TW201911992A - Method for manufacturing multilayer printed wiring board and multilayer printed wiring board - Google Patents

Abstract

Provided are a method of manufacturing a multilayer printed wiring board and a multilayer printed wiring board to prevent the accumulation of positional deviations of wiring patterns in each layer, and to improve the positional accuracy of the wiring patterns in each layer. A method of manufacturing a multilayer printed wiring board according to an embodiment of the present invention includes the steps of: patterning a metal foil 12 of a metal foil-clad laminate 10 to form a target mark 14 having an alignment hole 14a; laminating the metal foil-clad laminate 20 on the metal foil-clad laminate 10 such that the alignment hole 14a is located in the through-holes 24 of the metal foil-clad laminate 20 as viewed from the thickness direction; laminating the metal foil-clad laminate 30 on the metal foil-clad laminate 10 such that the alignment hole 14a is located in the through-holes 34 of the metal foil-clad laminate 30 as viewed from the thickness direction; and forming the wiring patterns 25 and 35 by patterning the metal foil 22 and the metal foil 32 based on the alignment hole 14a as the reference.

Description

   Method for manufacturing multilayer printed wiring board and multilayer printed wiring board   

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

Conventionally, in response to a demand for higher density of printed wiring boards, a multilayer printed wiring board in which a plurality of printed wiring boards are laminated has been developed. As one of the multilayer printed wiring boards, Patent Document 1 describes a hybrid multilayer circuit board. The multilayer printed wiring board includes a multilayer flexible printed wiring board (multilayer FPC) having flexibility.

The conductive pattern of each layer of the multilayer printed wiring board is formed using a well-known photofabrication method. That is, after the photoresist layer is formed on the copper foil of the copper-clad laminate, the exposure mask (photomask) on which the pattern is drawn is aligned on the photoresist layer and arranged. Then, the photoresist layer is irradiated with light through an exposure mask, and then developed to form an etching mask. Then, the copper foil is etched by using an etching mask to form a conductive pattern. In the formation of the conductive pattern, it is important to improve the positional accuracy between the conductive patterns of the respective layers. By improving the positional accuracy of the conductive pattern, for example, the land of the interlayer connection portion can be reduced in diameter.

Patent Document 2 describes the manufacture of a multilayer printed wiring board in which an object for positioning is provided on the inner layer and positioning is performed with laser processing to expose it to obtain positional alignment data for through-hole formation processing. method. In this method, because the target is exposed, the target can be clearly identified for positioning, and the positioning accuracy is high

[Prior technical literature]

[Patent Literature]

Patent Document 1: Japanese Patent No. 2631287.

Patent Document 2: Japanese Patent Laid-Open No. 10-256737.

However, with the progress of miniaturization and high density of electronic equipment using multilayer printed wiring boards, in recent years, it has been required to reduce the distance between the end face of a multilayer printed wiring board and a wiring pattern.

For example, a multi-layer flexible printed wiring board having a very narrow cable-like shape and having a plurality of wiring patterns at the same horizontal position in each layer is required. In this case, it is necessary to improve the positional accuracy of the wiring pattern of each layer so that the wiring pattern of each layer is not exposed on the side end surfaces of the multilayer flexible printed wiring board during the outline processing.

The exposure step for forming the wiring pattern of each layer has been conventionally performed as described in Patent Document 2 by using a target mark formed simultaneously with the wiring pattern closest to the inner side of the copper foil being processed to align the exposure mask position. . That is, a wiring pattern is formed using a target mark located on an inner layer side of a processed conductive film as a reference.

However, this method has a problem that the positional deviation of the wiring pattern accumulates as the multilayering progresses. That is, in the conventional method, it is necessary to estimate the positional accuracy at the time of exposure x the positional deviation of the number of exposures. For example, in the case where the alignment accuracy (the placement accuracy of the exposure mask) is ± 10 μm when the wiring of each layer is patterned, and the 6-layer multilayer printed wiring board is manufactured by a total of 5 exposures, the positional deviation of the wiring pattern must be Estimated ± 50 μm. If the estimated value is smaller than this value, the yield rate may decrease. If the external shape processing accuracy using laser light is set to, for example, ± 25 μm, only the external shape processing end can be brought closer to 75 μm from the wiring pattern.

Therefore, an object of the present invention is to provide a method for manufacturing a multilayer printed wiring board and a multilayer printed wiring board, which can prevent the accumulation of positional deviations of the wiring patterns of the respective layers and improve the positional accuracy of the wiring patterns of the respective layers.

The method for manufacturing a multilayer printed wiring board according to the present invention includes the steps of preparing a first metal foil-clad laminate, the first metal foil-clad laminate having a first main surface and an opposite side to the first main surface. A core substrate on the second main surface of the side and a first metal foil formed on the first main surface; a step of patterning the first metal foil to form a target mark with positioning holes; preparing a second metal foil stack In the step of laminating, the second metal foil-clad laminate includes a first composite substrate having a third main surface and a fourth main surface opposite to the third main surface, and a first base material formed on the third main surface. A second metal foil; a step of forming a first through hole penetrating the second metal foil-clad laminate in a thickness direction; a step of preparing a third metal foil-clad laminate, the third metal-clad laminate includes: A second composite substrate having a fifth main surface and a sixth main surface opposite to the fifth main surface; and a third metal foil formed on the fifth main surface; forming a third coating penetrating the third cover in a thickness direction; Second penetration of metal foil laminate Step of making holes; the second metal foil-clad laminate is laminated on the first main surface so that the fourth main surface faces the first main surface and the positioning hole is located in the first through hole as viewed from the thickness direction. The step of covering the first metal foil laminated sheet; covering the third covering surface with the sixth main surface facing the second main surface and positioning the positioning hole in the second through hole as viewed from the thickness direction; A step of laminating a metal foil laminate on the first metal foil laminate; and patterning the second metal foil and the third metal foil based on the positioning holes of the target mark, to form first Steps of a wiring pattern and a second wiring pattern.

In addition, the method for manufacturing a multilayer printed wiring board of the present invention includes the steps of preparing a first metal foil-clad laminate, the first metal foil-clad laminate having a first main surface and a first main surface. The core substrate of the second main surface on the opposite side and the first metal foil formed on the first main surface; a step of patterning the first metal foil to form a target mark with positioning holes; preparing a second metal-clad In the step of a foil laminate, the second metal-clad laminate includes a first composite substrate having a third main surface and a fourth main surface opposite to the third main surface, and is formed on the third main substrate. A second metal foil on the surface; a step of forming a first through hole penetrating the second metal foil-clad laminate in the thickness direction; so that the fourth main surface faces the first main surface and is viewed from the thickness direction A step of laminating the second metal-clad laminate on the first metal-clad laminate in a manner that the positioning holes are located in the first through-holes; using the positioning holes marked by the target as a reference, The aforementioned second metal foil A step of patterning to form a wiring pattern; a step of preparing a third metal-clad laminate, the third metal-clad laminate having a sixth main surface and a sixth main surface opposite to the fifth main surface Step of forming a second through-hole through the third metal foil-clad laminate in the thickness direction; and forming the sixth main The third metal foil-clad laminate is laminated on the third main surface of the second metal-clad laminate, and the positioning hole is located in the second through-hole as viewed from the thickness direction. The step of the second metal foil-clad laminate; and the step of patterning the third metal foil based on the positioning hole of the target mark to form a wiring pattern.

The multilayer printed wiring board of the present invention includes a core wiring board including a core substrate having a first main surface and a second main surface opposite to the first main surface, and a core substrate formed on the first main surface and provided with the core substrate. Target mark of positioning hole; a first combination wiring board including a first combination substrate having a third main surface and a fourth main surface opposite to the third main surface; and a first combination substrate formed on the third main surface. A wiring pattern; a second combined wiring board comprising: a second combined substrate having a fifth main surface and a sixth main surface opposite to the fifth main surface; and a second wiring formed on the fifth main surface Pattern; the first combination wiring board is laminated on the core wiring board via an adhesive in such a manner that the fourth main surface and the first main surface face each other; the second combination wiring board uses the sixth main surface and The second main surface faces the core wiring board through an adhesive layer; the core wiring board is formed with a bottomed hole penetrating the core substrate in the thickness direction; and the first combined wiring board is formed with Through the first combination in the thickness direction A first through hole of the base material; the second combined wiring board is formed with a second through hole that penetrates the second combined base material in the thickness direction and communicates with the bottomed hole; and the positioning hole in the first through hole The bottom surface is exposed and can be viewed from the third main surface side, and the bottom surface with the bottomed hole is exposed, and also can be viewed from the fifth main surface side.

The multilayer printed wiring board of the present invention includes a core wiring board including a core substrate having a first main surface and a second main surface opposite to the first main surface, and a core substrate formed on the first main surface and A target mark provided with a positioning hole; a first combined wiring board including a first combined base material having a third main surface and a fourth main surface opposite to the third main surface; and a third main surface formed on the third main surface. A first wiring pattern; a second combined wiring board, the second combined wiring board comprising: a second combined base material having a fifth main surface and a sixth main surface opposite to the fifth main surface; The second wiring pattern on the fifth main surface; the first combination wiring board is laminated on the core wiring board via an adhesive in a manner that the fourth main surface and the first main surface face each other; the second combination wiring The board is laminated on the first combination wiring board through an adhesive so that the sixth main surface and the third main surface face each other; the first combination wiring board is formed to penetrate the first combination substrate in a thickness direction. Material through hole; The two combined wiring boards are formed with a second through hole penetrating the second combined base material in the thickness direction and communicating with the first through hole; and the positioning hole is exposed on the bottom surface of the first through hole and can be exposed from the fifth main Observed from the side.

According to the present invention, it is possible to provide a multilayer printed wiring board manufacturing method and a multilayer printed wiring board capable of preventing the accumulation of the positional deviation of the wiring pattern of each layer and improving the positional accuracy of the wiring pattern of each layer.

1‧‧‧ core wiring board

2, 3‧‧‧ combined wiring board

10, 20, 30‧‧‧‧ metal foil laminate

11‧‧‧ core substrate

11a, 11b, 21a, 21b, 31a, 31b

12, 13, 22, 32‧‧‧ metal foil

14‧‧‧ target mark

14a‧‧‧ Positioning hole

15, 16, 25, 26, 35, 36‧‧‧ wiring patterns

17‧‧‧ with bottom hole

21, 31‧‧‧ combined substrate

23, 33‧‧‧Adhesive layer

24, 34‧‧‧through holes

41, 42‧‧‧ dry film

41a, 41b, 42a, 42b

C1, C2‧‧‧tangent

FIG. 1 is a process sectional view for explaining a method for manufacturing a multilayer printed wiring board according to the first embodiment.

FIG. 2A is a plan view of a target mark of the first example.

FIG. 2B is a plan view of the target mark of the second example.

FIG. 2C is a plan view showing an arrangement example of two target marks and a wiring pattern.

3 is a cross-sectional view for explaining steps in a method for manufacturing a multilayer printed wiring board according to the first embodiment.

4 is a cross-sectional view for explaining steps in a method for manufacturing a multilayer printed wiring board according to the first embodiment.

5 is a cross-sectional view illustrating a step of the method for manufacturing the multilayer printed wiring board according to the first embodiment, following FIG. 4.

FIG. 6 is a cross-sectional view illustrating a step of the method for manufacturing the multilayer printed wiring board according to the first embodiment, following FIG. 5.

FIG. 7 is a cross-sectional view illustrating a step of the method for manufacturing the multilayer printed wiring board according to the first embodiment, following FIG. 6;

FIG. 8 is a sectional view illustrating a step of the method for manufacturing the multilayer printed wiring board according to the first embodiment, following FIG. 7.

FIG. 9 is a process sectional view for explaining a method for manufacturing a multilayer printed wiring board according to the second embodiment.

FIG. 10 is a sectional view illustrating a step of a method for manufacturing a multilayer printed wiring board according to the second embodiment, following FIG. 9.

FIG. 11 is a sectional view illustrating a step of a method for manufacturing a multilayer printed wiring board according to the second embodiment, following FIG. 10;

FIG. 12 is a sectional view illustrating a step of a method for manufacturing a multilayer printed wiring board according to the second embodiment, following FIG. 11;

13 is a cross-sectional view illustrating a step of a method for manufacturing a multilayer printed wiring board according to the second embodiment, continued from FIG. 12;

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, components having the same function in each figure are given the same reference numerals. In addition, the illustration is schematic, and the characteristic parts of each embodiment are mainly shown. The relationship between the thickness and the plane size and the ratio of the thickness of each layer are different from the actual situation.

[First Embodiment]

A method for manufacturing a multilayer printed wiring board according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 8.

First, as shown in (1) in FIG. 1, a metal foil-clad laminate 10 (a first metal foil-clad laminate) is prepared. The metal foil-clad laminate 10 is a so-called double-sided metal foil-clad laminate having a core substrate 11, a metal foil 12, and a metal foil 13.

The core substrate 11 has a main surface 11 a (first main surface) and a main surface 11 b (second main surface) opposite to the main surface 11 a. The metal foil 12 is formed on the main surface 11 a of the core base material 11, and the metal foil 13 is formed on the main surface 11 b of the core base material 11. The thickness of the core substrate 11 is, for example, 50 μm, and the thickness of the metal foils 12 and 13 is, for example, 12 μm.

The core substrate 11 is made of an insulating material. In this embodiment, the core substrate 11 is made of a flexible material such as a liquid crystal polymer (LCP) and polyimide. In addition, the core substrate 11 may be composed of another insulating material, or may be composed of a material having no flexibility. The metal foils 12 and 13 are copper foils in the present embodiment, but are not limited thereto, and may be metal foils made of other metals (for example, silver, aluminum).

Next, as shown in (2) in FIG. 1, the metal foil 12 is patterned to form a target mark 14 having a positioning hole 14a. The target mark 14 is used in common when a wiring pattern of each layer is formed in a subsequent step. The diameter of the target mark 14 is, for example, 3 mm, and the diameter of the positioning hole 14 a is, for example, 0.5 mm.

The patterning of the metal foil 12 is performed by etching the metal foil 12 using a known photolithography method. By patterning the metal foil 12, the target mark 14 and the wiring pattern 15 can be formed.

The external shape of the target mark 14 is circular as shown in FIG. 2A, but is not limited thereto. For example, as shown in FIG. 2B, the outer shape of the target mark 14 may be a quadrangle. The target mark 14 may be formed in plural. For example, as shown in FIG. 2C, two target marks 14 may be formed by sandwiching the wiring pattern 15.

As shown in (2) in FIG. 1, the metal foil 13 is patterned to form a wiring pattern 16. In this embodiment, the metal foil 12 and the metal foil 13 are processed simultaneously to form the wiring pattern 15 and the wiring pattern 16 respectively.

Here, the detail of the patterning method of a metal foil is demonstrated.

First, a photoresist layer (not shown) is formed on the metal foil 12 and the metal foil 13. This photoresist layer may be formed by laminating a dry film on the metal foils 12, 13 or may be formed by applying a resist paste on the metal foils 12, 13. Next, on the photoresist layer covering the metal foil 12, an exposure mask (not shown) for the surface side is aligned and arranged. Similarly, the exposure mask (not shown) for the back side is arrange | positioned on the photoresist layer which coat | covers the metal foil 13, and is arrange | positioned.

Then, the photoresist layer is exposed and developed to form an etching mask. Then, the metal foil 12 and the metal foil 13 are etched using an etching mask. After the etching is completed, the etching mask is peeled.

The target mark 14, the wiring pattern 15, and the wiring pattern 16 are formed in this manner. The wiring patterns 15 and 16 can be formed with relatively high positional accuracy (for example, within ± 10 μm). In this embodiment, the wiring pattern 16 is formed so as to substantially overlap the wiring pattern 15 in a plan view. The wiring patterns 15 and 16 extend in a direction perpendicular to the paper surface in (2) in FIG. 1. In addition, in this embodiment, if the center lines of the wiring patterns 15 and 16 are almost the same, the widths may be different.

After patterning the metal foils 12 and 13 as described above, and after forming the target mark 14 and the wiring patterns 15 and 16, as shown in (3) of FIG. 1, a bottom hole 17 is formed. The diameter of the bottomed hole 17 is larger than the diameter of the positioning hole 14a, and is, for example, 1 mm.

The bottomed hole 17 penetrates the core substrate 11 in the thickness direction, and the positioning hole 14 a is exposed on the bottom surface of the bottomed hole 17. By forming the bottom hole 17, the target mark 14 (positioning hole 14a) can also be viewed from the main surface 11b side of the core base material 11.

In this embodiment, the bottomed hole 17 is formed by laser processing the core substrate 11 by irradiating the main surface 11b with laser light. This laser processing uses a CO2 laser or the like. The laser light is aimed at approximately the center of the target mark 14 (near the positioning hole 14a) and irradiated. The laser light irradiation position can be adjusted based on the wiring pattern 16 or a target mark (not shown) formed at the same time as the wiring pattern 16. Thereby, the bottomed hole 17 can be formed without special positioning.

In addition, after the bottom hole 17 is formed, the inner surface of the metal foil 12 constituting the target mark 14 (the surface to which the core base material 11 is adhered) may be mirror-finished. For example, the target mark 14 is subjected to a plasma treatment or an etching treatment (for example, a slight etching of about 1 μm), thereby mirror-finishing the inner surface of the metal foil 12. This can improve the visibility of the target mark 14 when viewed from the main surface 11b side.

Next, as shown in (1) in FIG. 3, a metal foil-clad laminate 20 (a second metal foil-clad laminate) is prepared. The metal foil-clad laminate 20 includes a composite substrate 21 (first composite substrate), a metal foil 22 (second metal foil), and an adhesive layer 23. In addition, the adhesive layer 23 is not necessary.

The composite substrate 21 has a main surface 21a (third main surface) and a main surface 21b (fourth main surface) opposite to the main surface 21a. The metal foil 22 is formed on the main surface 21a, and the adhesive layer 23 is temporarily attached to the main surface 21b. The thickness of the composite substrate 21 is, for example, 50 μm, and the thickness of the metal foil 22 is, for example, 12 μm.

The composite substrate 21 is made of an insulating material. In this embodiment, the composite substrate 21 is made of a flexible material such as a liquid crystal polymer or polyimide. In addition, the composite substrate 21 may be composed of another insulating material, or may be composed of a material having no flexibility. The metal foil 22 is a copper foil in this embodiment, but it is not limited to this, and it may be a metal foil made of another metal (for example, silver, aluminum).

Next, as shown in (2) of FIG. 3, a through hole 24 (first through hole) that penetrates the metal foil-clad laminate 20 in the thickness direction is formed. The through hole 24 is formed by partially removing the composite substrate 21 by, for example, laser processing. The diameter of the through hole 24 is, for example, 2.5 mm. The diameter of the through hole 24 needs to be larger than the diameter of the positioning hole 14a.

The diameter of the through hole 24 is preferably slightly smaller than the diameter of the target mark 14. Thereby, the peripheral part of the target mark 14 can be pressed by the adhesive layer 23 (refer (1) in FIG. 6).

Next, as shown in (1) of FIG. 4, a metal foil-clad laminate 30 (a third metal foil-clad laminate) is prepared. The metal foil-clad laminate 30 includes a composite substrate 31 (second composite substrate), a metal foil 32 (third metal foil), and an adhesive layer 33. In addition, the adhesive layer 33 is not necessary.

The composite substrate 31 has a main surface 31a (a fifth main surface) and a main surface 31b (a sixth main surface) opposite to the main surface 31a. The metal foil 32 is formed on the main surface 31a, and the adhesive layer 33 is temporarily attached to the main surface 31b. The thickness of the composite substrate 31 is, for example, 50 μm, and the thickness of the metal foil 32 is, for example, 12 μm.

The composite substrate 31 is made of an insulating material. In this embodiment, the composite substrate 31 is made of a flexible material such as a liquid crystal polymer or polyimide. In addition, the composite substrate 31 may be made of another insulating material, or may be made of a material having no flexibility. The metal foil 32 is a copper foil in the present embodiment, but is not limited thereto, and may be a metal foil made of another metal (for example, silver, aluminum).

Next, as shown in (2) of FIG. 4, a through hole 34 (second through hole) that penetrates the metal foil-clad laminate 30 in the thickness direction is formed. The through-hole 34 is formed by partially removing the composite substrate 31 by, for example, laser processing. The diameter of the through hole 34 is, for example, 2.5 mm. The diameter of the through hole 34 needs to be larger than the diameter of the positioning hole 14a.

The diameter of the through hole 34 is preferably larger than the diameter of the bottomed hole 17. Therefore, even if a certain degree of positional deviation occurs when the metal foil-clad laminate 30 is laminated on the metal foil-clad laminate 10 in a subsequent step, the positioning holes can be viewed through the through holes 34 from the outside. 14a.

Next, as shown in (1) of FIG. 5 and FIG. 6, the main surface 21 b of the composite substrate 21 and the main surface 11 a of the core substrate 11 are opposed to each other and the positioning hole 14 a is located in the through hole 24 as viewed from the thickness direction. In the internal method, the metal foil-clad laminate 20 is laminated on the metal-clad laminate 10 via an adhesive layer 23. This lamination is performed by, for example, pin alignment of the metal foil-clad laminates. The same applies to the following lamination steps.

Next, as shown in (1) of FIG. 5 and FIG. 6, the main surface 31 b of the composite substrate 31 is opposed to the main surface 11 b of the core substrate 11 and the positioning hole 14 a is located in the through hole 34 as viewed from the thickness direction. In the internal method, the metal foil-clad laminate 30 is laminated on the metal foil-clad laminate 10 via an adhesive layer 33. At this time, the metal foil-clad laminate 30 is laminated on the metal foil-clad laminate 10 so that the through-holes 34 communicate with the bottomed holes 17.

In addition, when the metal foil-clad laminates 20 and 30 are not provided with the adhesive layers 23 and 33, a low flow bonding sheet may be laminated on both sides of the core substrate 11, and then the metal-clad laminate may be laminated. The foil laminated plates 20 and 30 are laminated on the core base material 11.

Next, the laminated metal foil-clad laminates 10, 20, and 30 (laminates) are integrated by heating and pressing. Specifically, the laminated body is heated and pressed using a vacuum pressing device or a vacuum laminator. For example, the laminated body is heated to about 150 ° C to 200 ° C and pressurized at a pressure of about 2 MPa to 4 MPa. The temperature is 50 ° C or more lower than the softening temperature of the liquid crystal polymer. With this step, the adhesive layers 23 and 33 are cured.

Next, as shown in (2) of FIG. 7, the metal foil 22 and the metal foil 32 are patterned based on the positioning hole 14 a of the target mark 14 to form a wiring pattern 25 (first wiring pattern) and a wiring pattern 35, respectively. (Second wiring pattern). In this embodiment, the wiring patterns 25 and 35 are formed so as to substantially overlap the wiring patterns 15 and 16 in a plan view.

The wiring patterns 25 and 35 are specifically formed as follows.

First, as shown in (2) of FIG. 6, dry films 41 and 42 are attached to the outer surface of the laminated body using a laminating apparatus. Thereby, the opening of the through-hole 24 is covered by the dry film 41, and the opening of the through-hole 34 is covered by the dry film 42. As the dry films 41 and 42, it is desirable to use a dry film photoresist having a thickness capable of tenting the through holes 24 and 34 (for example, 30 μm thick).

Next, the positioning holes 14a of the laminated body are identified by two cameras (not shown) provided on the front and back sides of the laminated body. Then, the positions of the two exposure masks (reticles) for the front side and the back side are aligned based on the positions of the identified positioning holes 14a, and they are arranged on the dry films 41 and 42, respectively. Then, the dry films 41 and 42 are exposed and developed to form etching masks 41a, 41b, 42a, and 42b as shown in (1) of FIG. 7. The exposure of the dry films 41 and 42 may be performed simultaneously by two-sided exposure, or may be performed one by one.

The etching covers 41 a and 42 a are formed to protect the target mark 14 from being etched when the metal foils 22 and 32 are etched. The etching covers 41 b and 42 b are etching covers for forming the wiring patterns 25 and 35. As described above, in this embodiment, since the exposure masks are arranged based on the common positioning hole 14a, the etching masks 41b and 42b can be formed with high positional accuracy.

Then, the metal foil 22 and the metal foil 32 are etched using the etching covers 41a, 41b, 42a, and 42b. After the etching is completed, the etching covers 41a, 41b, 42a, and 42b are peeled off. Thereby, the wiring patterns 25 and 35 are formed. Since the etching covers 41b and 42b are formed with high position accuracy, the wiring patterns 25 and 35 can be formed with high position accuracy (for example, within ± 10 μm) with respect to the wiring patterns 15 and 16.

The wiring patterns 25 and 35 extend in a direction perpendicular to the paper surface in (2) in FIG. 7. In addition, in this embodiment, if the center lines of the wiring patterns 25 and 35 are almost the same, the widths may be different.

Through the above steps, as shown in (2) of FIG. 7, a four-layer multilayer printed wiring board is obtained. The four-layer wiring patterns 15, 16, 25, and 35 are formed with high positional accuracy.

In the case of further manufacturing a multilayer printed wiring board, the above steps (preparation of a metal-clad laminate for lamination, formation of through holes, formation of a laminate, and patterning of a metal foil) may be repeated. FIG. 8 shows a six-layer multilayer printed wiring board in which a metal foil-clad laminate is laminated on both sides of the four-layer multilayer printed wiring board shown in (2) of FIG. 7. The wiring patterns 26 and 36 in the outermost layer are formed by etching using an etching mask formed using the common positioning hole 14 a as a reference in the same manner as the wiring patterns 25 and 35. Thereby, the wiring patterns 26 and 36 are formed with high positional accuracy. Therefore, the wiring patterns 26 and 36 are formed with high positional accuracy (for example, within ± 10 μm) with respect to the wiring patterns 25 and 35. As a result, six-layer wiring patterns 15, 16, 25, 26, 35, and 36 can be formed with high positional accuracy.

The wiring patterns 26 and 36 extend in a direction perpendicular to the paper surface in FIG. 8. In addition, in this embodiment, if the center lines of the wiring patterns 26 and 36 are almost the same, the widths may be different.

As described above, according to the manufacturing method of the multilayer printed wiring board of this embodiment, the wiring pattern of each layer can be formed with high positional accuracy. Thereby, for example, the distance between the wiring pattern and the outer shape processed end of the multilayer printed wiring board can be shortened. Taking FIG. 8 as an example, since the positional deviations of the wiring patterns 15, 16, 25, 26, 35, and 36 in the lateral direction are small, the length between the tangent line C1 and the tangent line C2 can be shortened. Thereby, for example, a cable-shaped elongated printed wiring board can be easily manufactured.

The outer shape processing of the multilayer printed wiring board is performed by, for example, laser processing of an image positioning method. That is, the positioning holes 14a of the target mark 14 are recognized by a camera, the laser light source and the multilayer printed wiring board are aligned, and the outline processing is performed along a tangent line. The tangent line can be set to a position close to the wiring pattern within the range of laser processing accuracy.

According to this embodiment, since the wiring pattern of each layer is formed based on a common target mark, it is possible to prevent accumulation of positional deviation. Thereby, a multilayer printed wiring board can be obtained in which the shape-processed end approaches the wiring pattern up to the laser processing accuracy (for example, ± 25 μm) and the root-mean-square (for example, ± 27 μm) of the wiring pattern formation position accuracy (for example, ± 10 μm).

In this way, according to this embodiment, the external shape processing end can be made closer to the wiring pattern than the conventional method without using a particularly expensive device.

In addition, in the example of FIG. 8, although the area where the target mark 14 is formed is cut out during the outline processing, the area may be retained.

The manufacturing method of the said multilayer printed wiring board is not limited to an example, It can change variously. For example, the order of carrying out the processing steps of each of the metal foil-clad laminates 10, 20, and 30 is arbitrary. After forming the through holes 24 and 34 in the metal foil-clad laminates 20 and 30, the target mark 14 and the bottomed hole 17 of the metal foil-clad laminate 10 may be formed.

In addition, the bottomed hole 17 may be formed after the target mark 14 is formed.

In addition, when the core base material 11 is made of a transparent material, when the camera can observe the target mark 14 through the insulating base material, the bottom hole 17 may not be formed.

In addition, although the metal foil-clad laminate 10 is a double-sided metal foil-clad laminate, it is not limited to this, and may be a single-sided metal foil-clad laminate in which metal foil is formed only on one side (main surface 11a).

In addition, the target mark 14 may be formed so that it may contain identification information of the multilayer printed wiring board manufactured by the said manufacturing method. For example, the target mark 14 may be formed into a shape such as a bar code or a two-dimensional code. Accordingly, the multilayer printed wiring board can be traced from the initial step (processing of the metal-clad laminate 10).

<Multilayer printed wiring board>

The multilayer printed wiring board manufactured by the manufacturing method of the multilayer printed wiring board of 1st Embodiment has the following structures.

As for the multilayer printed wiring board of this embodiment, as shown in (2) of FIG. 7, a core wiring board 1 and a combination wiring board 2 laminated on one main surface of the core wiring board 1 are laminated on the core wiring board 1. The combination wiring board 3 on the other main surface.

The core wiring board 1 includes a core base material 11 and a target mark 14 formed on the main surface 11 a of the core base material 11 and provided with positioning holes 14 a. The composite wiring board 2 includes a composite substrate 21 and a wiring pattern 25 formed on a main surface 21 a of the composite substrate 21. The composite wiring board 3 includes a composite substrate 31 and a wiring pattern 35 formed on a main surface 31 a of the composite substrate 31.

The composite wiring board 2 is laminated on the core wiring board 1 via an adhesive layer 23 so that the main surface 21 b and the main surface 11 a of the core base material 11 face each other. The composite wiring board 3 is laminated on the core wiring board 1 via an adhesive layer 33 such that the main surface 31 b faces the main surface 11 b of the core base material 11.

The core wiring board 1 is formed with a bottomed hole 17 penetrating the core substrate 11 in the thickness direction. The combination wiring board 2 is formed with a through hole 24 penetrating the combination substrate 21 in the thickness direction. The combination wiring board 3 is formed with a through hole 34 penetrating the combination substrate 31 in the thickness direction and communicating with the bottom hole 17.

The positioning hole 14 a of the target mark 14 is exposed on the bottom surface of the through-hole 24, can be viewed from the main surface 21 a side of the composite substrate 21, and is exposed on the bottom surface of the bottomed hole 17, or can be viewed from the main surface 31 a of the composite substrate 31. Observed from the side.

In addition, as for the multilayer printed wiring board of this embodiment, as shown in FIG. 7 (2), each layer has wiring patterns 15, 16, 25, and 35 extending in the longitudinal direction of the multilayer printed wiring board. The positions of the wiring patterns 15, 16, 25, and 35 in the width direction orthogonal to the length direction are almost the same from the thickness direction of the multilayer printed wiring board.

[Second Embodiment]

Next, a method for manufacturing a multilayer printed wiring board according to a second embodiment of the present invention will be described with reference to FIGS. 9 to 13. One difference between the second embodiment and the first embodiment is the method of laminating the metal foil-clad laminates 20 and 30. In the first embodiment, the metal foil-clad laminate 20 is laminated on one main surface of the metal foil-clad laminate 10 and the metal foil-clad laminate 30 is laminated on the other main surface. In contrast, in the second embodiment, the metal foil-clad laminates 20 and 30 are laminated on one side of the metal foil-clad laminate 10.

Hereinafter, the description of the overlapping portions with the first embodiment is appropriately omitted, and the second embodiment will be described focusing on the differences.

First, as shown in FIG. 9, after the metal foil-clad laminate 10 is prepared, the metal foil 12 is patterned to form a target mark 14 having a positioning hole 14 a. Similarly to the first embodiment, the wiring patterns 15 and 16 are also formed. However, in this embodiment, it is not necessary to form the bottom hole 17.

Next, after the metal foil-clad laminate 20 is prepared, as shown in FIG. 9, a through hole 24 is formed to penetrate the metal foil-clad laminate 20 in the thickness direction.

Next, as shown in (1) of FIG. 9 and FIG. 10, the main surface 21 b of the composite substrate 21 is opposed to the main surface 11 a of the core substrate 11 and the positioning hole 14 a is located in the through hole 24 as viewed from the thickness direction. In the internal method, the metal foil-clad laminate 20 is laminated on the metal-clad laminate 10 via an adhesive layer 23. Then, the laminated metal foil-clad laminates 10 and 20 (laminates) are integrated by heating and pressing. Through this step, the adhesive layer 23 is cured.

Next, as shown in (2) in FIG. 11, the metal foil 22 is patterned to form the wiring pattern 25 with reference to the positioning hole 14 a of the target mark 14. The wiring pattern 25 is formed as follows.

First, as shown in (2) of FIG. 10, a dry film 41 is stuck on the metal foil 22. Thereby, the opening of the through-hole 24 is covered with the dry film 41. Next, the positioning hole 14 a is recognized through the dry film 41 from the outside of the laminated body using a camera (not shown). Then, the position of the exposure mask is aligned based on the position of the identified positioning hole 14 a, and the exposure mask is placed on the dry film 41. Then, by exposing and developing the dry film 41, as shown in (1) of FIG. 11, etching masks 41a and 41b are formed. Then, the metal foil 22 is etched using the etching covers 41a and 41b. Thereby, as shown in (2) in FIG. 11, the wiring pattern 25 is formed.

Next, after the metal foil-clad laminate 30 is prepared, as shown in FIG. 12, a through hole 34 is formed to penetrate the metal foil-clad laminate 30 in the thickness direction.

In addition, in FIG. 12, the diameters of the through holes 24 and the through holes 34 are the same, but are not limited thereto, and the diameter of the through holes 34 may be larger than the diameter of the through holes 24. Therefore, in the subsequent steps, even if a certain degree of positional deviation occurs when the metal-foil-clad laminate 30 is laminated on the metal-foil-clad laminate 20, positioning can be observed through the through hole 34 from the outside. Hole 14a.

Next, as shown in (1) of FIG. 12 and FIG. 13, the main surface 31 b of the composite substrate 31 is opposed to the main surface 21 a of the composite substrate 21 and the positioning hole 14 a is located in the through hole 34 as viewed from the thickness direction. In the internal method, the metal foil-clad laminate 30 is laminated on the metal foil-clad laminate 20 via an adhesive layer 33. Moreover, it arrange | positions so that the through-hole 34 and the through-hole 24 may communicate. Then, the laminated metal foil-clad laminates 10, 20, and 30 are integrated by heating and pressing. By this step, the adhesive layer 33 is cured.

Next, as shown in (2) of FIG. 13, the metal foil 32 is patterned to form the wiring pattern 35 based on the positioning hole 14 a of the target mark 14. The wiring pattern 35 is formed by the same method as the wiring pattern 25.

Through the above steps, as shown in (2) of FIG. 13, a four-layer multilayer printed wiring board is obtained. Since the four-layer wiring patterns 15, 16, 25, and 35 are formed based on the common positioning hole 14a, they are formed with high positional accuracy.

In addition, by repeating the above steps, printed wiring boards of more layers can be manufactured.

As mentioned above, according to the manufacturing method of the multilayer printed wiring board which concerns on this embodiment, the wiring pattern of each layer can be formed with high positional accuracy. Thereby, for example, the distance between the wiring pattern and the outer shape processed end of the multilayer printed wiring board can be shortened.

<Multilayer printed wiring board>

The multilayer printed wiring board manufactured by the manufacturing method of the multilayer printed wiring board of 2nd Embodiment has the following structures.

As shown in (2) of FIG. 13, the multilayer printed wiring board of this embodiment includes a core wiring board 1, a combination wiring board 2 laminated on the core wiring board 1, and a combination wiring board 3 laminated on the combination wiring board 2. .

The core wiring board 1 includes a core base material 11 and a target mark 14 formed on the main surface 11 a of the core base material 11 and provided with positioning holes 14 a. The composite wiring board 2 includes a composite substrate 21 and a wiring pattern 25 formed on a main surface 21 a of the composite substrate 21. The composite wiring board 3 includes a composite substrate 31 and a wiring pattern 35 formed on a main surface 31 a of the composite substrate 31.

The composite wiring board 2 is laminated on the core wiring board 1 via an adhesive layer 23 so that the main surface 21 b of the composite substrate 21 and the main surface 11 a of the core substrate 11 face each other. The composite wiring board 3 is laminated on the composite wiring board 2 via an adhesive layer 33 so that the main surface 31 b of the composite substrate 31 and the main surface 21 a of the composite substrate 21 face each other.

The combination wiring board 2 is formed with a through hole 24 penetrating the combination substrate 21 in the thickness direction. The combination wiring board 3 is formed with a through hole 34 that penetrates the combination substrate 31 in the thickness direction and communicates with the through hole 24.

The positioning hole 14 a of the target mark 14 is exposed on the bottom surface of the through hole 24 and can be viewed from the main surface 31 a side of the composite substrate 31 (that is, from the outside of the laminated body).

Moreover, as for the multilayer printed wiring board of this embodiment, as shown in (2) of FIG. 13, each layer has the wiring pattern 15, 16, 25, 35 extended in the longitudinal direction of a multilayer printed wiring board. The positions of the wiring patterns 15, 16, 25, and 35 in the width direction orthogonal to the length direction are almost the same from the thickness direction of the multilayer printed wiring board.

Based on the foregoing description, those skilled in the art can conceive of additional effects and various modifications of the present invention, but aspects of the present invention are not limited to the above-mentioned embodiments. Various additions, changes, and partial deletions can be made within the scope of the conceptual idea and gist of the present invention derived from the content specified in the scope of the patent application and its equivalents.

Claims (11)

    A method for manufacturing a multilayer printed wiring board, comprising the steps of preparing a first metal foil-clad laminate, the first metal foil-clad laminate having a first main surface and a side opposite to the first main surface A core substrate of a second main surface and a first metal foil formed on the first main surface; a step of patterning the first metal foil to form a target mark with positioning holes; preparing a second metal foil-clad laminate The second metal foil-clad laminate includes a first composite substrate having a third main surface and a fourth main surface opposite to the third main surface, and a first composite substrate formed on the third main surface. Two metal foils; a step of forming a first through hole penetrating through the second metal-clad laminated board in a thickness direction; a step of preparing a third metal-clad laminated board, the third metal-clad laminated board having A second combined substrate of a fifth main surface and a sixth main surface opposite to the fifth main surface; and a third metal foil formed on the fifth main surface; formed to penetrate the third metal-clad in a thickness direction Second through hole of foil laminate Step: The second metal foil-clad laminate is laminated on the first so that the fourth main surface is facing the first main surface and the positioning hole is located in the first through hole as viewed from the thickness direction. A step of covering a metal foil laminated plate; placing the third metal foil on the third main surface such that the positioning hole is located in the second through hole as viewed from the thickness direction when the sixth main surface is facing the second main surface A step of laminating a laminated board on the first metal foil-clad laminated board; and patterning the second metal foil and the third metal foil based on the positioning holes of the target mark, to form first wirings, respectively Step of patterning and second wiring pattern.         The method for manufacturing a multilayer printed wiring board according to claim 1, further comprising the steps of: forming a bottomed hole penetrating the core substrate in a thickness direction and exposing the positioning hole on the bottom surface; and the third layer The metal foil laminate is laminated on the first metal-clad laminate so that the second through-holes communicate with the bottomed holes.         The method for manufacturing a multilayer printed wiring board according to claim 2, wherein the core substrate is made of a liquid crystal polymer or polyimide.         The method for manufacturing a multilayer printed wiring board according to claim 2, wherein a diameter of the second through hole is larger than a diameter of the bottomed hole.         The method for manufacturing a multilayer printed wiring board according to claim 2, wherein after forming the bottomed hole, a process of mirror-finishing the inner surface of the metal foil constituting the target mark is performed.         The method for manufacturing a multilayer printed wiring board according to any one of claims 1 to 5, wherein the core substrate, the first combined substrate, and the second combined substrate have flexibility.         A method for manufacturing a multilayer printed wiring board includes the following steps: a step of preparing a first metal foil-clad laminate, the first metal foil-clad laminate having a first main surface and an opposite side to the first main surface A core substrate of a second main surface and a first metal foil formed on the first main surface; a step of patterning the first metal foil to form a target mark with positioning holes; preparing a second metal foil-clad laminate The second metal foil-clad laminate includes a first composite substrate having a third main surface and a fourth main surface opposite to the third main surface, and a first composite substrate formed on the third main surface. Two metal foils; a step of forming a first through hole penetrating the second metal foil-clad laminate in a thickness direction; so that the fourth main surface faces the first main surface and the positioning hole is viewed from the thickness direction The method of being located in the first through hole, laminating the second metal foil-clad laminate on the first metal foil-clad laminate; taking the positioning hole marked by the target as a reference, Patterned metal foil, A step of forming a wiring pattern; a step of preparing a third metal foil-clad laminate, the third metal foil-clad laminate having a first main surface having a fifth main surface and a sixth main surface opposite to the fifth main surface; Two steps of assembling a base material and a third metal foil formed on the fifth main surface; forming a second through hole penetrating through the third metal-clad laminate in the thickness direction; The third metal foil-clad laminate is laminated on the second metal foil-laminated board in such a manner that the positioning hole is located in the second through-hole as viewed from the thickness direction. A step of covering the metal foil laminate; and a step of patterning the third metal foil based on the positioning holes of the target mark to form a wiring pattern.         The method for manufacturing a multilayer printed wiring board according to claim 7, wherein a diameter of the second through hole is larger than a diameter of the first through hole.         The method for manufacturing a multilayer printed wiring board according to claim 7 or 8, wherein the core substrate, the first combined substrate, and the second combined substrate have flexibility.         A multilayer printed wiring board including a core wiring board including a core base material having a first main surface and a second main surface opposite to the first main surface, and positioning is formed on the first main surface and provided with positioning. A target mark for a hole; a first combined wiring board including a first combined substrate having a third main surface and a fourth main surface opposite to the third main surface; and a first composite substrate formed on the third main surface. A wiring pattern; a second combined wiring board comprising: a second combined base material having a fifth main surface and a sixth main surface opposite to the fifth main surface; and a second formed on the fifth main surface Wiring pattern; the first combination wiring board is laminated on the core wiring board via an adhesive in such a manner that the fourth main surface and the first main surface face each other; the second combination wiring board uses the sixth main surface The second main surface is laminated with an adhesive on the core wiring board; the core wiring board is formed with a bottomed hole penetrating the core substrate in the thickness direction; and the first combined wiring board is formed. There are through the first group in the thickness direction A first through hole of the base material; a second through hole that penetrates the second combined base material in the thickness direction and communicates with the bottomed hole; and the positioning hole is in the first through hole The bottom surface of is exposed and can be viewed from the third main surface side, and the bottom surface of the bottomed hole is exposed, and also can be viewed from the fifth main surface side.         A multilayer printed wiring board including a core wiring board including a core base material having a first main surface and a second main surface opposite to the first main surface, and positioning is formed on the first main surface and provided with positioning. A target mark of a hole; a first combined wiring board including a first combined base material having a third main surface and a fourth main surface opposite to the third main surface; and a first formed on the third main surface. A wiring pattern; a second combined wiring board including a second combined substrate having a fifth main surface and a sixth main surface opposite to the fifth main surface; and a second wiring pattern formed on the fifth main surface The first combination wiring board is laminated on the core wiring board via an adhesive in such a manner that the fourth main surface and the first main face are facing each other; the second combination wiring board is connected with the sixth main surface and the foregoing The third main face is placed on the first combined wiring board through an adhesive layer; the first combined wiring board is formed with a first through hole penetrating the first combined substrate in a thickness direction; Two combined wiring boards are formed in the thickness side A second through hole penetrating upward through the second composite substrate and communicating with the first through hole; and the positioning hole is exposed on the bottom surface of the first through hole and can be viewed from the fifth main surface side.