JP2003008231A - Metal foil for electrical interconnection formation, circuit board using the same and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure stability of the connection resistance of an electrical interconnection for a long period. SOLUTION: The metal foil for electrical interconnection formation is used to form the electrical interconnection, which is formed on an insulator layer 11 or between insulator layers 11. A surface treatment layer 3A and a surface treatment layer 3B whose characteristic has been set are formed respectively on both faces of the foil, so as to be adapted to a relative positional relationship between the insulator layer 11 and each foil face. The foil face, which requires adhesive property and rust preventing property, selectively exhibits its characteristics, and the foil face which requires an electrical continuity property selectively displays its characteristics. Consequently, the circuit board of high reliability is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal foil for forming electric wiring used in various electronic devices, a circuit board using the same, and a method for manufacturing a circuit board.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become smaller, lighter and more sophisticated, circuit boards have been required to have smaller size, lighter weight, higher speed signal processing, and higher density packaging.
Circuit boards that meet such demands require multi-layering, via-hole diameter reduction, and circuit fine-tuning technology. These requirements are no longer required for conventional multi-layer boards that have an electrical connection between layers due to the through-hole structure. Was extremely difficult to satisfy. Therefore, a circuit board having a new structure has been developed, and in terms of materials, not only a conventional glass base material but also a circuit board using a base material or a film made of an organic fiber has been developed.

As a typical example thereof, instead of the through-hole structure which has been the mainstream of the conventional interlayer connection of circuit boards, a complete IV in which the interlayer connection is secured by a conductive paste.
A circuit board having an H structure (Japanese Patent No. 2601128) has been developed. This circuit board has an aramid-
A composite material such as epoxy resin is used,
Utilizing the advantages of low thermal expansion, low dielectric constant, and light weight, it is used in many electronic devices that require downsizing and weight reduction.

[0004]

However, with higher density and higher reliability, it is required for the metal foil for forming electric wiring to make the wiring layer of the circuit board finer and to ensure high reliability. , It was necessary to ensure the long-term stability of the connection resistance of the circuit board.

An object of the present invention is to secure stability of connection resistance of electric wiring for a long term.

[0006]

In order to solve the above-mentioned problems, according to the present invention, an electric wiring forming metal foil used for forming electric wiring provided on or between insulating layers is used. Therefore, it is characterized in that a surface treatment layer having characteristics set according to the relative positional relationship between the insulating layer and each foil surface is provided on each of both sides of the foil.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The invention according to claim 1 of the present invention is an electric wiring forming metal foil used for forming an electric wiring provided on an insulating layer or between insulating layers. A surface treatment layer having characteristics set according to the relative positional relationship between the insulator layer and each foil surface is provided on each of both foil surfaces, which has the following effect.

On each foil surface, the required characteristics differ depending on the relative positional relationship with the insulating layer. For example, a metal foil (or a wiring layer obtained by patterning a metal foil) is attached to the entire surface of the insulating layer, a through hole for interlayer connection is formed in the insulating layer, and a conductive paste is further formed in the formed through hole. Circuit, by adhering another metal foil (or a wiring layer obtained by patterning the metal foil) to the other surface of the insulator layer and then thermocompression bonding the metal foil and the insulator layer. Consider the case of forming a substrate.

In this case, when the through hole for interlayer connection is formed in the insulator layer, the foil surface located on the side exposed at the bottom of the hole (one surface side of the insulator layer) is the same as the through hole formation. It is possible to remove the surface treatment layer exposed at the bottom of the through hole. Therefore, there is no problem even if the surface treatment layer provided on this foil surface is thickened by containing a large amount of a component that enhances adhesiveness and rust prevention.

On the other hand, on the foil surface located on the side contacting the top of the conductive paste (the other surface side of the insulating layer), the area of the surface treatment layer contacting the conductive paste is selectively removed. It is not possible. Therefore, if the surface treatment layer formed on the foil surface contains a large amount of a component that enhances the adhesiveness and the rustproof property and the thickness thereof becomes large, the electrical conductivity of the electrical wiring is adversely affected. Therefore, in the surface treatment layer formed on this foil surface, it is more suitable to reduce the content of the component that enhances the adhesiveness and the rust preventive property as much as possible to reduce the thickness.

As described above, in the metal foil for forming an electric wiring having the surface treatment layers on both sides, the characteristics required for the surface treatment layers provided on the respective foil surfaces depend on the relative positions of the respective foil surfaces and the insulating layer. Is different. In consideration of this, according to the present invention, the characteristics of the surface treatment layer provided on the foil surface are made different according to the relative position of the foil surface and the insulating layer, thereby forming an electric wiring having excellent characteristics. It is possible. As a result, a surface treatment layer suitable for the adhesive surface and the rust preventive effect is provided on the foil surface, and the adhesive surface and the rust preventive effect are minimal on the foil surface where the electrical conductivity is prioritized. It is possible to provide a surface treatment layer that preferentially exhibits electrical conductivity.

In order to exert such an effect, the present invention provides that, as described in claim 2, one of the surface treatment layers has an adhesive property with the insulating layer and / or
Alternatively, it is preferable that the layer has a property in which rust prevention is prioritized, and the other surface treatment layer is a layer in which the electric conductivity at the time of interlayer connection of electric wiring is prioritized.

Further, specifically, the surface treatment layer is preferably made of a metal compound as described in claim 3. Further, in this case, as described in claim 4, one of the surface-treated layers contains Ni to give priority to adhesion and / or rust prevention with the insulator layer. A layer having characteristics, and the other surface treatment layer may be a layer having characteristics that prioritize electrical conductivity at the time of interlayer connection of electric wiring by not containing Ni.

Further, a method for manufacturing a circuit board is constructed by using the metal foil for forming an electric wiring of the present invention to electrically connect the electric wiring provided on both surfaces of the insulating layer through a via provided in the insulating layer. In this case, as described in claim 7, a step of preparing the electrical wiring forming metal foil according to any one of claims 2 to 4 as the electrical wiring forming metal foil, and the one surface treatment. A layer in the direction of abutting the insulator layer, a step of adhering the metal foil to one surface of the insulator layer, and a through hole reaching the metal foil from the other surface of the insulator layer, A step of forming an insulating layer, a step of selectively removing the one surface treatment layer exposed at the bottom of the through hole, a step of filling the through hole with a conductive paste,
Another metal foil, a step of adhering the other surface treatment layer to the other surface of the insulator layer in a state where the other of the surface treatment layer is opposed to the insulator layer, and heating and pressing the insulator layer, It is preferable to include a step of integrating the insulator layer and the metal foil and changing the conductive paste into vias.

Further, in this case, as described in claim 8, an electric wiring layer is adhered on a supporting base material instead of the metal foil, and the supporting base material contact surface has: Using the one provided with one of the surface treatment layers on the back surface of the support base contact surface while providing the other of the surface treatment layers, and sticking this electric wiring layer to the insulator layer. The method of manufacturing a circuit board can also be configured with.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing the structure of a metal foil 1 for forming an electric wiring of the present invention. In FIG. 1, 2 is a metal foil body, 3A and 3B are surface treatment layers. The electric wiring forming metal foil 1 shown in FIG. 1 is configured by providing surface treatment layers 3A and 3B having different treatment states on the front and back surfaces of a metal foil main body 2. The surface treatment layer 3A is a treatment layer that exhibits adhesiveness and / or rust prevention. On the other hand, the surface treatment layer 3B is a treatment layer that preferentially exhibits electrical conductivity rather than adhesiveness and rust prevention.

FIG. 2 is a sectional view showing the structure of the multilayer circuit board 10 of the present invention. In FIG. 2, reference numeral 11 is an insulating layer which is laminated and arranged. Reference numeral 12 is a wiring layer provided between the surface of the outermost insulating layer 11 and the interlayer of the intermediate insulating layer 11.

Reference numerals 3A and 3B denote surface treatment layers provided on the front and back surfaces of the wiring layer 12, respectively. In each wiring layer 12, the surface treatment layers 3A and 3B are formed to have different properties. Specifically, the surface treatment layer 3A is a treatment layer that exhibits high adhesive strength and rust prevention. On the other hand, the surface treatment layer 3B is a treatment layer that preferentially exhibits electrical conductivity rather than adhesive strength and rust prevention. 13 is
It is a via for interlayer connection that is provided so as to penetrate in the thickness direction of the insulator layer 11.

The multilayer wiring board 10 is constructed by alternately laminating the insulating layers 11 and the wiring layers 12 and connecting the wiring layers 12 to each other through the vias 13. The wiring layer 12 is formed by patterning the electric wiring forming metal foil 1 shown in FIG.

Next, a method of manufacturing a circuit board embodying the present invention will be described in detail with reference to FIG.

First, as shown in FIG. 3 (a), a metal foil 1 for forming an electric wiring made of a copper foil or the like is attached onto a supporting base material 20 made of an aluminum foil or the like. In the present invention,
As the metal foil 1, one having surface treatment layers 3A and 3B having different properties from each other is used as shown in FIG. Specifically, the surface treatment layer 3A is a treatment layer that exhibits high adhesiveness and high rust resistance, and the surface treatment layer 3B is
This is a treatment layer that preferentially exhibits electrical conductivity rather than adhesive strength and rust prevention. Then, the surface treatment layer 3B is attached to the supporting base material 20.
The metal foil 1 for forming an electric wiring is attached to the supporting base material 20 in a state of being brought into contact with.

Next, as shown in FIG. 3B, the metal foil 1
Is patterned by a well-known photolithography process or the like to form the wiring layer 12A. Thus, first, the wiring layer 12A is formed on the supporting base material 20. The metal foil 1 is selectively patterned due to the difference in etching rate from the support base material 20.

Next, as shown in FIG. 3C, an insulator layer 11 is prepared, a release film 21 is laminated on one surface of the insulator layer 11, and then the wiring layer 12A is formed on the insulator layer 11. Stick on layer 11. At this time, the surface 11a of the insulator layer 11 on which the release film 21 is not laminated is opposed to the wiring layer 12A. As a result, the surface treatment layer 3A is brought into surface contact with the insulator layer 11.

Next, as shown in FIG. 3D, a through hole 14 is formed in the insulating layer 11 by using a laser processing method or the like. The through hole 14 is formed after being aligned so as to reach the wiring layer 12A. When forming the through hole 14, the surface treatment layer 3A on the wiring layer 12A located at the bottom of the through hole is selectively removed. The removal of the surface treatment layer 3A may be performed by laser processing performed at the time of forming the through holes, or may be performed separately by dry etching. If the surface treatment layer 3A is removed together with the formation of the through holes, it is possible to reduce the number of steps and shorten the manufacturing time and the manufacturing cost.

Then, the through-hole 14 formed as described above is filled with a conductive paste 15 as shown in FIG. 3 (e). After the conductive paste 15 is filled, the release film 21 is peeled off as shown in FIG.

With respect to the insulating layer 11 filled with the conductive paste from which the release film 21 has been peeled off, the insulating layer 11 shown in FIG.
The metal foil 1 is attached as shown in (g). The metal foil 1 attached here is the same as the metal foil 1 used in the step of FIG. At this time, the metal foil 1 is attached to the surface of the insulating layer 11 from which the release film 21 is peeled off in a state where the surface treatment layer 3B is attached to the insulating layer 11. And
The insulator layer 11 to which the metal foil 1 is attached is subjected to press-pressure heating treatment to be integrated. At this time, the conductive paste 15 is simultaneously heated and pressed to form the conductive paste 15 as the via 16 for interlayer connection.

Further, as shown in FIG. 3H, the wiring layer 12B is formed by patterning the metal foil 1 by a well-known photolithography process or the like.

Next, the thus-formed insulating layer 11 with a wiring layer (with the supporting base material 20) is treated in the same manner as the wiring layer with a supporting base material in FIG. ) ~
Each step shown in FIG. 3 (h) is sequentially repeated a predetermined number of times, and the supporting base material 20 is finally removed by etching or the like to obtain the multilayer circuit board shown in FIG. 2 having an arbitrary number of layers.

The above is the basic structure of the method for manufacturing a circuit board (multilayer circuit board) using the metal foil of the present invention. In each of the embodiments of the present invention, the metal foil (specifically, copper foil) shown in Table 1 was used in the above manufacturing method.

[0031]

[Table 1]

(Embodiment 1) In the present embodiment, the basic manufacturing method described above has the following features. A polyimide film is used as the insulator layer 11. -Copper foil is used as the metal foil 1. As the surface treatment layer 3A on the surface side, as shown in Table 1,
Each film of Ni, Zn, and Cr is laminated on the surface of the metal foil 1 (non-contact surface of the via). Here, each film is made of Ni: Zn: C.
The thickness is set to r = 10: 10: 1 (weight ratio).
It should be noted that each film has a porous shape, the components of each film are mixed with each other at the boundary of each film, and a strict interface does not exist. Such a characteristic of the surface treatment film 3A is also possessed similarly in the surface treatment film 3B described below. As the surface treatment layer 3B on the back side, as shown in Table 1,
A film made of Ni: Zn: Cr = 0: 10: 1 (weight ratio) is formed on the back surface (via contact surface) of the metal foil 1. here,
It should be noted that the surface treatment layer 3B is not formed with a Ni film, so that the characteristics of the layer are different from those of the surface treatment layer 3A and the thickness of the layer is thin. . The through hole 14 is formed by a laser processing method or the like, but at that time, the surface treatment layer 3A at the bottom of the through hole 14 is not actively removed. As the conductive paste 15, epoxy resin containing copper powder is used.・ The condition of the heating and pressurizing treatment in FIG.
C., 150 kg / cm ² , 1 hour.

(Embodiment 2) In this embodiment, basically, a multilayer circuit board is formed under the same conditions as in Embodiment 1, except for the following points. -As shown in Table 1, as the surface treatment layer 3A on the surface side,
A film made of Ni: Zn: Cr = 5: 5: 1 (weight ratio) is formed on the metal foil 1. Here, it should be noted that, in the second embodiment, the thickness of the Ni layer in the surface treatment layer 3A is set to about half the weight ratio in comparison with the first embodiment. The point is that the thickness of 3A as a whole is slightly reduced.

(Third Embodiment) In this embodiment, a multilayer circuit board is basically formed under the same conditions as in the first embodiment, except for the following points. The through hole 14 is formed by a laser processing method or the like, and the surface treatment layer 3A at the bottom of the through hole 14 is positively removed at that time.

(Embodiment 4) In this embodiment, a multilayer circuit board is basically formed under the same conditions as in Embodiment 2, except for the following points. The through hole 14 is formed by a laser processing method or the like, and the surface treatment layer 3A at the bottom of the through hole 14 is positively removed at that time.

In addition to the embodiments of the present invention described above,
Comparative examples 1 and 2 which fall outside the scope of the present invention will also be described.

Comparative Example 1 In this comparative example, basically,
A multilayer circuit board is formed under the same conditions as in the first embodiment, but is different from the present invention except for the following points. As the surface treatment layer 3B ′ on the back surface side, as shown in Table 1, the same film as the surface treatment layer 3A on the front surface side of Ni: Zn: Cr = 10: 10: 1 (weight ratio) is formed on the metal foil 1. It is formed on the back surface (via contact surface).

(Comparative Example 2) In this comparative example, basically,
A multilayer circuit board is formed under the same conditions as in the third embodiment, but is different from the present invention only in the following points. As the surface treatment layer 3B ′ on the back surface side, as shown in Table 1, the same film as the surface treatment layer 3A on the front surface side of Ni: Zn: Cr = 10: 10: 1 (weight ratio) is formed on the metal foil 1. It is formed on the back surface (via contact surface).

As described above, the Ni film forming the surface treatment layer 3A formed on the surface side of the metal foil 1 is different in film thickness between the first embodiment and the second embodiment (2 in weight ratio). 1) The points are different.

Further, the first and third embodiments are different from each other.
Although the surface treatment layers 3A and 3B have the same composition, the surface treatment layer 3A at the bottom of the through hole is not removed (Embodiment 1) and is removed (Embodiment 3). Similarly, the second embodiment and the fourth embodiment are
Although the surface treatment layers 3A and 3B have the same composition, the surface treatment layer 3A at the bottom of the through hole is not removed (Embodiment 1) and is removed (Embodiment 3).

Although Comparative Example 1 is similar to the first embodiment, the composition of the surface treatment layer 3B on the back surface side is the same as the composition of the surface treatment layer 3A on the front surface side, and this point is an embodiment. 1, which is outside the scope of the present invention.

Comparative Example 3 is similar to the third embodiment, but the composition of the surface treatment layer 3B on the back surface side is the same as the composition of the surface treatment layer 3A on the front surface side, and this point is the same as the embodiment mode. 3, which is outside the scope of the present invention.

Table 2 shows the results of the connection reliability evaluation (PCT test, solder reflow resistance test, popcorn test) of the circuit boards obtained in Embodiments 1 to 4 and Comparative Examples 1 and 2.

The PCT test is 121 ° C./2 at
In this method, the connection resistance is measured before and after the test object is put in the environment of m for 300 hours, and the connection reliability is tested by the resistance change rate.

The solder reflow resistance test is a reflow treatment of 260 ° C./30 seconds in which the test object is exposed by a normal solder reflow, and the connection resistance before and after repeatedly charging the test object 10 times (10 cycles) is measured, This is a method of testing the connection reliability based on the rate of change in resistance.

In the popcorn test, the connection resistance is measured before and after the reflow treatment (260 ° C./30 seconds) is carried out after the test object is put in an environment of temperature 85 ° C./humidity 85% for 168 hours, and the rate of change in resistance is measured. This is a method for testing connection reliability. The connection resistance was measured at 3456
A (manufactured by Hewlett-Packard Co.) was used for measurement by the 4-terminal method.

[0047]

[Table 2]

As is clear from Table 2, in the circuit board using the metal foil of the present invention, the adhesive force and the rust preventive property are enhanced on the foil surface where the contribution to the interlayer adhesiveness and the rust preventive property is prioritized. The surface treatment layer 3A is provided in which the components are contained in a relatively large amount and the thickness thereof is slightly thicker. On the other hand, the surface of the foil, which is prioritized for its contribution to electrical conductivity, does not contain much components that enhance the adhesive strength and rust resistance, and the surface treatment is improved by reducing the thickness and improving the electrical conductivity. A layer 3B is provided. This makes it possible to provide a highly reliable circuit board. The details will be described below.

The surface treatment layers 3A and 3B are provided for adhering the insulating layers 11 to each other, and therefore, adhesiveness and rust prevention are required. However, the surface treatment layer 3
Since A and 3B are also present in connection sites such as interlayer connection sites (wiring layers 12A and 12B and vias 16), electrical conductivity can be reduced in the processing layer region located in the connection sites. It is also required not to block.

On the other hand, the circuit board manufacturing method of the present invention is characterized in that the surface treatment layer 3B located at the bottom of the through hole 14 is selectively removed. However, after filling the conductive paste 15, the insulating layer 1
In the wiring layer 12B provided in No. 1, the surface treatment layer 3B contacting the conductive paste 15 cannot selectively remove the region related to the interlayer connection.

For the above reasons, each wiring layer 12
In the metal foil 1 constituting A and 12B, the surface treatment layer 3A provided on one foil surface located on the side exposed to the bottom of the through hole 14 contributes to the realization of good interlayer connection. Also, it is required to contribute to the realization of high adhesiveness and rustproofness between the insulating layers 11.
On the other hand, in the surface treatment layer 3B provided on the other foil surface of the metal foil 1 located on the side abutting on the top of the conductive paste 15, the insulating layers 11 have high adhesive strength and rust preventive property. In addition to contributing to the realization, it is required to contribute to the realization of good interlayer connection.

On the other hand, among the components constituting the surface treatment layers 3A and 3B, Ni plays an important role in exerting the adhesiveness and the rust preventive property. When the thickness of the treatment layer is increased, the electrical conductivity of the surface treatment layer may deteriorate. Furthermore, N
i is a component that is a rather inhibiting factor in maintaining electrical conductivity.

Therefore, in each of the first to fourth embodiments of the present invention, in the surface treatment layer 3A in which high adhesiveness and rust prevention are preferentially required, the thickness of the treatment layer becomes large (thus electrical conductivity). Ni is contained without any fear of becoming worse. On the other hand, in the surface treatment layer 3B where good electrical conductivity is preferentially required, N
By eliminating the content of i, the electrical conductivity is increased, and at the same time, the thickness of the treatment layer is reduced, and the electrical conductivity is increased by that amount. Furthermore, even in the surface-treated layer 3A that is required to have high adhesiveness and rust prevention, by adjusting the Ni content, it is possible to adjust the Ni content and reduce the thickness of the treated layer to obtain almost no adhesive strength. The electrical conductivity is improved without dropping.

The surface treatment layers 3A and 3B as described above
The measurement result of each embodiment in which the component adjustment is performed will be described in detail. In the first embodiment, in the surface treatment layer 3A,
By maintaining the adhesive strength by containing Ni, and by not containing Ni in the surface treatment layer 3B, N
The electrical conductivity between the layers is enhanced by the effect of no i and the effect of thinning the processing layer. As a result, the change rate of the connection resistance value is 5 in the PCT test and the popcorn test.
In the solder reflow resistance test, the good result that the rate of change of the connection resistance value is less than 3% was obtained.

In addition to the structure of the first embodiment, the through hole 14
In the third embodiment in which the electrical conductivity is enhanced by removing the surface treatment layer 3A at the bottom of the through hole when forming the PCT,
The change rate of the connection resistance value is 5% to 3% in the test, and the change rate of the connection resistance value is less than 3% in the popcorn test and the solder reflow resistance test. It was

Further, in the surface treatment layer 3A, the loading amount of Ni is adjusted (slightly reduced (weight ratio 10 →
5)), in Embodiments 2 and 4 in which the adhesiveness and the rust preventive property are exhibited, and the electrical conductivity is improved by reducing the thickness of the treatment layer, the change of the connection resistance value is performed in all the tests. The rate is less than 3%, which is a better result than in the first and third embodiments. In this case, in particular, the above results were obtained in the second embodiment, which is an example in which the surface treatment layer 3A at the bottom of the through hole is not removed when forming the through hole 14.
It shows how the adjustment of the components of the surface treatment layer (including the adjustment of the thickness) is effective in achieving both good adhesion, rust prevention and electrical conductivity, which is noteworthy.

On the other hand, in Comparative Examples 1 and 2, PCT
In the test and the popcorn test, the change rate of the connection resistance value was 10% or more, which was significantly inferior to those of the first to fourth embodiments of the present invention.

In the present invention, the surface treatment layer 3
A and 3B are metal oxide forming layers (Ni, Zn, Cr).
Other than the above), a roughening treatment layer, an organic compound forming layer, a coupling agent treatment layer, etc. can be preferably used. In short, as the surface treatment layer 3A, a treatment layer having a component that contributes to high adhesive strength is provided,
As the surface treatment layer 3B, a treatment layer that preferentially exhibits better electrical conductivity than adhesive strength may be provided, but the composition thereof is not particularly limited.

As the metal foil 1, known metal foils such as stainless foil, aluminum foil, nickel foil and the like can be used in addition to copper foil.

Further, as a method of removing the surface treatment layer 3A at the bottom of the through hole, a removal method by laser irradiation after via processing is preferable, but the method is not limited to this, and dry etching using a halogen gas is preferable. Known chemical and physical methods such as

In the present embodiment, the conductive powder forming the conductive paste 15 is a metal powder such as copper powder, silver powder, nickel powder or aluminum powder, and powder having a coating layer made of the above metal. Is mentioned. The shape of the conductive powder may be any of resin, flake, sphere, and amorphous. Moreover,
Needless to say, a resin, an additive, or a solvent may be added to facilitate the filling of the through holes 14.

[0062]

As described above, according to the present invention, a surface treatment layer exhibiting such characteristics is provided on the foil surface requiring adhesiveness and rust prevention, while electrical conductivity is required. By providing a surface treatment layer exhibiting such characteristics on the foil surface, it has become possible to form highly reliable electrical wiring.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a metal foil for forming an electric wiring according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a configuration of a multilayer circuit board formed by using the electric wiring forming metal foil of the present invention.

FIG. 3 is a cross-sectional view showing the main part of the method for manufacturing the multilayer circuit board of FIG. DESCRIPTION OF SYMBOLS 1 Metal foil for electric wiring formation 2 Metal foil main body 3A, 3B Surface treatment layer 10 Multilayer circuit board 11 Insulator layers 12A, 12B Wiring layer 13 Via 14 Through hole 15 Conductive paste 16 Via 20 Support base material 21 Release film

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) // C22C 18/00 C22C 18/00 19/03 19/03 M (72) Inventor Daizo Ando Kadoma Osaka Prefecture 1006, Kadoma, Ichimaji, Matsushita Electric Industrial Co., Ltd. F term (reference) 4E351 BB01 DD04 DD54 DD55 GG09 5E343 AA07 BB24 BB44 BB67 DD56 EE53 GG20 5E346 AA15 CC32 FF18 HH40

Claims (8)

[Claims] 1. A metal foil for forming an electric wiring, which is used for forming an electric wiring provided on an insulating layer or between insulating layers, wherein the insulating layer and each foil surface are provided on both sides of the foil. A metal foil for forming an electric wiring, characterized in that a surface treatment layer having characteristics set according to a relative positional relationship with is provided. 2. The electric wiring forming metal foil according to claim 1, wherein one of the surface treatment layers has a property in which adhesiveness with the insulating layer and / or rust prevention is prioritized. A metal foil for forming an electric wiring, wherein the other one of the surface treatment layers is a layer having a property in which electric conductivity at the time of interlayer connection of electric wiring is prioritized. 3. The metal foil for forming an electric wiring according to claim 2, wherein the surface treatment layer is made of a metal compound. 4. The electric wiring forming metal foil according to claim 3, wherein one of the surface treatment layers contains Ni so that the adhesiveness and / or the rust preventive property with respect to the insulating layer is high. Characterized in that the other of the surface-treated layers is a layer having a property of giving priority to electrical conductivity during interlayer connection of electrical wiring by not containing Ni. Metal foil for forming electrical wiring. 5. A circuit board having two or more electric wiring layers stacked and an insulator layer for electrically insulating the electric wiring layers, wherein the electric wiring layers are any one of claims 1 to 4. A circuit board, which is obtained by patterning the metal foil for forming an electric wiring according to any one of 1. 6. The circuit board according to claim 5, wherein the circuit board has a via provided in the insulator layer for electrically connecting the electric wiring layers to each other. Characteristic circuit board. 7. A method of manufacturing a circuit board, comprising: electrically connecting wirings provided on both surfaces of an insulating layer to each other via vias provided in the insulating layer; A step of preparing a metal foil for forming an electric wiring according to any one of 1 to 4, and the metal foil on one surface of the insulator layer in a direction in which the one surface treatment layer is brought into contact with the insulator layer. The step of adhering, the step of forming a through hole reaching the metal foil from the other surface of the insulating layer in the insulating layer, and the one surface treatment layer exposed at the bottom of the through hole are selectively formed. And a step of filling the through-holes with a conductive paste, and another metal foil with the other of the surface treatment layers facing the insulator layer. A step of adhering to the surface, and heating and pressurizing the insulator layer, With integration of the edge layer and the metal foil, a step of changing the conductive paste in the via, method of manufacturing a circuit board, which comprises. 8. The method for manufacturing a circuit board according to claim 7, wherein an electric wiring layer is attached on a supporting base material instead of the metal foil, and the supporting base material contact surface has an electric wiring layer. , The other of the surface treatment layer is provided, and the one having the one of the surface treatment layers is provided on the back surface of the supporting substrate contacting surface, and the electric wiring layer is attached to the insulator layer. A method of manufacturing a circuit board, comprising: