JP2001308534A - Wiring board and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a microscopic wiring board which exhibits a high reliability and few variations in connection resistance by realizing a stable inter-layer connection with respect to the wiring board whose several wiring layers separated by electrically insulating base are electrically connected by inner via holes. SOLUTION: The wiring board is provided with an electrically insulating base 401 made of a compressible porous base, wiring patterns 406 placed on both sides of the electrically insulating base 401, via holes 403 formed through the electrically insulating base 401, and conductive paste 404 with which the via holes 403 are filled and whose wiring patterns 406 are electrically connected between both sides of the electrically insulating base 401 by only conductive paste 404. At least one of the wiring patterns 406 is formed by plating, is adhered on the surface of the electrically insulating base 401, and is coupled to conductive particles in the conductive paste 404.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wiring board in which a plurality of wiring layers are electrically connected by inner via hole connection, and a method of manufacturing the wiring board.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and high performance of electronic devices, multilayer wiring circuit boards on which semiconductor chips such as LSIs can be mounted at a high density have become inexpensive not only in industrial applications but also in the field of consumer devices. There is a strong demand that it be supplied to In such a multilayer wiring circuit board, it is important that a plurality of wiring patterns formed at a fine wiring pitch can be electrically connected with high connection reliability.

[0003] In response to such a demand in the market, an arbitrary electrode of a multilayer printed wiring board is replaced with an arbitrary electrode in place of the metal plating conductor on the inner wall of the through hole which has been the mainstream of the conventional interlayer connection of the multilayer wiring board. Inner via hole connection method that enables interlayer connection at the wiring pattern position, ie, all layers I
There is a so-called VH structure resin multilayer substrate (Japanese Unexamined Patent Publication No.
No. 6-268345). This is because it is possible to fill the via holes of the multilayer printed wiring board with a conductor and connect only the necessary layers, and to provide the inner via holes directly under the component lands. And high-density mounting can be realized. Further, since the electrical connection in the inner via hole uses a conductive paste, the stress applied to the via hole can be reduced, and a stable electrical connection can be realized with respect to a dimensional change due to a thermal shock or the like. .

[0004] As this all-layer IVH structure resin multilayer substrate,
2. Description of the Related Art A configuration manufactured by processes shown in FIGS. 1A to 1H and FIGS. 2A to 2C has been conventionally proposed. FIG.
Reference numeral 101 shown in FIG. 1A denotes an electrically insulating substrate made of a compressible porous substrate. As shown in FIG. 1B, protective films 102 are attached to both sides of the electrically insulating substrate 101 by laminating. Subsequently, FIG.
As shown in (c), a via hole 103 penetrating through the entire electrically insulating substrate 101 and the protective film 102 is formed by a laser or the like. Next, as shown in FIG. 1D, the via holes 103 are filled with a conductive paste 104, and then, as shown in FIG.
02 is peeled off. In this state, as shown in FIG.
A foil-like wiring material 105 is laminated from both sides, and the wiring material 105 is adhered to the electrically insulating base material 101 by heating and pressing in a step shown in FIG. At this time, since the electrically insulating substrate 101 has a compressible characteristic, it contracts in the thickness direction by heating and pressing. In addition, the conductive paste 104 is compressed in the thickness direction by the heating and pressing process. Due to this compression, the conductive particles in the conductive paste come into high-density contact, and at the same time, the electrical connection between the wiring material 105 and the conductive paste 104 is realized. Next, as shown in FIG. 1H, the wiring material 105 is patterned to complete the double-sided wiring board.

FIGS. 2F to 2H show FIGS. 1F to 1F.
It is the figure which expanded and showed the via hole vicinity of (h). FIG. 2 shows a state in which the conductive paste 104 is compressed and the conductive particles in the conductive paste 104 come into high-density contact when the wiring material 105 is bonded to the electrically insulating base material 101 by heating and pressing. ing.

[0006]

In the above-described conventional structure and manufacturing method, when the diameter of the via hole 103 is reduced, the wiring material 105 and the conductive particles in the conductive paste 104 are inversely proportional to the area of the via hole 103. The number of contact points with is reduced. Actually, the electrical connection at the interface between the wiring material 105 and the conductive paste 104 is
5 and the conductive particles in the conductive paste 104 are secured by contact with each other. When the number of contact points is reduced, a portion where the initial connection resistance value is high occurs, and the variation in the initial connection resistance value increases. Occurs. Further, in a portion where the initial connection resistance value is high, a phenomenon that the connection resistance value fluctuates in a reliability test such as a temperature cycle test or a pressure cooker test is observed.

An object of the present invention is to solve the above-mentioned problem and realize a stable interlayer connection in a wiring board having a configuration in which a plurality of wiring layers separated by an electrically insulating base material are electrically connected by inner via holes. Accordingly, it is an object of the present invention to provide a fine and highly reliable wiring board having a small variation in connection resistance value.

[0008]

In order to solve the above-mentioned problems, a wiring board according to the present invention comprises: an electrically insulating base made of a compressible porous base; And a via hole formed through the electrically insulating base material, and a conductive paste filled in the via hole, wherein the wiring is formed between both surfaces of the electrically insulating base material. In a wiring board electrically connected only by a conductive paste, at least one of the wirings is a plating wiring attached to a surface of the electrically insulating base material and combined with conductive particles in the conductive paste. And

According to the above configuration, by forming the wiring as a plated wiring bonded to the conductive particles in the conductive paste, the bonding at the interface between the conductive paste and the wiring becomes strong. Further, in this configuration, although a strong metallic bond is realized at the interface between the conductive paste and the wiring, the resin component in the conductive paste plays a role of buffering the stress inside the via hole, and the dimension due to thermal shock or the like is increased. It is possible to provide a wiring board that realizes stable interlayer connection against changes.

In the wiring board having the above structure, the electrically insulating base made of a compressible porous base may be replaced with an electrically insulating base having adhesive layers formed on both surfaces. Also in this case, it is possible to provide a wiring substrate that realizes stable interlayer connection by strengthening the bond between the interface between the conductive paste and the wiring.

In the wiring board having the above structure, it is preferable that a plurality of irregularities are provided at an interface between the conductive paste and the plating wiring. According to this configuration, the contact area between the conductive paste and the wiring is substantially increased, and as a result, the bonding area between the plated wiring and the conductive particles in the conductive paste can be increased, and the variation in resistance value can be further reduced. It is possible to provide a wiring board which realizes a small and stable interlayer connection.

A multilayer board according to the present invention has a configuration including at least one wiring board according to any of the above configurations.
According to this configuration, it is possible to provide a multilayer wiring board that realizes stable interlayer connection.

[0013] In the above-mentioned multilayer wiring board, it is preferable that plated wiring bonded to conductive particles in the conductive paste is provided in at least one outermost layer. According to this configuration, the bond between the outermost wiring and the conductive paste where stress concentration is likely to occur can be strengthened.
It is possible to provide a wiring board whose connection stability does not fluctuate due to mounting stress.

Further, in the method for manufacturing a wiring board according to the present invention, a step of forming a via hole in an electrically insulating base material containing a thermosetting resin, and a step of forming a conductive paste comprising conductive particles and a thermosetting resin in the via hole. A filling step, a hot pressing step of heating and pressurizing the electrically insulating base material and the conductive paste and curing, and a step of forming a wiring electrically connected to the conductive paste, In the forming step, at least one of the plating wirings that adheres to the electrically insulating base material and bonds to the conductive particles in the conductive paste is formed. According to this manufacturing method, it is possible to improve the bonding strength at the interface between the wiring and the conductive paste where stress concentration is likely to occur, and to realize a wiring board that realizes stable interlayer connection against dimensional changes due to thermal shock and the like. Can be provided.

In the above-described manufacturing method, in the hot pressing step, a metal foil made of a material different from conductive particles in the conductive paste is laminated on the surface of the electrically insulating substrate on which the plating wiring is to be formed. It is preferable to cure the electrically insulating substrate and the conductive paste. According to this manufacturing method,
Only the metal foil can be selectively removed by etching, so that the conductive paste can be exposed without applying mechanical stress to the conductive paste in the via hole. As a result, damage to the conductive paste during the process is suppressed, and a wiring board that realizes stable interlayer connection can be provided.

In the above-described manufacturing method, it is preferable that at least a surface of the metal foil that is in contact with the electric insulating layer is roughened. According to this manufacturing method, the exposed area of the conductive paste can be increased, so that the bonding area in forming the plated wiring can be increased, and the stability of interlayer connection can be enhanced. Further, it is possible to provide a wiring board having plated wiring with high adhesion due to the anchor effect.

In the above manufacturing method, it is preferable to form a wiring pattern by electroless plating using a photosensitive palladium catalyst. According to this manufacturing method, the plating wiring forming step can be simplified, and a wiring substrate excellent in productivity can be provided.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) A wiring board according to Embodiment 1 will be described with reference to the drawings. As shown in FIG. 3, the printed wiring board according to the present embodiment has a configuration in which plated wirings 302 a and 302 b are formed on both surfaces of an electrically insulating base material 301.
This is a so-called double-sided printed wiring board. Plating wiring 30
2a and the plated wiring 302b
Paste 30 which is a conductor provided to penetrate through
3 and is electrically connected to the conductive particles in the conductive paste 303.

Here, the manufacturing process of the present printed wiring board will be described with reference to FIGS.

First, the electrically insulating substrate 401 shown in FIG. 4A is characterized by being a compressible porous substrate. That is, by applying compression in the thickness direction of the electrically insulating base material 401, its size is reduced. The degree of shrinkage can be adjusted by controlling the holes formed in the electrically insulating substrate 401. As the material of the electrically insulating substrate 401, a material obtained by impregnating a resin with fiber paper such as a woven fabric or a nonwoven fabric can be used, and pores are also formed at the time of the impregnation. If non-woven paper containing aramid fiber as a main component is used as the paper and a thermosetting resin containing epoxy as a main component is used as the resin, the pores in the electrically insulating base material 401 can be uniformly and efficiently formed. Thus, an insulating substrate having high compressibility can be obtained.

As shown in FIG.
As shown in (b), a protective film 402 is formed.
The protective film 402 is formed by laminating a film containing PET or PEN as a main component by laminating the film.
Is a simple and highly productive manufacturing method.

Next, as shown in FIG. 4C, a via hole 403 penetrating the protective film 402 and the electrically insulating substrate 401 is formed. The via hole 403 can be formed by punching, drilling, or laser processing, but if a carbon dioxide gas laser or a YAG laser is used, a small-diameter via hole can be formed in a short time, realizing processing with excellent productivity. it can.

Subsequently, as shown in FIG. 4D, a conductive paste 404 is filled in the via hole 403. The conductive paste 404 includes metal conductive particles of copper, silver, or the like and a resin component. At this time, the protective film 402 has a role of protecting the conductive paste 404 from adhering to the surface of the electrically insulating substrate 401 and a role of ensuring the filling amount of the conductive paste. Since the conductive paste 404 can be filled by printing, it also has an advantage of excellent productivity.

By peeling off the protective film 402, the state shown in FIG. 4E is obtained. The filling amount of the conductive paste 404 is ensured by the protective film 402. That is, the conductive paste 404 is in a state of protruding from the surface of the electrically insulating substrate 401 by a height corresponding to the thickness of the protective film 402.

After peeling off the protective film 402, FIG.
As shown in (f), heat and pressure are applied to both surfaces of the electrically insulating base material 401 via the press sheet 405 to compress the conductive paste 404. After the heating and pressing, as shown in FIG. 4 (g), the dimension of the electrically insulating substrate 401 shrinks in the thickness direction. FIGS. 5F and 5G show this state in an enlarged manner in the vicinity of the via hole. Fig. 4
(F) and (g). As shown in FIG.
The filled conductive paste 404 has a large amount of resin components between conductive particles in the conductive paste, and does not ensure sufficient electrical connection. On the other hand, by applying a heating / pressing step via the press sheet 405, the thickness of the electrically insulating base material 401 shrinks as shown in FIG. In addition, the conductive particles in the conductive paste 404 come into close contact with each other, so that electrical connection in the conductive paste 404 can be secured.

Next, as shown in FIG. 4H, the press sheets 405 on both sides are removed. As the press sheet 405, a film obtained by subjecting the surface of a heat-resistant film to a silicate treatment can be used. In this case, press sheet 405
Is mechanically peeled off. Press sheet 4
As 05, a metal foil of a material different from the conductive particles in the conductive paste 404 can be used. In this case, only the metal foil can be removed by etching. By choosing a chemical that etches the metal foil,
The press sheet 405 can be removed without eroding the conductive particles in the conductive paste. Further, by chemically removing the press sheet 405, no mechanical stress is applied to the conductive paste, so that the conductive state in the conductive paste does not deteriorate during the process.

Subsequently, as shown in FIG. 4I, a plated wiring to be bonded to the exposed conductive paste 404 is formed. Electroless plating and electrolytic plating are used for forming the wiring by plating. When wiring is formed by electroless plating, pattern plating may be performed after subjecting the electrically insulating substrate 401 to a catalytic treatment, or patterning may be performed by etching after forming a wiring material on the entire surface by electroless plating. good. When electroless plating is used in combination with electroless plating over the entire surface, a thick film can be formed in a short time.

As a simple manufacturing method for forming the plated wiring, the manufacturing method shown in FIGS. 9A to 9E can be used. FIG. 9A shows a state after the electrically conductive base material 901 is filled with the conductive paste 902 and compressed by heating and pressing. This state corresponds to FIG. Next, as shown in FIG.
01 is coated with a photosensitive palladium catalyst 903.
This catalyst has a property of being activated by irradiation with ultraviolet rays. Next, as shown in FIG.
Irradiation with ultraviolet light 904 is performed through a photomask 906. As a result, the photosensitive palladium catalyst 905 in the portion irradiated with the ultraviolet ray 904 is activated. Here, if parallel light is used as the ultraviolet ray 904 and a gap is provided between the photomask 906 and the electrically insulating substrate 901 as shown in the figure, contamination such as adhesion of dust to the surface of the photomask 906 is suppressed. When performing repeated exposure, a stable process can be realized.

Subsequently, by performing the electroless plating, as shown in FIG. 9D, the plating wiring 907 is selectively formed only at the portion where the photosensitive palladium catalyst is activated. Next, the photosensitive palladium catalyst in the unactivated portion is removed to obtain a double-sided printed wiring board as shown in FIG. By using such a manufacturing process, a wiring pattern can be formed without using a photoresist, and a printed wiring board excellent in productivity can be provided.

As described above, the plated wiring formed so as to bond with the conductive particles in the conductive paste has excellent strength at the bonding interface, and is subjected to mechanical stress such as mounting of electronic components on the wiring. In this case, cracks are less likely to occur at the bonding interface with the conductive paste. That is, by making the bonding strength between the wiring and the conductive paste stronger than the bonding strength between the conductive particles in the conductive paste, the relaxation when stress occurs can be realized inside the conductive paste.
Since the conductive particles are three-dimensionally densely contacted inside the conductive paste, the state of the electrical connection is not deteriorated even if the position of the conductive particles changes due to stress.
As a result, it is possible to provide a wiring board that realizes stable interlayer connection.

The steps (f) to (i) in FIG. 4 may be steps as shown in FIGS. 6 (a) to (d). In this example, irregularities are easily formed on the surface of the electrically insulating base material 602 by providing irregularities on the surface of the metal foil as the press sheet 601.

As shown in FIG. 6A, the press sheet 6
In No. 01, irregularities are formed on the surface that comes into contact with the electrically insulating substrate. In order to form the unevenness, a method of roughening the surface by an etching treatment, a method of forming bumpy particles by attaching bump-like particles by plating, or a method of mechanically roughening the surface can be used. As shown in FIG. 6B, the irregularities are transferred to the surface of the electrically insulating substrate 602 during the heating and pressing step. Next, as shown in FIG. 6C, the press sheets 601 on both sides are removed. Subsequently, as shown in FIG. 6D, a plated wiring 603 to be bonded to the exposed conductive paste 604 is formed.

When unevenness is formed by the bump processing,
A stronger anchor effect can be obtained between the plating wiring 603 and the electrically insulating base material 602, and strong adhesion can be realized. In addition, a large exposed area of the conductive paste 604 can be secured by the unevenness, and the adhesion between the plating wiring 603 and the conductive paste 604 can be improved.

In the above embodiment, an example of a compressible porous substrate has been described as an electrically insulating substrate, but an electrically insulating substrate having an adhesive layer formed on both surfaces as an electrically insulating substrate. A material may be used. By embedding the wiring in at least one of the adhesive layers, the conductive paste can be compressed, and the electrical connection of the conductive particles inside the paste can be secured. Especially when embedding wiring only from one side,
A stable connection state can be ensured by applying the plating wiring that is bonded to the conductive particles to the wiring on the side where no plating is embedded.

In the case of a structure in which the compression of the conductive paste is ensured by the adhesive layer, an organic film substrate, a glass epoxy substrate or the like can be used as the electrically insulating material. A flexible printed wiring board can be provided by using an organic film base, and an inexpensive printed wiring board can be provided by using a glass epoxy base.

The manufacturing process in that case will be briefly described with reference to FIG. Adhesive layers 802 are formed on both sides of the electrically insulating substrate 801 shown in FIG. As the adhesive layer, a thermosetting epoxy resin, a thermosetting polyimide resin, or the like is used. Adhesive layer 802
From the viewpoint of compressing the conductive paste, it is preferable that the material has a small flowability while embedding the wiring. As shown in FIG. 8B, this electrically insulating substrate 80
A protective film 803 is stuck on both sides of 1 by lamination. Next, as shown in FIG. 8C, a via hole 804 penetrating the electrically insulating base material 801 and the protective film 803 is formed, and as shown in FIG. 8D, a conductive paste 805 is applied to the via hole 804. Fill. Subsequently, the protective films 803 on both sides are removed, and the electrically insulating base material 80 is removed.
8 where the conductive paste 805 protrudes from the surface of FIG.
The state of (e) is obtained. Next, as shown in FIG. 8F, the support base 807 on which the wiring 806 is already formed and the press sheet 808 are laminated and heated and pressed. Here, FIG.
As shown in (g), when the wiring 806 is embedded in the adhesive layer 802, the conductive paste 805 is compressed. Next, as shown in FIG. 8 (h), the press sheet 808 is removed, and as shown in FIG. 8 (i), a plating wiring 809 to be bonded to the conductive paste 805 is formed.
Subsequently, by removing the supporting base material 807, FIG.
Can be obtained. The removal of the support base material 807 is preferably performed in a later process as much as possible in consideration of the effect of avoiding damage such as chipping or contamination of the wiring during the process.

Although the structure in which the conductive paste is compressed by embedding the wiring from one side has been described in the present embodiment, it is needless to say that the same effect can be realized by a structure in which the compression is performed from both sides.

(Embodiment 2) Another embodiment of the present invention will be described with reference to FIG. FIG. 7 shows a configuration in a manufacturing stage of a six-layer printed wiring board as an example of the multilayer printed wiring board according to the present invention. Note that the number of layers of the multilayer printed wiring board is not limited to six, and can be manufactured according to the manufacturing process described below.

With reference to FIGS. 7A to 7D, the steps of manufacturing a multilayer printed wiring board will be briefly described. First, as shown in FIG. 7A, a press sheet 701 is arranged on both sides of a four-layer printed wiring board 703 via an electrically insulating base material 702 filled with a conductive paste 704. FIG. 7 shows an example in which a compressible porous substrate is used as the electrically insulating substrate, but the same effect can be obtained by using an electrically insulating substrate having an adhesive layer on both surfaces. The electrically insulating base material 702 is aligned and laminated on the four-layer printed wiring board 703. 4-layer printed circuit board 703
Shows an example of an all-layer IVH structure resin multilayer substrate, but the structure of the multilayer printed wiring board is not limited to this.

Subsequently, as shown in FIG. 7B, heat and pressure are applied from both sides to compress the conductive paste 704. Next, the press sheet 701 is removed as shown in FIG.
As shown in FIG. 7D, the exposed conductive paste 70
By forming the plating wiring 705 to be combined with the wiring 4, a six-layer printed wiring board is obtained. In this example, the wiring of the outermost layer of the six-layer printed wiring board and the conductive paste are bonded by plating. However, if this bonding is also applied to the inner wiring of the multilayer printed wiring board, Stable interlayer connection is realized even inside the substrate.

On the other hand, there is a wiring portion for mounting components on the outermost layer of the multilayer printed wiring board, and the connection between the wiring of the outermost layer and the conductive paste is strengthened, thereby connecting the multilayer printed wiring board. Reliability can be effectively improved. In other words, when bending stress is applied to the multilayer printed wiring board, stress concentration is more likely to occur at the interface between the outermost layer wiring and the conductive paste than at the inner layer, so that the bond between the outermost layer wiring and the conductive paste is strengthened. By doing so, the connection stability of the multilayer printed wiring board can be effectively improved.

Further, the occurrence of stress concentration between the outermost wiring and the conductive paste is the same even when components are mounted.

In particular, when a wiring layer on which stress is concentrated is evident by simulation or the like, a multilayer printed wiring board is formed so as to strengthen the interface according to the above-described manufacturing method, thereby achieving effective connection stability. Improvement can be realized.

[0044]

According to the present invention, it is possible to enhance the bonding between the conductive paste and the wiring in the layer where stress concentration occurs. As a result, it is possible to provide a wiring board that realizes stable interlayer connection.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a conventional method of manufacturing a printed wiring board for each of main manufacturing steps.

FIG. 2 shows steps (f) to (h) in the manufacturing method of FIG.
Cross-sectional view showing the configuration in FIG.

FIG. 3 is a sectional view showing the configuration of the printed wiring board according to the first embodiment;

FIG. 4 is a cross-sectional view showing a main step of the method for manufacturing a printed wiring board according to the first embodiment;

FIG. 5 is an enlarged cross-sectional view showing a configuration of a main part in the manufacturing method of FIG. 4 in the vicinity of a via hole;

FIG. 6 shows steps (f) and (g) in the manufacturing method of FIG.
Figure showing an enlarged view of the vicinity of the via hole showing another configuration of

FIG. 7 is a cross-sectional view illustrating a method of manufacturing the multilayer printed wiring board according to the second embodiment for each of main manufacturing steps.

FIG. 8 is a cross-sectional view showing a manufacturing method using an electrically insulating base material having another configuration according to the embodiment of the present invention for each of main steps.

FIG. 9 is a cross-sectional view showing an example of a method for forming a plated wiring in each embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 101 electric insulating base material 102 protective film 103 via hole 104 conductive paste 105 wiring material 301 electric insulating base material 302a plating wiring 302b plating wiring 303 conductive paste 401 electric insulating base material 402 protective film 403 via hole 404 conductive paste 405 Press sheet 406 Plating wiring 601 Press sheet 602 Electric insulating base material 603 Plating wiring 604 Conductive paste 701 Press sheet 702 Electric insulating base material 703 Four-layer printed wiring board 704 Conductive paste 705 Plating wiring 801 Electric insulating base material 802 Adhesive layer 803 Protective film 804 Via hole 805 Conductive paste 806 Wiring 807 Supporting base 808 Press sheet 809 Plating wiring 901 Electrically insulating base 902 Conductive Paste 903 photosensitive palladium catalyst 904 ultraviolet light 905 photosensitive palladium catalyst 906 photomask 907 plated wiring

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Nakamura 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. Terms (reference) 5E317 AA21 AA24 CC25 CC31 CC51 CD21 CD25 CD27 CD32 GG11 5E346 AA43 CC05 CC09 DD12 DD23 EE02 FF18 GG15 HH07

Claims (9)

[Claims] 1. An electric insulating base material comprising a compressible porous base material, wirings arranged on both surfaces of the electric insulating base material, and formed through the electric insulating base material. In a wiring board including a via hole and a conductive paste filled in the via hole, and the wiring is electrically connected only between the two surfaces of the electrically insulating base material by the conductive paste, at least one of the wirings is A wiring substrate, wherein the wiring substrate is a plated wiring attached to the surface of the electrically insulating substrate and bonded to conductive particles in the conductive paste. 2. An electrically insulating base material having an adhesive layer formed on both surfaces thereof, and wirings arranged on both surfaces of the electrically insulating base material,
A via hole formed through the electrically insulating substrate, and a conductive paste filled in the via hole, wherein the wiring is electrically connected only by the conductive paste between both surfaces of the electrically insulating substrate. Wherein at least one of the wirings is a plating wiring attached to the surface of the electrically insulating base material and bonded to conductive particles in the conductive paste. 3. The wiring board according to claim 1, wherein a plurality of irregularities are provided at an interface between the conductive paste and the plating wiring. 4. A multilayer wiring board comprising at least one wiring board according to claim 1 or 2. 5. The multilayer wiring board according to claim 4, wherein a plated wiring bonded to conductive particles in the conductive paste is provided on at least one outermost layer. 6. A step of forming a via hole in an electrically insulating base material containing a thermosetting resin, a step of filling the via hole with a conductive paste composed of conductive particles and a thermosetting resin, A hot pressing step of heating and pressing the material and the conductive paste for curing, and a step of forming a wiring electrically connected to the conductive paste, wherein the step of forming the wiring comprises: A method of manufacturing a wiring board, comprising: forming a plated wiring attached to a material and bonded to the conductive particles in the conductive paste on at least one side. 7. In the hot pressing step, a metal foil made of a material different from conductive particles in a conductive paste is laminated on a surface of the electrically insulating substrate on which the plating wiring is formed, and the electric foil is heated and pressurized. 7. The method according to claim 6, wherein the insulating base and the conductive paste are cured. 8. The method according to claim 7, wherein at least a surface of the metal foil that is in contact with the electrical insulating layer is roughened. 9. The method according to claim 6, wherein in the step of forming the wiring, a wiring pattern is formed by electroless plating using a photosensitive palladium catalyst.