Method for manufacturing multilayer wiring board

Abstract

The present invention is a method for manufacturing a multilayer wiring board, the method comprising: a preparation step for preparing a wiring board having a stack of an organic insulating film and a metal film on the organic insulating film; a laser processing step that includes providing an opening section in the metal film of the wiring board by means of laser processing; and an etching step for etching the organic insulating film while using the metal film provided with the opening section as a mask to provide a via hole and a trench in the stack. In the laser processing step: a portion of the location where the via hole is to be formed in the organic insulating film is removed to form a recess section, and the location in the organic insulating film where the trench is to be formed is not removed; or a recess section having a smaller dimension in the depth direction than the recess section formed at the location where the via hole is to be formed is formed at the location in the organic insulating film where the trench is to be formed. Consequently, the multilayer wiring board can be manufactured with high productivity and at a low cost.

Description

Method for manufacturing multilayer wiring board

[0001] The present invention relates to a method for manufacturing a multilayer wiring board.

[0002] Multilayer wiring boards, for example semiconductor package substrates, have been developed mainly for the purpose of improving mounting density. Furthermore, multilayer wiring boards are tending to increase in size. In a multilayer wiring board, for example, trenches for intra-layer connection and via holes for interlayer connection are formed. Various proposals have been made as techniques for forming via holes and trenches in multilayer wiring boards, for example, Patent Documents 1 to 3.

[0003] Japanese Patent Application Laid-Open No. 2021-177527, Re-publication No. 2020 / 066074, Japanese Patent Application Laid-Open No. 2020-177943

[0004] Now, the trench for intra-layer connection and the via hole for interlayer connection have different depths from each other. Performing processing with different depths requires different operations for each. Therefore, further improvements have been demanded in terms of productivity and associated cost with respect to the method for forming trenches and via holes.

[0005] The present invention has been made to solve the above problems, and an object of the present invention is to provide a method for manufacturing a multilayer wiring board that can manufacture a multilayer wiring board with high productivity and low cost.

[0006] To solve the above problems, the present invention provides a method for manufacturing a multilayer wiring board, comprising: a preparation step of preparing a wiring substrate having a stack of an organic insulating film and a metal film on the organic insulating film; a laser processing step including providing openings in the metal film of the wiring substrate by laser processing; and an etching step of etching the organic insulating film while using the metal film with the openings as a mask to provide via holes and trenches in the stack, wherein in the laser processing step, a portion of the organic insulating film where the via holes are to be formed is removed to form recesses, and the portion of the organic insulating film where the trenches are to be formed is not removed, or a recess is formed in the portion of the organic insulating film where the trenches are to be formed that is smaller in depth than the recess formed in the portion of the organic insulating film where the via holes are to be formed.

[0007] In the multilayer wiring board manufacturing method according to the present invention, in the laser processing step, a portion of the area where via holes are to be formed is removed to form recesses, while in the area where trenches are to be formed, no recesses are formed, or recesses with a smaller depth dimension than the recesses formed in the area where via holes are to be formed are formed. Subsequently, in the etching step, via holes and trenches are provided, thereby enabling the simultaneous formation of via holes and trenches. Thanks to this, the multilayer wiring board manufacturing method according to the present invention allows for the production of multilayer wiring boards with high productivity and low cost.

[0008] For example, the wiring board may have two or more stacks, and in the etching process, a via hole can be provided that penetrates one of the stacks.

[0009] In another embodiment, the wiring board may include one stack and a further metal film disposed below the organic insulating film of the stack, and the via holes penetrating the one stack may be provided during the etching process.

[0010] The wiring board is not particularly limited as long as it has one or more stacks of an organic insulating film and a metal film, but for example, it may have two or more stacks, or it may include one stack and a further metal film placed below the stack. In addition, via holes may be provided through one stack during the etching process.

[0011] For example, a Cu film can be used as the metal film.

[0012] Furthermore, for example, a Cu film can be used as an additional metal film.

[0013] The metal film and the further metal film are not particularly limited, but may be, for example, a Cu film.

[0014] In the laser processing step, it is preferable to make the minimum width of the opening for forming the via hole larger than the minimum width of the opening for forming the trench.

[0015] In the laser processing process, by making the minimum width of the opening for forming via holes in the metal film larger than the minimum width of the opening for forming trenches, it becomes easier to remove a portion of the area where via holes are to be formed in the organic insulating film to form a recess, while leaving the area where trenches are to be formed intact, or to form a recess in the area where trenches are to be formed that is smaller in depth than the recess formed in the area where via holes are to be formed. Furthermore, the etching rate for forming via holes in the etching process can be made larger than the etching rate for forming trenches, thereby making it easier to make the depth of the formed via holes larger than the depth of the trenches.

[0016] For example, in the laser processing step, processing can be performed using an excimer laser.

[0017] The laser used in the laser processing process is not particularly limited, but for example, using an excimer laser allows for efficient and precise processing.

[0018] For example, in the etching process, etching can be performed by plasma etching.

[0019] The specific etching method used in the etching process is not particularly limited, but for example, plasma etching can reliably form via holes and trenches simultaneously. It is also advantageous in that it allows for easy removal of smear remaining at the bottom of the via holes and does not degrade any further metal films exposed at the bottom of the via holes.

[0020] Furthermore, a pad may be formed.

[0021] The present invention's method for manufacturing multilayer wiring boards also allows for the manufacture of multilayer wiring boards that include pads in addition to via holes and trenches.

[0022] As described above, the method for manufacturing multilayer wiring boards according to the present invention makes it possible to manufacture multilayer wiring boards with high productivity and low cost.

[0023] This is a flowchart of the method for manufacturing a multilayer wiring board according to the present invention. This is a schematic cross-sectional view of an example of a wiring substrate prepared in the preparation step of the method for manufacturing a multilayer wiring board according to the present invention. This is a schematic cross-sectional view of an example of an intermediate substrate obtained by the laser processing method of the method for manufacturing a multilayer wiring board according to the present invention. This is a schematic cross-sectional view of another example of an intermediate substrate obtained by the laser processing method of the method for manufacturing a multilayer wiring board according to the present invention. This is a schematic cross-sectional view of an example of a multilayer wiring board obtained by the method for manufacturing a multilayer wiring board according to the present invention. This is a schematic cross-sectional perspective view of an example of a multilayer wiring board obtained by the method for manufacturing a multilayer wiring board according to the present invention.

[0024] As mentioned above, there was a need to develop a manufacturing method for multilayer printed circuit boards that could produce them with high productivity and low cost.

[0025] As a result of diligent study on the above-mentioned problems, the inventors of the present invention have found that a method for manufacturing a multilayer printed circuit board that includes a laser processing step in which a portion of the area where via holes are to be formed is removed to form recesses, while in the area where trenches are to be formed, recesses are not formed or recesses with a smaller depth dimension than the recesses formed in the area where via holes are to be formed, and an etching step in which via holes and trenches are provided, allows for the simultaneous formation of via holes and trenches, thereby enabling the manufacture of multilayer printed circuit boards with high productivity and low cost, and thus the present invention has been completed.

[0026] That is, the present invention is a method for manufacturing a multilayer wiring board, comprising: a preparation step of preparing a wiring substrate having a stack of an organic insulating film and a metal film on the organic insulating film; a laser processing step of providing openings in the metal film of the wiring substrate by laser processing; and an etching step of etching the organic insulating film while using the metal film with the openings as a mask to provide via holes and trenches in the stack, wherein in the laser processing step, a portion of the organic insulating film where the via holes are to be formed is removed to form recesses, and the portions of the organic insulating film where the trenches are to be formed are not removed, or recesses with a depth smaller than the recesses formed in the portions of the organic insulating film where the via holes are to be formed are formed in the portions of the organic insulating film where the trenches are to be formed.

[0027] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0028] Figure 1 shows a general flow chart of the manufacturing method for the multilayer wiring board of the present invention.

[0029] As shown in Figure 1, the method for manufacturing a multilayer printed circuit board of the present invention generally includes a preparation step, a laser processing step, and an etching step. As will be described in detail later, according to the method for manufacturing a multilayer printed circuit board of the present invention, it is possible to manufacture a multilayer printed circuit board 100 provided with via holes 20 and trenches 30, as shown in Figures 5 and 6.

[0030] The following describes in detail each step of the manufacturing method for the multilayer wiring board of the present invention.

[0031] [Preparation Step] In the preparation step, a wiring board 10 having a stack 3 of an organic insulating film 1 and a metal film 2 on the organic insulating film 1 is prepared, for example, as shown in Figure 2. However, the wiring board 10 is not limited to the structure shown in Figure 2.

[0032] The material of the organic insulating film 1 is not particularly limited as long as it is an insulating organic material, but typically, materials used as interlayer insulating films can be used. Specific examples of materials for the organic insulating film 1 include build-up materials, solder resists, molding materials, and other process materials.

[0033] The organic insulating film 1 is generally preferably a cured product of a curable resin composition, but it may also be a molded product of a thermoplastic resin composition.

[0034] The curable resin composition typically includes a curable resin. Curable resins generally include thermosetting resins, photocurable resins, and resins that exhibit curability by heat and light. One of these may be used alone as the curable resin composition, or a combination of several types may be used.

[0035] Examples of thermosetting resins include epoxy resins, bismaleimide resins, phenolic resins, activated ester resins, cyanate resins, carbodiimide resins, acid anhydride resins, amine resins, benzoxazine resins, thiol resins, and radical polymerizable resins.

[0036] The thermosetting resin may, if necessary, contain a curing agent that reacts with the thermosetting resin to cure the resin composition.

[0037] Examples of photocurable resins include radical polymerizable resins and cationic polymerizable resins. Furthermore, the photocurable resin may contain photoinitiators such as photoradical generators and photoacid generators, as needed.

[0038] From the viewpoint of mechanical properties of the cured product, the curable resin composition preferably contains a curable resin, but it may be a composition containing a combination of a thermoplastic resin and a radically polymerizable monomer, or a combination of a thermoplastic resin and a cationically polymerizable monomer, depending on the required properties.

[0039] Furthermore, these resin compositions may contain fillers such as inorganic fillers and additives, for example.

[0040] In addition, these resin compositions can be provided, for example, in the form of a solution, or in the form of a sheet in which a layer of the resin composition is formed on a support.

[0041] The thickness of the organic insulating film 1 is not particularly limited, and for example, can be 100 µm or less, preferably 50 µm or less, more preferably 40 µm or less. Although the lower limit of the thickness of the organic insulating film 1 is not particularly limited, it can be 1 µm or more, 5 µm or more, or the like.

[0042] The material of the metal film 2 is not particularly limited as long as it is a conductive metal material or metal-containing material. The material of the metal film 2 includes, for example, one or more metals selected from the group consisting of gold, platinum, palladium, silver, copper, aluminum, cobalt, chromium, zinc, nickel, titanium, tungsten, iron, tin, and indium. The material of the metal film 2 may be a single metal or an alloy. Examples of the alloy include a layer formed from an alloy of two or more metals selected from the above group (for example, nickel-chromium alloy, copper-nickel alloy, and copper-titanium alloy).

[0043] The metal film 2 may have a single-layer structure, or may have a multi-layer structure including two or more single metal films or alloy films made of different types of metals or alloys.

[0044] The thickness of the metal film 2 is not particularly limited, and for example, can be 3 µm or more and 35 µm or less, and is preferably 5 µm or more and 30 µm or less.

[0045] The method for forming the metal film 2 is not particularly limited, but examples include plating, sputtering, and methods combining these. When a sheet formed on a metal foil is used as the organic insulating film, the metal foil may be used as the metal film 2. Furthermore, the metal film 2 can be patterned by methods such as subtractive or semi-additive methods.

[0046] The wiring board 10 only needs to have one or more stacks 3. For example, it can have two stacks 3 as shown in Figure 2, or it can have more than two stacks 3.

[0047] Furthermore, the wiring board 10 may also include an additional metal film 2' that does not constitute a stack 3, as shown in Figure 2, for example. The additional metal film 2' may be located below one stack 3 (on the opposite side from the other stack 3), as shown in Figure 2. In Figure 2, the organic insulating film 1 included in one stack 3 is sandwiched between the metal film 2 included in this stack 3 and the additional metal film 2'.

[0048] The material of the metal film 2' is not particularly limited as long as it is a conductive metallic material or a metal-containing material. The material of the metal film 2' can be the same as the example of the material of the metal film 2.

[0049] The thickness of the metal film 2' is not particularly limited, but for example, it can be 3 μm or more and 35 μm or less, and preferably 5 μm or more and 30 μm or less.

[0050] The method for preparing the wiring board 10 is not particularly limited, but a conventional method can be used.

[0051] [Laser Processing Process] Next, a laser processing process is performed, which includes creating openings in the metal film of the wiring board by laser processing.

[0052] Furthermore, in this laser processing step, a portion of the area in the organic insulating film where the via holes are to be formed is removed to form a recess. On the other hand, in this laser processing step, the area in the organic insulating film where the trenches are to be formed is not removed, or a recess is formed in the area where the trenches are to be formed that is smaller in depth than the recess formed in the area where the via holes are to be formed.

[0053] Specifically, as shown in Figures 3 and 4, for example, first, openings 4 and 5 are made in the metal film 2 of the wiring board 10 prepared in the preparation step. Opening 4 is an opening for forming a via hole. Opening 5 is an opening for forming a trench.

[0054] The metal film 2 in which the openings 4 and 5 are provided is typically the metal film 2 located on the outermost surface.

[0055] Furthermore, as shown in Figures 3 and 4, a portion of the area 11 where via holes are to be formed in the organic insulating film 1 is removed to form a recess 12.

[0056] On the other hand, as shown in Figure 3, for example, the area 13 where a trench in the organic insulating film 1 is to be formed is not removed.

[0057] Alternatively, as shown in Figure 4, for example, a recess 14 is formed in the location 13 where a trench is to be formed in the organic insulating film 1, and the recess 14 is smaller in depth than the recess 12 formed in the location 11 where a via hole is to be formed. That is, the average depth d of the recess 12 １２ However, the average depth d of the recess 14 １４ Make it larger than [the specified value].

[0058] I don't want to be constrained by theory, but for example, the minimum width w of the opening 4 to be made in the metal film 2. ４ The minimum width of opening 5 w ５By making it larger, it is thought that it becomes easier to remove a portion of the area 11 where via holes are to be formed in the organic insulating film 1 to form a recess 12, while not removing the area 13 where trenches are to be formed in the organic insulating film 1, or to form a recess 14 in the area 13 where trenches are to be formed in the organic insulating film 1 that has a smaller depth dimension than the recess 12 formed in the area 11 where via holes are to be formed.

[0059] The openings 4 and recesses 12 for beer holes can be formed one or more of each, depending on the number of beer holes to be formed. Similarly, the openings 5 ​​(and recesses 14, if formed) for trenches can be formed one or more of each, depending on the number of trenches to be formed.

[0060] The laser used in the laser processing process is not particularly limited, but for example, using an excimer laser allows for efficient and precise processing.

[0061] In laser processing, more precise processing can be achieved by using an appropriate photomask.

[0062] Through this laser processing process, an intermediate substrate 10A, such as the one shown in Figure 3 or Figure 4, can be obtained.

[0063] [Etching Process] Next, an etching process is performed on the intermediate substrate 10A, using the metal film 2 with openings 4 and 5 as a mask, to etch the organic insulating film 1 and create via holes and trenches in the stack 3.

[0064] As explained earlier, in the intermediate substrate 10A, recesses 12 are formed where a portion of the area 11 where via holes of the organic insulating film 1 are to be formed has been removed. On the other hand, the area 13 where trenches of the organic insulating film 1 are to be formed is not removed (for example, Figure 3), or a recess 14 (for example, Figure 4) with a smaller depth dimension than the recess 12 is formed in the area 13 where trenches of the organic insulating film 1 are to be formed.

[0065] By etching the intermediate substrate 10A, for example, as shown in Figure 5, via holes 20 are formed below the opening 4 and trenches 30 are formed below the opening 5.

[0066] In this etching process, the locations 11 (recesses 12) where via holes 20 are to be formed in the organic insulating film 1 and the locations 13 (recesses 14 if trenches have already been formed) where trenches are to be formed are simultaneously etched in the depth direction. As described above, in the organic insulating film 1, before the etching process, location 11 is etched further than location 13. Therefore, by performing the etching process through the metal film 2 with openings 4 and 5 provided on the entire surface of the intermediate substrate 10A, when etching at location 11 is completed, that is, when the formation of via holes 20 penetrating one stack 3 is completed, the trenches 30 will not penetrate the stack 3. Thus, via holes 20 and trenches 30 can be provided simultaneously by such a simple etching process. In other words, according to the manufacturing method of the multilayer wiring board of the present invention, a multilayer wiring board 100 having via holes 20 and trenches 30, such as shown in Figure 5, can be obtained with high efficiency and, consequently, low cost.

[0067] The etching process is preferably carried out by plasma etching. By performing plasma etching, which is a type of dry etching, it is possible to reliably create via holes 20 and trenches 30 simultaneously, and it is also possible to prevent damage to the metal film 2 exposed at the bottom of the via holes 20, thereby suppressing the generation of foreign matter.

[0068] If the wiring board 10 has two or more stacks 3, a via hole 20 can be provided that penetrates one of the stacks 3 during the etching process.

[0069] Alternatively, if the wiring board 10 includes one stack 3 and a further metal film 2' positioned below the organic insulating film 1 of the stack 3, via holes can be provided in the etching process that penetrate one stack 3 to expose the further metal film 2'.

[0070] After the etching process, the metal film 2 with openings 4 and 5 may be removed. The removal of the metal film 2 can be carried out as appropriate depending on the material of the metal film 2. For example, a metal film 2 containing Cu can be easily dissolved and removed with an etching solution. Examples of components of the etching solution for Cu include, but are not limited to, chlorides such as ferric chloride and cupric chloride, acids such as hydrochloric acid and ammonium oxalate, oxidizing agents such as hydrogen peroxide and aqueous ammonia, and additives such as water and surfactants.

[0071] Furthermore, the method for manufacturing a multilayer wiring board according to the present invention may include further forming of pads 40 as shown in Figure 6.

[0072] The method of forming the pads is not particularly limited. For example, when vias and trenches are formed in a metal film 2 as a contact mask layer using different processes, the pad diameter is machined so that the area around the via processing location is processed in the same way as the trench processing area. When vias and trenches are formed in the same process as a metal film 2 as a contact mask layer, a halftone photomask is used to reduce the photomask transmittance of the pad and trench areas surrounding the via area compared to the via area, thereby making the processing depth shallower.

[0073] Furthermore, as a modification of the present invention, the metal film 2 can be changed to, for example, a film of a material resistant to plasma etching of the organic insulating film 1. Also, the metal film used as a contact mask layer is not used in the seed (electrode) layer for forming a conductive layer by electroplating, and the contact mask film is highly likely to be peeled off after etching of the organic insulating film 1. That is, a modification of the present invention is a method for manufacturing a multilayer wiring board, comprising a preparation step of preparing a wiring substrate having a stack of an organic insulating film and a mask film on the organic insulating film; a laser processing step including making openings in the mask film of the wiring substrate by laser processing; and an etching step of etching the organic insulating film while using the mask film with the openings as a mask to make via holes and trenches in the stack, wherein in the laser processing step, a portion of the organic insulating film where the via holes are to be formed is removed to form recesses, and the portion of the organic insulating film where the trenches are to be formed is not removed, or a recess with a smaller depth dimension in the organic insulating film where the trenches are to be formed is formed.

[0074] Examples of mask film materials include fluorine-based polymers and Al ２ O ３ and Y ２ O ３ We can list the following:

[0075] This specification includes the following embodiments: [1] A method for manufacturing a multilayer wiring board, comprising: a preparation step of preparing a wiring board having a stack of an organic insulating film and a metal film on the organic insulating film; a laser processing step of providing openings in the metal film of the wiring board by laser processing; and an etching step of etching the organic insulating film while using the metal film with the openings as a mask to provide via holes and trenches in the stack, wherein in the laser processing step, a portion of the organic insulating film where the via holes are to be formed is removed to form recesses, and the portion of the organic insulating film where the trenches are to be formed is not removed, or a recess is formed in the portion of the organic insulating film where the trenches are to be formed that is smaller in depth than the recess formed in the portion of the organic insulating film where the via holes are to be formed. [2] The method for manufacturing a multilayer wiring board according to [1], wherein the wiring board has two or more stacks, and in the etching step, the via holes penetrating one of the stacks are provided. [3] The method for manufacturing a multilayer wiring board according to [1], wherein the wiring board comprises one stack and a further metal film disposed below the organic insulating film of the stack, and the via hole penetrating the one stack is provided in the etching step. [4] The method for manufacturing a multilayer wiring board according to any one of [1] to [3], wherein the metal film is a Cu film. [5] The method for manufacturing a multilayer wiring board according to [3], wherein the further metal film is a Cu film. [6] The method for manufacturing a multilayer wiring board according to any one of [1] to [5], wherein in the laser processing step, the minimum width of the opening for forming the via hole is greater than the minimum width of the opening for forming the trench. [7] The method for manufacturing a multilayer wiring board according to any one of [1] to [6], wherein in the laser processing step, the processing is performed using an excimer laser. [8] The method for manufacturing a multilayer wiring board according to any one of [1] to [7], wherein in the etching step, the etching is performed by plasma etching. [9] A method for manufacturing a multilayer wiring board according to any one of [1] to [8], further comprising forming the pads.

[10] A method for manufacturing a multilayer wiring board, comprising: a preparation step of preparing a wiring board having a stack of an organic insulating film and a mask film on the organic insulating film; a laser processing step of providing an opening in the mask film of the wiring board by laser processing; and an etching step of etching the organic insulating film using the mask film with the opening as a mask to provide via holes and trenches in the stack, wherein in the laser processing step, a portion of the organic insulating film where the via holes are to be formed is removed to form a recess, and the portion of the organic insulating film where the trenches are to be formed is not removed, or a recess is formed in the portion of the organic insulating film where the trenches are to be formed that is smaller in depth than the recess formed in the portion of the organic insulating film where the via holes are to be formed.

[11] The method for manufacturing a multilayer wiring board according to

[10] , wherein the wiring board has two or more stacks, and in the etching step, the via holes penetrating one of the stacks are provided.

[12] The method for manufacturing a multilayer wiring board according to

[10] , wherein the wiring board includes one stack and a metal film disposed below the organic insulating film of the stack, and in the etching step, the via holes penetrating the one stack are provided.

[13] The method for manufacturing a multilayer wiring board according to any one of

[10] to

[12] , wherein in the laser processing step, the minimum width of the opening for forming the via holes is greater than the minimum width of the opening for forming the trenches.

[14] The method for manufacturing a multilayer wiring board according to any one of

[10] to

[13] , wherein in the laser processing step, the processing is performed using an excimer laser.

[15] The method for manufacturing a multilayer wiring board according to any one of

[10] to

[14] , wherein in the etching step, the etching is performed by plasma etching.

[16] The method for manufacturing a multilayer wiring board according to any one of

[10] to

[15] , further comprising forming the pads.

[0076] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention.

Claims

1. A method for manufacturing a multilayer wiring board, comprising: a preparation step of preparing a wiring substrate having a stack of an organic insulating film and a metal film on the organic insulating film; a laser processing step of providing openings in the metal film of the wiring substrate by laser processing; and an etching step of etching the organic insulating film while using the metal film with the openings as a mask to provide via holes and trenches in the stack, wherein in the laser processing step, a portion of the organic insulating film where the via holes are to be formed is removed to form recesses, and the portion of the organic insulating film where the trenches are to be formed is not removed, or a recess is formed in the portion of the organic insulating film where the trenches are to be formed that is smaller in depth than the recess formed in the portion of the via holes.

2. The method for manufacturing a multilayer wiring board according to claim 1, wherein the wiring board has two or more stacks, and in the etching step, a via hole is provided that penetrates one of the stacks.

3. The method for manufacturing a multilayer wiring board according to claim 1, wherein the wiring board comprises one stack and a further metal film disposed below the organic insulating film of the stack, and the etching step provides the via holes penetrating the one stack.

4. The method for manufacturing a multilayer wiring board according to claim 1, wherein a Cu film is used as the metal film.

5. The method for manufacturing a multilayer wiring board according to claim 3, wherein a Cu film is used as the further metal film.

6. The method for manufacturing a multilayer wiring board according to any one of claims 1 to 5, wherein in the laser processing step, the minimum width of the opening for forming the via hole is made larger than the minimum width of the opening for forming the trench.

7. A method for manufacturing a multilayer wiring board according to any one of claims 1 to 5, wherein the laser processing step is performed using an excimer laser.

8. A method for manufacturing a multilayer wiring board according to any one of claims 1 to 5, wherein the etching step is performed by plasma etching.

9. A method for manufacturing a multilayer wiring board according to any one of claims 1 to 5, further comprising forming pads.

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