular is h1, the length of the foot of the perpendicular drawn from the bottom 44f of the inclined portion 44c to the surface of the base film 2 is h2, and the plane distance of the base film 2 between the top 44e and the bottom 44f is W. In this case, the average value of the rate of change in thickness represented by (h1-h2) / W is 0.01 or more and 1.0 or less.

The printed wiring board 41 has a connection wiring 43b in which the conductive pattern 43 is connected in a T shape to the end of at least one wiring 43a among the plurality of wirings 43a, and the connection portion of the wiring 43a and the connection wiring 43b. In C, the width w of the first side edge 43c of the connection wiring 43b and the second side edge 43d facing the first side edge 43c is uniform, so that the plating thickness of the connection portion C is larger than that of the other portions. Can be suppressed from becoming large. As a result, as shown in FIG. 16, the printed wiring board 41 can prevent the thickness of the connecting portion C from becoming larger than that of the other portions. This makes it possible to prevent the connection portion C from being exposed to the outer surface side of the insulating layer 2 due to the step between the connection portion C and the surface of the base film 2.

(Conductive pattern)
The conductive pattern 43 is a layer made of conductive conductors, and includes a plurality of wirings 43a arranged in parallel and connection wirings 43b connected in a T shape to the ends of at least one wiring 43a. .. Similar to the printed wiring board 1 of FIG. 1, the plurality of wirings 43a may be a laminated body of a seed layer and an electroplating layer, and a coating layer is laminated on a core body composed of the laminated body of the seed layer and the electroplating layer. It may have the same configuration.

Similar to the printed wiring board 1 of FIG. 1, the connection wiring 43b may be a laminated body of a seed layer and an electroplating layer, and a coating layer is laminated on a core body composed of the laminated body of the seed layer and the electroplating layer. It may be configured. When the connection wiring 43b has the same laminated structure as the plurality of wirings 43a, it is easy to make the thickness uniform with the plurality of wirings 43a. Further, the plurality of wirings 43b are configured by laminating a coating layer on the core body, and the connection wiring 43b connected to these wirings 43b is a two-layered body of the seed layer and the electroplating layer (that is, the coating layer is laminated). In the case of no configuration), it is easy to reduce the thickness of the connection wiring 43b and reduce the step between the connection wiring 43b and the surface of the base film 2.

In the present embodiment, the connection wiring 43b connects the ends of the plurality of wirings 43a arranged in parallel. As shown in FIG. 15, the connection wiring 43b has a uniform width. The connection wiring 43b has a structure in which an arch structure that is recessed on the wiring 43a side at a connection portion C with a plurality of wirings 43a and protrudes on the opposite side to the wiring 43a in a region between adjacent wirings 43a is continuous in the longitudinal direction. As a result, the connection wiring 43b is connected to the plurality of wirings 43a in a Y shape. The connection wiring 43b is provided so that the perpendicular line drawn from the first side edge 43c is substantially orthogonal to the other side edge of the first side edge 43c. As a result, in the connection portion C of the wiring 43a and the connection wiring 43b, the width w between the first side edge 43c of the connection wiring 43b and the second side edge 43d facing the first side edge 43c is kept uniform. There is. The "connection portion of wiring and connection wiring" means a portion where the wiring and the connection wiring intersect when the wiring is extended to the connection wiring side.

(Insulation layer)
The insulating layer 44 is laminated in a region where the conductive pattern 43 and the conductive pattern 43 of the base film 2 are not laminated. The insulating layer 44 mainly prevents damage and short circuit due to contact with other members of the conductive pattern 43. Therefore, it is preferable that the insulating layer 44 completely covers the outer surface of the conductive pattern 43 except for intentionally provided openings and notches.

Similar to the printed wiring board 1 of FIG. 1, the insulating layer 44 can be formed of a solder resist, a coverlay, or the like, and is preferably formed by curing a photosensitive dry film. The average thickness of the insulating layer 44 laminated on the surface of the plurality of wirings 43a opposite to the base film 2 is such that the plurality of wirings 3a in the printed wiring board 1 of FIG. 1 are laminated on the surface opposite to the base film 2. It can be the same as the average thickness of the insulating layer 4 to be formed.

As described above, the insulating layer 44 has a first region 44a that overlaps the forming region of the conductive pattern 43 in a plan view and a second region 44b that does not overlap the forming region of the conductive pattern 43 in a plan view. In the insulating layer 44, a region other than the first region 44a is configured as the second region 44b. Further, in a plan view, the outer edge of the first region 44a coincides with the outer edge of the formation region of the conductive pattern 43. At the boundary surface X of the first region 44a and the second region 44b, the plurality of wirings 43a and the connection wirings 43b are not exposed on the outer surface side of the insulating layer 44 except for the intended openings and notches.

The inclined portion 44c is formed in the second region 44b with the boundary surface X with the first region 44a as an end edge. The thickness of the inclined portion 44c is gradually reduced toward the second region 44b with the position of the boundary surface X with the first region 44a as the top portion 44e in the cross section in the thickness direction perpendicular to the boundary surface X. In the present embodiment, the bottom portion 44f of the inclined portion 44c is located on the outer edge of the printed wiring board 41.

In the cross section in the thickness direction perpendicular to the boundary surface X of the first region 44a and the second region 44b, the average value of the change rate of the thickness represented by (h1-h2) / W is the printed wiring board 1 of FIG. The same can be done.

<Manufacturing method of printed wiring board>
Next, an example of the manufacturing method of the printed wiring board 41 of FIG. 14 will be described. The method for manufacturing the printed wiring board includes a first laminating step of laminating a conductive pattern 43 including a plurality of wirings 43a arranged in parallel on a base film 2 having an insulating property, and a base after the first laminating step. A second laminating step of laminating the insulating layer 44 on the film 2 and the conductive pattern 43 is provided. In the method for manufacturing the printed wiring board, the insulating layer 44 has a first region 44a that overlaps the forming region of the conductive pattern 43 in a plan view and a second region 44b that does not overlap the forming region of the conductive pattern 43 in a plan view. The second region 44b has an inclined portion 44c which is continuous from the first region 44a and whose thickness from the surface of the base film 2 gradually decreases.

(First laminating process)
In the first laminating step, the connection wiring 43b connected in a T shape is laminated on the surface of the base film 2 at the end of at least one of the plurality of wirings 43a and the plurality of wirings 43a. In the first laminating step, in the connection portion C of the wiring 43a and the connecting wiring 43b, the side edge (first side edge 43c) opposite to the side connected to the wiring 43a of the connecting wiring 43b and the first side edge thereof. A plurality of wirings 43a and connection wirings 43b are laminated so that the width w with the side edge (second side edge 43d) facing the 43c is uniform. The first laminating step can be performed by using a semi-additive method, for example, as in the first laminating step of the method for manufacturing a printed wiring board of FIG.

(Second laminating process)
In the second laminating step, the insulating layer 44 is laminated by curing the photosensitive dry film. In the second laminating step, the insulating layer 44 is laminated in the same manner as in the method for manufacturing the printed wiring board of FIG. In the method for manufacturing the printed wiring board, since the swelling of the connection portion C of the wiring 43a and the connection wiring 43b can be suppressed in the first laminating step, the photosensitive dry film is used for insulation in the second laminating step. When the layers 44 are laminated, it is possible to prevent the raised portion from being exposed on the outer surface side of the insulating layer 44.

In the second laminating step, the length of the foot of the perpendicular line drawn from the top portion 44e of the inclined portion 44c to the surface of the base film 2 in the cross section in the thickness direction perpendicular to the boundary surface X of the first region 44a and the second region 44b is determined. When h1, the length of the foot of the perpendicular line drawn from the bottom 44f of the inclined portion 44c to the surface of the base film 2 is h2, and the plane distance of the base film 2 between the top 44e and the bottom 44f is W, (h1-h2). The average value of the rate of change in thickness indicated by / W is controlled to be 0.01 or more and 1.0 or less. The preferable lower limit value and preferable upper limit value of the rate of change are the same as those in the method for manufacturing the printed wiring board of FIG.

[Other embodiments]
It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present disclosure is not limited to the configuration of the above embodiment, but is indicated by the scope of claims and is intended to include all modifications within the meaning and scope equivalent to the scope of claims. To.

For example, the printed wiring board can be used by combining the above-described configurations from the first embodiment to the fifth embodiment as necessary. Further, in the first embodiment and the second embodiment, the configuration in which a plurality of wirings form a coil pattern has been described, but the arrangement pattern of the plurality of wirings is not limited to the coil pattern. Further, in the printed wiring board, the conductive pattern and the insulating layer may be laminated only on one side of the base film, or the conductive pattern and the insulating layer may be laminated on both sides of the base film.

In each of the above embodiments, as a specific configuration of the plurality of wirings, a laminate of a seed layer and an electroplating layer, or a configuration in which the laminate is coated with a coating layer has been described, but the specific layer structure of the plurality of wirings is described. The configuration is not limited to the configuration described in the above embodiment. Further, the configurations of the seed layer and the electroplating layer are not limited, and for example, the electroplating layer may be a laminated body having two or more layers. Further, the land portion does not necessarily have to be a through-hole land.

The printed wiring board may have only one dummy wiring (first dummy wiring) outside the width direction of the plurality of wirings. Further, the printed wiring board may have only one dummy wiring (second dummy wiring) surrounding the land portion.

In the printed wiring board, the thickness of one or a plurality of wirings arranged on the second region side among the plurality of wirings is smaller than the thickness of one wiring arranged on the center side of the first region. You may. For example, in the printed wiring board, a plurality of wirings are arranged on one first wiring having a first thickness and on the second region side of the first wiring, and the second wiring is smaller than the first thickness. It may include one or more second wires having a thickness of.

In the method for manufacturing the printed wiring board, the insulating layer may be laminated using a material other than the photosensitive dry film in the second laminating step. For example, in the second laminating step, an insulating layer may be formed by using a resin film other than the photosensitive dry film. In the first laminating step, the conductive pattern may be laminated on the base film by a method other than the semi-additive method.

As described above, the printed wiring board according to the embodiment of the present disclosure can prevent the conductive pattern from being exposed to the outer surface side of the insulating layer, and is therefore suitable for preventing damage and short circuit of the conductive pattern.

1,11,21,31,41 Printed wiring board 2 Base film 3,13,23,33,43 Conductive pattern 3a, 13a, 33a, 43a Wiring 3b, 13b, 33c Land portion 4,14,24,34,44 Insulating layers 4a, 14a, 24a, 34a, 44a First region 4b, 14b, 24b, 34b, 44b Second region 4c, 14c, 24c, 34c, 44c Inclined portions 4e, 14e, 24e, 34e, 44e Top 4f, 14f , 24f, 34f, 44f Bottom 5a 1st dummy wiring 13c 1st wiring 13d 2nd wiring 13e, 33d Core 13f Coating layer 23a Plated lead wire 25a Dummy lead wire 33b Through hole 35a 2nd dummy wiring 43b Connection wiring 43c 1st Side edge 43d Second side edge X Boundary surface C Connection part

Claims (9)

Insulating base film and
A conductive pattern including a plurality of wires laminated on the base film and arranged in parallel,
A printed wiring board provided with the base film and an insulating layer laminated on the conductive pattern.
The insulating layer has a first region that overlaps the conductive pattern forming region in a plan view and a second region that does not overlap the conductive pattern forming region in a plan view.
The second region is continuous with the first region and has an inclined portion in which the thickness from the surface of the base film gradually decreases.
In the cross section in the thickness direction perpendicular to the boundary surface of the first region and the second region, the length of the foot of the perpendicular line drawn from the top of the inclined portion to the surface of the base film is h1, and the length of the foot of the perpendicular line is from the bottom of the inclined portion to the base. When the length of the foot of the perpendicular line drawn on the film surface is h2 and the plane distance of the base film between the top and bottom is W, the average rate of change in thickness indicated by (h1-h2) / W is average. A printed wiring board having a value of 0.01 or more and 1.0 or less. The printed wiring board according to claim 1, further comprising one or a plurality of dummy wirings arranged outside the plurality of wirings in the width direction in an electrically insulated state from the wirings and in parallel with the wirings. .. Among the plurality of wirings, the thickness of one or a plurality of wirings arranged on the second region side is smaller than the thickness of the one or a plurality of wirings arranged on the center side of the first region. The printed wiring board according to claim 1 or 2. The plurality of wirings are arranged on the second region side of the one or more first wirings having the first thickness and the one or more first wirings, and are smaller than the first thickness. The printed wiring board according to claim 3, wherein the printed wiring board includes one or a plurality of second wirings having a second thickness. The conductive pattern has plated leads and
The printed wiring according to any one of claims 1 to 4, further comprising one or a plurality of dummy lead wires arranged in parallel with the plated lead wire in an electrically insulated state. Board. The conductive pattern has a land portion and has a land portion.
The printed wiring board according to any one of claims 1 to 5, further comprising one or a plurality of dummy wirings that are electrically insulated from the land portion and are arranged so as to surround the land portion. The conductive pattern has a connection wiring connected in a T shape to the end of at least one of the plurality of wirings.
Claims 1 to claim 1 to claim that the width of the side edge of the connection wiring on the side opposite to the side connected to the wiring and the side edge facing the side edge is uniform in the connection portion of the wiring and the connection wiring. 6. The printed wiring board according to any one of 6. The first laminating step of laminating a conductive pattern including a plurality of wires arranged in parallel on an insulating base film, and
A method for manufacturing a printed wiring board, comprising a second laminating step of laminating an insulating layer on the base film and the conductive pattern after the first laminating step.
The insulating layer has a first region that overlaps the conductive pattern forming region in a plan view and a second region that does not overlap the conductive pattern forming region in a plan view.
The second region is continuous with the first region and has an inclined portion in which the thickness from the surface of the base film gradually decreases.
In the cross section in the thickness direction perpendicular to the boundary surface of the first region and the second region, the length of the foot of the perpendicular line drawn from the top of the inclined portion to the surface of the base film is h1, and the length of the foot of the perpendicular is from the bottom of the inclined portion to the base. When the length of the foot of the perpendicular line drawn on the film surface is h2 and the plane distance of the base film between the top and bottom is W, the thickness shown by (h1-h2) / W in the second laminating step. A method for manufacturing a printed wiring board that controls the average value of the rate of change to 0.01 or more and 1.0 or less. The method for manufacturing a printed wiring board according to claim 8, wherein the insulating layer is laminated by curing the photosensitive dry film in the second laminating step.

Images