JP2013045828A - Circuit board manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a circuit board manufacturing method which can form a conductive film having less variation and a uniform thickness when transferring a mold pattern on a resin base material by imprint to form the conductive layer in a recess of the resin base material.SOLUTION: A circuit board manufacturing method comprises: forming a laminated base material by laminating a second resin base material on a first resin base material; forming on the laminated base material, a recess reaching halfway down a thickness of the first resin base material by press fitting an imprint mold from one surface of the second resin base material so as to penetrate the second resin base material and reach halfway down the thickness of the first resin base material; further, forming a conductive layer composed of a conductive first material so as to cover at least an inner surface of the recess; subsequently, forming a thin film composed of a second material different from the first material so as to cover at least the conductive layer in the recess on a bottom side and so as not to cover the conductive layer in the recess on a side wall side; subsequently, removing the conductive layer formed in the recess on the side wall side by selective etching; and further, removing the second resin base material.

Description

  The present invention relates to a method of manufacturing a circuit board used in various electronic devices, and more particularly to a method of forming a conductor pattern on a substrate by transfer.

Examples of techniques for forming a conductor pattern on a substrate by transfer include nanoimprint (NIL), injection molding, and hot embossing. Among these, NIL has attracted attention in recent years as a technique for forming an extremely fine pattern.
In the method of manufacturing a circuit board by applying nanoimprint, basically, a mold (imprint mold) having a convex pattern corresponding to a fine conductor pattern to be finally formed is used. Then, the imprint mold is pressed against the surface of the resin base material to form (transfer) a concave pattern corresponding to the convex pattern on the resin base material, and the conductive material is filled into the concave pattern.

  As a conventional method for manufacturing this type of circuit board, for example, a method disclosed in Patent Document 1 is known. The method disclosed in Patent Document 1 will be described with reference to FIGS.

  In the method of Patent Document 1, first, the thin metal layer 103 is formed on the resin layer 101 by electroless plating or the like. Next, the imprinting mold 105 is pressed on the thin metal layer 103 to form a recess 107 in the resin layer 101 corresponding to the wiring pattern to be finally formed. Then, after the imprinting mold 105 is released, a conductive layer (electrolytic plating layer) 109 is formed on the entire surface of the thin metal layer 103 by electrolytic plating. Further, the excess electrolytic plating layer and the metal thin layer other than the inside of the recess 107 are removed by etching, and the wiring pattern is formed only in the recess 107, leaving the conductor layer 110 composed of the metal thin layer 103 and the electrolytic plating layer 109. To do.

JP 2007-243181 A

In the method disclosed in Patent Document 1, since the main part of the conductor layer 110 is formed by electrolytic plating, the thickness of the conductor layer 110 in the recess 107 tends to be nonuniform.
For example, as shown in FIG. 5D, in the wide concave portion 107a, the thickness of the electrolytic plating layer 109a tends to be smaller than the thickness of the electrolytic plating layer 109b in the narrow concave portion 107b. As a result, as shown in FIG. 5E, as a final wiring pattern, the conductor layer 110a formed in the wide concave portion 107a is likely to be thin, which causes a problem in electrical characteristics. May end up. Also, when removing excess plating metal by etching, the conductor layer 110a is excessively etched in the wide concave portion 107a, and the conductor layer 110a becomes thinner or disappears in an extreme case. There are also times when

  In order to avoid the above problem, if the etching amount is reduced, the conductor layer cannot be completely removed by etching at the portion where the thickness of the conductor layer on the convex portion of the resin layer 101 is large, as shown in FIG. Inconveniently, the conductor layer 110c remains in a portion other than the wiring pattern to be formed.

It is also conceivable to remove unnecessary conductor layers by applying mechanical polishing such as buffing instead of or in combination with etching. Then, the polishing depth of the conductor layer becomes large, and the thickness of the finally remaining conductor layer tends to be thin.
Thus, in the circuit board manufacturing method described in Patent Document 1 to which imprinting is applied, it is difficult to suppress variations in the thickness of the conductor layer.

  The present invention has been made in view of the above circumstances, and in forming a conductive pattern embedded in a resin substrate by applying imprint, a method capable of forming a conductive layer with a uniform thickness with little variation. It is an issue to provide.

  In order to solve the problems as described above, in the present invention, a laminated base material in which concave portions are formed by an imprint mold is basically produced as a laminated base material in which two resin base materials are laminated, and thereafter After forming a conductive layer at least on the inner surface of the recess, a thin film functioning as an etching mask is formed on the conductive layer on the bottom surface of the recess, and then the excess conductive layer is removed by selective etching, whereby the recess The conductive layer is left with a predetermined thickness on the bottom surface of the substrate to reduce the variation in the thickness of the conductive layer.

That is, a method for manufacturing a circuit board according to a basic aspect (first aspect) of the present invention includes:
A laminating step of laminating a second resin base material on the first resin base material to form a laminated base material;
With respect to the laminated base material, an imprint mold having a convex portion of a pattern corresponding to a conductor pattern to be formed is formed from one surface of the second resin base material so that the convex portion penetrates the second resin base material and A press-fitting process for press-fitting so that the thickness of the resin substrate reaches halfway;
A mold release step of releasing the imprint mold from the laminated base material to form a recess that penetrates the second resin base material and reaches the middle of the thickness of the first resin base material;
A conductive layer forming step of forming a conductive layer made of a conductive first material so as to cover at least the inner surface of the recess;
Forming a thin film made of a second material different from the first material so as to cover at least the conductive layer on the bottom surface of the recess and not to cover the conductive layer on the side wall surface of the recess;
A selective etching step of removing the conductive layer formed on the side wall surface in the recess by selective etching that selectively dissolves only the first material without dissolving the second material;
A second resin substrate removing step of removing the second resin substrate;
It is characterized by having.

In the method for manufacturing a circuit board according to the first aspect, in the selective etching step, the conductive layer on the sidewall surface of the recess is removed by etching in the conductive layer in the recess of the laminated base material. As for the conductive layer on the bottom surface, the thin film made of the second material functions as an etching mask. Therefore, after etching, the conductive layer in the first resin base material in the concave portion is not etched and remains at the filling thickness in the concave portion. . The conductive layer formed other than the recesses can be completely absent by peeling the second resin base material.
Note that, in the conductive layer on the bottom surface of the concave portion, the portions near both ends in the width direction are slightly etched in the selective etching step, and the thickness (height from the bottom surface of the concave portion) is the center in the width direction (covered with a thin film) However, it can be made almost flat by adjusting the etching time.
In the conductive layer forming step and the thin film forming step, even if a conductive layer or thin film is formed on a portion other than the concave portion of the laminated base material (for example, on one surface of the second resin base material), the conductive layer of that portion is also formed. The thin film is removed together with the second resin base material in the second resin base material removing step after the selective etching step. Therefore, the conductive layers and thin films formed at these locations do not cause inconvenience as circuit board products. Furthermore, in this case, there is no need to remove the conductive layer and the thin film at these locations in a separate process.

A circuit board manufacturing method according to the second aspect of the present invention includes:
A press-fitting step of press-fitting an imprint mold having a convex portion corresponding to a conductor pattern to be formed so that the convex portion reaches from the one surface of the first resin base material to the middle of the thickness of the first resin base material;
A penetration step of pushing the convex portion of the imprint mold into the second resin base material from one surface of the second resin base material so that the convex portion of the imprint mold penetrates the second resin base material;
A laminating step of laminating the second resin base material on the first resin base material to form a laminated base material having a recess that penetrates the second resin base material and reaches the middle of the thickness of the first resin base material;
A conductive layer forming step of forming a conductive layer made of a conductive first material so as to cover at least the inner surface of the recess;
Forming a thin film made of a second material different from the first material so as to cover at least the conductive layer on the bottom surface of the recess and not to cover the conductive layer on the side wall surface of the recess;
A selective etching step of removing the conductive layer formed on the side wall surface in the recess by selective etching that selectively dissolves only the first material without dissolving the second material;
A second resin substrate removing step of removing the second resin substrate;
It is characterized by having.

  In the method for manufacturing the circuit board according to the second aspect, the steps until the formation of the laminated base material having a recess that penetrates through the second resin base material and reaches the middle of the thickness of the first resin base material are as follows. Although different from the manufacturing method of the circuit board manufacturing method of the first aspect, the subsequent conductive layer forming step, thin film forming step, selective etching step, and second resin base material removing step are the same as those of the circuit board manufacturing method of the first aspect. The method is the same. Therefore, it is possible to obtain the same operational effects as the operational effects of the circuit board manufacturing method of the first aspect as described above.

  A circuit board manufacturing method according to a third aspect of the present invention is the circuit board manufacturing method according to the first or second aspect, further comprising the step of forming the conductive layer in the recess in the conductive layer forming step. 1 It forms by the thickness corresponded to the recessed part depth formed in the resin base material.

  According to the circuit board manufacturing method of the third aspect, the surface position of the conductive layer finally remaining in the recess is substantially the same as the surface position of the second resin base material, and the conductive layer is embedded in the plane. A circuit board can be obtained.

  The circuit board manufacturing method according to the fourth aspect of the present invention is characterized in that, in the circuit board manufacturing method according to the first to third aspects, a conductive material is used as the second material. .

  According to the fourth aspect, since the thin film on the conductive layer in the recess also functions as a conductor, it can be used as a circuit board while leaving the thin film on the conductive layer in the recess.

  The circuit board manufacturing method according to the fifth aspect of the present invention is the method for manufacturing a circuit board according to the fourth aspect, wherein Cu is used as the first material and Sn or Al is used as the second material. It is characterized by using.

  According to the fifth aspect, in the selective etching step, the conductive layer made of the first material formed on the side wall surface of the recess is reliably and easily etched without etching the thin film made of the second material. Can do.

  According to the present invention, it is possible to manufacture a circuit board with less variation in the thickness of the conductive layer embedded in the resin base material.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows 1st Embodiment of the circuit board manufacturing method of this invention to process order. FIG. 2 is an enlarged schematic view showing a main part of the first embodiment shown in FIG. 1. It is a schematic diagram which shows the one part process of 2nd Embodiment of the circuit board manufacturing method of this invention in order of a process. It is an approximate solution figure showing a part of process of a 3rd embodiment of a circuit board manufacturing method of the present invention in order of a process. It is a schematic diagram which shows an example of the manufacturing method of the conventional circuit board to which nanoimprint is applied in steps.

Hereinafter, embodiments of the present invention will be described in detail.
FIGS. 1A to 1I show the manufacturing method of the first embodiment of the present invention step by step, and FIGS. 2A to 2E show an enlarged main part thereof. 2A to 2E correspond to FIGS. 1E to 1I, respectively.

First, as shown in FIG. 1A, a sheet-like first resin base material 11 and a second resin base material 12 are laminated as a lamination process. In this way, the one in which the first and second resin base materials are laminated is hereinafter referred to as a laminated base material 13.
The material of the 1st resin base material 11 and the 2nd resin base material 12 will not be specifically limited if it is a nonelectroconductive resin which can be plastically deformed with the applied pressure at the time of the pressurization by the imprint mold mentioned later. In general, thermoplastic resins such as ABS (acrylonitrile butadiene styrene copolymer) resin, LCP (liquid crystal polymer), PTFE (polytetrafluoroethylene) resin, and polyester resin are suitable. Depending on the temperature at the time of pressurization, a thermosetting resin such as an epoxy resin, a phenol resin, or a silicone resin can also be used. Although the thickness of the 1st resin base material 11 and the 2nd resin base material 12 is not specifically limited, Usually, about 5-50 micrometers is suitable respectively. In addition, when the first and second resin base materials 11 and 12 are laminated, they may be simply overlapped, but in consideration of handling in a later process, they may be bonded to the extent of temporary fixing with an adhesive, or It may be heated and crimped appropriately.

On the other hand, as a preparatory stage of the press-fitting process, as shown in FIG. 1B, an imprint mold 14 having a convex pattern corresponding to the conductor pattern to be formed is prepared. In the imprint mold 14, the convex portion 14A on the lower surface side corresponds to the conductor pattern to be formed, and the concave portion 14B between the convex portions 14A corresponds to the non-formed portion of the conductor pattern. As a material for the imprint mold, a mold for transferring a fine pattern conventionally used for manufacturing a circuit board by nanoimprint, for example, Si (silicon), ceramic such as SiO ₂ , SiC, Al ₂ O ₃ , quartz, etc. Further, a material made of a hard material such as a metal such as quartz glass, Ni, or diamond-like carbon (DLC) can be used.

  As the press-fitting step, as shown in FIG. 1C, the imprint mold 14 is pressed against the upper surface (one surface) side of the second resin substrate 12 in the laminated substrate 13 to press the imprint mold 14. The part 14A is press-fitted into the laminated base material 13. At this time, the press-fit depth of the imprint mold 14 is adjusted so that the convex portion 14 </ b> A penetrates the second resin base material 12 and reaches the middle of the thickness of the first resin base material 11.

  Next, as a mold release step, the imprint mold 14 is raised and the imprint mold 14 is released from the laminated base material 13. Thereby, as shown in FIG.1 (d), the laminated base material 13 will be in the state by which the recessed part 15 which penetrates the 2nd resin base material 12 and reaches the middle of the thickness of the 1st resin base material 11 was formed.

  Thereafter, as a conductive layer forming step, as shown in FIG. 1 (e) and FIG. 2 (a), the conductive layer is formed so as to cover at least the inner surface (the bottom surface 15A and the side wall surface 15B of the concave portion) of the concave portion 15 in the laminated base material 13. The conductive layer 16 made of a first material having a property is formed. As the first material, a highly conductive metal generally used for a conductor pattern on a circuit board, such as Cu or Ag, is used. In the present embodiment, the conductive layer 16 is formed so as to cover not only the inner surface of the recess 15 in the laminated base material 13 but also the upper surface of the laminated base material 13 (one surface of the second resin base material 12).

  As a specific method for forming the conductive layer 16, for example, a method of forming a thin seed layer by electroless plating or vapor deposition and then performing electrolytic plating is preferable. Alternatively, the conductive layer 16 can be formed by coating a conductive paste by printing or the like and then baking it. The conductive layer 16 is preferably formed in a so-called conformal shape that conforms to the shape of the inner surface of the recess 15 rather than the so-called via filling that fills the entire recess 15. In addition, the thickness of the conductive layer 16 is desirably determined to be the same as or close to the recess depth D of the first resin substrate 11 in the recess 15 (see FIG. 2A).

  Next, as a thin film forming step, as shown in FIGS. 1 (f) and 2 (b), at least the conductive layer on the bottom surface 15 </ b> A of the concave portion 15 in the laminated base material 13 is covered and at least the concave portion 15 in the laminated base material 13. A thin film 17 made of the second material is formed so as not to cover the conductive layer on the side wall surface 15B. In the present embodiment, the thin film 17 covers the conductive layer on the bottom surface 15A of the recess 15 in the laminated base material 13 and the conductive layer on the top surface of the laminated base material 13 (one surface of the second resin base material 12). It forms so that the conductive layer on the side wall surface 15B of the recessed part 15 in the base material 13 may not be covered.

  The thin film 17 functions as an etching mask for the conductive layer etching in the subsequent selective etching process. Therefore, as the material (second material) of the thin film 17, a material that is different from the first material constituting the conductive layer and is not etched in the selective etching step is selected. The second material of the thin film 17 may be non-conductive, but considering the final usage pattern, it is desirable to use a material made of a highly conductive metal as will be described later. For example, when Cu is used as the material (first material) of the conductive layer 16, it is desirable to use Sn or Al as the material (second material) of the thin film 17. In addition, Ni, Ti, Co, Cr, etc. can be used.

  A specific method for forming the thin film 17 is not particularly limited, and various film forming methods such as vapor deposition and sputtering can be applied. However, a film forming method in which the film forming direction is controlled so as to form a film on the conductive layer on the bottom surface 15A of the recess 15 without covering the conductive layer on the side wall surface 15B of the recess 15 is selected. That is, it is only necessary to select a film forming method in which film formation is not performed on a surface perpendicular to the upper surface of the second resin base material 12 but mainly on a surface parallel to the upper surface of the second resin base material 12. Even in a general vapor deposition method, such film formation direction control can be easily achieved.

  Next, as a selective etching step, as shown in FIGS. 1G and 2C, the conductive layer 16 formed on the side wall surface 15B of the recess 15 is selectively dissolved and removed. That is, the second material constituting the thin film 17 is not dissolved, and a selective etching solution that selectively dissolves only the first material constituting the conductive layer 16 is used to form the film on the side wall surface 15B. The conductive layer is removed by etching. For example, when Cu is used as the conductive layer 16 (first material) and Sn, Ag, or Al is used as the thin film 17 (second material), a commercially available sulfuric acid / hydrogen peroxide etching solution is used as the etching solution. Can do.

By performing such selective etching, the conductive layer formed on the side wall surface 15B in the recess 15 is removed by etching, but the conductive layer on the bottom surface 15A in the recess 15 is prevented from being etched by the thin film 17. Therefore, it remains in the recess 15.
More specifically, in the conductive layer 16 on the bottom surface 15 </ b> A of the recess 15, the conductive layer in the central region Q excluding the region P (see FIG. 2C) near both ends in the width direction is covered with the thin film 17. Therefore, the thickness before the selective etching remains as it is. On the other hand, among the conductive layer 16 on the bottom surface 15A of the recess 15, the conductive layer in the region P near both ends in the width direction is slightly eroded by etching. However, the etching of the conductive layer 16 in the selective etching process mainly proceeds in the direction from the space in the recess 15 toward the side wall surface 15B. Therefore, the etching depth (the erosion depth in the direction toward the bottom surface 15A) in the region P near both ends in the width direction is relatively small. Therefore, even in the region P near both ends in the width direction, the conductive layer 16 remains with a considerable thickness. Eventually, the conductive layer 16 remains on the bottom portion 15A of the recess 15 with the central portion being relatively thick and the portions near both ends being slightly thin. However, as a whole, the conductive layer 16 in the recess 15 is relatively flat. It can be said that

  Thereafter, as the second resin base material removing step, the second resin base material 12 on the first resin base material 11 is removed as shown in FIGS. 1 (h) and 2 (d). As this removal method, the second resin base material 12 may be selectively dissolved, or the second resin base material 12 may be mechanically peeled from the first resin base material 11. In addition, with the removal of the 2nd resin base material 12, the conductive layer and thin film on the 2nd resin base material 12 are also removed simultaneously.

  After removing the second resin base material 12, a circuit board (FIG. 2D) in which the conductive layer 16 remains only in the recess 15 of the first resin base material 11 is obtained. In this state, the thin film 17 also remains on the central region Q of the conductive layer 16 in the recess 15. Here, when a highly conductive material such as Sn or Al is used as the material (second material) of the thin film 17, the thin film 17 remains on the conductive layer 16 and is used as a circuit board. Can do.

  In some cases, as shown in FIGS. 1 (i) and 2 (e), the thin film 17 on the conductive layer 16 is etched or polished as a thin film removing process after the second resin base material removing process is completed. It is good also as a circuit board by removing. If the thin film 17 is removed in this manner, the thin film 17 can be suitably used as a circuit board even when the material (second material) of the thin film 17 is not a highly conductive material.

  As the imprint mold 14, for example, as shown in FIGS. 3 (a) to 3 (d), a projection 14A having a multi-stage shape may be used. In that case, a finer conductor pattern is used. Can be formed. FIGS. 3A to 3D are shown corresponding to FIGS. 1B to 1E, and the steps after FIG. 3D are shown in FIGS. 1F to 1H. Or what is necessary is just to be the same as the process shown to FIG.1 (f)-(i).

  Although not shown, the circuit board on which the conductor pattern is formed as described above may be used as a single-side sealed circuit board by covering the surface on the conductor pattern side with a protective resin. it can.

  Further, if a via hole penetrating the resin base material is formed by any means such as a laser processing method or an imprint method, and the via hole is filled with a conductor to form a penetrating electrode, the circuit substrate is formed as 2 It is also possible to provide a multilayer substrate in which multiple layers are stacked.

  In the above description, after the first resin base material and the second resin base material are laminated to form a laminated base material, the convex portion of the surface imprint mold of the second resin base material in the laminated base material is formed. By pressing, a concave portion that penetrates the second resin base material and reaches the middle of the thickness of the first resin base material is formed in the laminated base material. Until a laminated base material having such a concave portion is manufactured This process is not limited to the process described above. For example, in the stage before laminating the first resin base material and the second resin base material, the portions of the shape to be the concave portions (the concave portions and the through portions) of the laminated base material are used as the first and second resin base materials. Each may be formed individually and then the first and second resin base materials may be laminated. An example in that case will be described with reference to FIGS.

  As shown in FIGS. 4A to 4C, the convex portion 14 </ b> A of the imprint mold 14 is pushed into the surface (one surface) of the first resin base material 11 and reaches the middle of the thickness of the first resin base material 11. The concave portion 15-1 is formed in the first resin base material 11. On the other hand, as shown in FIGS. 4 (d) to 4 (f), the first resin base material 11 is formed by pressing the convex portion 14 </ b> A of the imprint mold 14 into the surface (one surface) of the second resin base material 12. A through portion 15-2 penetrating the entire thickness of the second resin base material 12 is formed. Thereafter, as shown in FIG. 4G, the first resin base material 11 and the second resin base material 12 are passed through the position of the concave portion 15-1 of the first resin base material 11 and the second resin base material 12. The first resin base material 11 and the second resin base material 12 are laminated while being aligned so that the position of the part 15-2 matches, and the laminated base material 13 is obtained. In such a laminated state, the concave portion 15-1 of the first resin base material 11 and the through portion 15-2 of the second resin base material 12 pass through the concave portion 15, that is, the second resin base material 12, and A concave portion 15 reaching the middle of the thickness of the first resin base material 11 is formed in the laminated base material 13. In addition, as a subsequent process, what is necessary is just to apply a process as shown, for example to FIG.1 (e)-(i).

  In addition, although not shown in the figure, as shown in FIGS. 4A to 4C, the convex portion of the imprint mold is pushed into the surface (one surface) of the first resin base material, and the first resin base material A concave portion reaching the middle of the thickness is formed in the first resin base material, and further, a second resin base material is formed by printing or the like on a portion other than the concave portion on the surface of the first resin base material. You may form the laminated base material which has a recessed part which penetrates material and reaches the middle of the thickness of the 1st resin base material.

  Although preferred embodiments of the present invention have been described above, the present invention is of course not limited to these embodiments. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 11 ... 1st resin base material, 12 ... 2nd resin base material, 13 ... Laminate base material, 14 ... Imprint mold, 14A ... Convex part (convex pattern) of imprint mold , 15... Recessed portion, 15 A... Bottom surface of the recessed portion, 15 B... Sidewall surface of the recessed portion, 16.

Claims (5)

A laminating step of laminating a second resin base material on the first resin base material to form a laminated base material;
With respect to the laminated base material, an imprint mold having a convex portion of a pattern corresponding to a conductor pattern to be formed is formed from one surface of the second resin base material so that the convex portion penetrates the second resin base material and A press-fitting process for press-fitting so that the thickness of the resin substrate reaches halfway;
A mold release step of releasing the imprint mold from the laminated base material to form a recess that penetrates the second resin base material and reaches the middle of the thickness of the first resin base material;
A conductive layer forming step of forming a conductive layer made of a conductive first material so as to cover at least the inner surface of the recess;
Forming a thin film made of a second material different from the first material so as to cover at least the conductive layer on the bottom surface of the recess and not to cover the conductive layer on the side wall surface of the recess;
A selective etching step of removing the conductor layer formed on the side wall surface in the recess by selective etching that selectively dissolves only the first material without dissolving the second material;
A second resin substrate removing step of removing the second resin substrate;
A method of manufacturing a circuit board, comprising: A press-fitting step of press-fitting an imprint mold having a convex portion corresponding to a conductor pattern to be formed so that the convex portion reaches from the one surface of the first resin base material to the middle of the thickness of the first resin base material;
A penetration step of pushing the convex portion of the imprint mold into the second resin base material from one surface of the second resin base material so that the convex portion of the imprint mold penetrates the second resin base material;
A laminating step of laminating the second resin base material on the first resin base material to form a laminated base material having a recess that penetrates the second resin base material and reaches the middle of the thickness of the first resin base material;
A conductive layer forming step of forming a conductive layer made of a conductive first material so as to cover at least the inner surface of the recess;
Forming a thin film made of a second material different from the first material so as to cover at least the conductive layer on the bottom surface of the recess and not to cover the conductive layer on the side wall surface of the recess;
A selective etching step of removing the conductive layer formed on the side wall surface in the recess by selective etching that selectively dissolves only the first material without dissolving the second material;
A second resin substrate removing step of removing the second resin substrate;
A method of manufacturing a circuit board, comprising:   3. The circuit board according to claim 1, wherein, in the conductive layer forming step, the conductive layer is formed with a thickness corresponding to a depth of a recess formed in the first resin base material in the recess. Manufacturing method.   The method for manufacturing a circuit board according to claim 1, wherein a conductive material is used as the second material. The method for manufacturing a circuit board according to claim 4, wherein Cu is used as the first material, and Sn or Al is used as the second material.

Images