JP7439487B2 - Wiring board, mounting board, and wiring board manufacturing method - Google Patents

Description

The present disclosure relates to a wiring board, a mounting board, and a method for manufacturing a wiring board.

Electrostatic damage has become a problem in wiring boards. A wiring board has a structure in which, for example, wiring and an insulating layer are arranged on one or both sides of a base material, and the surface of the wiring board is covered with an insulating layer and is therefore easily charged. If the insulating layer on the surface of the wiring board is charged, electrostatic discharge may occur between the insulating layer on the surface of the wiring board and the element when mounting the element on the wiring board, and the element may be destroyed by static electricity. There is.

As a countermeasure against electrostatic discharge damage, it is common to provide a protection element to protect the element from electrostatic discharge damage. For example, Patent Document 1 discloses a method for mounting a semiconductor element, in which a protective resistor for preventing electrostatic damage to the semiconductor element is attached to a circuit pattern of a printed circuit board, and then the semiconductor element is attached to the circuit pattern. There is.

Japanese Patent Application Publication No. 11-340412

However, when providing a protection element, it is necessary to provide a dedicated circuit, which complicates the design and increases costs, and requires wiring and mounting space, which makes miniaturization difficult. be.

The present disclosure has been made in view of the above circumstances, and its main purpose is to provide a wiring board, a mounting board, and a method for manufacturing a wiring board that can suppress electrostatic damage with a simple configuration. .

In order to achieve the above object, the present disclosure provides a base material having a first surface and a second surface opposite to the first surface, and a wiring line disposed on the first surface side of the base material and including a pad portion. an insulating layer disposed on the first surface side of the base material and having a pad opening located on the pad portion; and a surface side of the insulating layer opposite to the surface on the base material side. a conductive layer disposed in a region other than the pad opening, the conductive layer does not function as a wiring and is not grounded.

In the present disclosure, the conductive layer is disposed at an end of the wiring board in a region other than the pad opening on a side of the insulating layer opposite to the base material side. Good too. Further, it is preferable that the conductive layer is disposed around the pad opening in a region other than the pad opening on the side of the insulating layer opposite to the base material side. . Furthermore, it is more preferable that the conductive layer is entirely disposed in a region other than the pad opening on the side of the insulating layer opposite to the surface on the base material side.

Further, in the present disclosure, it is preferable that the conductive layer is a metal film or a metal oxide film.

The wiring board according to the present disclosure further includes a protective layer disposed on a surface of the pad portion of the wiring layer opposite to the surface on the base material side, and the conductive layer and the protective layer are made of the same material. It is preferable that there be.

Further, in the present disclosure, it is preferable that the insulating layer has an overhang shape.

The wiring board according to the present disclosure includes a through wiring disposed in the through hole of the base material, a second wiring layer disposed on the second surface side of the base material and including a second pad portion, and a second wiring layer disposed in the through hole of the base material. a second insulating layer disposed on the second surface side and having a second pad opening located above the second pad portion; , and a second conductive layer disposed in a region other than the second pad opening. The second conductive layer does not function as a wiring and is not grounded.

Further, the present disclosure provides a mounting board including the above-described wiring board and an element mounted on a pad portion of the wiring board.

Further, the present disclosure includes a wiring layer forming step of forming a wiring layer including a pad portion on the first surface of the base material having a first surface and a second surface opposite to the first surface; an insulating layer forming step of forming an insulating layer having a pad opening located on the pad portion on the first surface; and a step of forming an insulating layer having a pad opening located on the pad portion on the first surface; a conductive layer forming step of forming a conductive layer in a region other than the above, and a protective layer forming step of forming a protective layer on a surface of the wiring layer opposite to the surface of the pad portion on the base material side. The method for manufacturing a wiring board, wherein the conductive layer does not function as a wiring and is not grounded, and in the insulating layer forming step, the insulating layer having an overhang shape is formed, and the conductive layer forming step and In the protective layer forming step, a method for manufacturing a wiring board is provided, in which the conductive layer and the protective layer are simultaneously formed using the same material by a dry film forming method.

The present disclosure has the advantage that it is possible to provide a wiring board and a mounting board that can suppress electrostatic damage with a simple configuration.

FIG. 1 is a schematic plan view and a cross-sectional view illustrating a wiring board according to the present disclosure. FIG. 2 is a schematic plan view illustrating a wiring board according to the present disclosure. FIG. 2 is a schematic plan view illustrating a wiring board according to the present disclosure. 1 is a schematic cross-sectional view illustrating a wiring board according to the present disclosure. FIG. 3 is a process diagram illustrating a method for manufacturing a wiring board according to the present disclosure. 1 is a schematic cross-sectional view illustrating a wiring board according to the present disclosure. 1 is a schematic cross-sectional view illustrating a wiring board according to the present disclosure. FIG. 2 is a schematic cross-sectional view illustrating a mounting board according to the present disclosure.

Embodiments of the present disclosure will be described below with reference to the drawings and the like. However, the present disclosure can be implemented in many different ways, and should not be construed as being limited to the description of the embodiments exemplified below. Further, in order to make the explanation clearer, the drawings may schematically represent the width, thickness, shape, etc. of each part compared to the actual form, but this is just an example and does not limit the interpretation of the present disclosure. It's not something you do. In addition, in this specification and each figure, the same elements as those described above with respect to the previously shown figures are denoted by the same reference numerals, and detailed explanations may be omitted as appropriate.

In this specification, when expressing a mode in which another member is placed on top of a certain member, when it is simply expressed as “above” or “below”, unless otherwise specified, the term This includes both cases in which another member is placed directly above or below a certain member, and cases in which another member is placed above or below a certain member via another member. In addition, in this specification, when expressing a mode in which another member is arranged on the surface of a certain member, when it is simply expressed as "on the surface side" or "on the surface", unless otherwise specified, This includes both cases in which another member is placed directly above or directly below a certain member, and cases in which another member is placed above or below a certain member via another member.

Hereinafter, the wiring board and the mounting board in the present disclosure will be described in detail.

A. Wiring Board The wiring board in the present disclosure includes: a base material having a first surface and a second surface opposite to the first surface; a wiring layer disposed on the first surface side of the base material and including a pad portion; an insulating layer disposed on the first surface side of the base material and having a pad opening located on the pad portion; and the pad opening on a surface side of the insulating layer opposite to the surface on the base material side. and a conductive layer disposed in a region other than the area, and the conductive layer does not function as a wiring and is not grounded.

1(a) and 1(b) are a schematic plan view and a cross-sectional view showing an example of a wiring board according to the present disclosure, and FIG. 1(b) is a cross-sectional view taken along the line AA in FIG. 1(a). As shown in FIGS. 1(a) and 1(b), a wiring board 1 according to the present disclosure includes a base material 2 having a first surface 2a and a second surface 2b opposite to the first surface 2a; A wiring layer 3 disposed on the first surface 2a side and including a pad section 13; an insulating layer 4 disposed on the first surface 2a side of the base material 2 and having a pad opening 14 located above the pad section 13; A conductive layer 5 is disposed in a region other than the pad opening 14 on the side of the layer 4 opposite to the surface on the base material 2 side. The conductive layer 5 does not function as a wiring and is not electrically connected to the wiring layer 3. Further, the conductive layer 5 is not grounded.

In the example shown in FIG. 1(b), the conductive layer 5 is disposed entirely in a region other than the pad opening 14 on the side of the insulating layer 4 opposite to the surface on the base material 2 side. The arrangement of the conductive layers is not limited to this.

In a wiring board, if an insulating layer is disposed on the outermost surface of the wiring board, it is likely to be charged by contact with a person or a machine. In contrast, according to the present disclosure, the conductive layer is disposed in a region other than the pad opening on the side of the insulating layer opposite to the base material side, and the conductive layer is disposed on the outermost surface of the wiring board. Because of this arrangement, it is possible to make the wiring board less likely to be charged. Furthermore, even if the wiring board is electrically charged, static electricity can be removed by grounding the conductive layer. Therefore, when mounting elements on the wiring board according to the present disclosure, it is possible to suppress electrostatic damage from occurring.

Furthermore, according to the present disclosure, the conductive layer is disposed in a region other than the pad opening on the side of the insulating layer opposite to the base material side, so it does not require a complicated design like a conventional protection element. No space is required, and the wiring board can have a simple configuration. Therefore, the wiring board according to the present disclosure can suppress electrostatic damage with a simple configuration. Furthermore, the manufacturing cost of the wiring board can also be reduced.

The wiring board according to the present disclosure will be described below.

1. Conductive Layer The conductive layer in the present disclosure is a member that is disposed in a region other than the pad opening on the side of the insulating layer opposite to the base material side, does not function as a wiring, and is not grounded.

Here, when we say that the conductive layer does not function as wiring, we mean that the conductive layer does not function as wiring for the signal layer (signal wiring), power supply layer (power supply wiring), ground layer (ground wiring), earth layer (earth wiring), etc. Say something. Since the conductive layer does not function as a wiring, it is not electrically connected to the wiring layer. Further, when an element is mounted on a pad portion of a wiring board according to the present disclosure via a bonding member, the conductive layer does not function as a wiring, and therefore is not electrically connected to the bonding member and the element.

Furthermore, the expression "the conductive layer is not grounded" means that the conductive layer is not earthed or grounded. That is, the conductive layer does not function as an earth layer or a ground layer.

Note that in the wiring board of the present disclosure, the conductive layer can be grounded from the outside, and when mounting an element on the pad portion of the wiring board of the present disclosure, it is possible to ground the conductive layer from the outside using, for example, a conductive tape or copper wire. Static electricity can be removed by grounding the conductive layer.

The conductive layer is arranged in a region other than the pad opening on the side of the insulating layer opposite to the base material side, and the conductive layer is electrically connected to the wiring layer. There is no particular limitation as long as the conductive layer is arranged so that it is not electrically connected to the bonding member and the element when the element is mounted on the pad portion of the wiring board via the bonding member. For example, as shown in FIG. 1(a), the conductive layer 5 is disposed entirely in a region other than the pad opening 14 on the side of the insulating layer 4 opposite to the surface on the base material 2 side. Alternatively, as shown in FIG. 2, it may be partially arranged in a region other than the pad opening 14 on the side of the insulating layer 4 opposite to the surface on the base material 2 side.

As mentioned above, wiring boards are easily charged due to contact with humans or machines, so the conductive layer is a region other than the pad opening on the side of the insulating layer opposite to the base material side, and It is preferable to arrange it in a part of the board that comes into contact with people or machines. For example, when mounting elements on a wiring board, people or machines often come into contact with the edges of the wiring board in order to transport, move, fix, etc. the wiring board. Therefore, the conductive layer can be disposed at the end of the wiring board in a region other than the pad opening on the side of the insulating layer opposite to the base material side. By disposing the conductive layer at the end of the wiring board, generation of static electricity due to contact between humans and machines can be suppressed. For example, in FIG. 3A, the conductive layer 5 is disposed at the end of the wiring board 1 in a region other than the pad opening 14 on the side of the insulating layer 4 opposite to the surface on the base material 2 side. has been done.

Further, the conductive layer is preferably disposed around the pad opening in a region other than the pad opening on the side of the insulating layer opposite to the base material side. By disposing the conductive layer around the pad opening, it is possible to effectively suppress electrostatic discharge damage when mounting an element on the pad portion of the wiring board. For example, in FIG. 3B, the conductive layer 5 is arranged around the pad opening 14 in a region other than the pad opening 14 on the side of the insulating layer 4 opposite to the surface on the base material 2 side. has been done.

In particular, the conductive layer is preferably disposed entirely in a region other than the pad opening on the side of the insulating layer opposite to the base material side. This is because the conductive layer can make it difficult to charge the wiring board, and it is possible to effectively suppress electrostatic damage when mounting elements on the pad portion of the wiring board.

Here, when the conductive layer is entirely arranged in a region other than the pad opening on the side of the insulating layer opposite to the base material side, it means that the conductive layer is arranged entirely on the base material side of the insulating layer in a plan view. This means that the area of the region where the conductive layer is arranged is 70% or more when the area of the region other than the pad opening on the side opposite to the surface is taken as 100%.

In plan view, when the area of the area other than the pad opening on the side of the insulating layer opposite to the base material side is taken as 100%, the area of the area where the conductive layer is arranged is, for example, 70%. % or more, more preferably 75% or more, even more preferably 80% or more, particularly preferably 90% or more. This is because when the area of the region where the conductive layer is arranged is within the above range, it is possible to effectively suppress electrostatic damage when mounting an element on a pad portion of a wiring board.

When the conductive layer is disposed around the pad opening in the insulating layer, for example, the conductive layer can have an opening located over the pad opening in the insulating layer, and in plan view, the conductive layer can have an opening located over the pad opening in the insulating layer. The portion can be located within the opening of the conductive layer. In this case, the size of the opening in the conductive layer may be the same as the size of the pad opening in the insulating layer, or may be larger than the size of the pad opening in the insulating layer. The size of the opening in the conductive layer is arranged so that the conductive layer is not electrically connected to the wiring layer, and the conductive layer is arranged so that it is not electrically connected to the wiring layer. It is not particularly limited as long as it is arranged so as not to be electrically connected to members and elements, and may be adjusted as appropriate depending on the size of the pad opening in the insulating layer, the thickness of the insulating layer, etc.

Further, as described above, when an element is mounted on a pad portion of a wiring board according to the present disclosure via a bonding member, the conductive layer is not electrically connected to the bonding member and the element. Therefore, for example, when using solder or the like as a bonding member, the conductive layer is not placed within a predetermined range around the pad opening of the insulating layer so that the conductive layer is not electrically connected to the bonding member. It is preferable. Specifically, the conductive layer is preferably not disposed within 10 μm, more preferably not within 50 μm, and preferably not within 100 μm of the pad opening of the insulating layer. More preferred. Note that "within a predetermined range around the pad opening of the insulating layer" means that the distance d from the end of the pad opening 14 of the insulating layer 4 is within a predetermined range, as shown in FIG. 2, for example. say.

The sheet resistance of the conductive layer is, for example, preferably 10 ⁵ Ω/□ or less, more preferably 10 ⁴ Ω/□ or less, and even more preferably 10 ³ Ω/□ or less. Further, the sheet resistance of the conductive layer can be, for example, 10 ⁻⁸ Ω/□ or more. When the conductive layer has high conductivity such that the sheet resistance of the conductive layer is within the above range, the wiring board can be made less likely to be charged.

Here, the above-mentioned sheet resistance is a value measured by a four-terminal four-probe method. As the resistivity meter, for example, a low resistivity meter Lorestar GX MCP-T700 manufactured by Mitsubishi Chemical Corporation can be used.

The material for the conductive layer is not particularly limited as long as it has conductivity, and conductive materials commonly used for wiring on wiring boards can be used. Examples of the conductive material used in the conductive layer include metal materials such as metals and metal oxides, conductive resins containing conductive fillers and resins, and conductive polymers.

Since the conductive layer is disposed on the outermost surface of the wiring board, the metal material is preferably a metal material whose electrical resistance does not easily change due to oxidation. Examples of such metal materials include metals such as chromium, molybdenum, aluminum, titanium, gold, platinum, and palladium, alloys containing at least one selected from these metals, and indium tin oxide (ITO) and oxide. Examples include metal oxides such as indium zinc (IZO), aluminum-added zinc oxide (AZO), and gallium-added zinc oxide (GZO).

Among these, the material of the conductive layer is preferably a metal material, and more preferably a metal material whose electrical resistance does not easily change due to oxidation. That is, the conductive layer is preferably a metal film or a metal oxide film. This is because by increasing the conductivity of the conductive layer, it is possible to effectively suppress electrostatic discharge damage when mounting an element on the pad portion of the wiring board according to the present disclosure.

The thickness of the conductive layer can be, for example, 1 nm or more and 10 μm or less, preferably 1 nm or more and 5 μm or less, and more preferably 1 nm or more and 1 μm or less. If the thickness of the conductive layer is within the above range, sufficient conductivity can be obtained.

The method for forming the conductive layer may be any method that can form the conductive layer in the area other than the pad opening on the side of the insulating layer opposite to the base material side, and can be any method that can be used for general wiring. Any formation method can be used and is appropriately selected depending on the material of the conductive layer and the like. Examples include a method in which a conductive film is formed by a dry film forming method such as a PVD method such as a CVD method or a sputtering method, a plating method, a coating method, etc., and then patterned by a photolithography method, or a printing method. . Furthermore, as described later, when the insulating layer has an overhang shape, a conductive layer may be formed by a dry film forming method such as a CVD method or a PVD method using the insulating layer having an overhang shape. can.

2. Insulating Layer The insulating layer in the present disclosure is a member that is disposed on the first surface side of the base material and has a pad opening located above the pad portion of the wiring layer.

The cross-sectional shape of the pad opening is not particularly limited, but in particular, the pad opening has an area of horizontal cross-section from the surface of the insulating layer on the base material side to the surface of the insulating layer opposite to the surface of the base material. It is preferable to have a tapered shape in which . That is, it is preferable that the insulating layer has an overhang shape. For example, in FIG. 4, the insulating layer 4 has an overhang shape, and the pad opening 14 has a tapered shape. Since the insulating layer has an overhang shape, when an element is mounted on the pad portion of the wiring board according to the present disclosure via a bonding member, the bonding member is likely to catch on the overhang portion of the insulating layer, thereby preventing the element from being mounted. It can be made difficult to come off.

Further, FIGS. 5(a) to 5(c) are process diagrams showing an example of the method for manufacturing a wiring board according to the present disclosure, and are examples in which the insulating layer has an overhang shape. First, as shown in FIG. 5(a), the wiring layer 3 is formed on the first surface 2a of the base material 2, and then, as shown in FIG. 5(b), the wiring layer 3 is formed on the first surface 2a of the base material 2. An insulating layer 4 having an overhang shape and having a pad opening 14 located on the pad part 13 of the wiring layer 3 is formed, and then, as shown in FIG. A conductive material is deposited on the layer 4 by sputtering or the like to form a conductive layer 5 on the insulating layer 4 and a protective layer 6 on the pad portion 13 of the wiring layer 3. In this way, when the protective layer is arranged on the side opposite to the base material side of the pad part of the wiring layer, the overhanging shape of the insulating layer prevents the conductive layer and the protective layer from forming. During formation, it is possible to prevent the conductive layer and the protective layer from being connected and to prevent the conductive layer and the protective layer from being electrically connected. Further, as a method for forming the conductive layer and the protective layer, a photolithography method can be used, but a method using an insulating layer having an overhang shape as illustrated in FIGS. 5(a) to 5(c), Since there is no need to perform etching as in photolithography, there is no etching residue, and reliability degradation due to etching residue can be avoided and reliability can be improved.

Further, the shape of the pad opening in plan view is not particularly limited, and may be any shape such as a circle, an ellipse, a square, or a rectangle.

The material of the insulating layer is not particularly limited as long as it has insulating properties, and insulating materials commonly used for insulating layers of wiring boards can be used, and both organic materials and inorganic materials can be used. be able to. When the insulating layer has an overhang shape, the material of the insulating layer is preferably a photosensitive resin composition. This is because by using the photosensitive resin composition, an insulating layer having an overhang shape can be easily formed.

The thickness of the insulating layer is determined as long as it is possible to prevent electrical connection between the conductive layer and the bonding member when the element is mounted on the pad portion of the wiring board according to the present disclosure via the bonding member. The thickness is not particularly limited, and can be the same as the thickness of an insulating layer in a general wiring board, and is appropriately selected depending on the type of element, mounting method, etc. The thickness of the insulating layer can be, for example, 1 μm or more and 500 μm or less, 1 μm or more and 300 μm or less, or 1 μm or more and 50 μm or less.

The method for forming the insulating layer may be any method that can form an insulating layer having a pad opening, and a general method for forming an insulating layer may be adopted, depending on the material etc. of the insulating layer. Selected appropriately. Examples include a method in which an insulating film is formed by a photolithography method using a photosensitive resin composition, a coating method, a dry film forming method, etc., and then patterned by a photolithography method, or a printing method. When the insulating layer has an overhang shape, a photolithography method using a photosensitive resin composition is preferred. This is because an insulating layer having an overhang shape can be easily formed.

3. Wiring Layer The wiring layer in the present disclosure is a member that is disposed on the first surface side of the base material and includes a pad portion.

The material for the wiring layer is not particularly limited as long as it has conductivity, and conductive materials commonly used for wiring layers can be used. Examples of the conductive material used in the wiring layer include metals such as copper, molybdenum, titanium, tungsten, tantalum, aluminum, gold, silver, nickel, and palladium; alloys containing at least one selected from these metals; Alternatively, metal oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO) can be used. By using highly conductive copper or aluminum, it is possible to suppress an increase in resistance. Furthermore, by using copper, which has relatively low hardness, it is possible to provide a wiring board on which more reliable electrical connections can be established.

The wiring layer may be a single layer or a multilayer in which a plurality of layers are laminated.

The thickness of the wiring layer can be the same as the thickness of the wiring layer in a general wiring board. The thickness of the wiring layer may be, for example, 0.05 μm or more and 100 μm or less, 0.1 μm or more and 50 μm or less, or 0.2 μm or more and 10 μm or less. Thereby, sufficient conductivity can be obtained.

As a method for forming the wiring layer, a general method for forming a wiring layer can be used. For example, after forming a conductive film by a dry film forming method of a PVD method such as a CVD method or a sputtering method, or a plating method, Examples include a method of patterning a conductive film using a photolithography method, a method of patterning a metal foil using a photolithography method, and the like.

4. Base Material The base material in the present disclosure has a first surface and a second surface opposite to the first surface, and is a member that supports the above-mentioned insulating layer, wiring layer, and conductive layer.

The base material is not particularly limited as long as it has insulating properties, and insulating base materials commonly used for wiring boards can be used. Examples include glass substrates, glass epoxy substrates, glass composite substrates, ceramic substrates such as alumina substrates, resin substrates such as fluororesin substrates and polyimide substrates, and paper phenol substrates.

As described later, when the wiring board according to the present disclosure has through wiring arranged in a through hole of a base material, the base material has the through hole.

The diameter of the through hole can be appropriately selected depending on the use of the wiring board, and is not particularly limited, but may be, for example, 10 μm or more and 1000 μm or less, or 20 μm or more and 500 μm or less.

Examples of methods for forming the through holes include etching such as plasma etching and wet etching, laser irradiation, and mechanical processing methods such as sandblasting and ultrasonic drilling.

The thickness of the base material is not particularly limited as long as it can support the above-mentioned insulating layer, wiring layer, and conductive layer, and can be appropriately selected depending on the use of the wiring board. The thickness of the base material may be, for example, 10 μm or more and 1000 μm or less, 100 μm or more and 800 μm or less, or 200 μm or more and 600 μm or less.

5. Protective Layer The wiring board according to the present disclosure may further include a protective layer disposed on a surface of the wiring layer opposite to the surface of the pad portion on the base material side. By disposing the protective layer, corrosion such as oxidation of the wiring layer can be suppressed and the wiring layer can be protected. For example, in FIGS. 4 and 6, the protective layer 6 is disposed on the surface of the pad portion 13 of the wiring layer 3 opposite to the surface on the base material 2 side.

The material for the protective layer may be any material that can suppress corrosion of the pad portion of the wiring layer, and materials that are generally used for the protective layer of the wiring layer in wiring boards can be used. Examples of the material for the protective layer include solder, flux, and gold.

Among these, the material of the protective layer is preferably the same as the material of the conductive layer. Since the conductive layer and the protective layer can be formed simultaneously, the manufacturing process can be simplified and manufacturing costs can be reduced. When the materials of the conductive layer and the protective layer are the same, the material of the conductive layer described above can be used as the material of the protective layer.

The thickness of the protective layer can be the same as the thickness of the protective layer of the wiring layer in a general wiring board. Further, when the conductive layer and the protective layer are made of the same material, the thickness of the protective layer can be the same as the thickness of the conductive layer described above.

As a method for forming the protective layer, a general method for forming a protective layer for a wiring layer can be used, and is appropriately selected depending on the material of the protective layer. Examples include surface treatment methods such as solder leveler treatment, preflux treatment, and plating treatment. Further, when the materials of the conductive layer and the protective layer are the same, the method of forming the protective layer can be the same as the method of forming the conductive layer described above.

6. Other Configurations The wiring board according to the present disclosure may be a single-sided wiring board or a multilayer wiring board in which a wiring layer is arranged only on the first surface side of the base material, or a wiring board on the first surface side and the second It may be a double-sided wiring board or a multilayer wiring board in which a wiring layer is arranged on the surface side.

When the wiring board according to the present disclosure is a multilayer wiring board in which wiring layers are arranged only on the first surface side of the base material, a plurality of wiring layers and a plurality of insulating layers are arranged on the first surface side of the base material. can have. When the wiring board has a plurality of wiring layers and a plurality of insulating layers arranged on the first surface side of the base material, a pad on the side of the outermost insulating layer opposite to the surface on the base material side. A conductive layer is arranged in a region other than the opening.

When the wiring board according to the present disclosure is a double-sided wiring board in which wiring layers are arranged on the first surface side and the second surface side of the base material, the wiring board includes through-hole wiring arranged in the through hole of the base material. a second wiring layer disposed on the second surface side of the base material and including a second pad portion; and a second wiring layer disposed on the second surface side of the base material and located on the second pad portion. a second insulating layer having two pad openings; and a second conductive layer disposed in a region other than the second pad opening on the side of the second insulating layer opposite to the base material side. , may further have. The second conductive layer does not function as a wiring and is not grounded.

FIG. 7 is a schematic cross-sectional view showing another example of the wiring board according to the present disclosure. As shown in FIG. 7, the wiring board 1 includes a base material 2 having a first surface 2a and a second surface 2b opposite to the first surface 2a; a first wiring layer 3a including a pad portion 13a; a first insulating layer 4a disposed on the first surface 2a side of the base material 2 and having a first pad opening 14a located above the first pad portion 13a; The first conductive layer 5a is disposed in a region other than the first pad opening 14a on the side of the first insulating layer 4a opposite to the base material 2 side, and the first conductive layer 5a is disposed in the through hole 2c of the base material 2. a second wiring layer 3b disposed on the second surface 2b side of the base material 2 and including a second pad portion 13b; A second insulating layer 4b having a second pad opening 14b located above, and a region other than the second pad opening 14b on the side of the second insulating layer 4b opposite to the surface on the base material 2 side. and a second conductive layer 5b. The first conductive layer 5a and the second conductive layer 5b do not function as wiring and are not grounded.

In this specification, the wiring layer disposed on the first surface side of the base material is referred to as a first wiring layer, the pad section disposed on the first surface side of the base material is referred to as a first pad section, and The insulating layer disposed on the first surface side of the substrate may be referred to as a first insulating layer, and the pad opening disposed on the first surface side of the base material may be referred to as a first pad opening. Further, the wiring layer disposed on the second surface side of the base material is referred to as a second wiring layer, the pad section disposed on the second surface side of the base material is referred to as a second pad section, and the second surface side of the base material The insulating layer disposed on the side is referred to as a second insulating layer, and the pad opening disposed on the second surface side of the base material is referred to as a second pad opening.

(1) Second conductive layer The second conductive layer in the present disclosure is disposed in a region other than the second pad opening on the side of the second insulating layer opposite to the base material side, and functions as a wiring. First, it is a member that is not grounded.

Note that the second conductive layer may be the same as the first conductive layer in that it does not function as a wiring and is not grounded.

Further, the arrangement, sheet resistance, material, thickness, formation method, etc. of the second conductive layer can be the same as the arrangement, sheet resistance, material, thickness, formation method, etc. of the first conductive layer.

(2) Penetrating Wiring The penetrating wiring in the present disclosure is a member disposed in the through hole of the base material.

The through wiring may be any wiring that can electrically connect the first surface and the second surface of the base material, and its form is not particularly limited. The form of the through wiring may be, for example, a through wiring that fills a through hole in a base material, a so-called filled via, or a through wiring that is placed only on the side wall of a through hole in a base material, a so-called conformal via. Good too. Further, when the through wiring is a conformal via, a hollow portion may be disposed within the through hole, and the inside of the through hole may be filled with a resin portion.

When the through wiring is a conformal via and a hollow portion is arranged in the through hole, the through wiring can be formed integrally with the first wiring layer and the second wiring layer.

The material for the through wiring is not particularly limited as long as it is a conductive material, and any conductive material used for general through wiring can be used. selected. Examples of the material for the through wiring include metals such as copper, gold, silver, platinum, rhodium, tin, aluminum, nickel, and chromium, and alloys containing these metals.

The through wiring may be a single layer or may be a multilayer structure in which a plurality of layers are laminated. For example, the through wiring may include a seed layer disposed on the side wall of the through hole of the base material, and a plating layer disposed on the surface of the seed layer opposite to the side wall of the through hole. The material for the seed layer can be appropriately selected from materials used for seed layers in general plating methods. The material of the seed layer is preferably a conductive material that has adhesiveness to the base material, such as titanium, molybdenum, tungsten, tantalum, nickel, chromium, aluminum, compounds thereof, alloys thereof, etc. be able to. When the plating layer contains copper, the material of the seed layer is preferably a material that can suppress diffusion of copper into the interior of the base material, such as titanium nitride, molybdenum nitride, tantalum nitride, etc. be able to. The material for the plating layer is preferably a conductive material that has adhesion to the seed layer, and examples thereof include the above-mentioned through-wiring material.

In addition, when the through wiring is a conformal via and the through hole is filled with a resin part, examples of the material of the resin part include epoxy resin, acrylic resin, polyimide, polyamide, polyester, etc. I can do it.

As the method for forming the through wiring, a general method for forming a through wiring can be used, and is appropriately selected depending on the form of the through wiring and the like. Examples of methods for forming the through wiring include PVD methods such as vacuum evaporation and sputtering, CVD, and plating.

(3) Second Wiring Layer The second wiring layer in the present disclosure is a member that is disposed on the second surface side of the base material and includes a second pad portion.

The second wiring layer may be a single layer or a multilayer in which a plurality of layers are laminated.

The material, thickness, formation method, etc. of the second wiring layer can be the same as the material, thickness, formation method, etc. of the first wiring layer.

The pitch and size of the second pad portions of the second wiring layer are not particularly limited, and may be, for example, the same as or different from the pitch and size of the first pad portions of the first wiring layer.

(4) Second Insulating Layer The second insulating layer in the present disclosure is a member that is disposed on the second surface side of the base material and has a second pad opening located above the second pad portion.

The material, thickness, forming method, etc. of the second insulating layer can be the same as the material, thickness, forming method, etc. of the first insulating layer.

B. Mounting Board The mounting board in the present disclosure includes the above-described wiring board and an element mounted on a pad portion of the wiring board.

FIG. 8 is a schematic cross-sectional view showing an example of a mounting board according to the present disclosure. As shown in FIG. 8, the mounting board 20 includes a wiring board 1 and an element 21 mounted on the pad portion 13 of the wiring board 1 via a bonding member 22. Note that the configuration of the wiring board 1 is similar to the wiring board 1 shown in FIG. 1 described above.

According to the present disclosure, by having the above-described wiring board, it is possible to suppress electrostatic damage during mounting of elements with a simple configuration.

The mounting board in the present disclosure will be described below.

The wiring board constituting the mounting board in the present disclosure is the same as the wiring board described above, so a description thereof will be omitted here.

Examples of elements in the present disclosure include active elements such as ICs, transistors, and diodes, and passive elements such as resistors, capacitors, and inductors. Further, examples of the element include an IC chip, an LSI chip, a MEMS chip, and the like.

As a method for mounting the element on the pad portion of the wiring board, for example, surface mounting, flip chip mounting, wire bonding, etc. can be used.

Elements can be mounted on the pad portions of the wiring board via bonding members. As the bonding member, a bonding member generally used for mounting elements can be used. Examples of the material for the joining member include solder, gold or gold alloy, conductive paste, anisotropic conductive paste, anisotropic conductive film, and the like.

Further, an underfill resin portion may be arranged by filling an underfill resin between the wiring board and the element. Further, the element may be sealed with mold resin, so that the mold resin portion may be disposed to cover the element.

The present disclosure can be applied not only to devices mounted on the surface of a wiring board but also to an element-embedded board (component-embedded board).

C. Method for Manufacturing a Wiring Board A method for manufacturing a wiring board according to the present disclosure includes wiring that forms a wiring layer including a pad portion on the first surface of a base material having a first surface and a second surface opposite to the first surface. A layer forming step, an insulating layer forming step of forming an insulating layer having a pad opening located on the pad portion on the first surface of the base material, and a surface of the insulating layer on the base material side. A conductive layer forming step of forming a conductive layer in a region other than the pad opening on the opposite surface, and forming a protective layer on a surface of the wiring layer opposite to the surface of the pad portion on the base material side. a protective layer forming step, wherein the conductive layer does not function as a wiring and is not grounded, and the insulating layer forming step includes forming the insulating layer having an overhang shape. In the conductive layer forming step and the protective layer forming step, the conductive layer and the protective layer are simultaneously formed using the same material by a dry film forming method.

FIGS. 5A to 5C are process diagrams illustrating an example of a method for manufacturing a wiring board according to the present disclosure. First, as shown in FIG. 5(a), the wiring layer 3 is formed on the first surface 2a of the base material 2. Next, as shown in FIG. 5(b), an insulating layer 4 having an overhang shape and having a pad opening 14 located above the pad portion 13 of the wiring layer 3 is formed on the first surface 2a of the base material 2. Form. Next, as shown in FIG. 5C, a conductive material is deposited on the pad portion 13 of the wiring layer 3 and the insulating layer 4 by sputtering or the like to form a conductive layer 5 on the insulating layer 4. A protective layer 6 is formed on the pad portion 13 of the wiring layer 3.

According to the present disclosure, the conductive layer is formed in a region other than the pad opening on the side of the insulating layer opposite to the base material side, and the conductive layer is disposed on the outermost surface of the wiring board. It is possible to suppress electrostatic damage from occurring when mounting elements on a wiring board.

Further, according to the present disclosure, the conductive layer is formed in a region other than the pad opening on the side of the insulating layer opposite to the base material side. Since no space is required, electrostatic damage can be suppressed with a simple configuration, and it can be manufactured using a simple process, and manufacturing costs can be reduced.

Further, in the present disclosure, the insulating layer has an overhang shape, so that the conductive layer and the protective layer are prevented from being connected to each other when the conductive layer and the protective layer are formed, and the conductive layer and the protective layer are electrically can be prevented from being connected to. Further, since there is no need to perform etching as in the case of photolithography, there is no etching residue, and a decrease in reliability due to etching residue can be avoided and reliability can be improved.

Further, according to the present disclosure, since the insulating layer has an overhang shape, when an element is mounted on the pad portion of the wiring board according to the present disclosure via the bonding member, the bonding member is attached to the overhang portion of the insulating layer. By being caught, it is possible to prevent the element from coming off.

Note that the method for forming each layer in each step was described in the section "A. Wiring board" above, so the explanation here will be omitted.

Note that the present disclosure is not limited to the above embodiments. The above-mentioned embodiments are illustrative, and any embodiment that has substantially the same configuration as the technical idea stated in the claims of the present disclosure and provides similar effects is the present invention. within the technical scope of the disclosure.

1... Wiring board 2... Base material 2a... First surface of base material 2b... Second surface of base material 3... Wiring layer 4... Insulating layer 5... Conductive layer 6... Protective layer 13... Pad portion 14... Pad opening 20 ... Mounting board 21 ... Element

Claims (9)

a base material having a first surface and a second surface opposite to the first surface;
a wiring layer disposed on the first surface side of the base material and including a pad portion;
an insulating layer disposed on the first surface side of the base material and having a pad opening located above the pad portion;
a conductive layer disposed in a region other than the pad opening on the side of the insulating layer opposite to the surface on the base material side;
has
further comprising a protective layer disposed on a surface of the pad portion of the wiring layer opposite to the surface on the base material side, the conductive layer and the protective layer are made of the same material;
A wiring board in which the conductive layer does not function as a wiring and is not grounded. 2. The conductive layer according to claim 1, wherein the conductive layer is disposed at an end of the wiring board in a region other than the pad opening on a side of the insulating layer opposite to the base material side. The wiring board described. 2. The conductive layer is disposed around the pad opening in a region other than the pad opening on a side of the insulating layer opposite to the base material side. The wiring board according to claim 2. Any one of claims 1 to 3, wherein the conductive layer is entirely disposed in a region other than the pad opening on a side of the insulating layer opposite to the base material side. A wiring board according to claim 1. The wiring board according to any one of claims 1 to 4, wherein the conductive layer is a metal film or a metal oxide film. The wiring board according to any one of claims 1 to 5, wherein the insulating layer has an overhang shape. a through wiring arranged in the through hole of the base material;
a second wiring layer disposed on the second surface side of the base material and including a second pad portion;
a second insulating layer disposed on the second surface side of the base material and having a second pad opening located above the second pad portion;
a second conductive layer disposed in a region other than the second pad opening on the side of the second insulating layer opposite to the surface on the base material side;
The wiring board according to any one of claims 1 to 6 , further comprising: the second conductive layer does not function as a wiring and is not grounded. A wiring board according to any one of claims 1 to 7 ,
an element mounted on a pad portion of the wiring board;
A mounting board with. a wiring layer forming step of forming a wiring layer including a pad portion on the first surface of a base material having a first surface and a second surface opposite to the first surface;
an insulating layer forming step of forming an insulating layer on the first surface of the base material, the insulating layer having a pad opening located above the pad portion;
a conductive layer forming step of forming a conductive layer in a region other than the pad opening on a surface of the insulating layer opposite to the base material side;
a protective layer forming step of forming a protective layer on a surface of the pad portion of the wiring layer opposite to the surface on the base material side;
A method for manufacturing a wiring board, comprising:
The conductive layer does not function as a wiring and is not grounded,
In the insulating layer forming step, forming the insulating layer having an overhang shape,
In the conductive layer forming step and the protective layer forming step, the conductive layer and the protective layer are simultaneously formed using the same material by a dry film forming method.

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