JP2004087697A - Method for manufacturing wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a wiring board having high reliability to be easily manufactured by accurately forming a fine wiring pattern. <P>SOLUTION: A method for manufacturing the wiring board includes the steps of covering the surface of a base material 12 having an electric insulation with a copper foil 30 with a copper carrier with which the carrier 30b at the base material side is releasably covered with a copper foil 30a, perforating holes at the material 12 covered with the foil 30 with the carrier, plating the material 12 and the foil 30, forming a plating film 18 on an inner surface of a through hole 16 and the surface of the foil 30 with the carrier, then releasing the carrier 30b together with the film 18 with which the foil 30 is covered from the foil 30a, etching the foil 30a with which the surface of the material 12 is covered in a predetermined pattern, and forming a wiring pattern 20 on the surface of the material. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a wiring board, and more particularly, to a method for manufacturing a wiring board using a copper foil with a copper carrier.
[0002]
[Prior art]
On a wiring board on which a semiconductor element is mounted to form a semiconductor device, a multi-layered wiring layer is formed via a two-layer wiring board in which wiring layers are formed on both surfaces of a resin substrate and an insulating layer having electrical insulation properties. There are products.
FIG. 5 shows a method generally used as a method of manufacturing a wiring board in a case where wiring patterns formed on both surfaces of a resin substrate are electrically connected through through holes and the wiring pattern is formed by a subtractive method. Show. In this manufacturing method, as shown in FIG. 5A, a wiring board is formed using a double-sided copper-clad board 10 in which copper foil 14 is adhered to both sides of a core material 12 made of resin.
[0003]
FIG. 5B shows a state in which a through hole 16 is formed in the double-sided copper-clad substrate 10 by drilling or laser processing. FIG. 5C shows a state in which the substrate in which the through hole 16 is formed is formed by electroless copper plating. This shows a state in which electrolytic copper plating (panel plating) has been performed. By performing panel plating with copper, a copper layer 18 is formed on the inner surface of the through hole 16 and the surface of the copper foil 14 attached to the surface of the core material 12. FIG. 5D shows a state in which the copper layer 18 and the copper foil 14 are etched by a subtraction method to form a wiring pattern 20, and a two-layer wiring board is obtained. The wiring patterns 20 on both surfaces of the substrate are electrically connected by a copper layer 18 formed on the inner surface of the through hole 16.
[0004]
[Problems to be solved by the invention]
In the above-described method of manufacturing a wiring board, since the conductor pattern in which the copper layer 18 is formed on the surface of the copper foil 14 is etched by panel plating with copper to form the wiring pattern 20, it is an object to be etched. The thickness of the conductor layer increases, and it becomes difficult to form the wiring pattern 20 in a fine pattern. Further, when the substrate is subjected to panel plating, the plating tends to be thinner at the periphery of the opening of the through hole 16, and cracks occur in the copper layer 18 provided on the inner surface of the through hole 16 from this portion. Sometimes. In addition, fine projections may be formed on the surface of the plating layer during panel plating, and if such projections are formed in the wire bonding portion, the bonding strength may be reduced, and the cause of disconnection of the wiring pattern may be caused. There is a problem that becomes.
[0005]
As a method for solving such a problem, as shown in FIG. 5E, after the substrate is subjected to panel plating (FIG. 5C), the through-hole 16 is filled with a resin 22, and the through-hole 16 is formed. There is a method in which the surface of the substrate is polished so as to leave the internal resin 22 (FIG. 5F), and then the copper foil 14 on the surface of the core material 12 is etched to form a wiring pattern. According to this method, when the resin layer 22 is polished and the copper layer 18 is polished and removed, the thickness of the conductor layer to be etched is reduced, so that a fine wiring pattern can be formed. By leaving the resin 22 inside the through-hole 16, the copper layer 18 inside the through-hole 16 is protected, and the wiring patterns formed on both sides of the substrate are reliably electrically connected by the copper layers 18 in the through-hole 16. Be connected.
[0006]
However, the process of filling the through holes 16 with the resin 22 and polishing both sides of the substrate is completely different from the operations such as plating and etching that are usually performed in the production process of the wiring substrate. There is a problem that the number of man-hours for manufacturing the device increases, the process becomes complicated, and the manufacturing cost increases. In addition, when the substrate is polished, there is a problem that the substrate is shrunk and deformed and the processing accuracy is reduced.
[0007]
Therefore, the present invention has been made to solve these problems, and an object of the present invention is to eliminate the need for complicated processing operations such as resin filling and polishing, and to easily manufacture a wiring board. In addition, another object of the present invention is to provide a method of manufacturing a wiring board capable of forming a fine wiring pattern with high accuracy and providing a highly reliable wiring board.
[0008]
[Means for Solving the Problems]
The present invention has the following configuration to achieve the above object.
That is, on the surface of a substrate having electrical insulation, a copper foil with a copper carrier that is removably coated with a copper foil on a copper carrier, the copper foil is applied with the copper foil as the base material side, and the copper with the copper carrier is coated. Drilling is performed on the base material on which the foil is adhered, plating is performed on the base material and the copper foil with the copper carrier, and the inner surface of the hole formed by the drilling process and the surface of the copper foil with the copper carrier are formed. After forming the plating film, the copper carrier is peeled off from the copper foil together with the plating film adhered to the copper foil with the copper carrier, and the copper foil adhered to the surface of the base material has a predetermined pattern. To form a wiring pattern on the surface of the substrate.
[0009]
As a drilling process to be performed on the base material on which the copper foil with the copper carrier is adhered, a via hole in which a wiring pattern formed on a lower wiring layer is exposed at the bottom is formed, and the base material and the copper foil with the copper carrier are formed. When plating is performed, a plating film is formed on the inner surface of the via hole and the surface of the copper foil with a copper carrier.
Further, when plating the base material and the copper foil with a copper carrier, the inside of the hole formed by the drilling is filled with a plating metal.
Further, when etching the copper foil to form a wiring pattern on the surface of the base material, forming a resist pattern covering a portion left as a wiring pattern on the surface of the copper foil adhered to the surface of the base material. The wiring pattern is formed by etching the copper foil using the resist pattern as a mask.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
The method for manufacturing a wiring board according to the present invention is characterized in that a wiring board is formed by using a copper foil with a copper carrier as a conductor material for forming a wiring pattern and electrically connecting the wiring patterns between wiring layers. And FIG. 1 shows an example of forming a two-layer wiring board in which wiring patterns are formed on both surfaces of a substrate. FIG. 1A shows a state in which a copper foil 30 with a copper carrier is applied to both surfaces of a core material 12 made of a resin such as glass or epoxy as a base material. In the conventional method of manufacturing a wiring board having a wiring pattern formed on both sides of the board, a double-sided copper-clad board 10 having copper foils 14 adhered to both sides of a core material 12 as shown in FIG. 5 is used. The present embodiment is characterized in that a copper foil 30 with a copper carrier is applied instead of the copper foil 14.
[0011]
The copper foil 30 with a copper carrier is obtained by supporting an extremely thin copper foil 30a with a copper carrier 30b, and the copper foil 30a and the copper carrier 30b are releasably bonded via a release layer. The thickness of the copper foil 30a of the copper foil 30 with a copper carrier is about several μm to about several tens μm, whereas the thickness of the copper carrier 30b is about 18 μm to 35 μm. Since the copper foil 30a and the copper carrier 30b are bonded via a release layer, the copper foil 30a is applied to the core material 12 by thermocompression bonding or the like with the copper foil 30a facing the core material 12, Only the copper carrier 30b can be peeled off from the copper foil 30 with a copper carrier, leaving only the copper foil 30a on the surface of the core material 12.
[0012]
FIG. 1B shows a state in which a through-hole 16 is formed in a substrate in which a copper foil 30 with a copper carrier is applied to both surfaces of the core material 12 by drilling or laser processing. After the drilling, a desmear process is performed to remove stains on the inner surface of the through hole 16.
FIG. 1 (c) shows that the inner surface of the through hole 16 is plated with electroless copper to form a plating power supply layer, and the inner surface of the through hole 16 with copper carrier is formed by electrolytic copper plating (panel plating). The copper layer 18 is formed as a plating film on the outer surface of the copper carrier 30b of the copper foil 30.
[0013]
FIG. 1D shows a characteristic process in the manufacturing process of the present embodiment, in which the copper carrier 30 b is peeled off and removed from the copper foil 30 with a copper carrier, leaving the copper foil 30 a on the surface of the core material 12. Is shown. As described above, the copper carrier 30b can be easily removed by peeling from the copper foil 30a. In this step, by removing the copper carrier 30b from the copper foil 30 with the copper carrier, the copper layer 18 attached to the outer surface of the copper carrier 30b is also removed at the same time, and only the copper foil 30a is formed on the surface of the core material 12. Is to remain. In this operation, the copper layer 18 adhered to the inner surface of the through hole 16 is broken at the end connected to the copper carrier 30b, and remains as it is adhered to the inner surface of the through hole 16; Electrical conduction between the copper layer 18 on the inner surface of the hole 16 and the copper foil 30a attached to the surface of the core material 12 is ensured.
[0014]
FIGS. 1E and 1F show a step of forming a wiring pattern 20 by etching a copper foil 30a remaining on the surface of the core material 12 into a predetermined pattern. In FIG. 1E, both surfaces of the substrate are covered with a photosensitive resist (photosensitive resin film), and the photosensitive resist is exposed and developed to form a resist pattern 32 covering a portion left as the wiring pattern 20. FIG. 1F shows a state in which the wiring pattern 20 is formed by etching the copper foil 30a using the resist pattern 32 as a mask.
[0015]
Thus, the wiring pattern 20 is formed on both surfaces of the substrate, and the wiring pattern 20 on both surfaces of the substrate is electrically connected by the copper layer 18 adhered to the inner surface of the through hole 16 penetrating the substrate in the thickness direction. Is obtained. The wiring patterns 20 formed on both sides of the substrate are configured to be connected only to the copper layer 18 covering the inner wall surface of the through hole 16 at the end face.
[0016]
According to the method for manufacturing a wiring board of the present embodiment, the inner surface of the through hole 16 is covered with the copper layer 18 by removing and removing the copper carrier 30b of the copper foil 30 with the copper carrier from the copper foil 20a. Accordingly, since only the copper foil 30a can be left on the surface of the core material 12, the wiring pattern 20 can be easily formed by etching the copper foil 30a left on the surface of the core material 12. Since the copper foil 30a of the copper foil 30 with a copper carrier is formed to be extremely thin and has a uniform thickness, a fine wiring pattern can be formed with extremely high precision. When the wiring pattern is formed with high precision with a fine pattern, it is extremely effective that the conductor layer is formed in such a uniform thickness. When the thickness of the conductor layer is controlled by polishing, the thickness of the conductor layer partially varies, so that the accuracy of forming the wiring pattern is reduced.
[0017]
Further, since the copper foil 30a is adhered to the surface of the core material 12 while being formed as the copper foil 30 with a carrier, the copper foil 30a is designed in advance to have a thickness required as a conductor layer for forming a wiring pattern. By doing so, a conductor layer having an optimum thickness for the wiring pattern to be formed can be formed, thereby making it possible to form a wiring pattern suitable for a product.
[0018]
In addition, the method for manufacturing a wiring board according to the present embodiment has an advantage that it is not necessary to perform complicated processing such as polishing, and the wiring board can be manufactured without using a complicated manufacturing process. In addition, since there is no processing step such as polishing that easily causes deformation such as shrinkage of the substrate, deformation of the substrate can be suppressed, and positional deviation of a through hole, which is a problem in forming a wiring pattern with high accuracy, can be reduced. Thus, a finer wiring pattern can be formed with high precision.
[0019]
FIG. 2 shows an example in which the through holes 16 provided in the substrate are filled with copper when performing panel plating with copper in the manufacturing process of the wiring substrate shown in FIG. FIGS. 2A and 2B show a state in which a through-hole 16 is formed in a substrate in which a copper foil 30 with a copper carrier is applied to both surfaces of a core material 12.
FIG. 2C shows that the inside of the through-hole 16 is filled with copper plating 18a as a plating metal by performing panel plating with copper, and the copper layer 18 as a plating film is formed on the surface of the copper foil 30 with a copper carrier. Indicates the status. FIG. 2D shows a state in which the copper carrier 30b of the copper foil 30 with a copper carrier is peeled off from the copper foil 30a and removed, leaving only the copper foil 30a on the surface of the core material 12, as in the above-described embodiment. Is shown.
[0020]
In the present embodiment, since the inside of the through hole 16 is filled with the copper plating 18a, when the copper carrier 30b is peeled off and removed from the copper foil 30 with a copper carrier, the copper filled in the through hole 16 is removed. Regarding the plating 18a, it is preferable that the copper carrier 30b be peeled off after partially removing the opening side in advance with a sharp blade, a water cutter, an air cutter, or the like.
When the copper carrier 30b is peeled off from the copper foil 30a, it is necessary to form a trigger for peeling the copper carrier 30b. However, the trigger is formed along an edge of the substrate that is not a final product. The copper foil 30 with a copper carrier may be formed by etching or cutting, and peeled off using the cut end of the copper carrier 30b as a trigger.
[0021]
2E and 2F, a resist pattern 32 is formed on the surface of the copper foil 30a adhered to the core material 12, and the copper foil 30a is etched by using the resist pattern 32 as a mask to form a resist pattern on both surfaces of the substrate. The state where the wiring pattern 20 is formed is shown. The wiring patterns 20 formed on both sides of the substrate are electrically connected via the copper plating 18a filled in the through holes 16.
When the through-hole 16 is filled with the copper plating 18a as in the present embodiment, the photosensitive resist (photosensitive resin film) formed by laminating on both surfaces of the substrate is formed such that the through-hole 16 is a through-hole. Since it is possible to use a thinner film than the resin film used when formed, fine patterning is possible by exposure and development, and even a fine wiring pattern can be formed with high precision. .
[0022]
In the wiring board obtained by the manufacturing method of the present embodiment, the through holes 16 formed in the board are filled with copper plating 18a, and the wiring patterns 20 formed on both sides of the board are formed of copper filled in the through holes 16. The connection is made only at the plating 18a and at its end face.
Also in the case of the present embodiment, the manufacturing process can be simplified and the wiring pattern can be formed with high accuracy, similarly to the method of manufacturing the wiring board shown in FIG. 1 described above.
[0023]
The method of forming a wiring board by electrically connecting wiring patterns between layers using a copper foil with a copper carrier is not limited to the above-described method of forming a two-layer wiring board. FIG. 3 shows an example in which a wiring board is formed in multiple layers using a copper foil with a copper carrier.
FIG. 3A shows a state in which an insulating layer 36 is formed as a base material on the lower wiring layer on which the wiring pattern 34 is formed. The insulating layer 36 can be formed by laminating a prepreg such as glass or epoxy on the wiring layer, or laminating an insulating film having electrical insulation such as a polyimide film. FIG. 3B shows a state in which the copper foil 30 with a copper carrier is attached to the surface of the insulating layer 36 by thermocompression bonding or the like with the copper foil 30a facing the insulating layer 36.
[0024]
FIG. 3C shows a state in which a via hole 38 for forming a via for electrically connecting a wiring pattern between layers is formed by punching the insulating layer 36. The via hole 38 can be formed by laser processing or the like so that the lower wiring pattern 34 is exposed on the bottom surface.
FIG. 3D shows that after forming a plating power supply layer on the inner surface of the via hole 38 by electroless copper plating or sputtering, electrolytic via plating (panel plating) is performed to fill the via hole 38 with copper plating 40a. In this state, the surface of the copper foil 30 with a copper carrier is covered with a copper layer 40 as a plating film.
In this state, by peeling the copper carrier 30b of the copper foil 30 with copper carrier from the copper foil 30a, the copper foil 30a can be left on the surface of the insulating layer 36 with the via holes 38 filled with the copper plating 40a. (FIG. 3E).
[0025]
FIG. 3F shows a state in which the wiring pattern 20 is formed by etching the copper foil 30a adhered to the surface of the insulating layer 36 by the subtraction method. The wiring pattern 20 is electrically connected to the lower wiring pattern 34 by the copper plating 40 a filled in the via hole 38. That is, the copper plating 40a serves as a via for electrically connecting the wiring pattern between the layers.
Also in the present embodiment, the copper carrier 30b of the copper foil 30 with a copper carrier is peeled off from the copper foil 30a, the copper foil 30a is left on the surface of the insulating layer 36, and the copper foil 30a is etched to form a fine wiring pattern. Even if there is, it can be formed with high precision.
[0026]
By repeating the above operation, it is possible to obtain a multilayer wiring board in which wiring patterns are electrically connected between layers by using the copper foil 30 with a copper carrier. In this embodiment, the electrolytic copper plating is performed so that the via hole 38 is completely filled with the copper plating 40a. However, a copper layer is formed on the inner bottom surface and the side surface of the via hole 38, and the copper layer is interposed. It is also possible that the wiring patterns are electrically connected between the layers.
[0027]
FIG. 4 shows still another embodiment in which a wiring board is formed using a copper foil with a copper carrier. For a multilayer wiring board having a wiring pattern in an inner layer, a copper carrier with a copper carrier is formed on the outermost surface of the board. A method for forming a wiring pattern using a foil will be described.
FIG. 4A shows a substrate in which a wiring pattern 42 and a via 44 are formed in an inner layer, and insulating layers 36a, 36b and 36c are stacked.
FIG. 4B shows a state in which copper foil 30 with a copper carrier is applied to both surfaces of the substrate by thermocompression bonding or the like, and a hole is formed in the substrate to form a through hole 46 penetrating the substrate in the thickness direction. Is shown.
FIG. 4C shows that the substrate is subjected to electroless copper plating and electrolytic copper plating (panel plating) to form a copper layer 48 on the inner surface of the through-hole 46 and a copper layer on the surface of the copper foil 30 with a copper carrier. 48 are formed.
[0028]
FIG. 4D shows a state in which the copper carrier 30b of the copper foil 30 with a copper carrier is peeled off from the copper foil 30a, and the copper layer 48 is applied to the inner surface of the through hole 46, and the copper foil 30a is left on both surfaces of the substrate. It is in the state as described above. FIG. 4E shows a state in which the copper foil 30a is etched by the subtraction method to form the wiring pattern 20 on the outermost surface of the substrate.
As described above, the wiring pattern can be easily and accurately formed by using the copper foil 30 with the copper carrier also for the multilayer wiring board in which the wiring pattern 42 is formed in the inner layer.
As described above, the method of forming the wiring board using the copper foil 30 with the copper carrier in each embodiment has been described. However, the copper foil 30 with the copper carrier is not limited to the usage example in the above embodiment, and may be used for various wiring boards. It can be used for manufacturing.
[0029]
【The invention's effect】
According to the method for manufacturing a wiring board according to the present invention, as described above, after a copper foil with a copper carrier is applied to a base material, the copper carrier is peeled off from the copper foil, so that a predetermined thickness is formed on the surface of the base material. Can be formed to a uniform thickness, and by etching this copper foil, it becomes possible to form even a fine wiring pattern with high precision. In addition, by performing drilling and plating with the copper foil with the copper carrier adhered to the base material, the wiring pattern can be reliably electrically conducted between the layers. Further, according to the present manufacturing method, the number of steps can be reduced, and a highly reliable wiring board can be manufactured by a simple method.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a method of forming a two-layer wiring board by a method of manufacturing a wiring board according to the present invention.
FIG. 2 is an explanatory view showing another method for forming a two-layer wiring board by the method for manufacturing a wiring board according to the present invention.
FIG. 3 is an explanatory view showing a method for forming a multilayer wiring board by the method for manufacturing a wiring board according to the present invention.
FIG. 4 is an explanatory view showing a method for forming a wiring board having a wiring pattern in an inner layer by the method for manufacturing a wiring board according to the present invention.
FIG. 5 is an explanatory view showing a conventional method for forming a two-layer wiring board.
[Explanation of symbols]
Reference Signs List 10 board 12 core material 14 copper foil 16 through hole 18 copper layer 18a copper plating 20 wiring pattern 20a copper foil 22 resin 30 copper foil with copper carrier 30a copper foil 30b copper carrier 32 resist pattern 34 wiring pattern 36, 36a, 36b, 36c Insulating layer 38 Via hole 40 Copper layer 40a Copper plating 42 Wiring pattern 46 Through hole 48 Copper layer

Claims (4)

On the surface of the substrate having electrical insulation, a copper foil with a copper carrier that is adhered to a copper carrier so that the copper foil can be peeled off, the copper foil is adhered as the substrate side,
The copper carrier-coated copper foil is subjected to a punching process on the adhered substrate,
After plating the base material and the copper foil with a copper carrier, after forming a plating film on the inner surface of the hole formed by the drilling process and the surface of the copper foil with the copper carrier,
The copper carrier is peeled off from the copper foil together with the plating film adhered to the copper foil with the copper carrier,
A method of manufacturing a wiring board, characterized by forming a wiring pattern on a surface of a base material by etching a copper foil applied on the surface of the base material into a predetermined pattern. As a drilling process to be performed on the substrate on which the copper foil with the copper carrier is adhered, a wiring pattern formed on a lower wiring layer is formed with a via hole that is exposed on the bottom surface,
2. The wiring board according to claim 1, wherein a plating film is formed on an inner surface of the via hole and a surface of the copper foil with the copper carrier when plating the base material and the copper foil with the copper carrier. Method. The method according to claim 1, wherein when plating the base material and the copper foil with a copper carrier, the inside of the hole formed by the drilling is filled with a plating metal. 4. Method. When etching the copper foil to form a wiring pattern on the surface of the substrate,
Forming a resist pattern covering a portion to be left as a wiring pattern on the surface of the copper foil adhered to the surface of the base material,
4. The method according to claim 1, wherein a wiring pattern is formed by etching the copper foil using the resist pattern as a mask.

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