JP2011151159A - Method for manufacturing circuit board and circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a circuit board excellent in conductor circuit precision, and the circuit board. <P>SOLUTION: The method for manufacturing a circuit board 1 includes steps of: preparing a lamination board 10 of a base material 105 and one metallic layer 101 formed on at least one surface of the base material 105; forming a first resist layer 22 having openings on the surface of the metallic layer 101; forming a conductor 31 by plating each opening of the first resist layer 22; removing the first resist layer 22; forming a second resist layer 51 so as to cover entire surfaces of the metallic layer 101 and the conductor 31; removing a portion of the second resist layer 51 to expose the metallic layer 101 while covering the side surface and the top surface of the conductor with the second resist layer; and removing the exposed metallic layer 101 by etching to expose the surface of the base material 105. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a circuit board manufacturing method and a circuit board.

  Subtractive methods and semi-additive methods are widely known as methods for forming a conductor circuit on a circuit board. In the semi-additive method, since the factor that determines the definition of the conductor circuit depends on the accuracy of the plating mask (photomask) used in the photolithography method, the accuracy of the conductor circuit formed by the semi-additive method is subtractive. Compared to the accuracy of the conductor circuit formed by the etching method in this method, this method is superior in circuit width accuracy. Therefore, the semi-additive method is advantageous as a method for forming a high-definition conductor circuit.

  A method of manufacturing a wiring board by a semi-additive method is described in, for example, Japanese Patent Application Laid-Open No. 2003-37137 (Patent Document 1). 4 and 5 are cross-sectional views of steps showing a method for manufacturing a circuit board when a conductor circuit is formed by a conventional semi-additive method.

  First, the laminated board 10 in which the metal layer 101 was formed in the at least one surface side of the base material 105 which consists of insulating resin shown to Fig.4 (a) is prepared. Thereafter, as shown in FIG. 4B, a photosensitive resist film (also called DFR) is laminated using a vacuum laminator or the like so as to cover the metal layer 101. Next, a resist pattern is formed by a photolithography method in which a plating mask is overlapped, exposed, and developed so that a portion corresponding to a desired conductor circuit is opened on the surface of the metal layer 101 (FIGS. 4C and 4D).

  Next, as shown in FIG. 4E, a conductor layer is laminated on the metal layer 101 exposed in the opening portion of the resist pattern by electroplating to form a conductor portion 31. Thereafter, as shown in FIG. 5A, the entire resist pattern is removed with a stripping solution or an alkaline solution, and the exposed metal layer 101 is dissolved and removed, as shown in FIG. 5B. Only the desired wiring circuit remains on the base material 105, whereby the circuit board 3 is manufactured.

  However, in such a semi-additive method, after the formed resist pattern is removed, the metal layer remaining on the substrate surface is removed using an etching solution or the like, but the conductor formed by electroplating simultaneously with the metal layer. The circuit was also etched at the same time, and there was a problem that a desired conductor circuit could not be obtained.

JP 2003-37137 A

  This invention is made | formed in view of the said situation, and is providing the manufacturing method and circuit board of a circuit board excellent in the conductor circuit precision.

  The method for manufacturing a circuit board according to the present invention includes a step of preparing a base material, a laminate having a metal layer formed on at least one surface side of the base material, and a step of providing an opening on the surface of the metal layer. A step of forming one resist layer, a step of forming a conductor portion by plating in the opening of the first resist layer, a step of removing the first resist layer, the metal layer and the conductor portion Forming a second resist layer so as to cover the entire surface, removing part of the second resist layer, covering the side surface and the upper surface of the conductor portion with the second resist layer, The method includes a step of exposing a metal layer and a step of removing the metal layer exposed by etching to expose the surface of the base material.

  In this method of manufacturing a circuit board, a part of the second resist layer is removed, the side surface and the upper surface of the conductor portion are covered with the second resist layer, the metal layer is exposed, and then etched. Remove the exposed metal layer. As a result, when the metal layer is removed by etching, the conductor portion is covered with the second resist layer, and therefore the conductor portion is not etched, so a circuit board manufacturing method with excellent conductor circuit accuracy is provided. Can be provided.

  The second resist layer may be a photosensitive resin.

  Further, the step of removing the second resist layer includes a step of placing a second plating mask on the upper surface of the second resist layer at a predetermined position, and a periphery of the conductor portion by irradiating light. The step of reacting the second resist layer and the step of removing other than the reacted second resist layer may be included.

  Moreover, it is good also as a circuit board obtained by said method.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method and circuit board of a circuit board excellent in the conductor circuit precision can be provided.

It is sectional drawing which shows one Embodiment of the circuit board of this invention. It is sectional drawing of the process which shows one Embodiment of the manufacturing method of the circuit board of this invention. It is sectional drawing of the process which shows one Embodiment of the manufacturing method of the circuit board of this invention. It is sectional drawing of the process which shows the manufacturing method of the conventional circuit board. It is sectional drawing of the process which shows the manufacturing method of the conventional circuit board. It is sectional drawing which shows other embodiment of the manufacturing method of a circuit board.

  Hereinafter, a method for manufacturing a circuit board and a circuit board according to the present invention will be described in detail based on preferred embodiments attached.

  FIG. 1 is a cross-sectional view showing a substrate 105 and a circuit board 1 in which a conductor portion 31 is formed on at least one surface side of the substrate 105 with a metal layer 102 interposed therebetween.

  A method for manufacturing the circuit board 1 of the present invention will be described (see FIGS. 2 and 3). For example, a laminate 10 is prepared in which a copper foil is attached as a metal layer 101 on one side of a base material 105 cured with a polyimide resin film, an epoxy resin, or the like (FIG. 2A). When a metal thin film is used as the metal layer, a vacuum deposition method, a sputtering method, or the like is preferably used as the dry method, and an electrolytic plating method, an electroless plating method, or the like is used as the wet method. The film thickness is preferably 0.05 μm to 5 μm, more preferably 0.1 μm to 2 μm. The metal species is preferably a single metal such as nickel, chromium, cobalt, molybdenum, vanadium, tungsten or copper, or an alloy thin film thereof. Moreover, when using ultra-thin metal foil, as a metal seed | species, stainless steel, nickel, aluminum, iron, copper etc. are used, and copper is used more suitably from etching property. The thickness of the metal foil is preferably 5 μm to 10 μm. In the present embodiment, a 2 μm copper foil is used as the metal layer 101.

  Next, the first resist layer 21 is formed on the surface of the metal layer 101. Although it does not specifically limit as the 1st resist layer 21, A liquid type (liquid resist), a film type (dry film), etc. can be used. In the case of a liquid resist, it can be formed using a screen printing method or a coater method. In the case of a dry film, it can be formed using a vacuum laminator (FIG. 2B). In the present embodiment, a negative dry film is used as the first resist layer 21. Although the thickness of the 1st resist layer 21 is determined by the thickness of the conductor of a desired conductor part, 10 micrometers-50 micrometers are preferable, for example, More preferably, they are 10 micrometers-25 micrometers. For example, when trying to obtain a conductor portion with a conductor thickness of 20 μm, it is preferably formed so as to be thicker than the conductor thickness of the conductor portion. For example, the first resist layer 21 with a thickness of 25 μm is formed. (FIG. 2D).

  Next, although not shown, a plating mask is disposed at a predetermined position on the first resist layer 21 surface side. The first resist layer 21 and the plating mask may be in contact or non-contact. The non-contact method is more preferable because contamination of the plating mask can be reduced, and an efficient production can be achieved because the step of bringing the first resist layer 21 and the plating mask into close contact with each other by suction is omitted. Next, it exposes and the 1st resist layer 21 used as the conductor part 31 is made to react and harden | cure (FIG.2 (c)). Next, development is performed to remove the first plating resist layer 21 that has not reacted in the exposure step, and a reacted first resist layer 22 is formed.

  Next, as shown in FIG. 2E, a conductor portion 31 made of a metal conductor layer is formed on the metal layer 101 at the bottom of the opening from which the first plating resist layer 21 that has not reacted is removed. . The metal conductor may be copper, silver, gold, nickel, tin, or an alloy composed of two or more selected from the group consisting of these, such as solder, and a simple substance of copper may be selected. preferable. As a method for forming the conductor part 31, it is common to use a wet method having a film formation rate faster than the dry method, and an electroplating method is preferably used. When forming the conductor part 31 with copper, a copper sulfate plating solution, a copper pyrophosphate plating solution, or the like can be used, but the use of a copper sulfate plating solution is preferable. The thickness of the conductor portion 31 is preferably smaller than the thickness of the first resist layer 21 described above, and is, for example, 5 μm to 35 μm, preferably 8 μm to 25 μm. desirable.

  Next, the reacted first resist layer 22 is peeled off (FIG. 3A). Usually, the reacted first resist layer 22 is stripped using a dedicated stripping solution or alkali solution.

  Subsequently, a second resist layer 51 is formed so as to cover the entire surface of the metal layer 101 and the conductor portion 31 (FIG. 3B). The second resist layer 51 is preferably a photosensitive resin. Thereby, the process of aligning the conductor portion 31 and the mask and performing the exposure development can be selected, so that the positional accuracy can be improved. Moreover, positive type, negative type etc. can be used for photosensitive resin, for example.

Although it does not specifically limit as the 2nd resist layer 51, A liquid type (liquid resist), a film type (dry film), etc. can be used. In consideration of the covering property to the conductor part 31, it is preferable to use a liquid resist.
In the case of a liquid resist, a screen printing method, a coater method, or the like can be formed. Moreover, when using the double-sided circuit board in which the conductor part 31 is formed in both surfaces, it is possible to form the 2nd resist layer 51 simultaneously on both surfaces by immersing a double-sided circuit board in a liquid resist. The shape of the resist film formed may be, for example, a shape having a substantially flat surface as shown in FIG. 3B, which is a process cross-sectional view, when a liquid resist is formed by a screen printing method. As shown in FIG. 6, the region where the conductor portion 31 is formed and the region where the conductor portion 31 is not formed may have a ridge shape. In such a case, the entire surface of the conductor part 31 and the surface of the metal layer 101 exposed between the conductor parts 31 are reliably covered with the second resist layer 51 even if the film thickness is different. It only has to be like this.
In the case of a dry film, it can be formed using a vacuum laminator or the like. In the present embodiment, a negative liquid resist is used as the second resist layer 51, and the second resist layer 51 is obtained by a screen printing method.

  Next, although not shown, a mask is disposed at a predetermined position on the second resist layer 51 surface side. The second resist layer 51 and the mask may be in contact or non-contact. The non-contact method is more preferable because contamination of the plating mask can be reduced and an efficient production can be achieved because the step of bringing the second resist layer 51 and the mask into close contact with each other is omitted.

Next, exposure is performed to react with the second resist layer 51 at the periphery of the conductor portion 31 to form a reacted second resist layer 53 (FIG. 3C). At this time, the region of the second resist layer 53 to be reacted is a region wider than the circuit width of the conductor portion 31. For example, if the circuit width of the conductor portion 31 is 50 μm, it is preferably 60 μm or more. Thereby, even if a positional deviation occurs between the mask and the conductor portion 31, the side edge surface of the conductor portion 31 can be reliably covered with the reacted second resist layer 53.
Next, development is performed to remove the second plating resist layer 51 that has not reacted in the exposure step, and a reacted second resist layer 53 is formed (FIG. 3D).

  Next, as shown in FIG. 3 (e), the metal layer 101 exposed at the opening of the conductor portion 31 covered with the reacted second resist layer 53 is removed by etching or the like, and the surface of the base material is removed. It is made to expose and each conductor part 31 is insulated (FIG.3 (e)). At this time, since the upper surface and the side edge of the conductor part are covered with the reacted second resist layer 53, the conductor part 31 is exposed to the etching solution while the metal layer 101 is removed by etching. It becomes possible to prevent. Further, in the process of removing the metal layer 101 in the opening by etching, the reacted second resist layer 53 functions as an umbrella to prevent the metal layer 102 from being removed by etching beyond a predetermined width. It can also have an effect.

  Next, the reacted second resist layer 53 is peeled off to obtain a circuit board having a desired conductor portion 31 (FIG. 3F). The reacted second resist layer 53 is stripped using a dedicated stripping solution or an alkaline solution.

  As mentioned above, although the circuit board 1 of the present invention and the manufacturing method thereof have been described by exemplifying the single-sided circuit board 1 described in the accompanying drawings, the present invention is not limited to this. For example, it can be used for a double-sided circuit board having conductor portions on both sides.

  In the present embodiment, a base plate 105 and a laminated plate 10 in which a metal layer 101 is formed on at least one surface side of the base material 105 are prepared, and a reacted first first plate provided with an opening on the surface of the metal layer 101. A resist layer 22 is formed. Next, after forming the conductor part 31 by plating in the opening part of the reacted first resist layer 22, the reacted first resist layer 22 is removed. Next, the second resist layer 51 is formed so as to cover the entire surface of the metal layer 101 and the conductor portion 31, a part of the second resist layer 51 is removed, and the side surface and the upper surface of the conductor portion 31 are reacted. A circuit board can be obtained by covering with the second resist layer 53, exposing the metal layer 101, and removing the exposed metal layer 101 by etching.

  In this method of manufacturing a circuit board, a part of the second resist layer is removed, the side surface and the upper surface of the conductor portion are covered with the second resist layer, the metal layer is exposed, and then etched. Remove the exposed metal layer. As a result, when the metal layer is removed by etching, the conductor portion is covered with the second resist layer, so that the conductor portion is not etched, and therefore the circuit board manufacturing method having excellent conductor circuit accuracy and can do.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to this.
As the laminate, a polyimide film having a substrate thickness of 25 μm was used, and a copper foil having a thickness of 5 μm was used as the metal layer. A dry film resist having a thickness of 25 μm was laminated as a first resist layer on the surface of the copper foil with a vacuum laminator, and was exposed and developed to form a first resist layer having an opening of 50 μm. Thereafter, a conductor portion was formed by electrolytic copper plating so as to have a thickness of 20 μm, and then the dry film resist layer was peeled off with an alkali peeling solution. Next, a liquid resist was printed as a second resist layer with a screen printing machine to cover the side and upper surfaces of the conductor portion with the liquid resist. As a mask, a negative film having an exposed portion having a width of 90 μm that is 20 μm wider than the conductor portion was prepared, and the copper foil laminated on the substrate surface was exposed by performing exposure and development. The exposed copper foil was dissolved using cupric chloride as an etchant to expose the substrate. Next, the remaining liquid resist layer was peeled off to obtain a circuit board. It was confirmed that the obtained circuit board had a conductor part width of about 50 μm and was substantially the same as the opening of the dry film resist layer.

DESCRIPTION OF SYMBOLS 1, 3 Circuit board 10 Laminated board 101, 102 Metal layer 105 Base material 21 First resist layer 22 Reacted first resist layer 31, 33 Conductor part 51 Second resist layer 53 Reacted second resist layer

Claims (6)

Preparing a base plate, and a laminate having a metal layer formed on at least one surface side of the base material;
Forming a first resist layer having an opening on the surface of the metal layer;
Forming a conductor portion by plating in the opening of the first resist layer;
Removing the first resist layer;
Forming a second resist layer so as to cover the entire surface of the metal layer and the conductor portion;
Removing a part of the second resist layer, covering a side surface and an upper surface of the conductor portion with the second resist layer, and exposing the metal layer;
Removing the metal layer exposed by etching to expose the substrate surface;
A method for manufacturing a circuit board, comprising:   The step of removing the second resist layer includes a step of placing a second plating mask on the upper surface of the second resist layer at a predetermined position, and a step of irradiating light to the periphery of the conductor portion. The method for producing a circuit board according to claim 1, comprising a step of reacting the second resist layer and a step of removing other than the reacted second resist layer.   The method for manufacturing a circuit board according to claim 1, wherein the second resist layer is a photosensitive resin.   4. The method for manufacturing a circuit board according to claim 1, wherein the metal layer is formed by a sputtering method.   The method for manufacturing a circuit board according to claim 1, wherein the metal layer is an ultrathin metal foil.   A circuit board obtained by the method according to claim 1.