JP6935268B2 - Manufacturing method of multi-layer printed wiring board and multi-layer printed wiring board - Google Patents

Description

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 also includes a flexible multilayer flexible printed wiring board (multilayer FPC).

The conductive pattern of each layer of the multilayer printed wiring board is formed by using a known photofabrication technique. 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 then arranged. Then, after irradiating the photoresist layer with light through an exposure mask, development processing is performed to form an etching mask. Then, a conductive pattern is formed by etching the copper foil with an etching mask. In forming the conductive pattern, it is important to improve the positional accuracy between the conductive patterns of each layer. By increasing the positional accuracy of the conductive pattern, for example, the land diameter of the interlayer connection portion can be reduced.

In Patent Document 2, a target for alignment is provided in the inner layer, and alignment is performed in a state where the target is exposed by laser processing to acquire alignment data for via hole forming processing. The manufacturing method is described. In this method, since the target is exposed, it is possible to clearly recognize this and perform alignment, and the alignment accuracy is high.

Patent No. 2631287 Japanese Unexamined Patent Publication No. 10-256737

By the way, in recent years, with the progress of miniaturization and high density of electronic devices in which multi-layer printed wiring boards are used, it has been required to reduce the distance between the end face of the multi-layer printed wiring board and the wiring pattern. It has become.

For example, a multi-layer flexible printed wiring board having a cable shape having a very narrow width and having a plurality of wiring patterns having 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 surface of the multilayer flexible printed wiring board during the outer shape processing.

The exposure process for forming the wiring pattern of each layer is conventionally exposed using a target mark formed at the same time as the inner wiring pattern closest to the copper foil to be processed, as described in Patent Document 2. It was done after the mask was aligned. That is, the wiring pattern was formed with reference to the target mark located on the inner layer side of one of the conductive films to be processed.

However, this method has a problem that the misalignment of the wiring pattern accumulates as the number of layers increases. That is, in the conventional method, it is necessary to anticipate the position accuracy at the time of exposure × the position deviation corresponding to the number of exposures. For example, when the alignment accuracy (exposure mask placement accuracy) at the time of forming the wiring pattern of each layer is ± 10 μm and a 6-layer multilayer printed wiring board is manufactured by a total of 5 exposures, the misalignment of the wiring pattern is ± 50 μm. You have to anticipate. If a value smaller than this is expected, the yield may decrease. If the external shape processing accuracy by the laser beam is, for example, ± 25 μm, the external shape processing end can be brought close to the wiring pattern only up to 75 μm.

Therefore, the present invention provides a method for manufacturing a multilayer printed wiring board and a multilayer printed wiring board capable of preventing the accumulation of misalignment of the wiring pattern of each layer and improving the positional accuracy of the wiring pattern of each layer. The purpose.

The method for manufacturing a multilayer printed wiring board according to the present invention is as follows.
A first metal having a core base material having a first main surface and a second main surface opposite to the first main surface, and a first metal foil formed on the first main surface. The process of preparing the foil-clad laminate and
A step of patterning the first metal foil to form a target mark having an alignment hole, and
It has a first build-up base material having a third main surface and a fourth main surface opposite to the third main surface, and a second metal foil formed on the third main surface. The process of preparing the second metal leaf-clad laminate and
A step of forming a first through hole that penetrates the second metal leaf-clad laminate in the thickness direction, and
It has a second build-up base material 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. The process of preparing the third metal leaf-clad laminate and
A step of forming a second through hole that penetrates the third metal leaf-clad laminate in the thickness direction, and
The second metal leaf-clad laminate is provided so that the fourth main surface faces the first main surface and the alignment hole is located in the first through hole when viewed in the thickness direction. The step of laminating on the first metal leaf-clad laminate and
The third metal leaf-clad laminate is provided so that the sixth main surface faces the second main surface and the alignment hole is located in the second through hole when viewed in the thickness direction. The step of laminating on the first metal leaf-clad laminate and
A step of patterning the second metal leaf and the third metal foil with reference to the alignment hole of the target mark to form a first wiring pattern and a second wiring pattern, respectively.
It is characterized by having.

Further, the method for manufacturing a multilayer printed wiring board according to the present invention is as follows.
A first metal having a core base material having a first main surface and a second main surface opposite to the first main surface, and a first metal foil formed on the first main surface. The process of preparing the foil-clad laminate and
A step of patterning the first metal foil to form a target mark having an alignment hole, and
It has a first build-up base material having a third main surface and a fourth main surface opposite to the third main surface, and a second metal foil formed on the third main surface. The process of preparing the second metal leaf-clad laminate and
A step of forming a first through hole that penetrates the second metal leaf-clad laminate in the thickness direction, and
The second metal leaf-clad laminate is provided so that the fourth main surface faces the first main surface and the alignment hole is located in the first through hole when viewed in the thickness direction. The step of laminating on the first metal leaf-clad laminate and
A step of patterning the second metal foil with reference to the alignment hole of the target mark to form a wiring pattern.
It has a second build-up base material 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. The process of preparing the third metal leaf-clad laminate and
A step of forming a second through hole that penetrates the third metal leaf-clad laminate in the thickness direction, and
The sixth main surface faces the third main surface of the second metal leaf-clad laminate so that the alignment hole is located in the second through hole when viewed in the thickness direction. A step of laminating the third metal leaf-clad laminate on the second metal leaf-clad laminate, and
A step of patterning the third metal foil with reference to the alignment hole of the target mark to form a wiring pattern.
It is characterized by having.

The multilayer printed wiring board according to the present invention
It has a core base material having a first main surface and a second main surface opposite to the first main surface, and a target mark formed on the first main surface and provided with an alignment hole. With the core wiring board
It has a first build-up base material having a third main surface and a fourth main surface opposite to the third main surface, and a first wiring pattern formed on the third main surface. The first build-up wiring board and
It has a second build-up base material 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. With a second build-up wiring board,
The first build-up wiring board is laminated on the core wiring board via an adhesive layer so that the fourth main surface faces the first main surface.
The second build-up wiring board is laminated on the core wiring board via an adhesive layer so that the sixth main surface faces the second main surface.
The core wiring board is formed with a bottomed hole that penetrates the core base material in the thickness direction.
The first build-up wiring board is formed with a first through hole that penetrates the first build-up base material in the thickness direction.
The second build-up wiring board is formed with a second through hole that penetrates the second build-up base material in the thickness direction and communicates with the bottomed hole.
The alignment hole is exposed on the bottom surface of the first through hole and is visible from the third main surface side, and is also exposed on the bottom surface of the bottomed hole and is visible from the fifth main surface side. It is characterized by being.

Further, the multilayer printed wiring board according to the present invention is
It has a core base material having a first main surface and a second main surface opposite to the first main surface, and a target mark formed on the first main surface and provided with an alignment hole. With the core wiring board
A first build-up substrate having a third main surface and a fourth main surface opposite to the third main surface, and a first wiring pattern formed on the third main surface. With the first build-up wiring board that has
A second build-up 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. With a second build-up wiring board that has
The first build-up wiring board is laminated on the core wiring board via an adhesive layer so that the fourth main surface faces the first main surface.
The second build-up wiring board is laminated on the first build-up wiring board via an adhesive layer so that the sixth main surface faces the third main surface.
The first build-up wiring board is formed with a first through hole that penetrates the first build-up base material in the thickness direction.
The second build-up wiring board is formed with a second through hole that penetrates the second build-up base material in the thickness direction and communicates with the first through hole.
The alignment hole is exposed on the bottom surface of the first through hole and is visible from the fifth main surface side.

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

It is a process sectional view for demonstrating the manufacturing method of the multilayer printed wiring board which concerns on 1st Embodiment. It is a top view of the target mark which concerns on 1st example. It is a top view of the target mark which concerns on the 2nd example. It is a top view which shows the arrangement example of two target marks and a wiring pattern. It is a process sectional view for demonstrating the manufacturing method of the multilayer printed wiring board which concerns on 1st Embodiment. It is a process sectional view for demonstrating the manufacturing method of the multilayer printed wiring board which concerns on 1st Embodiment. It is a process cross-sectional view for demonstrating the manufacturing method of the multilayer printed wiring board which concerns on 1st Embodiment following FIG. It is a process cross-sectional view for demonstrating the manufacturing method of the multilayer printed wiring board which concerns on 1st Embodiment following FIG. It is a process cross-sectional view for demonstrating the manufacturing method of the multilayer printed wiring board which concerns on 1st Embodiment following FIG. It is a process cross-sectional view for demonstrating the manufacturing method of the multilayer printed wiring board which concerns on 1st Embodiment following FIG. It is a process sectional view for demonstrating the manufacturing method of the multilayer printed wiring board which concerns on 2nd Embodiment. It is a process cross-sectional view for demonstrating the manufacturing method of the multilayer printed wiring board which concerns on 2nd Embodiment following FIG. It is a process cross-sectional view for demonstrating the manufacturing method of the multilayer printed wiring board which concerns on 2nd Embodiment following FIG. It is a process cross-sectional view for demonstrating the manufacturing method of the multilayer printed wiring board which concerns on 2nd Embodiment following FIG. It is a process cross-sectional view for demonstrating the manufacturing method of the multilayer printed wiring board which concerns on 2nd Embodiment following FIG.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In each figure, components having the same function are designated by the same reference numerals. Further, the drawings are schematic and show mainly the characteristic portions according to each embodiment, and the relationship between the thickness and the plane dimension, the ratio of the thickness of each layer, and the like are different from the actual ones.

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

First, as shown in FIG. 1 (1), a metal foil-clad laminate 10 (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 base material 11, a metal foil 12, and a metal foil 13.

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

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

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

The patterning of the metal leaf 12 is performed by etching the metal leaf 12 using a known photofabrication technique. The wiring pattern 15 may be formed together with the target mark 14 by patterning the metal foil 12.

The outer shape of the target mark 14 is circular as shown in FIG. 2A, but is not limited to this. For example, as shown in FIG. 2B, the outer shape of the target mark 14 may be a quadrangle. A plurality of target marks 14 may be formed. For example, as shown in FIG. 2C, two target marks 14 may be formed with the wiring pattern 15 interposed therebetween.

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

Here, the details of the patterning method of the metal foil will be described.

First, a photoresist layer (not shown) is formed on the metal foil 12 and the metal foil 13. The photoresist layer may be formed by laminating a dry film on the metal foils 12 and 13, or may be formed by applying an etching resist paste on the metal foils 12 and 13. Next, an exposure mask (not shown) for the front side is aligned and arranged on the photoresist layer covering the metal foil 12. Similarly, an exposure mask (not shown) for the back side is aligned and arranged on the photoresist layer covering the metal foil 13.

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 the etching mask. After the etching is completed, the etching mask is peeled off.

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

After patterning the metal foils 12 and 13 as described above to form the target marks 14 and the wiring patterns 15 and 16, the bottomed holes 17 are formed as shown in FIG. 1 (3). The diameter of the bottomed hole 17 is larger than the diameter of the alignment hole 14a, for example, 1 mm.

The bottomed hole 17 penetrates the core base material 11 in the thickness direction, and the alignment hole 14a is exposed on the bottom surface of the bottomed hole 17. By forming the bottomed hole 17, the target mark 14 (alignment hole 14a) can be visually recognized from the main surface 11b side of the core base material 11.
In the present embodiment, the bottomed hole 17 is formed by irradiating the main surface 11b with a laser beam and laser-machining the core base material 11. _{A CO 2} laser or the like is used for this laser processing. The laser beam is emitted aiming at the substantially center of the target mark 14 (near the alignment hole 14a). The laser light irradiation position may be adjusted with reference to the wiring pattern 16 or the target mark (not shown) formed at the same time as the wiring pattern 16. This makes it possible to form the bottomed hole 17 regardless of special alignment.

After forming the bottomed hole 17, the back surface (the surface that was adhered to the core base material 11) of the metal foil 12 that constitutes the target mark 14 may be mirrored. For example, the back surface of the metal foil 12 is mirrored by performing plasma treatment or etching treatment (for example, light etching of about 1 μm) on the target mark 14. Thereby, the visibility of the target mark 14 when viewed from the main surface 11b side can be improved.

Next, as shown in FIG. 3 (1), the metal foil-clad laminate 20 (second metal foil-clad laminate) is prepared. The metal foil-clad laminate 20 has a build-up base material 21 (first build-up base material), a metal foil 22 (second metal foil), and an adhesive layer 23. The adhesive layer 23 is not essential.

The build-up base material 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 build-up base material 21 is, for example, 50 μm, and the thickness of the metal foil 22 is, for example, 12 μm.

The build-up base material 21 is made of an insulating material. In the present embodiment, the build-up base material 21 is made of a flexible material such as a liquid crystal polymer or polyimide. The build-up base material 21 may be made of another insulating material, or may be made of a non-flexible material. The metal foil 22 is a copper foil in the present embodiment, but is not limited to this, and may be made of another metal (for example, silver or aluminum).

Next, as shown in FIG. 3 (2), 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 build-up base material 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 alignment hole 14a.

The diameter of the through hole 24 is preferably slightly smaller than the diameter of the target mark 14. As a result, the peripheral edge of the target mark 14 can be pressed by the adhesive layer 23 (see FIG. 6 (1)).

Next, as shown in FIG. 4 (1), a metal foil-clad laminate 30 (third metal foil-clad laminate) is prepared. The metal foil-clad laminate 30 has a build-up base material 31 (second build-up base material), a metal foil 32 (third metal foil), and an adhesive layer 33. The adhesive layer 33 is not essential.

The build-up base material 31 has a main surface 31a (fifth main surface) and a main surface 31b (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 build-up base material 31 is, for example, 50 μm, and the thickness of the metal foil 32 is, for example, 12 μm.

The build-up base material 31 is made of an insulating material. In the present embodiment, the build-up base material 31 is made of a flexible material such as a liquid crystal polymer or polyimide. The build-up base material 31 may be made of another insulating material, or may be made of a non-flexible material. The metal foil 32 is a copper foil in the present embodiment, but is not limited to this, and may be made of another metal (for example, silver or aluminum).

Next, as shown in FIG. 4 (2), 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 build-up base material 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 alignment hole 14a.

The diameter of the through hole 34 is preferably larger than the diameter of the bottomed hole 17. As a result, even if some misalignment occurs when the metal foil-clad laminate 30 is laminated on the metal foil-clad laminate 10 in the subsequent process, the alignment hole 14a can be visually recognized from the outside through the through hole 34. can.

Next, as shown in FIGS. 5 and 6 (1), the main surface 21b of the build-up base material 21 faces the main surface 11a of the core base material 11, and the alignment hole 14a is a through hole when viewed in the thickness direction. The metal foil-clad laminate 20 is laminated on the metal foil-clad laminate 10 via the adhesive layer 23 so as to be located inside the 24. This lamination is performed, for example, after aligning the metal foil-clad laminates with a pin guide. The same applies to the following laminating steps.

Next, as shown in FIGS. 5 and 6 (1), the main surface 31b of the build-up base material 31 faces the main surface 11b of the core base material 11, and the alignment hole 14a is a through hole when viewed in the thickness direction. The metal foil-clad laminate 30 is laminated on the metal foil-clad laminate 10 via the adhesive layer 33 so as to be located inside 34. At this time, the metal leaf-clad laminate 30 is laminated on the metal foil-clad laminate 10 so that the through hole 34 communicates with the bottomed hole 17.

If the metal foil-clad laminates 20 and 30 are not provided with the adhesive layers 23 and 33, the low-flow bonding sheets are laminated on both sides of the core base material 11, and then the metal foil-clad laminates 20 and 30 are attached. It may be laminated on the core base material 11.

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

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

Specifically, the wiring patterns 25 and 35 are formed as follows.

First, as shown in FIG. 6 (2), the dry films 41 and 42 are attached to the outer surface of the laminate using a laminator device. As a result, the opening of the through hole 24 is covered with the dry film 41, and the opening of the through hole 34 is covered with the dry film 42. As the dry films 41 and 42, it is desirable to use a dry film resist having a thickness (for example, 30 μm thickness) capable of tenting the through holes 24 and 34.

Next, the alignment holes 14a of the laminated body are recognized by two cameras (not shown) provided on the front side and the back side of the laminated body. Then, based on the recognized positions of the alignment holes 14a, the two exposure masks (photomasks) for the front side and the back side are aligned and arranged on the dry films 41 and 42, respectively. After that, the dry films 41 and 42 are exposed and developed to form etching masks 41a, 41b, 42a and 42b as shown in FIG. 7 (1). The dry films 41 and 42 may be exposed at the same time by double-sided exposure, or may be exposed on one side at a time.

The etching masks 41a and 42a are formed to protect the target mark 14 from being etched when the metal foils 22 and 32 are etched. The etching masks 41b and 42b are etching masks for forming the wiring patterns 25 and 35. As described above, in the present embodiment, since the exposure mask is arranged with reference to the common alignment hole 14a, the etching masks 41b and 42b can be formed with high position accuracy.

Then, the metal foil 22 and the metal foil 32 are etched using the etching masks 41a, 41b, 42a, 42b. After the etching is completed, the etching masks 41a, 41b, 42a, 42b are peeled off. As a result, the wiring patterns 25 and 35 are formed. Since the etching masks 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 the direction perpendicular to the paper surface in FIG. 7 (2). In the present embodiment, the wiring patterns 25 and 35 may have different widths as long as the center lines are substantially the same.

Through the steps up to this point, as shown in FIG. 7 (2), a four-layer multilayer printed wiring board can be obtained. The four-layer wiring patterns 15, 16, 25, and 35 are formed with high position accuracy.

Further, in the case of manufacturing a multi-layer printed wiring board, the above steps (preparation of metal foil-clad laminate for build-up, formation of through holes, lamination, and patterning of metal foil) may be repeated. FIG. 8 shows a 6-layer multilayer printed wiring board in which a metal foil-clad laminate is laminated on both sides of the 4-layer multilayer printed wiring board shown in FIG. 7 (2). The wiring patterns 26 and 36 of the outermost layer are formed by etching using an etching mask formed with reference to the common alignment hole 14a as in the wiring patterns 25 and 35. Therefore, the wiring patterns 26 and 36 are formed with high position 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, the 6-layer wiring patterns 15, 16, 25, 26, 35, 36 can be formed with high position accuracy.

The wiring patterns 26 and 36 extend in the direction perpendicular to the paper surface in FIG. In the present embodiment, the wiring patterns 26 and 36 may have different widths as long as the center lines are substantially the same.

As described above, according to the method for manufacturing a multilayer printed wiring board according to the present embodiment, the wiring pattern of each layer can be formed with high position 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. In the example of FIG. 8, since the lateral misalignment of the wiring patterns 15, 16, 25, 26, 35, 36 is small, the length between the cut line C1 and the cut line C2 can be shortened. Thereby, for example, a cable-shaped elongated printed wiring board can be easily manufactured.

The outer shape of the multilayer printed wiring board is processed by, for example, laser processing of an image alignment method. That is, the alignment hole 14a of the target mark 14 is recognized by the camera, the laser light source and the multilayer printed wiring board are aligned, and the outer shape is processed along the cut line. The cut line can be set at a position close to the wiring pattern within the processing accuracy of the laser.

According to this embodiment, since the wiring pattern of each layer is formed with reference to a common target mark, it is possible to prevent the accumulation of misalignment. Therefore, a multilayer printed wiring board whose outer shape processing end is close to the wiring pattern up to the square average value (for example, ± 27 μm) of the laser processing accuracy (for example, ± 25 μm) and the wiring pattern formation position accuracy (for example, ± 10 μm) is obtained. be able to.

As described above, according to the present embodiment, it is possible to bring the outer shape processed end closer to the wiring pattern as compared with the conventional method without applying a particularly expensive device.

In the example of FIG. 8, the region where the target mark 14 was formed was cut off during the outer shape processing, but the region may be left.

The above-mentioned method for manufacturing a multilayer printed wiring board is only an example, and various modifications may be made. For example, the execution order of the processing steps for each of the metal leaf-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.

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

Further, when the core base material 11 is made of a transparent material and the camera can see the target mark 14 through the insulating base material, the bottomed hole 17 does not have to be formed.

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

Further, the target mark 14 may be formed so as to include identification information of the multilayer printed wiring board manufactured by the above manufacturing method. For example, the target mark 14 may be formed in a shape such as a bar code or a two-dimensional code. This makes it possible to trace the multilayer printed wiring board from the initial process (processing of the metal leaf-clad laminate 10).

<Multilayer printed wiring board>
The multilayer printed wiring board manufactured by the method for manufacturing a multilayer printed wiring board according to the first embodiment has the following configuration.

As shown in FIG. 7 (2), the multilayer printed wiring board according to the present embodiment includes a core wiring board 1, a build-up wiring board 2 laminated on one main surface of the core wiring board 1, and a core wiring board. A build-up wiring board 3 laminated on the other main surface of 1 is provided.

The core wiring board 1 has a core base material 11 and a target mark 14 formed on the main surface 11a of the core base material 11 and provided with an alignment hole 14a. The build-up wiring board 2 has a build-up base material 21 and a wiring pattern 25 formed on the main surface 21a of the build-up base material 21. The build-up wiring board 3 has a build-up base material 31 and a wiring pattern 35 formed on the main surface 31a of the build-up base material 31.

The build-up wiring board 2 is laminated on the core wiring board 1 via the adhesive layer 23 so that the main surface 21b faces the main surface 11a of the core base material 11. The build-up wiring board 3 is laminated on the core wiring board 1 via the adhesive layer 33 so that the main surface 31b faces the main surface 11b of the core base material 11.

The core wiring board 1 is formed with a bottomed hole 17 that penetrates the core base material 11 in the thickness direction. The build-up wiring board 2 is formed with a through hole 24 that penetrates the build-up base material 21 in the thickness direction. The build-up wiring board 3 is formed with a through hole 34 that penetrates the build-up base material 31 in the thickness direction and communicates with the bottomed hole 17.

The alignment hole 14a of the target mark 14 is exposed on the bottom surface of the through hole 24 and is visible from the main surface 21a side of the build-up base material 21, and is exposed on the bottom surface of the bottomed hole 17 and is the main part of the build-up base material 31. It is also visible from the surface 31a side.

Further, as shown in FIG. 7 (2), the multilayer printed wiring board according to the present embodiment has wiring patterns 15, 16, 25, and 35 extending in the longitudinal direction of the multilayer printed wiring board in each layer. The positions of the wiring patterns 15, 16, 25, and 35 in the width direction orthogonal to the longitudinal direction are substantially the same when viewed in the thickness direction of the multilayer printed wiring board.

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

Hereinafter, the description of the overlapping portion with the first embodiment will be omitted as appropriate, and the second embodiment will be described focusing on the differences.

First, as shown in FIG. 9, after preparing the metal foil-clad laminate 10, the metal foil 12 is patterned to form the target mark 14 having the alignment holes 14a. Wiring patterns 15 and 16 are also formed in the same manner as in the first embodiment. However, in this embodiment, it is not necessary to form the bottomed hole 17.

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

Next, as shown in FIGS. 9 and 10 (1), the main surface 21b of the build-up base material 21 faces the main surface 11a of the core base material 11, and the alignment hole 14a is a through hole when viewed in the thickness direction. The metal foil-clad laminate 20 is laminated on the metal foil-clad laminate 10 via the adhesive layer 23 so as to be located inside the 24. After that, the laminated metal leaf-clad laminates 10 and 20 (laminated body) are heated and pressurized to be integrated. The adhesive layer 23 is cured by this step.

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

First, as shown in FIG. 10 (2), the dry film 41 is attached on the metal foil 22. As a result, the opening of the through hole 24 is covered with the dry film 41. Next, the alignment hole 14a is recognized from the outside of the laminated body through the dry film 41 with a camera (not shown). Then, the exposure mask is aligned based on the recognized position of the alignment hole 14a, and the exposure mask is placed on the dry film 41. After that, the dry film 41 is exposed and developed to form etching masks 41a and 41b as shown in FIG. 11 (1). Then, the metal foil 22 is etched using the etching masks 41a and 41b. As a result, the wiring pattern 25 is formed as shown in FIG. 11 (2).

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

Although the diameters of the through hole 24 and the through hole 34 are the same in FIG. 12, the diameter of the through hole 34 may be larger than the diameter of the through hole 24. As a result, even if some misalignment occurs when the metal foil-clad laminate 30 is laminated on the metal foil-clad laminate 20 in the subsequent process, the alignment hole 14a can be visually recognized from the outside through the through hole 34. can.

Next, as shown in FIGS. 12 and 13 (1), the main surface 31b of the build-up base material 31 faces the main surface 21a of the build-up base material 21, and the alignment hole 14a penetrates in the thickness direction. The metal foil-clad laminate 30 is laminated on the metal foil-clad laminate 20 via the adhesive layer 33 so as to be located in the hole 34. The through hole 34 is arranged so as to communicate with the through hole 24. After that, the laminated metal leaf-clad laminates 10, 20, and 30 are heated and pressurized to be integrated. The adhesive layer 33 is cured by this step.

Next, as shown in FIG. 13 (2), the metal foil 32 is patterned with reference to the alignment hole 14a of the target mark 14 to form the wiring pattern 35. The wiring pattern 35 is formed in the same manner as the wiring pattern 25.

Through the steps up to this point, as shown in FIG. 13 (2), a four-layer multilayer printed wiring board can be obtained. Since the four-layer wiring patterns 15, 16, 25, and 35 are formed with reference to the common alignment hole 14a, they are formed with high position accuracy.

By repeating the above steps, it is possible to further manufacture a multi-layer printed wiring board.

As described above, according to the method for manufacturing a multilayer printed wiring board according to the present embodiment, the wiring pattern of each layer can be formed with high position 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 method for manufacturing a multilayer printed wiring board according to the second embodiment has the following configuration.

As shown in FIG. 13 (2), the multilayer printed wiring board according to the present embodiment is laminated on the core wiring board 1, the build-up wiring board 2 laminated on the core wiring board 1, and the build-up wiring board 2. It also has a build-up wiring board 3.

The core wiring board 1 has a core base material 11 and a target mark 14 formed on the main surface 11a of the core base material 11 and provided with an alignment hole 14a. The build-up wiring board 2 has a build-up base material 21 and a wiring pattern 25 formed on the main surface 21a of the build-up base material 21. The build-up wiring board 3 has a build-up base material 31 and a wiring pattern 35 formed on the main surface 31a of the build-up base material 31.

The build-up wiring board 2 is laminated on the core wiring board 1 via the adhesive layer 23 so that the main surface 21b of the build-up base material 21 faces the main surface 11a of the core base material 11. The build-up wiring board 3 is laminated on the build-up wiring board 2 via an adhesive layer 33 so that the main surface 31b of the build-up base material 31 faces the main surface 21a of the build-up base material 21.

The build-up wiring board 2 is formed with a through hole 24 that penetrates the build-up base material 21 in the thickness direction. The build-up wiring board 3 is formed with a through hole 34 that penetrates the build-up base material 31 in the thickness direction and communicates with the through hole 24.

The alignment hole 14a of the target mark 14 is exposed on the bottom surface of the through hole 24 and is visible from the main surface 31a side of the build-up base material 31 (that is, from the outside of the laminate).

Further, as shown in FIG. 13 (2), the multilayer printed wiring board according to the present embodiment has wiring patterns 15, 16, 25, and 35 extending in the longitudinal direction of the multilayer printed wiring board in each layer. The positions of the wiring patterns 15, 16, 25, and 35 in the width direction orthogonal to the longitudinal direction are substantially the same when viewed in the thickness direction of the multilayer printed wiring board.

Based on the above description, those skilled in the art may be able to conceive of additional effects and various modifications of the present invention, but the embodiments of the present invention are not limited to the above-described embodiments. Various additions, changes and partial deletions are possible without departing from the conceptual idea and purpose of the present invention derived from the contents defined in the claims and their equivalents.

1 Core wiring board 2, 3 Build-up wiring board 10 Metal leaf-clad laminate 11 Core base material 11a, 11b Main surface 12, 13 Metal leaf 14 Target mark 14a Alignment hole 15, 16 Wiring pattern 17 Bottom hole 20, 30 Metal Foil-covered laminated board 21,31 Build-up base material 21a, 21b, 31a, 31b Main surface 22, 32 Metal leaf 23, 33 Adhesive layer 24, 34 Through hole 25, 26, 35, 36 Wiring pattern 41, 42 Dry film 41a, 41b, 42a, 42b Etching masks C1, C2 Cut lines

Claims (5)

A first metal having a core base material having a first main surface and a second main surface opposite to the first main surface, and a first metal foil formed on the first main surface. The process of preparing the foil-clad laminate and
A step of patterning the first metal foil to form a target mark having an alignment hole, and
A step of penetrating the core base material in the thickness direction to form a bottomed hole in which the alignment hole is exposed on the bottom surface.
After forming the bottomed hole, a process of mirroring the back surface of the metal foil constituting the target mark and a step of performing the process.
It has a first build-up base material having a third main surface and a fourth main surface opposite to the third main surface, and a second metal foil formed on the third main surface. The process of preparing the second metal leaf-clad laminate and
A step of forming a first through hole that penetrates the second metal leaf-clad laminate in the thickness direction, and
It has a second build-up base material 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. The process of preparing the third metal leaf-clad laminate and
A step of forming a second through hole that penetrates the third metal leaf-clad laminate in the thickness direction, and
The second metal leaf-clad laminate is provided so that the fourth main surface faces the first main surface and the alignment hole is located in the first through hole when viewed in the thickness direction. The step of laminating on the first metal leaf-clad laminate and
The third metal leaf-clad laminate is formed with the first metal foil so that the sixth main surface faces the second main surface and the second through hole communicates with the bottomed hole. The process of laminating on a stretched laminate and
A step of patterning the second metal leaf and the third metal foil with reference to the alignment hole of the target mark to form a first wiring pattern and a second wiring pattern, respectively.
A method for manufacturing a multilayer printed wiring board, which comprises. The method for manufacturing a multilayer printed wiring board according to claim 1 , wherein the core base material is made of a liquid crystal polymer or polyimide. The method for manufacturing a multilayer printed wiring board according to claim 1 or 2 , wherein the diameter of the second through hole is larger than the diameter of the bottomed hole. The multilayer printed wiring board according to any one of claims 1 to 3 , wherein the core base material, the first build-up base material, and the second build-up base material have flexibility. Production method. It has a core base material having a first main surface and a second main surface opposite to the first main surface, and a target mark formed on the first main surface and provided with an alignment hole. With the core wiring board
It has a first build-up base material having a third main surface and a fourth main surface opposite to the third main surface, and a first wiring pattern formed on the third main surface. The first build-up wiring board and
It has a second build-up base material 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. With a second build-up wiring board,
The first build-up wiring board is laminated on the core wiring board via an adhesive layer so that the fourth main surface faces the first main surface.
The second build-up wiring board is laminated on the core wiring board via an adhesive layer so that the sixth main surface faces the second main surface.
The core wiring board is formed with a bottomed hole that penetrates the core base material in the thickness direction.
The first build-up wiring board is formed with a first through hole that penetrates the first build-up base material in the thickness direction.
The second build-up wiring board is formed with a second through hole that penetrates the second build-up base material in the thickness direction and communicates with the bottomed hole.
The alignment hole is exposed on the bottom surface of the first through hole and is visible from the third main surface side, and is also exposed on the bottom surface of the bottomed hole and is visible from the fifth main surface side. der is,
A multilayer printed wiring board characterized in that the target mark exposed on the bottom surface of the bottom hole is mirror-finished.

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