TW201519719A - Wiring board and method for manufacturing same - Google Patents

Abstract

To provide a wiring board applicable to micro-miniaturization of wiring, and a method for manufacturing the wiring board. A wiring board (1) is configured by laminating a resin insulating layer (20) and a conductor layer (33). The conductor layer (33) includes wiring (36) having a width equal to or less than 5 [mu]m, and the wiring (36) is formed on a resin insulating layer (20) surface having a maximum height (Rz) of less than 1.0 [mu]m.

Description

Wiring substrate and method of manufacturing same

The present invention relates to a wiring board in which a resin insulating layer and a conductor layer are laminated, and a method of manufacturing the same.

In recent years, with the miniaturization of electrical equipment and the like, wiring boards and the like to be mounted on such devices have been required to be downsized and increased in density. As this wiring board, a wiring board manufactured by an extension method in which a plurality of layers of a resin insulating layer and a plurality of layer conductor layers are alternately laminated is put into practical use. Further, in such a wiring board, in order to improve the adhesion between the conductor layer formed by the semi-additive process and the resin insulating layer on the resin insulating layer, the surface of the resin insulating layer which has been roughened is used. The conductor layer is also put into practical use. (For example, refer to Patent Document 1).

In the general semi-additive method, a conductor layer composed of an electroless copper plating layer and an electrolytic copper plating layer is formed by sequentially performing the following steps, that is, sequentially: roughening the surface of the resin insulating layer a step of forming an electroless copper plating layer on the entire surface of the roughened resin insulating layer, a step of forming a photosensitive dry film resist on the electroless copper plating layer, and a dry film resistance by performing exposure development The step of forming an opening of a predetermined pattern, the step of forming an electrolytic copper plating layer in the opening of the dry film resist, the step of removing the dry film resist, and removing the electroless copper plating exposed by removing the dry film resist by etching The steps of the layer.

Prior technical literature Patent literature

Patent Document 1 Japanese Patent Laid-Open Publication No. 2005-150553

However, in order to miniaturize the wiring constituting the conductor layer in response to the demand for miniaturization and high density of the wiring board, there is a problem that the adhesion strength between the resin insulating layer and the fine wiring in which the surface is roughened cannot be sufficiently ensured. . Specifically, as shown in FIG. 9, in the wiring substrate in which the electroless copper-plated layer 61 and the electrolytic copper-plated layer 62 are formed on the resin insulating layer 60 whose surface has been roughened, unnecessary etching is removed by etching. When the copper plating layer 61 is electrolytically plated, the electroless copper plating layer 61 directly under the electrolytic copper plating layer 62 is partially etched, that is, an undercut is formed. As a result, as shown in the wiring board 10 shown in FIG. 10, the contact area between the wiring 66 composed of the electroless copper plating layer 61 and the electrolytic copper plating layer 62 and the resin insulating layer 60 cannot be sufficiently ensured, resulting in wiring. The problem of peeling off from the resin insulating layer 60 is 66.

In order to suppress the undercut of the wiring, there is also a countermeasure for shortening the etching treatment time of the electroless plating layer. However, in the case where the depth of the surface of the roughened resin insulating layer is large, if the etching treatment time is too short, as shown in FIG. 11, there is a recess in the surface of the roughened resin insulating layer 60. The electroless copper plating layer 61 to be removed, and the plurality of adjacent wirings 66 are caused to be short-circuited by the electroless copper plating layer 61 remaining on the surface of the resin insulating layer 60.

The present invention has been made to solve the above problems, and an object thereof is to provide a wiring board which can be made fine in accordance with wiring constituting a conductor layer, and a method of manufacturing the same.

A means for solving the above-mentioned problems (method 1) is a wiring board in which a resin insulating layer and a conductor layer are laminated, wherein the conductor layer includes a wiring having a width of 5 μm or less, and the maximum height Rz is less than 1.0. Wiring is formed on the surface of the aforementioned resin insulating layer of μm.

According to the invention of the first aspect, since the maximum height Rz of the surface of the resin insulating layer is less than 1.0 μm, wiring capable of suppressing undercut formation can be formed, and thus the contact area between the resin insulating layer and the wiring can be ensured. Therefore, in the case of forming fine wiring having a width of 5 μm or less, peeling of the wiring can be prevented.

In addition, a means for producing a wiring board in which a resin insulating layer and a conductor layer are laminated is provided, and the first metal layer forming step is performed in the order described above. a first metal layer is formed on the surface of the resin insulating layer; a resin film is disposed on the first metal layer; an opening forming step forms an opening in the resin film; and a second metal layer forming step is performed on the resin film The second metal layer is formed by electrolytic plating on the first metal layer exposed; the resin film removing step removes the resin film; and the conductor layer forming step is performed by exposing the resin film The metal layer is removed by etching to form the conductor layer composed of the first metal layer and the second metal layer; In the first metal layer forming step, the first metal layer is formed on the surface of the resin insulating layer having a maximum height Rz of less than 1.0 μm, and the conductor including the wiring having a width of 5 μm or less is formed in the conductor layer forming step. Floor.

According to the invention of the second aspect, since the first metal layer and the second metal layer are formed on the surface of the resin insulating layer having a maximum height Rz of less than 1.0 μm, the first metal layer can be prevented from being excessively etched in the conductor layer forming step. The formation of the undercut. Therefore, it is possible to ensure a sufficient contact area between the resin insulating layer and the wiring, and to prevent peeling of the wiring when forming a fine wiring having a width of 5 μm or less.

1, 10‧‧‧ wiring substrate

20, 40, 60‧‧‧ resin insulation

31, 61‧‧‧ Electroless copper plating

32, 62‧‧‧ electrolytic copper plating

33‧‧‧Conductor layer

34‧‧‧through holes

35‧‧‧ Path conductor

36, 46, 66‧‧‧ wiring

DF‧‧ resin film (dry film resist)

41‧‧‧metal foil

50‧‧‧ openings

W1‧‧‧Width

H1, H2‧‧‧ height

Fig. 1 is a cross-sectional view showing a schematic configuration of a wiring board of the present embodiment.

Fig. 2 is an explanatory view showing a method of manufacturing the wiring board of the embodiment.

Fig. 3 is an explanatory view showing a method of manufacturing the wiring board of the embodiment.

Fig. 4 is an explanatory view showing a method of manufacturing the wiring board of the embodiment.

Fig. 5 is an explanatory view showing a method of manufacturing the wiring board of the present embodiment.

Fig. 6 is an explanatory view showing a method of manufacturing the wiring board of the embodiment.

Fig. 7 is an explanatory view showing a method of manufacturing a wiring board of another embodiment.

Fig. 8 is an explanatory view showing a method of manufacturing a wiring board of another embodiment.

FIG. 9 is an explanatory view showing a method of manufacturing a conventional wiring board.

FIG. 10 is an explanatory view showing a method of manufacturing a conventional wiring board.

FIG. 11 is an explanatory view showing a method of manufacturing a conventional wiring board.

Hereinafter, an embodiment in which the present invention is embodied as a wiring board will be described in detail with reference to FIGS. 1 to 6. Fig. 1 is a cross-sectional view showing a schematic configuration of a wiring board 1 of the present embodiment.

As shown in FIG. 1, the wiring board 1 of this embodiment has a resin insulating layer 20 and a conductor layer 33 laminated on the resin insulating layer 20. The resin insulating layer 20 is made of a thermosetting resin such as an epoxy resin, and the maximum height Rz of the surface of the resin insulating layer 20 is less than 1.0 μm. In addition, the maximum height Rz in this specification is defined by the specification of JIS B0601 (2001).

The conductor layer 33 is mainly composed of copper, and is composed of an electroless copper plating layer 31 (first metal layer) formed on the surface of the resin insulating layer 20 and an electrolytic copper plating layer formed on the electroless copper plating layer 31. 32 (second metal layer). Further, the conductor layer 33 has a plurality of wires 36 electrically independent of each other, and the wiring 36 has a width of 5 μm or less.

The width of the wiring 36 in the present specification means the width W1 of the position at the half height H2 of the height H1 of the upper end when the lower end of the wiring 36 that is in contact with the resin insulating layer 20 is used as a reference.

Next, a method of manufacturing the wiring board 1 of the present embodiment will be described with reference to FIGS. 2 to 6 .

First, a resin insulating layer 20 having a thickness of about 30 μm made of a thermosetting resin such as an epoxy resin is prepared. Then, the surface of the resin insulating layer 20 is roughened by an etching liquid such as potassium permanganate so as to have a maximum height Rz of the surface of less than 1.0 μm.

Thereafter, an electroless copper plating treatment is performed on the entire surface of the resin insulating layer 20, and an electroless copper plating layer 31 (first metal layer) is formed on the resin insulating layer 20. (Refer to Figure 2)

Then, as shown in FIG. 3, a photosensitive dry film resist DF (resin film) is attached to the electroless copper plating layer 31, and exposure and development of the dry film resist DF are performed. By this exposure development, an opening 50 corresponding to the shape of the wiring 36 to be formed is formed in the dry film resist DF. (Refer to Figure 4)

Further, the opening 50 can also be formed by laser processing of a dry film resist DF (resin film).

After the dry film resist DF is exposed and developed, electrolytic copper plating is performed to form an electrolytic copper plating layer 32 (second metal layer) on the electroless copper plating layer 31 exposed from the opening 50. (Refer to Figure 5)

After the electrolytic copper plating layer 32 is formed, the dry film resist DF is removed as shown in FIG. Then, by removing the dry film resist DF, the electroless copper plating layer 31 exposed on the surface is removed by etching using a well-known etching liquid until the surface of the resin insulating layer 20 is exposed. The wiring substrate 1 shown in FIG. 1 is manufactured through the above steps.

Therefore, according to this embodiment, the following effects can be obtained.

In the wiring substrate 1 of the present embodiment, since it is the most Since the conductor layer 33 composed of the electroless copper plating layer 31 and the electrolytic copper plating layer 32 is formed on the surface of the resin insulating layer 20 having a large height Rz of less than 1.0 μm, it is difficult to form the wiring 36 having a width of 5 μm or less. The wiring 36 is formed as an undercut, and it is ensured that the adhesion area of the resin insulating layer 20 and the wiring 36 is sufficient. Therefore, the wiring 36 can be prevented from being peeled off from the resin insulating layer 20.

In this embodiment, because the system is not full at the maximum height Rz The surface of the resin insulating layer 20 of 1.0 μm is formed with the electroless copper plating layer 31. Therefore, even if the unnecessary electroless copper plating layer 31 is completely removed by etching in the conductor layer forming step, it is difficult to form an undercut in the wiring 36, and The wiring 36 is prevented from being peeled off from the resin insulating layer 20.

<Example>

Next, an embodiment performed to confirm the effect of the present embodiment will be described.

In the present embodiment, the description is made according to FIGS. 1 to 6 In the A to F samples in which the surface roughness (arithmetic mean roughness Ra and maximum height Rz) of the resin insulating layer 20 in the wiring board 1 are different, a plurality of types of wirings 36 having different widths are formed for each sample, and it is confirmed whether or not the wiring 36 is peeled off. , the confirmation results are shown in Table 1.

Moreover, the surface roughness of the resin insulating layer 20 is controlled by changing the time of roughening treatment using an etching liquid.

As shown in Table 1, it can be confirmed that the use within the scope of the present invention The samples D and E of the resin insulating layer may be in close contact with the resin insulating layer after forming wiring having a width of 5 μm. On the other hand, it was confirmed that the samples A, B, and C outside the range of the present invention were peeled off from the resin insulating layer after the wiring having a width of 5 μm was formed.

Further, the embodiment of the present invention can be modified as follows.

In the above-described embodiment, the wiring board 1 is formed by laminating the resin insulating layer 20 and the conductor layer 33 one by one. However, a wiring board in which a plurality of resin insulating layers and a plurality of conductor layers are laminated to each other may be used.

For example, in the case of manufacturing a wiring board in which a plurality of layers of a resin insulating layer and a conductor layer are laminated, as shown in FIG. The resin insulating layer 40 on which the metal foil 41 such as copper foil is formed in advance is laminated on the resin insulating layer 20 on which the conductor layer 33 has been formed. In this case, the conductor layer can be formed on the surface of the resin insulating layer 40 in the following steps. First, laser processing is performed in a state where the surface of the resin insulating layer 40 after lamination is provided with the metal foil 41, whereby the through hole 34 penetrating the metal foil 41 and the resin insulating layer 40 and exposing the conductor layer 33 is formed. Next, after the metal foil 41 is provided on the surface of the resin insulating layer 40, the desmear process for removing the stain in the through hole 34 is performed, and then the metal foil 41 is removed by etching. Then, after removing the metal foil 41, by performing the same electroless copper plating and electrolytic copper plating as the conductor layer 33, as shown in FIG. 8, the via conductor 35 formed by filling the through hole can be manufactured. A wiring board 1' of the conductor layer 39 composed of the electroless copper plating layer 37 and the electrolytic copper plating layer 38.

Moreover, the manufacture of the wiring board using the metal foil 41 mentioned above In the method, the resin insulating layer 40 exposed on the surface is roughened by performing a desmutting treatment. However, since the region where the wiring 46 is formed in the surface of the resin insulating layer 40 is covered by the metal foil 41, the surface of the resin insulating layer 40 is not unnecessarily roughened. Therefore, the wiring board 1' thus manufactured has a feature that the maximum height Rz of the wall surface of the through hole 34 of the resin insulating layer 40 roughened by the desmear process is larger than the maximum height Rz of the surface of the resin insulating layer 40.

In the above embodiment, although formed by electroless copper plating The electroless copper plating layer 31 (first metal layer) is not limited, and the method of forming the first metal layer may be formed by a sputtering method or a CVD method.

1‧‧‧Wiring substrate

20‧‧‧Resin insulation

31‧‧‧1st metal layer

32‧‧‧2nd metal layer

33‧‧‧Conductor layer

36‧‧‧Wiring

W1‧‧‧Width

H1, H2‧‧‧ height

Claims (2)

A wiring board in which a wiring resin layer and a conductor layer are laminated, wherein the conductor layer includes a wiring having a width of 5 μm or less, and the surface of the resin insulating layer having a maximum height Rz of less than 1.0 μm is formed. Wiring. A method for producing a wiring board, comprising: a method of manufacturing a wiring board formed by laminating a resin insulating layer and a conductor layer, wherein the first metal layer forming step sequentially forms a first metal on a surface of the resin insulating layer a resin film arranging step of disposing a resin film on the first metal layer; an opening forming step of forming an opening in the resin film; and a second metal layer forming step of exposing the first metal layer from an opening of the resin film Forming a second metal layer by electrolytic plating; removing the resin film by a resin film removing step; and forming a conductor layer, and removing the first metal layer exposed by the removal of the resin film by etching Forming the conductor layer composed of the first metal layer and the second metal layer; and forming the first metal layer on the surface of the resin insulating layer having a maximum height Rz of less than 1.0 μm in the first metal layer forming step; In the conductor layer forming step, the conductor layer including a wiring having a width of 5 μm or less is formed.