JP2015156481A - Printed wiring board and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily provide a printed wiring board in which the width of a wiring layer does not become narrow due to removal of an exposed first metal layer by dissolving in a semi-additive method and to solve a problem on signal delay for a high frequency signal.

SOLUTION: Wiring layers 10 and 11 of printed wiring boards, which are each formed on an insulation substrate 1 include a first metal layer 2, a second metal layer 7 laminated on the first metal layer, and a protective layer 8 formed on the upper surface and a part of a side surface of the second metal layer. The width of the part of the second metal layer, on which the protective layer is formed is wider than those of the first metal layer and the part of the second metal layer, on which the protective layer is not formed.

COPYRIGHT: (C)2015,JPO&INPIT

Description

  The present invention relates to a printed wiring board and a manufacturing method thereof.

  Printed wiring boards are widely used for mounting electronic components, semiconductor elements, and the like. With recent demands for downsizing and higher functionality of electronic devices, printed wiring boards are desired to have higher circuit density, thinner thickness, and higher frequency response.

  As a method for manufacturing this high-density printed wiring board, a multilayer build-up wiring board using a build-up method is known. In this method, a multilayer build-up is performed by repeating the steps of forming an insulating layer on a core layer having a wiring layer formed on an insulating substrate, further forming a wiring layer thereon, and further forming an insulating layer. A wiring board is formed.

  As a conventional method for forming a wiring layer of a multilayer build-up wiring board, for example, there is a semi-additive construction method. Below, this semi-additive construction method is demonstrated based on FIG.

  First, as shown in FIG. 5A, a first metal layer 2 is formed on an insulating substrate 1 on which an insulating resin is laminated by electroless copper plating. This is performed in order to impart conductivity to the insulating substrate 1 so that the second metal layer 7 can be formed by electrolytic copper plating. Next, as shown in FIG. 5B, a photosensitive resist 5 is applied to the entire surface of the insulating substrate 1. For the photosensitive resist 5, materials such as a dry film type having excellent thickness uniformity are used. Then, as shown in FIG. 5C, a resist pattern 6 'is formed by photolithography. Then, as shown in FIG. 5D, a metal film is formed on the portion not covered with the resist pattern 6 ′ by electrolytic plating to form the second metal layer 7. Next, as shown in FIG. 5E, the resist pattern 6 'is stripped with an alkaline aqueous solution such as sodium hydroxide. Thereafter, as shown in FIG. 5 (f), the exposed first metal layer 2 was dissolved and removed with an aqueous solution such as hydrogen peroxide / sulfuric acid, and finally patterned as shown in FIG. 5 (g). A tin plating layer 8 is formed on the surfaces of the first metal layer 2 and the second metal layer 7 which are wiring layers, and further treated with a silane coupling agent to form a silane coupling treatment layer 9 to obtain a wiring layer 11 ′.

  However, in the conventional semi-additive method, when the exposed first metal layer 2 is dissolved and removed with an aqueous solution such as hydrogen peroxide / sulfuric acid, the upper surface and side surfaces of the second metal layer 7 are also dissolved and removed. There is a problem that the width of the metal wiring layer composed of the layer 2 and the second metal layer 7 becomes narrow.

  Patent Document 1 includes 0.1 to 10% by weight of hydrogen peroxide and 0.5 to 50% by weight of phosphoric acid as an etching solution for the first metal layer 2, and a weight ratio of hydrogen peroxide / phosphoric acid. It is described that when the etching solution having 0.02 to 0.2 is used, a reduction in the width of the wiring layer can be suppressed. However, the metal that is the target of the etching solution of Patent Document 1 is copper or nickel formed by a physical method such as sputtering, vacuum deposition, ion plating, or chemical vapor deposition.

Patent Document 2 describes that after the second metal layer 7 is formed, a metal protective layer other than copper is formed on the surface of the second metal layer 7 before the resist pattern 6 ′ is peeled off. Yes. However, in order to form a metal protective layer other than copper on the surface of the second metal layer 7 before peeling the resist pattern 6 ′, a metal protective layer other than copper is formed on the side surface of the second metal layer 7. When the first metal layer 2 is not formed and dissolved and removed with an aqueous solution such as hydrogen peroxide / sulfuric acid, the side surfaces of the second metal layer 7 are dissolved and removed.

  Further, in Patent Document 2, after the resist pattern 6 ′ is peeled and before the exposed first metal layer 2 is dissolved and removed, the distance between the adjacent second metal layers 7 is between the adjacent second metal layers 7. It is described that a mask pattern having a narrower width is formed, a metal protective layer other than copper is formed on the upper surface and side surfaces of the second metal layer 7, and then the mask pattern is peeled off.

However, it is not always easy to form a mask pattern having a width smaller than the interval between the adjacent second metal layers 7 between the adjacent second metal layers 7.
In addition, when multi-layer build-up is performed, the surface of the underlying wiring layer is roughened and adhesion to the insulating layer formed thereon is increased, but the surface roughening state of the wiring layer is a signal transmission delay. The problem that causes the problem is no longer negligible.

JP 2006-294797 A JP 2003-078234 A

  The present invention has been made in consideration of such circumstances, and can easily provide a printed wiring board in which the width of the wiring layer does not become narrow due to dissolution and removal of the exposed first metal layer, and is suitable for high-frequency signals. It is an object to solve the problem of signal delay.

The invention of claim 1 of the present invention for solving the above problems is a printed wiring board in which a wiring layer is formed on an insulating substrate using a semi-additive method,
The wiring layer is formed on the first metal layer formed on the insulating substrate, the second metal layer formed on the upper surface of the first metal layer, and a part of the upper surface and side surface of the second metal layer. With a protective layer,
The width of the second metal layer in the portion where the protective layer is formed is wider than the width of the first metal layer and the width of the second metal layer in the portion where the protective layer is not formed. It is a printed wiring board.

  Moreover, Claim 2 of this invention is a printed wiring board of Claim 1 in which the said protective layer consists of a tin plating layer.

  According to a third aspect of the present invention, a silane coupling treatment layer is formed on the protective layer made of the tin plating layer, on the side surface of the first metal layer, and on a part of the second metal layer. The printed wiring board according to claim 2.

According to a fourth aspect of the present invention, the step of forming the first metal layer on the insulating substrate;
Laminating a first resist mask that is a photosensitive resist layer on the first metal layer;
Laminating a second resist mask, which is a photosensitive resist layer different from the first resist mask, on the first resist mask;
An exposure / development step for exposing and developing the first resist mask and the second resist mask;
Laminating a second metal layer on the first metal layer exposed after the exposure and development steps;
Selectively peeling only the second resist mask;
Forming a protective layer on the second metal layer exposed after peeling of the second resist mask;
A peeling step of peeling the first resist mask;
And a step of removing the first metal layer exposed after peeling of the first resist mask,
In the first resist mask peeling step, the second resist mask is not peeled off.

  Moreover, Claim 5 of this invention is the manufacturing method of the printed wiring board of Claim 4 whose process of forming the said protective layer is a process of forming a tin plating layer.

According to a sixth aspect of the present invention, the step of forming the first metal layer on an insulating substrate;
Laminating a first resist mask on the first metal layer;
Laminating a second resist mask on the first resist mask;
An exposure / development step for exposing and developing the first resist mask and the second resist mask;
Laminating a second metal layer on the first metal layer exposed after the exposure and development steps;
Selectively peeling only the second resist mask;
Forming a protective layer on the second metal layer exposed after peeling of the second resist mask;
A peeling step of peeling the first resist mask;
Removing the first metal layer exposed after peeling of the first resist mask;
A step of forming a silane coupling treatment layer on a side surface of the protective layer, the first metal layer, and a part of the second metal layer, and the second resist mask is not peeled in the peeling step of the first resist mask. This is a method for manufacturing a printed wiring board.

  According to the printed wiring board and the manufacturing method thereof of the present invention, it is possible to easily provide a printed wiring board in which the width of the wiring layer is not reduced due to dissolution and removal of the exposed first metal layer. In addition, when the second insulating layer is formed on the wiring layer, it is not necessary to roughen the surface of the wiring layer in order to increase the adhesion. The effect that the transmission delay with respect to can be suppressed is produced.

1 is a schematic cross-sectional view showing an example of a printed wiring board in a first embodiment of the present invention. Schematic explanatory drawing which shows an example of the flow of the manufacturing process of the printed wiring board in 1st embodiment of this invention. The schematic sectional drawing which shows an example of the printed wiring board in 2nd embodiment of this invention. Schematic explanatory drawing which shows an example of the flow of the manufacturing process of the printed wiring board in 2nd embodiment of this invention. Schematic explanatory drawing which shows the flow of the manufacturing process of the manufacturing method of the printed wiring board by the conventional semi-additive construction method.

<First embodiment>
First, an embodiment of the printed wiring board of the present invention will be described below.

As shown in FIG. 1, the printed wiring board of the present invention is a printed wiring board in which a wiring layer 9 is formed on an insulating substrate 1, and the wiring layer 9 includes a first metal layer 2 and a first metal. A second metal layer 7 laminated on the layer 2, and a protective layer 8 formed on the upper surface of the second metal layer 7 and a portion above the lower end 11 of the side surface. In order from the bimetallic layer 7 side, the tin layer 8a and the silane coating layer 8
The width of the second metal layer 7 above the lower end vicinity 11 of the side surface on which the protective layer 8 is formed is the width of the first metal layer 2 and the side surface on which the protective layer 8 is not formed. This is a printed wiring board wider than the width of the second metal layer 7 in the vicinity of the lower end 11 of.

  As will be described later, the reason why the protective layer 8 is not formed in the vicinity of the lower end 11 of the side surface of the second metal layer 7 is that the first resist mask 3 covered it.

  Next, an embodiment of a method for manufacturing a printed wiring board according to the present invention will be described below in accordance with the manufacturing process flow shown in FIG.

  First, as shown in FIG. 2A, a first metal layer 2 is formed on an insulating substrate 1 on which an insulating resin is laminated by electroless copper plating. This is performed in order to impart conductivity to the insulating substrate 1 so that the second metal layer 7 can be formed by electrolytic copper plating.

  Next, as shown in FIG. 2B, a photosensitive first resist mask 3 is applied to the entire surface of the insulating substrate 1 on the first metal layer 2. Next, as shown in FIG. 2C, a photosensitive second resist mask 4 is applied to the entire surface of the insulating substrate 1 on the first resist mask 3.

  The first resist mask 3 is made of a material that cannot be peeled off by an alkaline aqueous solution such as sodium hydroxide, but can be peeled off by an amine-based stripping solution having higher peelability, and the second resist mask 4 is made of sodium hydroxide or the like. It is made of a material that can be peeled off with an alkaline aqueous solution of the above and an amine-based stripping solution having a stronger peelability. For the photosensitive first resist mask 3 and the second resist mask 4, materials such as a dry film type having excellent thickness uniformity are used. The thickness of each resist mask is such that when the first resist mask 3 is thinner than the second resist mask 4, the range of the protective film 8 formed on the side surface of the second metal layer 7 is further expanded at the lower end. ,desirable.

  Next, as shown in FIG. 2D, a resist pattern 6 including a first resist mask 3 and a second resist mask 4 is formed by photolithography. And as shown in FIG.2 (e), a copper film is formed in the part which is not coat | covered with the resist pattern 6 by electrolytic plating, and the 2nd metal layer 7 is formed.

  Next, as shown in FIG. 2F, the second resist mask 4 is peeled off with an alkaline aqueous solution such as sodium hydroxide. At this time, the first resist mask 3 remains without being stripped with an alkaline aqueous solution such as sodium hydroxide.

  Next, as shown in FIG. 2G, a tin layer 8a, which is a third metal film, is formed on the surface of the second metal layer 7 exposed from the first resist mask 3 by plating, and further silane coupling is performed. The protective layer 8 is formed by forming a silane coating layer 8b by treatment with an agent. The protective layer 8 can ensure adhesion between the copper wiring as the second metal layer 7 and the insulating resin laminated thereon.

  Here, in the multilayer build-up wiring board, when the wiring layer of the build-up layer is formed by the semi-additive method, the wiring layer surface after the roughening is uneven in the roughening of the wiring layer by the micro etching method. Therefore, a signal transmission delay occurs due to the skin effect on the high-frequency signal. Therefore, it is important that the surface of the wiring layer is smooth for high frequency applications. As an alternative to roughening by the microetching method, when a tin layer is formed on the surface of the wiring layer and treated with a silane coupling agent, the surface of the wiring layer is smooth and effective for high-frequency signal transmission.

Therefore, the surface of the second metal layer 7 exposed from the first resist mask 3 as shown in FIG. 2G, the first metal layer 2 and the second metal layer as shown in FIG. It is preferable to form a tin layer on the surface of the copper wiring layer composed of 7 and treat with a silane coupling agent to ensure adhesion with the upper insulating resin.

  Next, as shown in FIG. 2 (h), the first resist mask 3 is stripped with an amine stripping solution having a strong stripping property.

Next, as shown in FIG. 2 (i), the electroless plating film as the exposed first metal layer 2 is dissolved and removed with an aqueous solution of hydrogen peroxide / sulfuric acid, etc. A wiring layer 9 having a second metal layer 7 laminated on the metal layer 2 and a protective layer 8 formed on the upper surface of the second metal layer 7 and the vicinity of the lower end of the side surface is formed.
At this time, the upper portion of the wiring layer 9 and the portion above the vicinity of the lower end of the side surface are protected by the tin layer 8a which is the third metal film, so that it is not dissolved and removed and the width of the wiring layer 9 is not reduced. Therefore, a sufficient time can be taken to dissolve and remove the first metal layer 2 between the wiring layers 9, so that the first metal layer 2 can be completely removed and a fine copper wiring pattern can be formed.

<Second Embodiment>
Next, a second embodiment of the printed wiring board of the present invention will be described. The printed wiring board of the present invention is a printed wiring board in which a wiring layer is formed on an insulating substrate using a semi-additive construction method.
When carrying out the semi-additive method, the resist pattern formed on the surface of the electroless copper plating layer formed on the insulating substrate as the first metal layer has a configuration different from that of the normal semi-additive method. A resist layer that can be removed relatively easily with a resist remover such as an aqueous solution of sodium hydroxide, and a resist layer that cannot be removed with a resist remover such as an aqueous solution of sodium hydroxide, and can only be removed with an amine-based remover. And a two-layer resist layer.

  Specifically, a resist layer that cannot be removed unless an amine-based stripping solution is used as a base is formed, and a resist layer that can be stripped relatively easily with a resist stripping solution such as an aqueous sodium hydroxide solution is formed thereon.

  By forming the two-layer resist layer in this manner by exposing and developing the two-layer resist layer to form a desired wiring layer pattern, an electrolytic copper plating layer is formed as the second metal layer. When the resist pattern is removed, the wiring pattern formed by the electrolytic copper plating layer is exposed. At this time, a resist layer that cannot be removed without an amine-based stripper as the first resist layer remains under the stripped resist pattern. At that stage, after forming a protective layer on the entire surface of the wiring pattern of the electrolytic copper plating layer, if the resist pattern remaining with the amine-based stripping solution is stripped, the electroless copper plating layer as the first metal layer is exposed. . Next, the patterning of the wiring is completed by dissolving and removing the electroless copper plating layer, but next, the protective layer, the exposed side surface of the first metal layer, and the first metal layer of the second metal layer are close to each other. The part from which the part has been dissolved and removed is treated with a silane coupling agent to form a silane coupling treatment layer.

  By doing in this way, since the electrolytic copper plating layer which is a 2nd metal layer which is a main component of a wiring layer is not melt | dissolved by the melt | dissolution removal process of a 1st metal layer, a line | wire width does not become thin. In addition, by forming the silane coupling treatment layer on the entire surface of the wiring layer, when forming a second insulating layer on the wiring layer, it is possible to ensure a strong adhesion between the wiring layer and the insulating layer. Become. It is not necessary to roughen the surface of the wiring layer.

As shown in FIG. 3, the printed wiring board of the present invention is a printed wiring board in which a wiring layer 11 is formed on an insulating substrate 1, and the wiring layer 11 includes a first metal layer 2 and a first metal. A second metal layer 7 laminated on the layer 2, and a protective layer 8 formed on the upper surface of the second metal layer 7 and a portion above the lower end portion 12 on the side surface. The portion 12 has a silane coupling treatment layer 9 laminated on the surface, and the width of the second metal layer 7 above the lower end portion 12 of the side surface on which the protective layer 8 is formed is as follows. The printed wiring board is wider than the width of the second metal layer 7 at the portion of the lower end portion 12 on the side surface where the width 2 and the protective layer 8 are not formed.

  As described later, the reason why the protective layer 8 is not formed on the lower end portion 12 of the side surface of the second metal layer 7 is that the first resist mask 3 has covered the protective layer 8. The material of the protective layer 8 is preferably tin (Sn).

  Next, an embodiment of a method for manufacturing a printed wiring board according to the present invention will be described below in accordance with the manufacturing process flow shown in FIG.

  First, as shown in FIG. 4A, a first metal layer 2 is formed on an insulating substrate 1 on which an insulating resin is laminated by electroless copper plating. This is performed in order to impart conductivity to the insulating substrate 1 so that the second metal layer 7 can be formed by electrolytic copper plating.

  Next, as shown in FIG. 4B, a photosensitive first resist mask 3 is applied to the entire surface of the first metal layer 2 on the insulating substrate 1. Next, as shown in FIG. 4C, a photosensitive second resist mask 4 is applied on the first resist mask 3.

  The first resist mask 3 is made of a material that cannot be peeled off with an alkaline aqueous solution such as sodium hydroxide, but can be peeled off with a more peelable amine-based stripping solution. The second resist mask 4 is made of sodium hydroxide or the like. It is made of a material that can be peeled even by an alkaline aqueous solution or by an amine-based stripper having a stronger peelability. For the photosensitive first resist mask 3 and the second resist mask 4, materials such as a dry film type having excellent thickness uniformity are used. The thickness of each resist mask is such that when the first resist mask 3 is thinner than the second resist mask 4, the range of the protective layer 8 formed on the side surface of the second metal layer 7 is expanded to the lower end. ,desirable.

  Next, as shown in FIG. 4D, a resist pattern 6 including a first resist mask 3 and a second resist mask 4 is formed by photolithography. And as shown in FIG.4 (e), a copper film is formed in the part which is not coat | covered with the resist pattern 6 by electrolytic plating, and the 2nd metal layer 7 is formed.

  Next, as shown in FIG. 4F, the second resist mask 4 is peeled off with an alkaline aqueous solution such as sodium hydroxide. At this time, the first resist mask 3 remains without being stripped with an alkaline aqueous solution such as sodium hydroxide.

  Next, as shown in FIG. 4G, a tin plating layer 8 as a third metal film is formed on the surface of the second metal layer 7 exposed from the first resist mask 3. At this time, the protective layer 8 is not formed on the surface of the first resist mask 3. Therefore, electrolytic tin plating may be used for plating of the protective layer 8, or electroless tin plating may be used. When electrolytic tin plating is used, an electrolytic tin plating film can be formed on the second metal layer 7 by passing an electric current through the first metal layer 2. In addition, when electroless tin plating is used, either displacement plating or autocatalytic electroless plating can be used.

  Next, as shown in FIG. 4H, the first resist mask 3 is stripped with an amine stripping solution having a strong stripping property.

Next, as shown in FIG. 4 (i), the electroless plating film as the exposed first metal layer 2 is dissolved and removed with an aqueous solution of hydrogen peroxide / sulfuric acid, etc. A wiring layer 10 having a second metal layer 7 laminated on the metal layer 2 and a tin plating layer 8 formed on the upper surface of the second metal layer 7 and a lower portion of the side surface is formed. At this time, the upper part of the wiring layer 10 and the part above the lower end of the side surface are protected by the tin plating layer 8 which is the third metal film, so that the wiring layer 10 is not thinned and not removed. Therefore, sufficient time can be taken to dissolve and remove the first metal layer 2 between the wiring layers 10, so that the first metal layer 2 can be completely removed and a fine copper wiring pattern can be formed.

  Next, as shown in FIG. 4J, the surface is treated with a silane coupling agent to form a wiring layer 11 covering the silane coupling treatment layer 9. The tin plating layer 8 and the silane coupling treatment layer 9 can ensure adhesion between the copper wiring as the second metal layer 7 and the insulating resin laminated thereon.

  Here, in the manufacturing process of a multilayer build-up wiring board, when the wiring layer of the build-up layer is formed by the semi-additive method, the wiring layer surface after roughening is uneven when the wiring layer is roughened by the micro-etching method. Due to the shape, there is a problem of signal transmission delay due to the skin effect on high-frequency signals. For this reason, it is important that the surface of the wiring layer is smooth for high frequency signals. As an alternative to roughening by the micro-etching method, in the printed wiring board manufactured by the printed wiring board manufacturing method of the present invention, a protective layer is formed on the surface of the wiring layer, and the surface is treated with a silane coupling agent. Since the coupling processing layer is formed and the surface of the wiring layer is kept smooth, transmission delay of the high frequency signal does not occur.

Next, examples of the present invention will be described.
As shown in FIG. 4A, a first metal layer 2 is formed to a thickness of 1 μm on an insulating substrate 1 in which insulating resins are laminated by electroless copper plating used in a normal printed wiring board manufacturing process. did. Next, as shown in FIG. 4B, a photosensitive resist 5 μm was formed on the surface of the first metal layer 2 as the photosensitive first resist mask 3. Next, as shown in FIG. 4C, a photosensitive resist, 15 μm, was formed on the surface of the first resist mask 3 as the photosensitive second resist mask 4. The two types of photosensitive resist used here are negative photosensitive resists.

  Next, as shown in FIG. 4D, a resist pattern 6 composed of the first resist mask 3 and the second resist mask 4 was formed by photolithography. And as shown in FIG.4 (e), as the 2nd metal layer 7, 18 micrometers of copper plating films were formed in the part which is not coat | covered with the resist pattern 6 by electrolytic plating. Copper plating used the copper sulfate plating process currently used in the manufacturing process of the normal printed wiring board.

  Next, as shown in FIG. 4F, the second resist mask 4 was stripped with a resist stripping solution made of an alkaline aqueous solution used in a normal printed wiring board manufacturing process mainly composed of sodium hydroxide.

Next, as shown in FIG. 4G, a protective layer 8 as a third metal film is formed by electrolytic tin plating on the surface exposed from the first resist mask 3 of the copper wiring as the second metal layer 7. did. The electrolytic tin plating used was a commercially available acidic tin plating bath (stannous sulfate: 50 g / L, sulfuric acid: 100 g / L, cresolsulfonic acid: 100 g / L, β-naphthol: 2 g / L, bath temperature: 25 ° C, current density: 2 A / dm ² ).
Next, as shown in FIG. 4 (h), the first resist mask 3 was peeled off by being heated to 50 ° C. with a highly peelable amine-based stripping solution and immersed for 180 seconds.

Next, as shown in FIG. 4 (i), the electroless plating film as the exposed first metal layer 2 is dissolved and removed with an aqueous solution of hydrogen peroxide / sulfuric acid, etc. The wiring layer 10 having the second metal layer 7 laminated on the metal layer 2 and the protective layer 8 formed on the upper surface of the second metal layer 7 and the lower portion of the side surface was formed.

  At this time, the upper part of the wiring layer 10 and the part above the lower end part of the side surface are protected by the protective layer 8 which is the third metal film, so that the wiring layer 10 was not thinned by being dissolved and removed. Furthermore, the first metal layer 2 between the wiring layers 10 could be completely dissolved and removed over a sufficient time, and a fine copper wiring pattern could be formed.

  Next, as shown in FIG. 4 (j), after the surface was immersed in a silane coupling agent at 25 ° C. for 60 seconds and then dried and baked with 100 ° C. hot air for 60 seconds to form a silane coupling treatment layer 9, A wiring layer 11 was formed.

  If this invention is used, the multilayer buildup wiring board which has a fine wiring pattern can be manufactured.

DESCRIPTION OF SYMBOLS 1 ... Insulating substrate 2 ... 1st metal layer 3 ... 1st resist mask 4 ... 2nd resist mask 5 ... Photosensitive resist 6, 6 '... Resist pattern 7 ... 2nd metal layer 8 ... Protective layer 8a ... Tin layer 8b ... Silane coating layers 9, 9 ', 10, 11', 13 ... wiring layer 11 ... near lower end 12 ... lower end portion 14 ... silane coupling treatment layer

Claims (6)

A printed wiring board having a wiring layer formed on an insulating substrate using a semi-additive method,
The wiring layer is formed on the first metal layer formed on the insulating substrate, the second metal layer formed on the upper surface of the first metal layer, and a part of the upper surface and side surface of the second metal layer. With a protective layer,
The width of the second metal layer in the portion where the protective layer is formed is wider than the width of the first metal layer and the width of the second metal layer in the portion where the protective layer is not formed. Printed wiring board.   The printed wiring board according to claim 1, wherein the protective layer is a tin plating layer.   The printed wiring board according to claim 2, wherein a silane coupling treatment layer is formed on the protective layer made of the tin plating layer, on a side surface of the first metal layer, and on a part of the second metal layer. . Forming a first metal layer on an insulating substrate;
Laminating a first resist mask that is a photosensitive resist layer on the first metal layer;
Laminating a second resist mask, which is a photosensitive resist layer different from the first resist mask, on the first resist mask;
An exposure / development step for exposing and developing the first resist mask and the second resist mask;
Laminating a second metal layer on the first metal layer exposed after the exposure and development steps;
Selectively peeling only the second resist mask;
Forming a protective layer on the second metal layer exposed after peeling of the second resist mask;
A peeling step of peeling the first resist mask;
And a step of removing the first metal layer exposed after peeling of the first resist mask,
A method of manufacturing a printed wiring board, wherein the second resist mask is not peeled in the peeling step of the first resist mask.   The method for producing a printed wiring board according to claim 4, wherein the step of forming the protective layer is a step of forming a tin plating layer. Forming the first metal layer on an insulating substrate;
Laminating a first resist mask on the first metal layer;
Laminating a second resist mask on the first resist mask;
An exposure / development step for exposing and developing the first resist mask and the second resist mask;
Laminating a second metal layer on the first metal layer exposed after the exposure and development steps;
Selectively peeling only the second resist mask;
Forming a protective layer on the second metal layer exposed after peeling of the second resist mask;
A peeling step of peeling the first resist mask;
Removing the first metal layer exposed after peeling of the first resist mask;
A step of forming a silane coupling treatment layer on a side surface of the protective layer, the first metal layer, and a part of the second metal layer, and the second resist mask is not peeled in the peeling step of the first resist mask. A printed wiring board manufacturing method characterized by the above.

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