JP2023037996A - Printed wiring board and method for manufacturing printed wiring board - Google Patents

Abstract

To provide a printed wiring board having stable performance.SOLUTION: A printed wiring board has a resin insulating layer having a first surface and a second surface opposite to the first surface, and a conductor layer formed on the first surface. The conductor layer is formed of a first metal layer formed on the first surface, a second metal layer formed on the first metal layer, and a third metal layer formed on the second metal layer. The first metal layer and the third metal layer are formed of copper. The second metal layer is formed of metal other than copper.SELECTED DRAWING: Figure 3

Description

The technology disclosed by this specification relates to printed wiring boards.

Patent Document 1 discloses a coil sheet having an insulating substrate and a spiral coil pattern formed on the insulating substrate. The coil sheet manufacturing method of Patent Document 1 includes forming a spiral lower-layer conductor pattern on an insulating substrate, and additionally forming an electrolytic plating film on the conductor pattern.

JP 2009-246363 A

[Problem of Patent Document 1]
In the technique disclosed in Patent Document 1, an electrolytic plating film is formed on the conductor pattern after the conductor pattern is formed on the insulating substrate. It is thought that this method causes variations in the thickness of the completed coil pattern. It is considered that the gaps between the wires forming the coil pattern are uneven.

A printed wiring board of the present invention has a resin insulating layer having a first surface and a second surface opposite to the first surface, and a conductor layer formed on the first surface. The conductor layer includes a first metal layer formed on the first surface, a second metal layer formed on the first metal layer, and a third metal layer formed on the second metal layer. made up of layers. The first metal layer and the third metal layer are made of copper. The second metal layer is made of metal other than copper.

In the printed wiring board of the embodiment of the present invention, the conductor layer has a second metal layer made of a metal other than copper disposed between a first metal layer made of copper and a third metal layer. It has a three-layer structure. Therefore, when a conductor circuit is formed using the conductor layer of the embodiment, the gap between the conductor circuits to be formed varies and the thickness of the conductor circuit increases compared to the case of using a conventional conductor layer composed only of a copper layer. Variation can be reduced. A printed wiring board with stable performance can be obtained.

A method of manufacturing a printed wiring board according to the present invention comprises forming a first metal layer on the first surface of a resin insulation layer having a first surface and a second surface opposite to the first surface; forming a second metal layer having a first opening on the first metal layer; and forming a third metal layer on the second metal layer and the first metal layer exposed through the first opening. forming a metal mask having a second opening located immediately above the first opening on the third metal layer; and the third metal layer and the first opening exposed from the second opening. and forming a conductor layer formed of the first metal layer, the second metal layer and the third metal layer by selectively removing the first metal layer exposed from. The first metal layer and the third metal layer are made of copper, and the second metal layer and the metal mask are made of a metal other than copper.

According to the printed wiring board manufacturing method of the embodiment of the present invention, the conductor layer is formed by selectively removing the third metal layer exposed from the second opening and the first metal layer exposed from the first opening. . Compared to the conventional method of forming a conductor layer by removing part of a metal layer consisting of only a copper layer, variations in the gap and thickness between conductor circuits included in the conductor layer can be reduced. . A printed wiring board with stable performance can be obtained.

1 is a plan view schematically showing a printed wiring board according to an embodiment; FIG. FIG. 2 is a bottom view schematically showing the printed wiring board of the embodiment; BRIEF DESCRIPTION OF THE DRAWINGS Sectional drawing which shows typically some printed wiring boards of embodiment. FIG. 4 is an enlarged explanatory view of part of FIG. 3; FIG. 4 is a cross-sectional view schematically showing a method for manufacturing a printed wiring board according to the embodiment; FIG. 4 is a cross-sectional view schematically showing a method for manufacturing a printed wiring board according to the embodiment; FIG. 4 is a cross-sectional view schematically showing a method for manufacturing a printed wiring board according to the embodiment; FIG. 4 is a cross-sectional view schematically showing a method for manufacturing a printed wiring board according to the embodiment; FIG. 4 is a cross-sectional view schematically showing a method for manufacturing a printed wiring board according to the embodiment; FIG. 4 is a cross-sectional view schematically showing a method for manufacturing a printed wiring board according to the embodiment; FIG. 4 is a cross-sectional view schematically showing a method for manufacturing a printed wiring board according to the embodiment; FIG. 4 is a cross-sectional view schematically showing a method for manufacturing a printed wiring board according to the embodiment; FIG. 4 is a cross-sectional view schematically showing a method for manufacturing a printed wiring board according to the embodiment; FIG. 4 is a cross-sectional view schematically showing a method for manufacturing a printed wiring board according to the embodiment; FIG. 4 is a cross-sectional view schematically showing a method for manufacturing a printed wiring board according to the embodiment;

[Embodiment]
FIG. 1 is a plan view showing a printed wiring board 2 of the embodiment. FIG. 2 is a bottom view showing the printed wiring board 2 of FIG. As shown in FIGS. 1 and 2 , printed wiring board 2 includes resin insulation layer 10 , conductor layer 20 formed on first surface 10 a of resin insulation layer 10 , second layer 20 of resin insulation layer 10 . and a conductor layer 30 formed on the surface 10b. The printed wiring board 2 of the embodiment is used as a motor coil substrate by being wound into a cylindrical shape. A motor is formed by arranging the formed motor coil substrate inside a cylindrical yoke and arranging a rotating shaft and a magnet inside the motor coil substrate (not shown).

Resin insulating layer 10 is formed using an insulating resin such as polyimide or polyamide. Resin insulation layer 10 has flexibility. The resin insulation layer can form a flexible substrate. Resin insulation layer 10 has first surface 10a and second surface 10b. The thickness of resin insulation layer 10 is in the range of 10 μm or more and 100 μm or less, for example, 12.5 μm.

The conductor layers 20 and 30 are formed using a conductor such as copper. The conductor layers 20 and 30 are spirally formed coils. As shown in FIG. 1, the conductor layer 20 formed on the first surface 10a is spirally formed clockwise from the outer circumference toward the inner circumference. A connection terminal for connecting a connection cord (not shown) for connecting the conductor layer 20 to the outside is formed on the outer peripheral side end portion 24 of the conductor layer 20 . A through hole 16 is formed in the inner peripheral side end portion 22 of the conductor layer 20 so as to penetrate between the first surface 10 a and the second surface 10 b of the resin insulation layer 10 . A via conductor 45 is formed in the through hole 16 . Through holes 16 and via conductors 45 will be described later in detail with reference to FIG. Via conductors 45 electrically connect conductor layer 20 on first surface 10a and conductor layer 30 on second surface 10b.

As shown in FIG. 2, the conductor layer 30 formed on the second surface 10b is formed in a counterclockwise spiral shape from the outer circumference to the inner circumference. A connection terminal for connecting a connection cord (not shown) for connecting the conductor layer 30 to the outside is formed on the outer peripheral side end portion 34 of the conductor layer 30 . The inner peripheral side end portion 32 of the conductor layer 30 is electrically connected to the inner peripheral side end portion 22 of the conductive layer 20 through the via conductors 45 described above.

The conductor layers 20 and 30 are spirally formed in the same winding direction when viewed from the same plane. The conductor layers 20 and 30 on the first surface 10a and the second surface 10b function as one coil electrically connected in series. Although not shown, the first surface 10a and the conductor layer 20 are covered with a resin insulating layer. Similarly, the second surface 10b and the conductor layer 30 are covered with a resin insulation layer.

FIG. 3 is a cross-sectional view of part of the printed wiring board 2. As shown in FIG. 3 is a cross-sectional view between III-III of FIGS. 1 and 2. FIG. The structure of the conductor layers 20, 30 will be described in detail with reference to FIG. As shown in FIG. 3, the conductor layer 20 includes a first conductor circuit 20a forming the coil (FIG. 1), a second conductor circuit 20b adjacent to the first conductor circuit 20a, and a conductor circuit 20b adjacent to the second conductor circuit 20b. and an inner peripheral side end portion 22 adjacent to the third conductive circuit 20c. The first conductive circuit 20a, the second conductive circuit 20b, the third conductive circuit 20c, and the inner peripheral end 22 are different parts of one continuous wire. Similarly, the conductor layer 30 includes a first conductor circuit 30a forming a coil (FIG. 2), a second conductor circuit 30b adjacent to the first conductor circuit 30a, and a third conductor circuit 30c adjacent to the second conductor circuit 30b. and an inner peripheral end 32 adjacent to the third conductive circuit 30c. The first conductive circuit 30a, the second conductive circuit 30b, the third conductive circuit 30c, and the inner peripheral side end portion 32 are different portions of one continuous wiring.

The conductor layer 20 has a copper foil 12 , a first metal layer 40 , a second metal layer 50 and a third metal layer 60 . The conductor layer 30 has a copper foil 14 , a first metal layer 41 , a second metal layer 51 and a third metal layer 61 . As described above, the through holes 16 are provided in the copper foil 12 and the resin insulation layer 10 under the inner peripheral end portion 22 . A via conductor 45 is provided in the through hole 16 . The via conductor 45 electrically connects the inner peripheral side end portion 22 of the conductor layer 20 and the inner peripheral side end portion 32 of the conductive layer 30 .

The components of the conductor layer 20 are described below. Copper foil 12 is a copper thin film formed on first surface 10 a of resin insulation layer 10 . Copper foil 12 is formed in advance on first surface 10 a of resin insulation layer 10 . The copper foil 12 may be an electroless plated film. The thickness of the copper foil 12 ranges from 5 μm to 20 μm, for example, 9 μm.

The first metal layer 40 is a metal layer formed on the copper foil 12 . The first metal layer 40 is made of copper. A portion of the first metal layer is filled in through hole 16 to form via conductor 45 . The thickness of the first metal layer 40 ranges from 10 μm to 100 μm, for example, 25 μm.

The second metal layer 50 is a metal layer formed on the first metal layer 40 . The second metal layer 50 is made of metal other than copper. The second metal layer 50 is made of nickel, for example. The second metal layer 50 may be made of tin. The second metal layer 50 is thinner than the first metal layer 40 . The thickness of the second metal layer 50 ranges from 5 μm to 30 μm, for example, 10 μm.

The third metal layer 60 is a metal layer formed on the second metal layer 50 . The third metal layer 60 is made of copper. The third metal layer 60 is thicker than the first metal layer 40 . The thickness of the third metal layer 60 ranges from 20 μm to 150 μm, for example, 40 μm.

FIG. 4 is an enlarged view of the first conductor circuit 20a and the second conductor circuit 20b portion in FIG. The gap between the first metal layer 40 forming the first conductive circuit 20a and the first metal layer 40 forming the second conductive circuit 20b is a first gap G1. The gap between the second metal layer 50 forming the first conductor circuit 20a and the second metal layer 50 forming the second conductor circuit 20b is a second gap G2. The distance between the third metal layer 60 forming the third conductor circuit 20c and the third metal layer 60 forming the second conductor circuit 20b is a third distance G3. As shown in FIG. 4, the second spacing G2 is smaller than the first spacing G1 and the third spacing G3. The first spacing G1 is smaller than the third spacing G3. The difference between the intervals G1 to G3 is caused by selective etching when the printed wiring board 2 is manufactured. The same applies to the spacing between the second conductive circuit 20b and the third conductive circuit 20c. The same can be said for the distance between the third conductive circuit 20c and the inner peripheral edge 22. As shown in FIG. A method for manufacturing the printed wiring board 2 will be described later in detail.

The components of the conductor layer 30 are described below. As shown in FIG. 3 , copper foil 14 is a copper thin film formed on second surface 10 b of resin insulation layer 10 . Copper foil 14 is formed in advance on second surface 10 b of resin insulation layer 10 . The copper foil 14 may be an electroless plated film. The thickness of copper foil 14 is substantially the same as that of copper foil 12 .

The first metal layer 41 is a metal layer formed on the copper foil 14 . The first metal layer 41 is made of copper. The thickness of the first metal layer 41 is substantially the same as that of the first metal layer 40 .

The second metal layer 51 is a metal layer formed on the first metal layer 41 . The second metal layer 51 is made of metal other than copper. The second metal layer 51 is made of nickel, for example. The second metal layer 51 may be made of tin. The thickness of the second metal layer 51 is substantially the same as that of the second metal layer 50 .

The third metal layer 61 is a metal layer formed on the second metal layer 51 . The third metal layer 61 is made of copper. The third metal layer 61 is thicker than the first metal layer 41 . The thickness of the third metal layer 61 is substantially the same as that of the third metal layer 60 .

Regarding the spacing between the first conductive circuit 30a and the second conductive circuit, the spacing between the second conductive circuit 30b and the third conductive circuit 30c, and the spacing between the third conductive circuit 20c and the inner peripheral side end 22, The same can be said for the spacing between the first conductive circuit 20a and the second conductive circuit 20b in FIG. 4 above.

In the embodiment, the conductor layers 20, 30 are formed of copper, and the second metal layer 50 is formed of nickel (or tin) between the first metal layers 40, 41 and the third metal layers 60, 61; It has a three-layer structure in which 51 is arranged. Therefore, when conductor circuits such as the first conductor circuits 20a and 30a and the second conductor circuits 20b and 30b are formed on the conductor layers 20 and 30, compared to the case of using a conventional conductor layer composed only of copper layers, Therefore, variations in gaps and thicknesses between formed conductor circuits are small. A printed wiring board 2 with stable performance can be obtained.

As shown in FIG. 4, the second spacing G2 is smaller than the first spacing G1 and the third spacing G3. The first spacing G1 is smaller than the third spacing G3. Therefore, compared to the case where the conductor circuits are formed using a conventional conductor layer composed only of copper layers, the intervals between the conductor circuits are formed smaller. As a result, printed wiring board 2 having conductor layers 20 and 30 with a higher space factor than in the past can be obtained. A printed wiring board 2 with stable performance can be obtained. High performance is exhibited even when a motor is formed using the printed wiring board 2 .

In embodiments, the third metal layers 60,61 are thicker than the first metal layers 40,41. By increasing the thickness of the third metal layers 60 and 61, the printed wiring board 2 having the conductor layers 20 and 30 with a high space factor can be obtained.

[Manufacturing Method of Printed Wiring Board 2 of Embodiment]
5A to 5K show a method for manufacturing the printed wiring board 2 of the embodiment. 5A-5K are cross-sectional views. FIG. 5A shows resin insulation layer 10, copper foil 12 previously provided on first surface 10a, and copper foil 14 previously provided on second surface 10b. The resin insulation layer 10 is a flexible substrate with copper foils 12 and 14 attached. At this point, the copper foils 12 and 14 cover the entire surfaces of the first surface 10a and the second surface 10b.

A laser is irradiated from above the copper foil 12 . As shown in FIG. 5B, through-holes 16 are formed through copper foil 12 and resin insulation layer 10 . Electroplating with copper is performed. A first metal layer 40 of copper is formed on the copper foil 12, as shown in FIG. 5C. A first metal layer 41 of copper is formed on the copper foil 14 . A portion of the first metal layer 40 fills the inside of the through hole 16 to form a via conductor 45 . Via conductors 45 are electrically connected to copper foil 14 .

A plating resist 70 is formed on the first metal layer 40, as shown in FIG. 5D. The plating resist 70 has openings 72 at positions where the first conductive circuit 20a, the second conductive circuit 20b, the third conductive circuit 20c, and the inner peripheral side edge 22 are to be formed (see FIG. 3). Opening 72 exposes first metal layer 40 . A plating resist 71 is similarly formed on the first metal layer 41 . The plating resist 71 has openings 73 at positions where the first conductive circuit 30a, the second conductive circuit 30b, the third conductive circuit 30c, and the inner peripheral side edge 32 are to be formed (see FIG. 3). Opening 73 exposes first metal layer 41 .

Electroplating with nickel is performed. A second metal layer 50 of nickel is formed on the first metal layer 40 exposed from the plating resist 70, as shown in FIG. 5E. Similarly, a second metal layer 51 made of nickel is formed on the first metal layer 41 exposed from the plating resist 71 .

As shown in FIG. 5F, the plating resists 70, 71 are removed. An opening 52 is formed in the second metal layer 50 to expose the first metal layer 40 . An opening 53 is formed in the second metal layer 51 to expose the first metal layer 41 .

Electroplating (panel plating) with copper is performed. As shown in FIG. 5G, a third metal layer 60 is formed covering the second metal layer 50 and the first metal layer 40 exposed from the second metal layer 50 . Opening 52 is filled with a portion of third metal layer 60 . Similarly, a third metal layer 61 covering the second metal layer 51 and the first metal layer 41 exposed from the second metal layer 51 is formed. The opening 53 is filled with a portion of the third metal layer 61 . The third metal layers 60, 61 are layers of copper. The third metal layers 60,61 are formed thicker than the first metal layers 40,41.

A plating resist 80 is formed on the third metal layer 60, as shown in FIG. 5H. The plating resist 80 has openings 82 at positions where the first conductive circuit 20a, the second conductive circuit 20b, the third conductive circuit 20c, and the inner peripheral side edge 22 are to be formed (see FIG. 3). Opening 82 exposes third metal layer 60 . A plating resist 81 is similarly formed on the third metal layer 61 . The plating resist 81 has openings 83 at positions where the first conductive circuit 30a, the second conductive circuit 30b, the third conductive circuit 30c, and the inner peripheral side edge 32 are to be formed (see FIG. 3). Opening 83 exposes third metal layer 60 . The width of the plating resists 80, 81 is wider than the plating resists 70, 71 (FIG. 5D).

A tin mask 90 is formed on the third metal layer 60 exposed from the plating resist 80, as shown in FIG. 5I. Similarly, a tin mask 91 is formed on the third metal layer 61 exposed from the plating resist 81 . Masks 90 and 91 are formed by electrolytic plating. Alternatively, the masks 90, 91 may be made of nickel. The masks 90 and 91 may be made of metal other than copper.

As shown in FIG. 5J, the plating resists 80, 81 are removed. An opening 92 is formed in the mask 90 to expose the third metal layer 60 . An opening 93 is formed in the mask 91 to expose the third metal layer 61 . The width of the openings 92,93 formed in the masks 90,91 is wider than the width of the openings 52,53 formed in the second metal layers 50,51. Opening 92 is formed directly above opening 52 . The opening 93 is formed directly above the opening 53 (directly above when viewed from the second surface 10b).

By performing selective etching, the third metal layer 60 exposed from the openings 92 and the first metal layer 40 and the copper foil 12 exposed from the openings 52 are selectively removed. Similarly, selective etching is performed to selectively remove the third metal layer 61 exposed from the openings 93 and the first metal layer 41 and the copper foil 14 exposed from the openings 53 . As a result, as shown in FIG. 5K, a conductor layer 20 having a first conductor circuit 20a, a second conductor circuit 20b, a third conductor circuit 20c, and an inner peripheral side edge 22 is formed. A conductor layer 30 having a first conductor circuit 30a, a second conductor circuit 30b, a third conductor circuit 30c, and an inner peripheral side edge 32 is formed.

Selective etching is wet etching using, for example, an alkaline etchant. The alkaline etchant is, for example, a copper remover manufactured by MEC Co., Ltd. (model number SF-5420, trade name “Mec Bright”). The selective etching selectively removes the third metal layer 60 made of copper, the first metal layer 40 and the copper foil 12, but does not remove the second metal layer 50 made of nickel and the mask 90 made of tin.

As mentioned above, the width of the openings 92, 93 formed in the masks 90, 91 is wider than the width of the openings 52, 53 formed in the second metal layers 50, 51 (see Figure 5J). Therefore, during selective etching, the third metal layers 60, 61 exposed from the openings 92, 93 come into contact with a large amount of etchant. More of the third metal layers 60, 61 exposed through the openings 92, 93 are removed. On the other hand, the first metal layers 40, 41 and the copper foils 12, 14 exposed through the openings 52, 53 come into contact with a relatively small amount of the etchant. A small amount of the first metal layers 40, 41 and the copper foils 12, 14 exposed through the openings 52, 53 are removed. As a result, as shown in FIG. 4, the second gap G2 is smaller than the first gap G1 and the third gap G3. The first spacing G1 is smaller than the third spacing G3.

Masks 90 and 91 are then removed. Masks 90, 91 are removed, for example, by a selective etch that selectively removes tin. As a result, the printed wiring board 2 (FIG. 3) of the embodiment is obtained.

According to the manufacturing method of the embodiment, the third metal layers 60 and 61 exposed from the openings 92 and 93 of the masks 90 and 91, the first metal layers 40 and 41 exposed from the openings of the second metal layers 50 and 51, and the copper foil By selectively removing 12, 14, conductor layers 20, 30 are formed. Compared to the conventional method of forming a conductor layer by removing a part of a metal layer composed only of a copper layer, variations in the gap and thickness between the conductor circuits included in the conductor layers 20 and 30 are reduced. small. A printed wiring board 2 with stable performance can be obtained. The openings 52 and 53 of the embodiment are an example of the "first opening" in the claims. The openings 92 and 93 are an example of the "second opening" in the claims.

[First modification of the embodiment]
In a first variant, the masks 90, 91 are left unremoved after selective etching has taken place (FIG. 5K). In a first modification, a printed wiring board 2 is obtained with masks 90, 91 remaining on each conductor circuit (see FIG. 5K).

[Second modification of the embodiment]
In a second modification, after the plating resists 80, 81 are formed on the third metal layers 60, 61 (FIG. 5H), a mask 90 is applied on the third metal layers 60, 61 exposed from the plating resists 80, 81. , 91 (FIG. 5I) are electroplated with copper. As a result, an electroplated copper film is further formed on the third metal layers 60 and 61 exposed from the plating resists 80 and 81 . As a result, the thickness of third metal layer 60 exposed from plating resists 80, 81 increases before masks 90, 91 (FIG. 5I) are formed.

[Third modified example of the embodiment]
In a third modification, the thickness of the third metal layers 60,61 is less than or equal to the thickness of the first metal layers 40,41.

[Fourth modification of the embodiment]
In the fourth modification, one of the conductor layer 20 and the conductor layer 30 is omitted. In the fourth modified example, a conductor layer is formed only on one of the first surface 10a and the second surface 10b.

2: printed wiring board 10: resin insulation layers 20, 30: conductor layers 20a, 30a: first conductor circuits 20b, 30b: second conductor circuits 40, 41: first metal layers 50, 51: second metal layer 52, 53: openings 60, 61: third metal layers 90, 91: masks 92, 93: openings G1: first spacing G2: second spacing G3: third spacing

Claims (14)

a resin insulation layer having a first surface and a second surface opposite to the first surface;
A printed wiring board having a conductor layer formed on the first surface,
The conductor layer includes a first metal layer formed on the first surface, a second metal layer formed on the first metal layer, and a third metal layer formed on the second metal layer. The first metal layer and the third metal layer are made of copper, and the second metal layer is made of a metal other than copper. 2. The printed wiring board of claim 1, wherein said conductor layer includes a first conductor circuit and a second conductor circuit formed adjacent to said first conductor circuit, said first conductor circuit forming said first conductor circuit. The distance between the metal layer and the first metal layer forming the second conductor circuit is a first distance, and the second metal layer forming the first conductor circuit and the second conductor circuit are formed. and the second metal layer forming the first conductor circuit and the third metal layer forming the second conductor circuit. The spacing is a third spacing, the second spacing being less than the first spacing and the third spacing. 2. The printed wiring board of claim 1, wherein said third metal layer is thicker than said first metal layer. 2. The printed wiring board according to claim 1, wherein said second metal layer is made of nickel or tin. 2. The printed wiring board of claim 1, wherein the conductor layer includes a spirally formed coil. forming a first metal layer on the first surface of a resin insulation layer having a first surface and a second surface opposite to the first surface;
forming a second metal layer having a first opening on the first metal layer;
forming a third metal layer on the second metal layer and the first metal layer exposed through the first opening;
forming a metal mask having a second opening positioned immediately above the first opening on the third metal layer;
the first metal layer, the second metal layer, and the third metal layer by selectively removing the third metal layer exposed from the second opening and the first metal layer exposed from the first opening; A printed wiring board manufacturing method comprising:
The first metal layer and the third metal layer are made of copper, and the second metal layer and the metal mask are made of a metal other than copper. 7. The method of manufacturing a printed wiring board according to claim 6, wherein said conductor layer includes a first conductor circuit and a second conductor circuit formed adjacent to said first conductor circuit to form said first conductor circuit. The distance between the first metal layer and the first metal layer forming the second conductor circuit is a first distance, and the second metal layer forming the first conductor circuit and the second conductor The distance between the second metal layer forming the circuit is a second distance, and the third metal layer forming the first conductive circuit and the third metal layer forming the second conductive circuit is a third interval, said second interval being less than said first interval and said third interval. 7. The method of manufacturing a printed wiring board according to claim 6, wherein the width of said second opening is wider than the width of said first opening. 7. The method of manufacturing a printed wiring board according to claim 6, wherein said third metal layer is thicker than said first metal layer. 7. The method of manufacturing a printed wiring board according to claim 6, wherein said second metal layer is made of nickel or tin. 7. The method of manufacturing a printed wiring board according to claim 6, wherein said metal mask is made of nickel or tin. 7. The method of manufacturing a printed wiring board of claim 6, further comprising removing said metal mask after said selectively removing. 7. The method of manufacturing a printed wiring board of claim 6, wherein said selectively removing includes treatment with an alkaline etchant. 7. The method of manufacturing a printed wiring board according to claim 6, wherein said conductor layer includes a spirally formed coil.

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