JP2000068620A - Circuit board and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve the connection reliability of a circuit board connected to an inner buyer hole (IVH) and to make a fine wiring pattern. SOLUTION: The interface between the conductive composition 3 of the wiring pattern 3 electrically connected to the conductive composition 2 filled in the through hole of the insulator layer 1 is compared with the interface with the insulator layer 1. To roughen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a circuit board and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, as electronic devices have become more sophisticated and smaller, circuit boards have been required to have higher multilayers and higher densities.
Higher densification is achieved by inner buyer hole (IVH) connection as an interlayer connection method of a substrate that can couple ICs and components with the shortest distance.

[0003] A multi-layer substrate for IVH connection is formed by connecting a circuit board connecting material such as a prepreg in which a conductive resin composition (for example, a paste-like material, ie, a conductive paste) is filled into a via, to a copper foil for forming a pattern. Alternatively, it is manufactured by laminating on a core material on which a pattern has been formed in advance and heating / pressing by a method such as hot pressing.

As the conductive paste, a synthetic resin binder such as an epoxy resin in which a conductive filler such as copper powder is dispersed is used. The conductive paste is formed at a desired position of a prepreg having release films on both sides. The through holes are filled by printing or the like.

[0005] In the heating / pressing step, the binder in the conductive paste adheres the conductive filler to the copper foil for forming a circuit, develops mechanical strength, and provides a mechanical contact between the conductive filler and the copper foil. To obtain an IVH connection.

[0006]

However, in the conventional IVH connection technique described above, since the conductive filler and the copper foil are only in point contact, the reliability of the electrical connection is insufficient. there were. Specifically, LSI
For semiconductor packages or modules (MC
M, CSP, etc.), the reliability required for the circuit board, for example, the pressure cooker test (PCT),
At the interface between the conductive composition and the copper foil in the via, the connection resistance becomes high, and in the worst case, there is a problem that disconnection occurs.

[0007] The reliability of the IVH connection is the most important in the performance of the multi-layer substrate, and the use of the IVH connection resin multi-layer substrate which can achieve a high density and can be reduced in weight for a semiconductor package or a module is required. The improvement was strongly demanded.

An object of the present invention is to solve the above-mentioned conventional problems and to provide a circuit board for realizing a circuit board having high reliability in IVH connection and a method for manufacturing the same.

[0009]

The present invention has the following configuration to achieve the above object.

[0010] A circuit board according to a first configuration of the present invention is formed on both sides of an insulator layer having a through hole, a conductive composition filled in the through hole, and the insulator layer. And a wiring pattern formed on both surfaces of the insulator layer, are electrically connected via the conductive composition, and include an interface between the wiring pattern and the conductive composition. Is characterized in that at least one is roughened as compared with the interface with the insulator layer.

[0011] According to the first configuration, since the contact interface between the wiring pattern and the conductive composition is roughened, the contact area increases, and the conductive filler in the conductive composition and the wiring are removed. The reliability of the connection is improved by the action of increasing the number of contact points of the pattern with the metal foil and increasing the adhesive force between the resin contained in the conductive composition and the wiring pattern.

Further, according to the first configuration, the roughened region of the wiring pattern is limited to the connection interface with the conductive composition. Fine pattern formation becomes easy. In a circuit board obtained by laminating a metal foil whose entire surface has been roughened on an insulator layer, the roughened portion is deeply embedded in the insulator layer when the metal foil is etched to form a circuit pattern. This is because over-etching must be performed, and it is difficult to increase the pattern accuracy.

In a second aspect of the present invention, there is provided a method of manufacturing a circuit board, comprising: laminating a metal foil on one surface of an insulator layer and a resin film on the other surface, respectively; From the step of forming a hole to the interface between the metal foil and the insulator layer, a step of roughening the surface of the metal foil on the bottom of the hole, and a step of filling the hole with a conductive composition. It is characterized by the following.

Further, a method of manufacturing a circuit board according to a third configuration of the present invention includes a step of laminating an insulating layer and a resin film in this order on a surface of a core layer on which a wiring pattern made of a metal foil is formed. Forming a hole from the resin film side to the interface between the metal foil and the insulator layer, roughening the surface of the metal foil on the bottom of the hole, and filling the hole with a conductive composition. And a step of performing

According to the second or third configuration, the circuit board according to the first configuration can be manufactured efficiently.

Further, a circuit board according to a fourth structure of the present invention is an insulator layer having a through hole formed therein, a conductive composition filled in the through hole, and formed on both sides of the insulator layer. Wiring pattern, having a conductive buffer layer provided between the wiring pattern and the conductive composition, the wiring pattern formed on both surfaces of the insulator layer is the conductive composition and It is electrically connected via the conductive buffer layer, and at least one of the interfaces of the wiring pattern with the conductive buffer layer is roughened as compared with the interface with the insulator layer. It is characterized by being.

According to the fourth configuration, the conductive buffer layer is formed between the wiring pattern and the conductive composition, and the contact interface between the wiring pattern and the conductive buffer layer is roughened. So, as the contact area increases,
The conductive buffer layer is deformed following the surface irregularities of the wiring pattern to increase the adhesion, and it is easy to form an alloy or an intermetallic compound with a metal component constituting the wiring pattern. Further, by forming the conductive buffer layer to be extremely thin, an uneven pattern due to the roughening of the wiring pattern is formed on the surface of the conductive buffer layer as it is. For this reason, the contact interface between the conductive buffer layer and the conductive composition is roughened, the contact area increases, and the conductive buffer layer deforms following the surface irregularities of the conductive filler in the conductive composition. Increases the adhesiveness, forms an alloy or an intermetallic compound with the metal component constituting the conductive filler, and further increases the adhesive force between the resin contained in the conductive composition and the conductive buffer layer. It is easier to raise. As a result, the reliability of the connection between the wiring pattern and the conductive composition is improved.

Further, according to the fourth configuration, the roughened region of the wiring pattern is limited to the connection interface with the conductive buffer layer. This makes it easier to form a fine wiring pattern as compared with the case where the surface is roughened.

Further, according to a fifth aspect of the present invention, there is provided a method of manufacturing a circuit board, comprising: laminating a metal foil on one surface of an insulator layer and a resin film on the other surface, respectively; From the step of performing a hole processing to the interface between the metal foil and the insulator layer, the step of roughening the surface of the metal foil on the bottom of the hole, and forming a conductive buffer layer on the roughened bottom of the hole And a step of filling the hole with a conductive composition.

Further, a method of manufacturing a circuit board according to a sixth configuration of the present invention includes a step of laminating an insulating layer and a resin film in this order on a surface of a core layer on which a wiring pattern made of a metal foil is formed. Forming a hole from the resin film side to the interface between the metal foil and the insulator layer; roughening the surface of the metal foil at the bottom of the hole; Forming a hydrophobic buffer layer;
Filling the hole with a conductive composition.

According to the fifth or sixth configuration, the circuit board according to the fourth configuration can be manufactured efficiently.

Further, in each of the above-described structures relating to the method of manufacturing a circuit board, the method of roughening the surface of the metal foil forming the wiring pattern is performed by abrasive grain processing or removing or plastically deforming a part of the metal foil. Preferably, a step is included.
According to such a preferred configuration, the surface of the metal foil can be efficiently roughened.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a circuit board and a method of manufacturing the same according to the present invention will be described with reference to the drawings.

(First Embodiment) FIGS. 1A and 1B schematically show the structure of a circuit board according to a first embodiment of the present invention. FIG. 1A is a schematic sectional view, and FIG. FIG. 2 is an enlarged sectional view of a portion A in FIG.

In FIG. 1, reference numeral 1 denotes a base material (prepreg sheet) obtained by impregnating an aramid nonwoven fabric with an epoxy resin as an insulator layer, and 2 denotes an epoxy resin as a conductive composition filled in through holes of the insulator layer 1. Is a conductive paste in which a copper powder is mixed, and 3 is a copper foil as a metal foil constituting a wiring pattern.

The interface of the copper foil 3 laminated on the outer surface of the outermost insulator layers 1a and 1b with the conductive paste 2 has a roughened structure as shown in FIG. .
In the figure, only the connection interface of the outermost copper foil requiring land strength is roughened, but a similar roughening treatment may be performed on the connection interface of the inner layer portion. The effect is particularly great when used on the shiny surface of the copper foil used for the inner layer.

The conductive composition is a composition that is generally filled in a via hole.
80 to 95% by weight of at least one metal powder (filler) selected from 20 μm of gold, silver, copper, nickel, palladium and alloys thereof, and a binder (as a main component, an epoxy resin, a phenol resin, a polyimide resin and an acrylic resin. At least one synthetic resin selected) 5
What contains about 20% by weight can be used. However,
The conductive composition is not limited to such a specific conductive resin composition, and any conductive composition having predetermined electrical characteristics can be used as long as it can be filled in the via hole. In addition, not only the conductive composition but also, for example, a resistor composition or a heat conductive composition can be used as needed.

As the prepreg used as an insulator of the circuit board, a prepreg generally used can be used. Specifically, it is not suitable for high heat-resistant organic synthetic fibers such as aromatic polyamide (aramid) fiber, polyimide fiber, or aromatic polyester fiber, or woven or non-woven fabric of high heat-resistant inorganic fiber such as glass fiber. A thermosetting resin in a cured state, for example, an epoxy resin, a phenol resin, a polybutadiene resin, a polyester resin, a resin impregnated with one or a combination of a plurality of polyimide resins and the like is dried and heat-treated, so that the resin is partially cured. The cured one can be used as a prepreg. In addition, when a synthetic resin sheet such as a polyimide sheet or a ceramic substrate or a paper phenol sheet cannot be used alone between layers of a circuit board,
By applying a thermoplastic resin or a thermosetting resin to the surface of the sheet, it can be used as the circuit board connecting member of the present invention. The thickness of prepreg is usually 20-60
0 μm, and preferably 40 to 150 μm.

As the metal foil used to form the wiring pattern, usually, copper or an alloy containing copper as a main component is used in the form of a foil. The thickness of the copper foil is 9-70 μm
Is generally used and electrolytic copper foil is generally used, but is not particularly limited. The wiring pattern may be formed by a known method such as a photolithography method.

(Second Embodiment) FIGS. 2A and 2B schematically show the structure of a circuit board according to a second embodiment of the present invention. FIG. 2A is a schematic sectional view, and FIG. FIG. 2 is an enlarged sectional view of a portion B in FIG.

In FIG. 2, reference numeral 1 denotes a substrate obtained by impregnating an aramid nonwoven fabric with an epoxy resin as an insulating layer, and 2 denotes a conductive composition filled in a through hole of the insulating layer 1 with copper powder in an epoxy resin. This is a mixed conductive paste, 3 is a copper foil as a metal foil constituting a wiring pattern, and 4 is a silver film as a conductive buffer layer.

The interface of the copper foil 3 laminated on the outer surface of the outermost insulator layers 1a and 1b with the conductive buffer layer 4 has a roughened structure as shown in FIG. I have.
In the figure, only the connection interface of the outermost copper foil requiring land strength is roughened, but the same processing may be performed on the connection interface of the inner layer portion. The effect is particularly great when used on the shiny surface of the copper foil used for the inner layer.

The conductive buffer layer is made of gold, silver, tin, lead,
By forming at least one kind of metal of indium and palladium, or an alloy thereof, or a metal compound thereof, one or both of the metal filler contained in the conductive composition described above and the wiring pattern described above. And an alloy or a metal compound.

Further, the conductive buffer layer is deformed following the irregularities of the wiring pattern and the conductive composition, and is made of a material which is in contact with a large contact area and a large number of contact points. A circuit board having flexibility can be realized.

In the present invention, the thickness of the conductive buffer layer is preferably in the range of 0.01 to 20 μm,
More preferably, it is 0.1 μm to 5 μm. If the thickness of the conductive buffer layer is less than 0.01 μm, it often does not fulfill its function, while if it is more than 20 μm, there is a problem that the cost is increased.

(Third Embodiment) A method of manufacturing a circuit board according to a third embodiment of the present invention will be described below.

3 and 4 are schematic cross-sectional views showing a method of manufacturing a circuit board according to the present embodiment in the order of steps.

First, a prepreg 1 in which an aramid nonwoven fabric as an insulator layer is impregnated with an epoxy resin is provided with a copper foil 3 on one side and a plastic film (polyethylene terephthalate (PET) film) 5 on the other side. (Fig. 3
(A)).

Next, a hole is made in the prepreg 1 from the surface to which the PET film 5 is adhered to the copper foil 3 with a laser or the like, and the surface of the copper foil 3 at the bottom of the hole is subjected to abrasive processing such as sandblasting or jet scrubbing to obtain a rough surface. After the formation, the holes are filled with a conductive paste 2 by a printing method (FIG. 3B).
FIG. 3B-1 is an enlarged sectional view of a portion C in FIG. As shown, the interface between the copper foil 3 and the conductive paste 2 has a roughened structure.

Next, the PET film 5 attached to the prepreg 1 filled with the conductive paste is peeled off, and the core material 6 having the wiring pattern 3 formed on both surface layers by copper foil.
After the alignment is performed from both sides of the (four-layer plate in the figure), they are superimposed (FIG. 4C) and temporarily fixed. The illustrated core material 6 forms a through hole at a predetermined position in the prepreg,
This is obtained by repeating a process of filling a conductive paste in the through hole, laminating a copper foil in an opening of the through hole, and forming a wiring pattern.

Finally, the laminated core material 6 and the prepreg 1 on both surfaces thereof are hot-pressed (for example, at a temperature of 200 ° C.,
After integration by pressure (50 kg / cm ² ), the outermost copper foil is patterned to form a wiring pattern 3 (FIG. 4).
(D)).

As described above, the circuit board as shown in the first embodiment is obtained.

(Fourth Embodiment) A method of manufacturing a circuit board according to a fourth embodiment of the present invention will be described below.

FIGS. 5 and 6 are schematic sectional views showing a method of manufacturing a circuit board according to the present embodiment in the order of steps.

First, a prepreg 1 in which an aramid nonwoven fabric as an insulator layer is impregnated with an epoxy resin is provided with a copper foil 3 on one side and a plastic film (polyethylene terephthalate (PET) film) 5 on the other side. (Fig. 5
(A)).

Next, a hole is made in the prepreg 1 from the surface to which the PET film 5 is adhered to the copper foil 3 with a laser or the like, and the surface of the copper foil 3 at the bottom of the hole is subjected to abrasive processing such as sandblasting or jet scrubbing to obtain a rough surface. After the formation, a conductive buffer layer 4 is formed by forming a film of, for example, 3 μm of silver (sputtering method), and the holes are filled with a conductive paste 2 by a printing method (FIG. 5B). FIG. 5B-1 is an enlarged sectional view of a portion D in FIG. As shown, the interface between the copper foil 3 and the conductive buffer layer 4 has a roughened structure.

Next, the PET film 5 attached to the prepreg 1 filled with the conductive paste is peeled off, and the core material 6 having the wiring pattern 3 formed on both surface layers by copper foil is formed.
After the positioning is performed from both sides of the (four-layer plate in the figure), they are overlapped (FIG. 6C) and temporarily fixed.

Finally, the laminated core material 6 and the prepregs 1 on both surfaces thereof are hot-pressed (for example, at a temperature of 200 ° C.,
After integration by a pressure of 50 kg / cm ² ), the outermost copper foil is patterned to form a wiring pattern 3 (FIG. 6).
(D)).

As described above, a circuit board as shown in the second embodiment is obtained.

(Fifth Embodiment) Hereinafter, a method for manufacturing a circuit board according to a fifth embodiment of the present invention will be described.

7 and 8 are schematic cross-sectional views showing a method of manufacturing a circuit board according to the present embodiment in the order of steps.

A through-hole is formed in a prepreg 1 in which an aramid nonwoven fabric as an insulator is impregnated with an epoxy resin, a conductive paste 2 is filled, a copper foil 3 is pressed and laminated, and then the copper foil 3 is patterned. By repeating the forming step, a core material 6 of a four-layer plate is obtained (FIG. 7A).

Next, the prepreg 1 and the PET film 5 are laminated in this order on both sides of the core material 6 of the four-layer plate. Then, the copper foil 3 is irradiated from the PET film 5 surface with a laser or the like.
A hole 7 is formed in the prepreg 1 until the surface of the copper foil 3 on the bottom of the hole is subjected to abrasive processing such as sandblasting or jet scrub to roughen the surface of the bottom of the hole (FIG. 7B). FIG.
-1) is an enlarged sectional view of a portion E in FIG. As shown, the surface of the copper foil 3 on the bottom surface of the hole 7 is roughened.

Next, the conductive paste 2 is filled into the hole 7 from above the PET film 5 by a printing method, the PET film 5 is peeled off, and a copper foil is laminated on both sides and pressed. The pattern is formed to form the wiring pattern 3 (FIG. 8C). FIG. 8C-1 is an enlarged sectional view of a portion F in FIG.

Thus, a six-layer circuit board is obtained.

(Sixth Embodiment) A method of manufacturing a circuit board according to a sixth embodiment of the present invention will be described below.

FIGS. 9 and 10 are schematic sectional views showing a method of manufacturing a circuit board according to the present embodiment in the order of steps.

A through hole is formed in a prepreg 1 in which an aramid nonwoven fabric as an insulator is impregnated with an epoxy resin, a conductive paste 2 is filled, a copper foil 3 is pressed and laminated, and then the copper foil 3 is patterned. By repeating the forming step, a four-layer board core material 6 is obtained (FIG. 9A).

Next, the prepreg 1 and the PET film 5 are laminated in this order on both sides of the core material 6 of the four-layer plate. Then, the copper foil 3 is irradiated from the PET film 5 surface with a laser or the like.
A hole 7 is formed in the prepreg 1 until the surface of the copper foil 3 on the bottom of the hole is subjected to abrasive processing such as sandblasting or jet scrub to roughen the surface of the bottom of the hole (FIG. 7B). FIG.
-1) is an enlarged cross-sectional view of a G section of (b). As shown, the surface of the copper foil 3 on the bottom surface of the hole 7 is roughened.

Next, on the roughened surface in the hole 7, for example, silver is formed to a thickness of 3 μm (sputtering method) to form a conductive buffer layer 4.
Is formed, the conductive paste 2 is filled into the holes 7 from above the PET film 5 by a printing method.
After the copper foil is laminated on both surfaces and pressed, the copper foil is patterned to form a wiring pattern 3 (FIG. 10C). FIG. 10C-1 is an enlarged sectional view of a portion H in FIG.

The conductive buffer layer is made of at least one metal selected from gold, silver, tin, lead, indium and palladium, or an alloy thereof, or a metal compound thereof, so that the conductive composition described above can be used. An alloy or a metal compound is formed with one or both of the contained metal filler and the wiring pattern described above.

Further, the conductive buffer layer is deformed following the irregularities of the wiring pattern and the conductive composition, and even if it is made of a material that comes into contact with a large contact area and a large number of contact points, excellent reliability can be obtained. A circuit board having flexibility can be realized.

The circuit board obtained in each of the above-described embodiments has good results in environmental tests of the CSP package and the MCM.
In the cooker test), no connection failure occurred, and the rate of change in resistance was much smaller than in the past.

[0064]

As described above, according to the circuit board of the present invention, since the contact interface between the wiring pattern and the conductive composition is roughened, Since a conductive buffer layer is formed between the layers and the contact interface between the wiring pattern and the conductive buffer layer is roughened, good results can be obtained in CSP package and MCM environmental tests. In addition, no connection failure occurred in the PCT (pressure cooker test), and the rate of change in resistance was much smaller than in the past.

Further, since the roughened region of the wiring pattern is limited to the connection interface with the conductive composition or the conductive buffer layer, it is easier to form a fine pattern of the wiring pattern than when the entire surface is roughened. become.

Further, according to the method for manufacturing a circuit board of the present invention, a circuit board having the above effects can be efficiently manufactured.

[Brief description of the drawings]

FIGS. 1A and 1B schematically show a configuration of a circuit board according to a first embodiment of the present invention, wherein FIG. 1A is a schematic cross-sectional view, and FIG. It is.

FIGS. 2A and 2B schematically show a configuration of a circuit board according to a second embodiment of the present invention, wherein FIG. 2A is a schematic cross-sectional view, and FIG. It is.

FIG. 3 is a schematic cross-sectional view illustrating a method of manufacturing a circuit board according to a third embodiment in the order of steps.

FIG. 4 is a schematic cross-sectional view illustrating a method of manufacturing a circuit board according to a third embodiment in the order of steps.

FIG. 5 is a schematic cross-sectional view showing a method of manufacturing a circuit board according to a fourth embodiment in the order of steps.

FIG. 6 is a schematic cross-sectional view showing a method of manufacturing a circuit board according to a fourth embodiment in the order of steps.

FIG. 7 is a schematic cross-sectional view showing a method of manufacturing a circuit board according to a fifth embodiment in the order of steps.

FIG. 8 is a schematic cross-sectional view illustrating a method of manufacturing a circuit board according to a fifth embodiment in the order of steps.

FIG. 9 is a schematic cross-sectional view showing a method of manufacturing a circuit board according to a sixth embodiment in the order of steps.

FIG. 10 is a schematic cross-sectional view showing a method of manufacturing a circuit board according to a sixth embodiment in the order of steps.

[Explanation of symbols]

 Reference Signs List 1 insulator layer (prepreg sheet) 2 conductive composition (conductive paste) 3 wiring pattern (copper foil) 4 conductive buffer layer 5 plastic film (PET film) 6 core material 7 hole

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4E351 AA03 AA04 BB30 BB38 BB49 CC11 DD04 DD06 DD52 DD54 DD55 GG02 GG08 5E317 AA21 AA24 AA27 BB02 BB12 BB13 BB14 BB15 BB18 BB19 BB25 CC13 CC25 CD05 A32 BB09 BB25 BB44 BB67 BB75 BB78 DD02 DD52 DD62 EE58 GG04 GG08 GG13

Claims (15)

[Claims] An insulating layer having a through hole formed therein, a conductive composition filled in the through hole, and a wiring pattern formed on both surfaces of the insulating layer; The wiring patterns formed on both surfaces of the wiring pattern are electrically connected via the conductive composition, and at least one of the interfaces between the wiring pattern and the conductive composition, the insulating layer and A circuit board characterized in that it is roughened as compared with an interface. 2. A step of laminating a metal foil on one surface of the insulator layer and a resin film on the other surface thereof, and forming a hole from the resin film side to an interface between the metal foil and the insulator layer. A method for manufacturing a circuit board, comprising: a step of roughening a surface of the metal foil on a bottom surface of the hole; and a step of filling the hole with a conductive composition. 3. A step of laminating an insulator layer and a resin film in this order on a surface of a core layer on which a wiring pattern made of a metal foil is formed, and an interface between the metal foil and the insulator layer from the resin film side. A method of manufacturing a circuit board, comprising: a step of performing a hole processing up to the step; a step of roughening a surface of the metal foil on a bottom surface of the hole; and a step of filling a conductive composition in the hole. 4. An insulator layer having a through hole formed therein, a conductive composition filled in the through hole, a wiring pattern formed on both sides of the insulator layer, the wiring pattern and the conductive layer. A conductive buffer layer provided between the conductive composition and the insulating layer, and wiring patterns formed on both surfaces of the insulator layer are electrically connected to each other via the conductive composition and the conductive buffer layer. At least one of the interface of the wiring pattern and the conductive buffer layer,
A circuit board, which is roughened compared to an interface with the insulator layer. 5. The circuit board according to claim 4, wherein the conductive buffer layer follows irregularities at an interface with the conductive composition and / or the wiring pattern. 6. The conductive buffer layer forms an alloy or an intermetallic compound with the conductive composition and / or a metal component contained in the wiring pattern.
A circuit board according to claim 1. 7. A step of laminating a metal foil on one surface of the insulator layer and a resin film on the other surface thereof, and performing a hole process from the resin film side to an interface between the metal foil and the insulator layer. A step of roughening the surface of the metal foil on the bottom of the hole, a step of forming a conductive buffer layer on the roughened bottom of the hole, and a step of filling the hole with a conductive composition. And a method for manufacturing a circuit board. 8. A step of laminating an insulator layer and a resin film in this order on a surface of a core layer on which a wiring pattern made of a metal foil is formed, and an interface between the metal foil and the insulator layer from the resin film side. A step of performing hole processing up to, a step of roughening the surface of the metal foil on the bottom of the hole, and a step of forming a conductive buffer layer on the roughened bottom of the hole,
Filling the hole with a conductive composition. 9. The method for manufacturing a circuit board according to claim 2, wherein the method for roughening the surface of the metal foil includes abrasive processing. 10. The method of roughening the surface of the metal foil,
9. The method for manufacturing a circuit board according to claim 2, further comprising a step of removing or plastically deforming a part of the metal foil. 11. The conductive composition contains, as a filler, at least one selected from gold, silver, copper, nickel, palladium and alloys thereof, and the wiring pattern contains copper or copper as a main component. Claim 1 which is an alloy
7. The circuit board according to 4, 5, or 6. 12. The conductive buffer layer may include gold, silver,
The circuit board according to any one of claims 4 to 6, wherein the circuit board is at least one metal of tin, lead, indium, and palladium, an alloy thereof, or a metal compound thereof. 13. The thickness of the conductive buffer layer,
The circuit board according to claim 4, having a thickness of 0.01 μm or more and 20 μm or less. 14. A method according to claim 1, wherein a resistor composition or a heat conductive composition is used in place of said conductive composition.
14. The circuit board according to 6, 11, 12, or 13. 15. The method according to claim 2, wherein a resistor composition or a heat conductive composition is used in place of said conductive composition.
The method for manufacturing a circuit board according to 8, 9, or 10.