JP2023167333A - Manufacturing method of wiring board - Google Patents

Abstract

To provide a manufacturing method of a wiring board with high reliability.SOLUTION: A manufacturing method of a wiring board comprises the steps of: preparing a lamination body containing a first insulation layer 11 and a first conductive layer 12 containing a conductive pad 12a; forming a coated insulation layer 10 having an open 10a exposing an upper surface of the conductive pad 12a; forming a metal film layer 101 covering a whole region of an upper surface of the coated insulation layer 10 and an inner surface of the open 10a; forming a resist layer on the metal film layer 101; forming a resist open part exposing the upper surface of the metal film layer 101 to the resist layer; forming a plated film layer 102 in the resist open part; removing the resist layer; and forming a metal post 100 containing the metal film layer 101 and the plated film layer 102 by removing the metal film layer 101 exposed by removing the resist layer. The manufacturing method comprises a step of executing a process of removing a residue in the resist open part before the formation of the plated film layer 102.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing a wiring board.

Patent Document 1 discloses a method for manufacturing a board including metal posts connected to connection pads. In the method for manufacturing a substrate disclosed in Patent Document 1, a metal post is formed on a seed layer that covers an open portion of a solder resist layer that exposes the upper surface of a connection pad.

Japanese Patent Application Publication No. 2010-129996

In the substrate manufacturing method disclosed in Patent Document 1, the seed layer covering the inside of the open portion of the solder resist layer is formed by exposing and developing a photosensitive resist for forming metal posts provided over the entire area on the seed layer. exposed within the opening formed. Residues of the photosensitive resist may remain on the seed layer exposed in the opening, and it is thought that this may cause defective metal post formation.

A method for manufacturing a wiring board according to the present invention includes preparing a laminate including a first insulating layer and a first conductor layer formed on the first insulating layer and including conductor pads; forming a covering insulating layer having an opening that exposes the upper surface of the conductive pad; forming a metal film layer covering the entire upper surface of the covering insulating layer and the inner surface of the opening; forming a resist layer covering the layer, forming a resist opening in the resist layer to expose an upper surface of the metal film layer in the opening, and forming a plating film layer in the resist opening. and forming a metal post including the metal film layer and the plating film layer, removing the resist layer, and removing the metal film layer exposed by removing the resist layer. I'm here. The method includes performing a process of removing residue within the resist opening before forming the plating film layer.

According to embodiments of the present invention, a highly reliable method for manufacturing a wiring board can be provided in which a metal film layer and a plating film layer are in good contact with each other, and occurrence of defects in formed metal posts is suppressed. it is conceivable that.

FIG. 1 is a cross-sectional view showing an example of a wiring board manufactured by a method according to an embodiment of the present invention. 1 is a diagram showing an example of a manufacturing method according to an embodiment of the present invention. 1 is a diagram showing an example of a manufacturing method according to an embodiment of the present invention. 1 is a diagram showing an example of a manufacturing method according to an embodiment of the present invention. 1 is a diagram showing an example of a manufacturing method according to an embodiment of the present invention. 1 is a diagram showing an example of a manufacturing method according to an embodiment of the present invention. 1 is a diagram showing an example of a manufacturing method according to an embodiment of the present invention. 1 is a diagram showing an example of a manufacturing method according to an embodiment of the present invention. 1 is a diagram showing an example of a manufacturing method according to an embodiment of the present invention. 1 is a diagram showing an example of a manufacturing method according to an embodiment of the present invention. 1 is a diagram showing an example of a manufacturing method according to an embodiment of the present invention.

Next, a wiring board manufactured by a wiring board manufacturing method according to an embodiment of the present invention will be described with reference to the drawings. Note that the drawings referred to hereinafter are not intended to show exact proportions of each component, but are drawn so that the features of the present embodiment can be easily understood. FIG. 1 partially shows a cross section of a wiring board 1, which is an example of the wiring board of this embodiment. The wiring board 1 is formed of insulating layers and conductor layers that are alternately laminated, and FIG. 1 shows some of the insulating layers 10 and 11 and the conductor layer 12. One surface F of the illustrated wiring board 1 may be a component mounting surface on which external electronic components such as semiconductor elements are mounted.

One surface F of the wiring board 1 shown in FIG. 1 fills the insulating cover layer 10 and the opening 10a formed in the insulating cover layer 10, and protrudes from the insulating cover layer 10 to the outside of the wiring board 1. It is made up of the surfaces (upper surface and side surfaces) of a metal post 100 having a shape of .

In FIG. 1, among the plurality of insulating layers 11 and conductive layers 12 that the wiring board 1 may have, three insulating layers 11 and three conductive layers 12 on one surface F side are illustrated. The wiring board of the embodiment has one or more insulating layers 11 and one or more conductor layers 12, and the insulating layer 11 and the conductor layer 12 closest to one surface F are A covering insulating layer 10 is formed. The number of insulating layers 11 and conductor layers 12 that wiring board 1 has is not particularly limited, and can be increased or decreased as appropriate. Note that the insulating layer 11 closest to one surface F is also referred to as a first insulating layer 11, and the conductor layer 12 closest to one surface F is also referred to as a first conductor layer 12.

In the description of the wiring board of the embodiment, one surface F side in the thickness direction of the wiring board of each component constituting the wiring board is referred to as "upper side", "outside", or simply "upper" or "outer". The opposite side of one surface F is referred to as the "lower side", "inside", or simply "lower" or "inner". Therefore, the surface of each component on the side of one surface F is also referred to as the "upper surface", and the surface facing opposite to the one surface F is also referred to as the "lower surface".

The conductor layer 12 has an arbitrary conductor pattern. The conductor layer 12 can be electrically connected to the conductor layer 12 on the opposite side of the insulating layer 11 via a via conductor 13 formed to penetrate the insulating layer 11 .

The uppermost conductor layer 12 (closest to one surface F) among the three illustrated conductor layers 12 is formed in a pattern including conductor pads 12a. The conductor pad 12a can be electrically connected to a connection pad of an external electronic component such as a semiconductor element via a metal post 100 formed thereon. That is, the conductor pad 12a may be a component mounting pad.

As illustrated, a recess may be formed in the portion of the conductor pad 12a exposed within the opening 10a. By forming the recess on the upper surface of the conductor pad 12a, the bonding surface between the metal post 100 (specifically, the first layer 101) and the conductor pad 12a is made relatively large, and the connection between the conductor pad 12a and the metal post 100 is made relatively large. A stronger bond may be achieved.

The metal post 100 has a first layer 101 and a second layer 102 formed on the first layer 101. The first layer 101 forming the metal post 100 covers the inner surface of the opening 10a. Specifically, the first layer 101 covers the upper surface of the conductive pad 12a exposed at the bottom of the opening 10a formed in the covering insulating layer 10 and the inner wall surface (side wall surface) of the opening 10a. In the illustrated example, the first layer 101 further covers the upper surface of the covering insulating layer 10 at the peripheral portion of the opening 10a. The second layer 102 covers the entire upper surface of the first layer 101. In the illustrated example, the metal post 100 further includes a third layer 103 covering the entire upper surface of the second layer 102 and a fourth layer 104 covering the entire upper surface of the third layer 103 on the upper side of the second layer 102. have.

The insulating layer 11 constituting the wiring board 1 may be formed using any insulating resin such as epoxy resin. Polyimide resins, BT resins (bismaleimide-triazine resins), polyphenylene ether resins, phenol resins, etc. may also be used. The insulating layer 11 may contain an inorganic filler such as silica. In the illustrated example of the wiring board 1, the insulating layer 11 does not include a core material, but may include a core material such as glass fiber or aramid fiber as necessary. By including the core material, the strength of the wiring board 1 can be improved. The plurality of insulating layers 11 may be made of different materials, or may be made of the same material.

Conductor layer 12 may be formed using any suitable electrically conductive material, such as copper or nickel. The conductor layer 12 is formed of, for example, an electrolytic plated film (preferably an electrolytic copper plated film), an electroless plated film (preferably an electroless copper plated film), or a combination thereof, and preferably, as shown in the figure, It is formed with a two-layer structure of an electroless plated film layer 121 and an electrolytic plated film layer 122. However, the configuration of each conductor layer 12 constituting wiring board 1 is not limited to the multilayer structure illustrated in FIG. 1 . For example, it may have a three-layer structure of a metal foil, an electroless plated film layer, and an electrolytic plated film layer. Further, it may have a single-layer structure of an electroless plated film layer or an electrolytic plated film layer.

As shown in FIG. 1, the via conductor 13 may be formed integrally with the electroless plated film layer 121 and the electrolytic plated film layer 122 that constitute the conductor layer 12. In the illustrated example, the via conductor 13 is a so-called filled via that fills the conductive hole 13a formed in the insulating layer 11, and is coated with an electroless plated film 121 and electrolytic plated film 121 that covers the bottom surface and inner wall surface of the conductive hole 13a. It is composed of a membrane 122.

The insulating cover layer 10 is formed using any insulating resin material. The covering insulating layer 10 may be formed using, for example, photosensitive polyimide resin, epoxy resin, or the like. The covering insulating layer 10 covers the edge of the conductive pad 12a, the side surface of the metal post 100 formed on the conductive pad 12a, and the upper surface of the insulating layer 11 exposed between the patterns of the conductive layer 12 including the conductive pad 12a. is covered. Covering insulating layer 10 may be a solder resist layer.

The first layer 101 constituting the metal post 100 may be a metal film layer containing any conductive metal such as copper or nickel. The first layer 101 may be an electroless plated film layer. The first layer 101 may include a sputtered film layer. In the illustrated example, the opening 10a filled with the metal post 100 is formed in a shape whose diameter decreases from the upper side of the insulating cover layer 10 toward the conductor pad 12a, but the opening 10a is not limited to this shape. It may also be formed into a substantially cylindrical shape having the same diameter in the thickness direction of the covering insulating layer 10 .

The second layer 102 constituting the metal post 100 may be a plating film layer containing any conductive metal. The second layer 102 may be an electroplated film layer formed using the first layer 101 as a power supply layer, as will be described later regarding the method for manufacturing a wiring board. The second layer 102 may be formed, for example, as an electrolytic copper plating layer. The third layer 103 formed on the upper surface of the second layer 102 may be, for example, a nickel plating layer. The fourth layer 104 formed on the upper surface of the third layer 103 may be, for example, a tin plating layer.

In the wiring board manufactured by the manufacturing method of the embodiment, foreign matter that may be present between the first layer 101 and the second layer 102 is removed, as will be described in detail later regarding the manufacturing method. The adhesion between the layer 101 and the second layer 102 is relatively excellent. Specifically, in forming the second layer 102, which may be an electroplated film layer, the amount of foreign matter (for example, resist residue) remaining at the interface between the first layer 101 and the second layer 102 is relatively small, and therefore, The first layer 101 and the second layer 102 are formed with good adhesion.

A method for manufacturing the wiring board 1 shown in FIG. 1 will be described below with reference to FIGS. 2A to 2J. 2A to 2J, similarly to FIG. 1, the entire wiring board is not shown, and only a partial cross section of the wiring board 1 on the side where the metal post 100 is formed is shown. Note that in the following description of the method for manufacturing the wiring board 1, similarly to the above description of the wiring board 1, in each element constituting the wiring board 1, one surface F of the wiring board 1 (see FIG. 1) is used. The side on which it is formed is referred to as the "upper", "upper side", "outer", or simply "outer".

First, a laminate in which the lamination of the outermost conductor layer 12 has been completed is prepared, for example, by a general wiring board manufacturing method using a build-up method. FIG. 2A shows that the build-up method has completed the stacking of an insulating layer (first insulating layer) 11 and a conductor layer (first conductor layer) 12 that is in contact with the first insulating layer 11 and includes a conductor pad 12a. A laminate 1p is shown.

Next, as shown in FIG. 2B, the covering insulating layer 10 is formed on the insulating layer 11 exposed from the conductor pad 12a and the conductor pattern of the conductor layer 12 including the conductor pad 12a. The insulating cover layer 10 is made of, for example, an insulating resin including photosensitive epoxy resin or polyimide resin. For example, the covering insulating layer 10, which is a solder resist layer, can be formed by forming a photosensitive epoxy resin film by spray coating, curtain coating, film adhesion, or the like.

Openings 10a are formed in the covering insulating layer 10 to expose conductor pads 12a, corresponding to positions where metal posts 100 (see FIG. 1) are to be formed. The opening 10a may be formed, for example, by exposure and development using a mask having an opening pattern corresponding to the position where the metal post 100 is to be formed.

After the opening 10a is formed in the covering insulating layer 10, the inner surface of the opening 10a may be subjected to a soft etching process using, for example, an etching solution containing an oxidizing agent such as persulfate or hydrogen peroxide. By this soft etching process, as shown in the figure, a concave portion may be formed in the conductor pad 12a exposed within the opening 10a, recessed in a direction in which the thickness of the conductor pad 12a decreases. By forming the recess on the upper surface of the conductor pad 12a, the bonding surface between the metal post 100 and the conductor pad 12a that is subsequently formed on the conductor pad 12a is made relatively large, and the contact surface between the conductor pad 12a and the metal post 100 is made relatively large. A stronger bond may be achieved.

Subsequently, as shown in FIG. 2C, the entire inner surface of the opening 10a (the upper surface of the conductor pad 12a and the inner wall surface of the opening 10a) and the upper surface of the covering insulating layer 10 is coated, for example, by electroless plating. A metal film layer (first layer) 101, which is, for example, an electroless copper plating film layer, is formed. The first layer 101, which is a metal film layer, may be formed by sputtering using a target containing copper, for example.

Next, as shown in FIG. 2D, a plating resist 101r for electrolytic plating is formed on the first layer 101. Specifically, for example, a photosensitive polyhydroxy ether resin is applied so as to cover the entire area on the first layer 101, including the area inside the opening 10a of the insulating cover layer 10 and the upper side of the upper surface of the insulating cover layer 10. A plating resist containing, for example, epoxy resin, phenolic resin, or polyimide resin is formed over the entire area by, for example, spray coating or film attachment.

Next, as shown in FIG. 2E, resist openings 101ro are formed in the plating resist 101r by, for example, exposing and developing the plating resist 101r using a mask having an appropriate opening pattern. The resist opening 101ro may be formed using a mask having an opening pattern corresponding to the arrangement pattern that the metal post 100 (see FIG. 1) that forms one surface of the wiring board 1 should have. The formed resist opening 101ro is formed so as to include inside thereof the entire area of the opening 10a formed in the insulating cover layer 10, as well as a portion of the upper surface of the insulating cover layer 10 at the periphery of the opening 10a. obtain.

In forming the resist opening 101ro, residues (scum) of the resist 101r from the development process of the resist 101r may remain in the resist opening. Specifically, as illustrated, the residue 101rs may adhere to the first layer 101 exposed inside the resist opening 101ro and to the inner wall surface of the resist opening 101ro made of the resist 101r. . If the second layer 102 (see FIG. 1) is formed on the first layer 101 with these residues 101rs remaining in the opening 10a, the residues will remain at the interface between the first layer 101 and the second layer 102. 101rs may be present, resulting in poor bonding.

In the wiring board manufacturing method of this embodiment, a process (descum process) for removing the residue 101rs is performed on the inner surface of the resist opening 101ro. The process for removing the residue 101rs can be performed by a dry process using oxygen plasma or CF4 (carbon tetrafluoride) plasma, or a wet process using a chemical solution. By performing this process, the residue 101rs in the resist opening 101ro is removed, resulting in the state shown in FIG. 2F.

When oxygen plasma is used for the descum treatment, irradiation treatment with argon-oxygen mixed plasma or fluorocarbon-oxygen mixed plasma may be performed depending on the amount of residue 101rs present.

Further, when the descum treatment is performed by a wet process, a chemical solution (acid solution) containing an oxidizing agent such as manganic acid peroxide or sulfuric acid may be used as the residue removing solution. Chemical solutions containing photoacid generators (PAGs) or thermal acid generators (TAGs) may also be used. These chemical solutions are sprayed by a spray nozzle into a range including the resist opening 101ro, and the residue 101rs is decomposed by reaction with the chemical solution. After the residue 101rs is decomposed, the residue 101rs inside the resist opening 101ro can be removed by cleaning with a rinsing liquid containing an alkaline aqueous solution, for example.

Subsequently, a plating film layer (second layer) 102 is formed within the resist opening 101ro. By electrolytic plating using the first layer 101 as a power supply layer, an electroplated film layer can be formed as the second layer 102 within the resist opening 101ro. A second layer, which is, for example, an electrolytic copper plating film, is placed on the power supply layer (on the first layer 101) inside the resist opening 101ro, including the inside of the opening 10a of the insulation coating layer 10 and the upper side of the top surface of the insulation coating layer 10. 102 is formed.

By performing the above-described descum treatment on the inner surface of the resist opening 101ro, the second layer 102 can be formed on the first layer 101 with relatively good adhesion. It is considered that bonding defects at the interface between the first layer 101 and the second layer 102 are suppressed. The thickness of the second layer 102 can be adjusted by appropriately adjusting the conditions (temperature, current density, plating time, etc.) of electrolytic plating using the first layer 101 as a power supply layer.

Next, as shown in FIG. 2H, a third layer 103 on the second layer 102 and a fourth layer 104 on the third layer 103 are formed. The third layer 103 may be formed as a nickel plating layer that directly covers the second layer 102 using, for example, a nickel plating solution containing nickel as a main component. The fourth layer 104 may be formed as a tin plating layer covering the third layer 103 using, for example, a tin plating solution containing tin as a main component.

The fourth layer 104 may be made of, for example, a metal that has a lower melting point than the second layer 102 and can be melted and formed into a hemispherical shape by reflow processing. The fourth layer 104 may be formed by filling a solder paste containing, for example, tin, silver, and copper. The fourth layer 104 is subjected to a reflow treatment after lamination, thereby forming an alloy layer between the third layer 103 and the fourth layer 104, and joining the third layer 103 and the fourth layer 104. As illustrated, the fourth layer 104 can be formed into a hemispherical shape through this reflow process.

Next, the plating resist 101r is removed, and the first layer 101 on the covering insulating layer 10 is exposed, as shown in FIG. 2I.

Next, the exposed first layer 101 on the insulating cover layer 10 is removed by etching, and as shown in FIG. 2J, the insulating cover layer 10 is exposed and the formation of the metal post 100 is completed. Formation of wiring board 1 is completed.

The method of manufacturing the wiring board of the embodiment is not limited to the method described with reference to each drawing, and the conditions, order, etc. may be changed as appropriate. In the method for manufacturing the wiring board of the embodiment, at least before the second layer 102 is formed, it is sufficient that the inner surface of the resist opening 101ro of the plating resist 101r is subjected to a process for removing a residue, and the wiring board is actually manufactured. Depending on the structure of the wiring board, some steps may be omitted or other steps may be added. For example, the opening 10a in the insulating cover layer 10 may be formed by partially removing the insulating cover layer 10 using a UV laser.

1 Wiring board 10 Covering insulating layer 11 Insulating layer 12 Conductor layer 12a Conductor pad 100 Metal post 101 First layer (metal film layer)
102 Second layer (plated film layer)
103 Third layer 104 Fourth layer 10a Opening 101r Plating resist 101ro Resist opening 101rs Residue

Claims (7)

preparing a laminate including a first insulating layer and a first conductor layer formed on the first insulating layer and including conductor pads;
forming an insulating covering layer on the first conductor layer having an opening that exposes the upper surface of the conductor pad;
forming a metal film layer covering the entire upper surface of the covering insulating layer and the inner surface of the opening;
forming a resist layer covering the metal film layer;
forming a resist opening in the resist layer that exposes the upper surface of the metal film layer within the opening;
forming a plating film layer within the resist opening, and forming a metal post including the metal film layer and the plating film layer;
removing the resist layer;
removing the metal film layer exposed by removing the resist layer;
A method for manufacturing a wiring board, the method comprising:
The method includes performing a process of removing residue within the resist opening before forming the plating film layer. 2. The method of manufacturing a wiring board according to claim 1, wherein oxygen plasma is used in the treatment for removing the residue. 2. The method of manufacturing a wiring board according to claim 1, wherein a residue removing liquid is used in the treatment for removing the residue. 2. The method of manufacturing a wiring board according to claim 1, wherein forming the metal film layer includes electroless copper plating. 2. The method of manufacturing a wiring board according to claim 1, wherein forming the plating film layer includes electrolytic copper plating using the metal film layer as a power supply layer. 6. The method for manufacturing a wiring board according to claim 5, further comprising forming a nickel plating layer on the plating film layer after forming the plating film layer, and forming a tin plating layer on the nickel plating layer. It includes even more. 7. The method of manufacturing a wiring board according to claim 6, further comprising molding the tin plating layer by a reflow process.

Images