JP2003092469A - Multilayer wiring board, base material for multilayer wiring, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide via-vias or chip-on-vias, and to provide high-density mounting and a flexible F
It is an object of the present invention to obtain a multilayer wiring board, a substrate for multilayer wiring, and a method for manufacturing the same, which can easily form a multilayer PC. SOLUTION: In the multilayer wiring substrate according to the present invention, a copper foil (2) is adhered to one surface of an adhesive resin film (1), and the copper foil (2) and the resin film (1) are bonded together. )
A copper-clad resin film (10) in which a through-hole (7) is formed so as to penetrate through the copper-clad resin film (10); A conductive paste (8) embedded by screen printing so as to protrude toward the adhesive layer side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer wiring board in which a plurality of printed wiring boards are stacked to form a multilayer structure, a multilayer wiring substrate used for the multilayer wiring board, and a method for manufacturing the same. (Flip Chip Mo
The present invention relates to a flexible multilayer wiring board capable of high-density mounting such as unting), a multilayer wiring substrate, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Flexible printed circuits (hereinafter referred to as FP
C) is formed by using a thin resin film in order to ensure plasticity. Therefore, in the case of FPC, it is very difficult to manufacture a substrate (multilayer wiring board) having a multilayer wiring structure. However, in recent years, along with the progress of high-density mounting of FPCs, it has become necessary to make multilayer wiring in FPCs, such as securing a lead portion in flip-chip mounting. Therefore, a plurality of FPCs with circuit patterns formed on one or both sides are laminated with a glass epoxy prepreg, etc., and all layers are collectively drilled, and through-hole plating is used to connect the layers. By doing so, a multi-layered FPC is manufactured.

However, in the conventional method of manufacturing a multilayer wiring board by such through-hole plating, since a hole is formed in the center of the through-hole even after plating, another via hole is formed on the via hole, that is, so-called via-on.・ The so-called chip-on-via that mounts a chip on a via or via hole was impossible. Therefore, in the conventional method for manufacturing a multilayer wiring board, it is impossible to draw out the lead line from directly under the chip, and the area is occupied more than necessary, which hinders high-density mounting.

On the other hand, as a rigid multilayer wiring board capable of via-on-via, for example, ALIVH (Any Layer) using a conductive paste for connection between layers of the multilayer wiring board is used.
Interstitial Via Hole; a registered trademark of Matsushita Electric Industrial Co., Ltd.) Substrate is known. The ALIVH substrate has a through hole formed in an uncured resin substrate, filled with a conductive paste in the through hole, and then a copper foil (Cu foil) is attached to the substrate, and the resin is cured while being pressure-bonded to connect the layers to each other. The circuit pattern is repeatedly formed by etching the foil to stack conductor layers to form a multilayer structure.

[0005]

However, the above-mentioned AL
In a method for manufacturing a multilayer wiring board such as IVH, via-on-via is possible because interlayer connection is performed by using a conductive paste. However, when this method for manufacturing a multilayer wiring board is applied to an FPC, the thickness is Since it is necessary to make a hole in a thin resin film such as polyimide and to fill the hole with a conductive paste, it is very difficult to manufacture an FPC having a multilayer wiring. This is because, in the case of thin resin film, when drilling holes, due to distortion of the resin film and the inclusion of a drill, the positions and dimensions of the holes will change, and the printing of conductive paste and the alignment accuracy of each layer cannot be obtained. Is caused.

Further, in the method for manufacturing a multilayer wiring board in which interlayer connection is made by a conductive paste such as ALIVH, via-on-via is possible, but in order not to deteriorate the electrical characteristics of the copper foil and the conductive paste, It is not easy to connect the copper foil and the conductive paste, and each company uses its own method. That is, generally, in the case of via-on-via interlayer connection, the copper foil is connected to the conductive paste by sandwiching the copper foil between the conductive paste of the via.
At this time, in order to prevent the electrical characteristics of the copper foil and the conductive paste from deteriorating, the copper foil is laminated so as to pierce the conductive paste.

However, when a material whose substrate thickness does not decrease during hot pressing, such as polyimide used for FPC resin film, is used, the effect of sticking the copper paste by the projection of such a conductive paste decreases. I will end up. As a result, it is difficult to connect the copper foil and the conductive paste without deteriorating the electrical characteristics.

Further, when the conductive paste is embedded in the through hole, the conductive paste is printed so as to be pressed in, so that the printed surface of the conductive paste is slightly recessed. Therefore, even if the substrates filled with the conductive paste are bonded together, there is a problem that sufficient electrical connectivity between the conductive pastes cannot be secured.

The present invention has been made in order to solve the above problems, and enables via-on-via and chip-on-via, and enables high-density mounting and flexibility. An object of the present invention is to obtain a multilayer wiring board, a multilayer wiring base material and a method for manufacturing the same, which can easily form a multilayered FPC.

Another object of the present invention is to uniformly apply a force to the entire wiring board at the time of adhering the multi-layer wiring base material, whereby a reliable bonding can be achieved and a better electrical connection can be achieved. Is to obtain a multi-layer wiring board that can obtain good properties.

[0011]

A substrate for multi-layer wiring according to the present invention has a copper foil attached to one surface of a resin film having adhesiveness, and penetrates so as to penetrate the copper foil and the resin film. A copper-clad resin film having holes formed therein, and a through-hole of the copper-clad resin film, and a conductive paste embedded by screen printing so that the tip projects from the copper foil side to the resin film side. It is characterized by

In the method for producing a multilayer wiring substrate according to the present invention, the copper foil and the resin film are penetrated into a copper-clad resin film in which a copper foil is attached to one surface of an adhesive resin film. The method is characterized by including a step of forming a through hole and a step of embedding a conductive paste in the through hole by screen printing so that a tip of the through hole projects from the copper foil side toward the resin film side.

Another method of manufacturing a multilayer wiring substrate according to the present invention is to etch a copper clad resin film in which a copper foil is attached to one surface of an adhesive resin film, by etching the copper foil. And forming a predetermined circuit pattern,
A step of forming a mask layer on the resin film side of the copper clad resin film on which the circuit pattern is formed, a step of forming a through hole penetrating the copper foil, the resin film and a mask material, and the through hole, It is characterized by comprising a step of embedding a conductive paste by screen printing from the copper foil side and a step of removing the mask material.

According to the multilayer wiring substrate and the method of manufacturing the same of the present invention, the through holes are formed in the copper clad resin film in which the copper foil is attached to one surface of the resin film, and the conductive paste is embedded. Therefore, as compared with a case where the resin film alone is used to form the through-hole and the conductive paste is embedded, the through-hole can be formed more easily as the thickness increases, and the conductive paste can be embedded more easily. In this case, if the conductive paste is embedded in the through hole so as to protrude around the opening of the through hole of the copper foil, the electrical connectivity between the copper foil and the conductive paste can be improved.

A multilayer wiring board according to the present invention is formed by laminating a plurality of the above-mentioned multilayer wiring base materials such that the tip of the conductive paste is connected to the copper foil or the conductive paste of the adjacent multilayer wiring base material. It is characterized by

In the method for manufacturing a multilayer wiring board according to the present invention, a plurality of the above-mentioned multilayer wiring base materials are connected so that the tip of the conductive paste is connected to the copper foil or the conductive paste of the adjacent multilayer wiring base material. It is characterized in that they are laminated and bonded together by the resin film having the adhesive property.

According to the multilayer wiring board and the method for manufacturing the same of the present invention, the conductive paste of the multilayer wiring substrate is applied to the through hole of the copper clad resin film so that the tip projects toward the resin film side. Since it is embedded by screen printing from multiple layers, when multiple layers of multilayer wiring base materials are stacked, the tip of the conductive paste is surely connected to the adjacent copper foil or conductive paste of the multilayer wiring base material, and as a multilayer wiring board. When configured, the electrical connectivity between layers can be significantly improved. In particular, the direct connection between the conductive pastes not via the copper foil contributes to the improvement of electrical connectivity.

As the adhesive resin film, for example, a thermoplastic resin such as thermoplastic polyimide can be used. In this case, by laminating the multilayer wiring base material and heating it, the multilayer wiring base materials are tightly coupled by the plasticized resin film, and the conductive paste and the adjacent multilayer wiring base material are connected. The copper foil of the material and the conductive paste can be connected more reliably. Further, in this case, if the conductive paste is main-cured at the same time as the multilayer wiring base material is bonded, an unnecessary load is not applied to the conductive paste portion, and smooth electrical connection can be secured. .

When laminating the multilayer wiring substrate,
It is desirable that the copper foil located in the outermost layer be embedded in the resin film to which it is attached. That is, usually, in this type of wiring board, gold or the like is plated in consideration of the oxidation prevention of the circuit and the adhesion to the connection member with the IC such as solder, but when the circuit is exposed, the wiring pattern The whole circuit including the side of must be plated, and much gold is required. In addition, since the side surface of the wiring pattern is plated, the circuit width is widened, making it difficult to form a fine circuit and increasing the incidence of insulation failure due to the contamination of metal impurities between circuits. Further, if the space between the wiring patterns is narrow, the liquid around the plating solution is deteriorated, which makes uniform plating difficult.

In this respect, since the copper foil located in the outermost layer is embedded in the resin film, the side surface of the wiring pattern is not plated, the amount of gold used is reduced, the circuit is miniaturized, and the plating solution is used. It is possible to improve the surroundings and prevent the occurrence of insulation failure due to contamination.

In the multilayer wiring substrate according to the present invention, a copper foil is attached to one surface of an adhesive resin film, and a through hole is formed so as to penetrate the copper foil and the resin film. And a conductive paste embedded in a through hole of the copper-clad resin film such that a tip of the copper-clad resin film protrudes from the copper foil side beyond the resin film.

In the method for producing a multilayer wiring substrate according to the present invention, the copper foil and the resin film are penetrated into a copper clad resin film in which a copper foil is attached to one surface of an adhesive resin film. And a step of embedding a conductive paste in the through hole such that the tip of the through hole protrudes from the copper foil side from the resin film.

In the multilayer wiring substrate according to the present invention, a copper foil is attached to one surface of an adhesive resin film, and a through hole is formed so as to penetrate the copper foil and the resin film. A copper-clad resin film and a through-hole of the copper-clad resin film, and a conductive paste embedded so that the front end protrudes from the resin film from the copper foil side and the rear end is at the same height as the copper foil. It is characterized by comprising.

In the multilayer wiring substrate according to the present invention, a copper foil is attached to one surface of an adhesive resin film, and a through hole is formed so as to penetrate the copper foil and the resin film. The copper-clad resin film and the through-hole of the copper-clad resin film are embedded by screen printing so that the tip projects from the copper foil side and protrudes around the opening of the through-hole of the copper foil from the copper foil side. And a conductive paste.

In the multilayer wiring board according to the present invention, a copper foil is attached to one surface of a resin film having adhesiveness, and a through hole is formed so as to penetrate the copper foil and the resin film. Tension resin film and a through hole of the copper clad resin film, a conductive member embedded by screen printing so that the tip projects from the resin film from the copper foil side and protrudes around the opening of the through hole of the copper foil. A first multilayer wiring substrate including a paste, and a copper foil is attached to one surface of a resin film having adhesiveness, and a through hole is formed so as to penetrate the copper foil and the resin film. The formed copper-clad resin film and the through hole of this copper-clad resin film are embedded so that the front end protrudes from the resin film from the copper foil side and the rear end is at the same height as the copper foil. A second multi-layer wiring base material comprising an embedded conductive paste, wherein the second multi-layer wiring base material is the outermost layer and the first multi-layer wiring base material is other than the outermost layer. It is characterized in that a plurality of multi-layer wiring base materials are laminated so as to be an inner layer and the tip of the conductive paste is connected to the copper foil or the conductive paste of the adjacent multi-layer wiring base material.

In the method for manufacturing a multilayer wiring board according to the present invention, the second multilayer wiring substrate is the outermost layer, the first multilayer wiring substrate is an inner layer other than the outermost layer, and the conductive paste is used. Is laminated with a plurality of multi-layer wiring base materials such that the tip ends of the multi-layer wiring base materials are connected to the copper foil or the conductive paste of the adjacent multi-layer wiring base material, and the multi-layer wiring base materials are attached to each other by the resin film.

According to the method for manufacturing a multilayer wiring substrate and a multilayer wiring board according to the present invention, the upper surface of the outermost layer (uppermost layer) is
Since the upper surface of the copper foil and the rear end portion of the conductive paste, that is, the printing surface side are continuously flat at the same height, it is possible to apply a uniform force to the entire wiring board at the time of bonding,
As a result, reliable bonding can be achieved,
Better electrical connectivity is obtained.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below.

FIG. 1 is a cross-sectional view showing a multilayer wiring base material constituting a multilayer wiring board according to an embodiment of the present invention in the order of manufacturing steps, and FIGS. 2 and 3 are multilayer views according to an embodiment of the present invention. It is sectional drawing which shows a wiring board in order of a manufacturing process.

The multi-layer wiring base material 20 is a connection material for multi-layer wiring for constructing a multi-layer wiring board, and is basically composed of an FPC made of a single-sided copper clad resin film. That is, as shown in FIG.
A copper clad resin film 10 in which a copper foil 2 is attached to one surface of a resin film 1 having adhesiveness such as thermoplastic polyimide (TPI), and a through hole 7 formed in the copper clad resin film 10 (see FIG. 1 (g)), and a conductive paste 8 forming an inner via hole embedded therein. The copper foil 2 has a predetermined circuit pattern formed by etching or the like. The conductive paste 8 is embedded by screen printing or the like from the copper foil 2 side, protrudes into the peripheral portion of the opening of the copper foil 2, and the tip portion projects from the resin film 1 side.

The multilayer wiring board is constructed by stacking a plurality of layers (three layers in FIGS. 2 and 3) of a multilayer wiring base material having a structure as shown in FIG. 1 (i). As shown in FIGS. 2 and 3, in the multilayer wiring board, the conductive paste 8 is provided in the through hole 7 of the multilayer wiring substrate.
Is filled (filled with holes), it is possible to connect between the layers by via-on-via. In addition, as shown in FIG. 1I, the conductive paste 8 is printed so that a protrusion is formed on the side opposite to the printed surface (back side). The height of the protrusion of the conductive paste 8 depends on the size of the depression, but is 10 μm.
Around m is preferable.

As described above, when the via-on-via interlayer connection is performed, the conductive paste 8 is not directly sandwiched between the conductive pastes 8 as described in the prior art, but directly.
The conductive pastes 8 are connected to each other.

Further, as shown in FIG. 1 (h), the conductive paste 8 reaches the surface of the copper foil 2 (however, at the time of hole filling printing, the printing surface side thereof protrudes from the perforated portion 5 of the copper foil 2).
Since the holes are filled up (although it may be slightly recessed from the surface), the end of the conductive paste 8 on the printed surface side is the hole 5 of the copper foil 2.
Is in contact with the side and peripheral edges of the.

Next, the manufacturing process (manufacturing method) of the multilayer wiring board of the present invention will be described with reference to FIGS. 1 to 3.

(1) Manufacturing Process of Multilayer Wiring Substrate (FIG. 1) First, as shown in FIG. 1A, a resin film 1 made of thermoplastic polyimide (TPI) having a thickness of 30 to 100 μm.
The one-sided copper-clad resin film 10 in which the copper foil 2 having a thickness of 5 to 18 μm is attached to one surface of the one is prepared or produced.

Next, as shown in FIG. 1B, a dry film (resist) 4 is laminated on the copper foil 2 attached to the resin film 1 with a vacuum laminator or a roll laminator. Next, as shown in FIG. 1C, the circuit pattern is exposed on the dry film 4 and then developed.

Next, as shown in FIG. 1D, the copper foil 2 is etched using the dry film 4 as a mask to form a predetermined circuit pattern. At this time, the punching portion 5 which is a portion for punching the through hole 7 later is also formed by etching at the same time. Next, as shown in FIG. 1E, the dry film 4 on the copper foil 2 is peeled off,
As shown in (f), a masking tape 6 of 10 to 50 μm is attached as a mask material to the surface of the resin film 1 opposite to the copper foil 2. As the masking tape 6, P
ET or the like can be used. In addition to the masking tape, a release-treated film may be used.

Next, as shown in FIG. 1 (g), the masking tape 6 and the resin film 1 together with the masking tape 6 are exposed to 0.05% by irradiating the perforated portion 5 with a laser beam such as a CO2 laser.
A through hole 7 with a diameter of 0.3 mm is opened. The drilling of the through holes 7 is not limited to laser irradiation, but drilling may be used.

Next, as shown in FIG. 1H, the through hole 7
Conductive paste 8 is screen-printed on the substrate to fill in the holes. At this time, the conductive paste 8 has a diameter larger than the hole diameter of the punched portion 5 (through hole 7) so as to protrude from the punched portion 5.
For example, screen printing is performed with a diameter that is about 1.1 to 2.0 times the hole diameter. As a result, the brim portion 8a connected to the land portion 2a of the copper foil 2 in the surface direction is formed.
As the conductive paste 8, it is possible to use Ag, Cu, C, Ag-coated Cu paste, or any other conductive paste.

Next, by heating in an oven at 80 ° C. for about 1 hour, the conductive paste 8 is temporarily hardened, and then, as shown in FIG.
As shown in FIG. 6, when the masking tape 6 is peeled off, the protrusion 8b of the conductive paste 8 protruding from the resin film 1 is formed on the side opposite to the printing surface. As a result, the multilayer wiring substrate 20 is completed.

(2) Step of pressing multilayer wiring board (FIGS. 2 and 3) As shown in FIGS. 2 (a), (b), and (c), each multilayer wiring base material (three multilayer wiring substrates Material) 20a, 20b, 20
A plurality of circuit patterns and through holes 7 are formed in each of c. In addition, the conductive paste 8 is provided in the through hole 7.
Is filled.

As shown in FIG. 3 (a), each of the multilayer wiring substrates 20a to 20c and the outermost copper foil 9 are bonded together by hot pressing, and as shown in FIG. By forming a circuit on the outer layer copper foil 9, the multilayer wiring board 30 of the present embodiment is completed. The lamination of the multilayer wiring substrates 20a to 20c and the copper foil 2 by hot pressing is
By heating at about 280 ° C. and pressing at about 9 MPa, the circuit pattern of the copper foil 2 and the brim portion 8a of the conductive paste 8 are embedded in the resin film 1 of thermoplastic polyimide having adhesiveness and fluidity. Done. At this time,
The outermost copper foil 2 on the opposite side of the copper foil 9 and the brim 8a of the conductive paste 8 are also embedded in the resin film 1 by the height. At the same time, the conductive pastes 8 of the multilayer wiring base materials 20a to 20c are simultaneously hardened by hot pressing while being hardened. Thereby, the multilayer wiring base materials 20a to 20c
And the copper foil 9 are integrated.

According to this embodiment, since the conductive paste 8 is filled in the through holes 7 of the multilayer wiring base materials 20a to 20c, it is possible to connect the layers by using the via-on-via method. Since the protruding portion 8b of the conductive paste 8 is formed on the side opposite to the printed surface (back side), the printed surface side of the conductive paste 8 is in close contact with the protruding portion 8a when performing interlayer connection by via-on-via. However, it becomes possible to easily connect the conductive pastes 8 having good electrical connectivity.

Further, at the time of the filling printing of the through holes 7, the conductive paste 8 is filled so that the printing surface side thereof protrudes from the punched portion 5 of the copper foil 2, so that the brim portion 8a on the printing surface side of the conductive paste 8 is formed. Reliably contact the side surface and the peripheral edge of the perforated portion 5 of the copper foil 2, and as a result, the copper foil 2 and the conductive paste 8
Copper foil 2 and conductive paste 8 without deteriorating the electrical connectivity of
It becomes possible to connect and.

Further, since the copper clad resin film 10 is used in the process of manufacturing the base material for multilayer wiring, the accuracy of the positional dimension in the process of fixing, drilling and filling holes of the sample is maintained and the handling becomes easy. As a result, the labor of manufacturing work is also reduced. That is, in the past, the sample fixing, drilling, and hole filling steps had to be performed with the resin film (polyimide film) having flexibility and thin thickness, but in this embodiment, the resin film 1 After sticking the copper foil 2 on, fix the sample, make a hole,
Since the hole filling step can be performed, it becomes easy to make holes and fill the conductive paste 8.

4 to 6 show the multilayer wiring board of the present invention and an IC.
FIG. 3 is a cross-sectional view showing an example of a connection terminal structure in the case of mounting the substrate or using the multilayer wiring board of the present invention as an interposer (rearrangement substrate).

In FIG. 4, the multilayer wiring board 3 shown in FIG.
0 is subjected to electrolytic or electroless gold plating to form a plating layer 11 on the externally exposed portions of the conductive paste 8 and the copper foil 9 as shown in FIG. 2B, and further shown in FIG. As described above, the solder bumps 12 are formed by printing. In addition to the gold plating, the plating may be nickel-gold plating, etc.
Any plating may be used as long as it can be solder-printed.

In FIG. 5, the multilayer wiring board 3 shown in FIG.
(B) in the exposed portion of the conductive paste 8 of FIG.
As shown in, the bumps 13 are formed by overcoating the conductive paste by printing.

In FIG. 6, the multilayer wiring board 3 shown in FIG.
This is an example in which an anisotropic conductive film 16 is attached to at least the periphery of the connection terminal portion on the surface of the conductive paste 8 of No. 0 on the externally exposed portion side, as shown in FIG.

As described above, according to the present invention, it is possible to provide a flexible FPC having a multilayer wiring structure capable of high-density mounting. Therefore, by using the FPC of this multilayer wiring board in an electronic device, It is possible to achieve miniaturization and to improve the performance of curved products, for example, to incorporate a high-density printed circuit in the belt portion of a wristwatch.

Next, still another embodiment of the multilayer wiring substrate and multilayer wiring board according to the present invention will be described with reference to FIGS. 7, 8, 9 and 10.

In this embodiment, a first multi-layer wiring substrate filled with a conductive paste so as to protrude around the opening of a through hole by using screen printing and a copper foil without using screen printing. Prepare two types of multilayer wiring base materials including a second multilayer wiring base material that is filled with conductive paste up to the same height as the above, and form the multilayer wiring board by combining the two types of multilayer wiring base materials. It is something that is done.
More specifically, the second multilayer wiring base material is used as the outermost layer, and the first multilayer wiring base material is used as at least one of the inner layers to form a multilayer wiring board. .

Next, the first multilayer wiring substrate will be described with reference to FIG.

The first multi-layer wiring substrate 20 is a multi-layer wiring connecting material for constructing a multi-layer wiring board, and is basically composed of an FPC made of a single-sided copper-clad resin film. That is, as shown in FIG. 7 (j), the multilayer wiring substrate 20 is a copper-clad material in which a copper foil 2 is attached to one surface of a resin film 1 having adhesiveness such as thermoplastic polyimide (TPI). Resin film 10 and this copper-clad resin film 1
And a conductive paste 12 forming an inner via hole embedded in the through hole 7 (see FIG. 7 (g)) formed in No. 0. The copper foil 2 has a predetermined circuit pattern formed by etching or the like. Conductive paste 12
Is embedded by screen printing from the copper foil 2 side,
In addition to protruding as a brim portion 12a in the peripheral portion of the opening of the copper foil 2, the printed surface side of the conductive paste 12 is flat, and the tip end portion protrudes from the resin film 1 side as a protrusion 12b.

In the above embodiment, a material having flexibility, that is, flexibility is used as the resin film 1, but a rigid material such as glass epoxy prepreg or aramid epoxy prepreg may be used as the resin film 1. it can.

As another material of the resin film 1, BT resin, PPO, PPE or the like can be used.

The multilayer wiring board has a plurality of layers (FIGS. 9 and 10) in which the first multilayer wiring base material having the structure shown in FIG.
In the case of the first, second, and third layers starting from the outermost layer above, the second and third layers are stacked. As shown in FIGS. 9 and 10, in the multilayer wiring board, since the conductive pastes 12 and 14 are filled (filled) in the through holes 7 of the multilayer wiring base material, the connection between the layers is made via-on-via. Is possible.

As described above, when the via-on-via interlayer connection is performed, the conductive paste 12 as described in the prior art is used.
Instead of sandwiching the copper foil between the conductive paste 12 and the conductive paste 12, the conductive pastes 12 are directly connected to each other.

Next, with reference to FIG. 7, a manufacturing process of the first multilayer wiring base material will be described.

First, as shown in FIG.
A single-sided copper-clad resin film 10 in which a copper foil 2 having a thickness of 5 to 18 μm is attached to one surface of a resin film 1 having an adhesive property made of a thermoplastic polyimide having a thickness of 00 μm is prepared or produced.

Next, as shown in FIG. 7B, a dry film (resist) 4 is laminated on the copper foil 2 attached to the resin film 1 with a vacuum laminator or a roll laminator. Next, as shown in FIG. 7C, the circuit pattern is exposed on the dry film 4 and then developed.

Next, as shown in FIG. 7D, the copper foil 2 is etched using the dry film 4 as a mask to form a predetermined circuit pattern. At this time, the punching portion 5 which is a portion for punching the through hole 7 later is also formed by etching at the same time. Next, as shown in FIG. 7E, the dry film 4 on the copper foil 2 is peeled off,
As shown in (f), a masking tape 6 having a thickness of 10 to 50 μm is attached to the surface of the resin film 1 as a mask material. PET or the like can be used as the masking tape 6.

Next, as shown in FIG. 7 (g), the masking tape 6 together with the resin film 1 is exposed to 0.05% by irradiating the perforated portion 5 with a laser beam with a CO2 laser or the like.
A through hole 7 of to 0.3 mm phi. The drilling of the through holes 7 is not limited to laser irradiation, but drilling may be used.

Although the through hole 7 is made in the hole making portion 5 with the CO 2 laser here, a smaller hole (50 to 250 μm) can be made by doing so. That is, when the through hole 7 is to be formed together with the copper foil 2 without forming the hole 5, it is difficult to use the CO2 laser (hole capable of drilling: 50 to 250 microns) and a drill (hole capable of drilling: Large holes (more than 200 microns) could only be made with more than 200 microns. It should be noted that although it is possible to make a small hole by using another laser such as a UV-YAG laser or an excimer laser, the cost becomes very high, which is not realistic.

Here, since the through hole 7 is penetrated together with the copper foil 2, voids are likely to be formed when the conductive paste 12 described later is embedded with the copper foil 2 left. There are no drawbacks such as difficulty in removing smear generated during laser drilling.

Next, as shown in FIGS. 7H and 7I, the conductive paste 12 is placed on the copper foil 2 and the mask 33,
The conductive paste 12 is filled in the through holes 7 by moving a squeegee 32 such as urethane or silicone in the direction of arrow A for printing. At this time, the conductive paste 12 is placed at the exit of the through holes 7 on the resin film 1 side. A silicone or fluorine-treated breathable release paper 31 is laid to hold it.

Here, the reason why the release paper 31 has air permeability is that air escapes when the conductive paste 12 is embedded. Further, the reason why at least the upper surface of the release paper 31 is treated with silicone or fluorine is that the conductive paste 12 in contact with the release paper 31 is easily peeled off from the release paper 31,
This is to prevent the conductive paste 12 from falling off the through hole 7 when the release paper 31 is later peeled off.

At this time, the conductive paste 12 is screen-printed with a diameter of about 10 to 50% larger than the diameter of the hole 5 (through hole 7) so as to protrude from the hole 5. As a result, a flange portion 12a connected to the land portion 2a of the copper foil 2 in the surface direction is formed. At this time, the printed surface side of the conductive paste 12 is flat.

As the conductive paste 12, Ag, C
Any material that exhibits conductivity, such as u, C, or Ag-coated Cu paste, can be used.

Next, the release paper 31 is peeled off, heated in an oven at 80 ° C. for about 1 hour to temporarily cure the conductive paste 12, and the masking tape 6 is peeled off as shown in FIG. A protrusion 12b of the conductive paste 12 protruding from the resin film 1 is formed on the surface opposite to the surface. As a result, the first multilayer wiring substrate 20 is completed.

Next, the second multilayer wiring substrate will be described with reference to FIG.

The second base material 20 'for multilayer wiring is a connecting material for multilayer wiring for forming a multilayer wiring board, and is basically composed of an FPC made of a single-sided copper clad resin film. That is, the multilayer wiring substrate 20 'is shown in FIG.
As shown in, a copper clad resin film 10 in which a copper foil 2 is attached to one surface of a resin film 1 having adhesiveness such as thermoplastic polyimide (TPI), and the copper clad resin film 10 are formed. Conductive paste 1 for forming inner via holes embedded in through holes 7 (see FIG. 8G)
4 and. The copper foil 2a has a predetermined circuit pattern formed by etching or the like. The conductive paste 14 is embedded by printing from the copper foil 2a side,
It has the same height as the upper surface 2c of a and the conductive paste 1
4 has a flat rear end, that is, the printing surface side 14c, and a front end protruding from the resin film 1 side as a protrusion 14b. That is, as shown in FIG. 8 (j), the upper surface 2c of the copper foil 22a and the printing surface side 14c of the conductive paste 14c.
And are continuously flat at the same height.

Here, in the above embodiment, a material having flexibility, that is, flexibility is used as the resin film 1, but a rigid material such as glass epoxy prepreg or aramid epoxy prepreg may be used as the resin film 1. it can.

As the material of the resin film 1, BT resin, PPO, PPE, etc. may be used.

In the multilayer wiring board, the second multilayer wiring substrate having the structure as shown in FIG. 8 (j) is used as the outermost layer (from the uppermost outer layer to the first, second and third layers in FIGS. 10 and 11). If it is a layer,
The first layer) is constructed by stacking. As shown in FIGS. 10 and 11, in the multilayer wiring board, the through hole 7 of the multilayer wiring base material is used.
Since the conductive pastes 12 and 14 are filled in (filled in), the layers can be connected by the via-on-via method.

Next, the manufacturing process of the second base material for multilayer wiring will be described with reference to FIG.

First, as shown in FIG.
A one-sided copper-clad resin film 10 in which a copper foil 2 having a thickness of 5 to 18 μm is attached to one surface of a resin film 1 made of a thermoplastic polyimide having a thickness of 00 μm is prepared or produced.

Next, as shown in FIG. 8B, a dry film (resist) 4 is laminated on the copper foil 2 attached to the resin film 1 with a vacuum laminator or a roll laminator. Next, as shown in FIG. 8C, the pattern of the perforated portion of the through hole 7 is exposed on the dry film 4 and then developed. At this time, the remaining dry film 4a is developed so that the portion other than the perforated portion 5 is continuous.

Next, as shown in FIG. 8D, the copper foil 2 is etched by using the dry film 4a as a mask to form a copper foil 2a having a predetermined perforation 5. At this time, the punching portion 5 which is a portion for punching the through hole 7 later is also formed by etching at the same time. As a result, as shown in FIG. 9A, the copper foil 2a is formed so as to be continuous in a portion other than the conductive paste 14.

Next, as shown in FIG. 8 (e), the copper foil 2a
The upper dry film 4a is peeled off, and as shown in FIG.
Stick the masking tape 6 of 0 μm. PET or the like can be used as the masking tape 6.

Next, as shown in FIG. 8 (g), the masking tape 6 together with the masking tape 6 is applied to the resin film 1 by irradiating laser light to the perforated portion 5 with a CO2 laser or the like.
A through hole 7 with a diameter of 0.3 mm is opened.

As described above, since the through hole 7 is formed after the hole forming portion 5 is formed, a small hole can be formed as described above.

Here, since the through hole 7 is penetrated together with the copper foil 2, voids are easily formed when the conductive paste 12 described below is embedded while leaving the copper foil 2. There are no drawbacks such as difficulty in removing smear generated during laser drilling.

Next, as shown in FIGS. 8H and 8I, the conductive paste 14 is placed on the copper foil 2 and a squeegee 32 such as urethane or silicone is moved in the direction of arrow A for printing. The conductive paste 14 is filled in the through holes 7 by means of a silicone or fluorinated release paper 31 for retaining the conductive paste 14 at the exit of the through holes 7 on the resin film 1 side. Lay out.

Here, the reason why the release paper 31 has air permeability is that air escapes when the conductive paste 14 is embedded. Further, the reason why at least the upper surface of the release paper 31 is treated with silicone or fluorine is that the conductive paste 14 in contact with the release paper 31 is easily peeled off from the release paper 31,
This is to prevent the conductive paste 14 from falling off the through hole 7 when the release paper 31 is later peeled off.

At this time, the conductive paste 14 is formed as shown in FIG.
As shown in (j), the upper surface 2c of the copper foil 22a and the rear end portion of the conductive paste 14, that is, the printing surface side 14c are continuous at the same height and are completely flat.

As the conductive paste 14, Ag, C
Any material that exhibits conductivity, such as u, C, or Ag-coated Cu paste, can be used.

Next, the release paper 31 is peeled off, heated in an oven at 80 ° C. for about 1 hour to temporarily cure the conductive paste 14, and the masking tape 6 is peeled off as shown in FIG. A protrusion 14b of the conductive paste 14 protruding from the resin film 1 is formed on the surface opposite to the surface. As a result, the second multilayer wiring substrate 20 'is completed.

The second multilayer wire base material 2 shown in FIG.
The modification of the manufacturing process of 0'is shown.

In this modification, the through hole 7 is formed in both the copper foil 2 without forming the hole 5 in the copper foil 2. By doing so, there is an advantage that the forming process of the perforated portion 5 can be omitted and the manufacturing process can be shortened.

That is, as shown in FIG.
A single-sided copper-clad resin film 10 in which a copper foil 2 having a thickness of 5 to 18 μm is attached to one surface of a resin film 1 made of a thermoplastic polyimide having a thickness of to 100 μm is prepared or produced.

Next, as shown in FIG. 9B, a through hole 7 of 0.2 mmφ or more is made in the resin film 1 together with the copper foil 2 and the masking tape 6 by a drill.

Next, as shown in FIGS. 9C and 9D, the conductive paste 14 is placed on the copper foil 2, and a squeegee 32 such as urethane or silicone is moved in the direction of arrow A for printing. The conductive paste 14 is filled in the through holes 7 by means of a silicone or fluorinated release paper 31 for retaining the conductive paste 14 at the exit of the through holes 7 on the resin film 1 side. Lay out.

Here, the reason why the release paper 31 has air permeability is that air escapes when the conductive paste 14 is embedded. Further, the reason why at least the upper surface of the release paper 31 is treated with silicone or fluorine is that the conductive paste 14 in contact with the release paper 31 is easily peeled off from the release paper 31,
This is to prevent the conductive paste 14 from falling off the through hole 7 when the release paper 31 is later peeled off.

As the conductive paste 14, Ag, C
Any material that exhibits conductivity, such as u, C, or Ag-coated Cu paste, can be used.

Next, the release paper 31 is peeled off, heated in an oven at 80 ° C. for about 1 hour to temporarily cure the conductive paste 14, and the masking tape 6 is peeled off as shown in FIG. A protrusion 14b of the conductive paste 14 protruding from the resin film 1 is formed on the surface opposite to the surface. As a result, the second multilayer wiring substrate 20 'is completed.

Next, the manufacturing and pressing step of the multilayer wiring board in which the first and second multilayer wiring base materials 20 and 20 'are combined will be described with reference to FIGS.

As shown in FIG. 10, this multilayer wiring board is
The second multilayer wiring substrate 20 ′ shown in FIG. 8 (j) or 9 (e) is arranged in the outermost layer (uppermost layer), and the other layers (inner layers) are shown in FIG. 7 (j). First multilayer wiring substrate 2
I am trying to match 0. A plurality of circuit patterns and through holes 7 are formed in each layer, and the through holes 7 are filled with conductive pastes 12 and 14.

As shown in FIG. 11 (a), the first and second multilayer wiring base materials 20 and 20 'and the lowermost copper foil 9 are bonded together by heat pressing in a batch or sequentially, As shown in (b), the multilayer wiring board of the present embodiment is completed by forming a circuit on the lowermost copper foil 9.

Here, as shown in FIG. 11 (a), the upper surface of the outermost layer (uppermost layer) has the same height as the upper surface 2c of the copper foil 22a and the rear end portion of the conductive paste 14, that is, the printing surface side 14c. Since it is completely flat and continuous, it is possible to uniformly apply force to the entire wiring board during hot pressing. Thereby, reliable bonding can be achieved and better electrical connectivity is obtained.

Substrates 2 for multi-layer wiring by the hot pressing
The 0, 20 'and the copper foil 2 are laminated to each other by heating at about 280 ° C. and pressing at about 9 MPa to form the copper foil 2 in the resin film 1 of thermoplastic polyimide having adhesiveness and fluidity.
It is performed by embedding the circuit pattern and the brim portion 12a of the conductive paste 12. At this time, at the same time, the conductive pastes 12 and 14 of the multilayer wiring base materials 20 and 20 'are simultaneously hardened while being pressed by a hot press.

Finally, as shown in FIG. 11B, the outermost copper foil 2a is shaved by etching or the like to form a circuit, and the copper foil 2a of the outermost circuit and the conductive paste 14 are electrically connected. Metal layer 1 to increase the connection area
5 (Au, Ni, Hg, Ag, Rh, Pd, etc., as long as they show conductivity, but when mounting an IC or the like on the via, Au is preferable in consideration of oxidation and bonding) .

As described above, according to this embodiment,
Since the conductive pastes 12 and 14 are filled in the through holes 7 of the first and second multilayer wiring base materials 20 and 20 ′,
Via-on-via enables connection between layers, and since the projections 12b and 14b of the conductive pastes 12 and 14 are formed, electrical connectivity is achieved during via-on-via interlayer connection. Good conductive paste 12, 14
It becomes possible to easily connect each other.

Further, at the time of the filling printing of the through hole 7, the conductive paste 12 of the first multilayer wiring base material 20 is filled so that the printed surface side thereof protrudes from the punched portion 5 of the copper foil 2, so that the conductive Slit portion 12a on the printing surface side of paste 12
Reliably contacts the side surface and the peripheral edge of the perforated portion 5 of the copper foil 2, and as a result, connects the copper foil 2 and the conductive paste 12 without deteriorating the electrical connectivity between the copper foil 2 and the conductive paste 12. It becomes possible to do.

Further, since the copper-clad resin film 10 is used in the process of manufacturing the base material for multilayer wiring, the accuracy of the positional dimension in the process of fixing, drilling and filling holes of the sample is maintained and the handling becomes easy. As a result, the labor of manufacturing work is also reduced. That is, in the past, the sample fixing, drilling, and hole filling steps had to be performed with the flexible and thin resin film (polyimide film) 1 being used, but in this embodiment, the resin film is used. After the copper foil 2 is attached to the substrate 1, the sample can be fixed, punched, and filled, so that the punching and the filling of the conductive paste 12 can be easily performed.

Further, since it is possible to form a desired multilayer wiring board simply by preparing the above-mentioned multilayer wiring base material, and combining and bonding them together, it is not necessary to process the multilayer wiring base material in the pressing step. The pressing process of the multilayer wiring board is simplified.

The above-mentioned FIGS. 1 (i), 7 (j), 8
(J) and 9 (e) for the multilayer wiring substrate 20, 20
Through hole 7 and conductive paste 8, 12, 14 in
Shape seen from the plane (Fig. 1 (i), 7 (j), 8
The shapes of (j) and 9 (e when viewed from above) are usually circular, but the shape is not limited to this and other shapes may be used.

[0108]

As described above, according to the present invention, a through hole is formed in a copper clad resin film in which a copper foil is attached to one surface of an adhesive resin film, and a conductive paste is embedded therein. Therefore, as compared with the case where the through hole is formed by the resin film alone and the conductive paste is embedded, the through hole can be formed more easily as the thickness increases, and the conductive paste can be embedded more easily.

Further, according to the present invention, the conductive paste of the multilayer wiring substrate is embedded in the through hole of the copper clad resin film by screen printing from the copper foil side so that the tip projects toward the resin film side. Therefore, when a plurality of multilayer wiring base materials are laminated, the tip of the conductive paste is securely connected to the adjacent copper foil or conductive paste of the multilayer wiring base material, and when the multilayer wiring board is configured, The electrical connectivity of can be significantly improved. In particular, the direct connection between the conductive pastes not via the copper foil contributes to the improvement of electrical connectivity.

From the above, according to the present invention, the via
On-via and chip-on-via are possible, high-density mounting is possible, and flexible FPCs can be easily multilayered.

Further, according to the present invention, the outermost layer (uppermost layer)
Since the upper surface of the copper foil and the rear end of the conductive paste, that is, the printing surface side, are continuously flat at the same height, it is possible to apply a uniform force to the entire wiring board during hot pressing. it can. Thereby, reliable bonding can be achieved and better electrical connectivity is obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a multilayer wiring base material forming a multilayer wiring board according to an embodiment of the present invention in the order of manufacturing steps.

FIG. 2 is a cross-sectional view showing a multilayer wiring board according to an embodiment of the present invention in the order of manufacturing steps.

FIG. 3 is a cross-sectional view showing a multilayer wiring board according to an embodiment of the present invention in the order of manufacturing steps.

FIG. 4 is a cross-sectional view showing an example of a connection terminal structure of a multilayer wiring board according to the present invention.

FIG. 5 is a cross-sectional view showing another example of the connection terminal structure of the multilayer wiring board according to the present invention.

FIG. 6 is a sectional view showing still another example of the connection terminal structure of the multilayer wiring board according to the present invention.

FIG. 7 is a cross-sectional view showing a first multilayer wiring base material forming a multilayer wiring board according to another embodiment of the present invention in the order of manufacturing steps.

FIG. 8 is a cross-sectional view showing a second multilayer wiring base material forming a multilayer wiring board according to another embodiment of the present invention in the order of manufacturing steps.

FIG. 9 is a cross-sectional view showing a second multilayer wiring base material forming a multilayer wiring board according to another embodiment of the present invention in the order of manufacturing steps.

FIG. 10 is a cross-sectional view showing a multilayer wiring board according to another embodiment of the present invention in the order of manufacturing steps.

FIG. 11 is a cross-sectional view showing a multilayer wiring board according to another embodiment of the present invention in the order of manufacturing steps.

[Explanation of symbols]

1 ... Resin film, 2 ... Copper foil, 4 ... Dry film, 5
… Perforated part, 6… Masking tape, 7… Through hole, 8…
Conductive paste, 9 ... Copper foil, 10 ... Copper clad resin film, 1
1 ... Plating layer, 12 ... Solder bump, 13 ... Bump, 16
... anisotropic conductive film, 20, 20a to 20c ... base material for multilayer wiring, 30 ... multilayer wiring board.

Continued front page    (72) Inventor Satoshi Nakao             1440 Rokuzaki, Sakura City, Chiba Prefecture Fujikura Ltd.             Sakura office F-term (reference) 5E317 AA24 BB03 BB12 BB14 BB19                       BB22 CC17 CC25 GG11 GG14                       GG16                 5E346 AA12 AA15 AA32 AA43 CC10                       CC32 CC39 DD02 DD32 EE06                       EE07 EE15 FF18 FF22 GG06                       GG15 GG22 GG28 HH07 HH25                       HH33

Claims (27)

[Claims] 1. A copper clad resin film in which a copper foil is attached to one surface of an adhesive resin film, and a through hole is formed so as to penetrate the copper foil and the resin film, and the copper clad resin. A substrate for multi-layer wiring, comprising a conductive paste embedded in a through hole of the film by screen printing so that a tip of the film projects from the copper foil side to the resin film side. 2. The multi-layer wiring substrate according to claim 1, wherein the conductive paste is embedded in the through hole so as to protrude around the opening of the through hole of the copper foil. 3. The multilayer wiring substrate according to claim 1, wherein the resin film is made of a thermoplastic adhesive. 4. A plurality of the multi-layer wiring base materials according to claim 1, wherein a tip of the conductive paste is connected to a copper foil or a conductive paste of an adjacent multi-layer wiring base material. A multilayer wiring board made by stacking. 5. The multilayer wiring board according to claim 4, wherein the outermost copper foil is embedded in the resin film to which the copper foil is attached. 6. A step of forming a through hole penetrating the copper foil and the resin film in a copper clad resin film in which a copper foil is attached to one surface of a resin film having adhesiveness, and the through hole. And a step of embedding a conductive paste by screen printing so that the tip of the copper foil is projected to the resin film side, the method for manufacturing a multilayer wiring substrate. 7. A step of forming a predetermined circuit pattern by etching the copper foil on a copper-clad resin film having a copper foil attached to one surface of an adhesive resin film, the circuit pattern comprising: A step of forming a mask layer on the resin film side of the formed copper clad resin film, a step of forming a through hole penetrating the copper foil, the resin film and a mask material, the through hole, the copper foil side A method for manufacturing a base material for multilayer wiring, comprising: a step of embedding a conductive paste by screen printing, and a step of removing the mask material. 8. A plurality of the multilayer wiring base materials according to claim 1 are connected so that the tip of the conductive paste is connected to a copper foil or a conductive paste of an adjacent multilayer wiring base material. A method for manufacturing a multilayer wiring board, comprising laminating and laminating with a resin film having the adhesive property. 9. The method of manufacturing a multilayer wiring board according to claim 8, wherein the conductive paste is fully cured at the same time when the multilayer wiring base material is attached. 10. A copper-clad resin film in which a copper foil is attached to one surface of an adhesive resin film and a through hole is formed so as to penetrate the copper foil and the resin film, and the copper-clad resin film. A substrate for multilayer wiring, comprising: a conductive paste embedded in a through hole of a resin film so that a tip of the resin film protrudes from the copper foil side of the resin film. 11. A step of forming a through hole penetrating the copper foil and the resin film in a copper clad resin film having a copper foil attached to one surface of an adhesive resin film, and the through hole And a step of embedding a conductive paste so that a tip of the conductive paste is projected from the copper foil side from the resin film. 12. A copper-clad resin film in which a copper foil is attached to one surface of an adhesive resin film and a through hole is formed so as to penetrate the copper foil and the resin film, and the copper-clad resin film. The through hole of the resin film, comprising a conductive paste embedded so that the front end protrudes from the copper foil side from the resin film and the rear end is flush with the copper foil. Base material for wiring. 13. A copper-clad resin film in which a copper foil is attached to one surface of an adhesive resin film and a through hole is formed so as to penetrate the copper foil and the resin film, and the copper-clad resin film. In the through hole of the resin film, the tip comprises a conductive paste embedded by screen printing so that the tip protrudes from the resin film from the resin film side and protrudes around the opening of the through hole of the copper foil. Characteristic multi-layer wiring substrate. 14. The multilayer wiring base material according to claim 12, wherein a plurality of the multilayer wiring base materials are connected so that a tip of the conductive paste is connected to a copper foil or a conductive paste of an adjacent multilayer wiring base material. A multilayer wiring board, which is used as an outermost layer of a laminated multilayer wiring board. 15. A copper-clad resin film in which a copper foil is attached to one surface of an adhesive resin film and a through hole is formed so as to penetrate the copper foil and the resin film, and the copper-clad resin film. A conductive paste embedded in the through hole of the resin film by screen printing so that the tip projects from the copper foil side from the resin film and protrudes around the opening of the through hole of the copper foil; A multilayer wiring substrate, and a copper clad resin film in which a copper foil is attached to one surface of a resin film having adhesiveness, and a through hole is formed so as to penetrate the copper foil and the resin film, In the through hole of this copper-clad resin film, a conductive paste embedded so that the front end protrudes from the resin film from the copper foil side and the rear end is flush with the copper foil. And a second base material for multilayer wiring, wherein the second base material for multilayer wiring is an outermost layer, the first base material for multilayer wiring is an inner layer other than the outermost layer, and A multilayer wiring board, wherein a plurality of multilayer wiring base materials are laminated so that their tips are connected to the copper foil or the conductive paste of the adjacent multilayer wiring base material. 16. The second multilayer wiring base material according to claim 15 is an outermost layer, the first multilayer wiring base material is an inner layer other than the outermost layer, and the tip of the conductive paste is adjacent to the outermost layer. A method for manufacturing a multilayer wiring board, comprising stacking a plurality of multilayer wiring base materials so as to be connected to a copper foil or a conductive paste of the multilayer wiring base material, and adhering the multilayer wiring base materials with the resin film. 17. The method of manufacturing a multilayer wiring board according to claim 16, wherein the conductive paste is main-cured at the same time as the multilayer wiring base material is bonded. 18. A step of forming a through hole penetrating the copper foil and the resin film in a copper clad resin film having a copper foil attached to one surface of an adhesive resin film, And a step of embedding a conductive paste so that the front end projects from the copper foil side from the resin film and the rear end is flush with the copper foil. Method. 19. A step of forming a predetermined circuit pattern by etching the copper foil on a copper-clad resin film having a copper foil attached to one surface of an adhesive resin film, the circuit pattern comprising: A step of forming a mask layer on the resin film side of the formed copper clad resin film, a step of forming a through hole penetrating the copper foil, a resin film, and a mask material; and a copper foil in the through hole. And a step of embedding a conductive paste so that the rear end is at the same height as the copper foil from the side, and a step of removing the mask material so that the front end of the conductive paste protrudes from the resin film. A method for producing a characteristic multilayer wiring substrate. 20. A step of forming a through hole penetrating the copper foil and the resin film in a copper clad resin film in which a copper foil is attached to one surface of an adhesive resin film, and the through hole. In addition, a step of embedding a conductive paste by screen printing so that the front end projects from the copper foil side from the resin film and the rear end protrudes around the opening of the through hole of the copper foil. A method for manufacturing a base material for multilayer wiring. 21. A step of forming a predetermined circuit pattern by etching the copper foil on a copper clad resin film having a copper foil adhered to one surface of an adhesive resin film, the circuit pattern comprising: A step of forming a mask layer on the resin film side of the formed copper clad resin film, a step of forming a through hole penetrating the copper foil, a resin film, and a mask material; and a copper foil in the through hole. A step of embedding a conductive paste by screen printing from the side so as to protrude around the opening of the through hole of the copper foil; and a step of removing the mask material so that the tip of the conductive paste projects from the resin film. A method of manufacturing a base material for multilayer wiring, comprising: 22. The multi-layer wiring substrate according to claim 10, wherein the resin film is made of a flexible material. 23. The multi-layer wiring substrate according to claim 10, wherein the resin film is made of a rigid material. 24. The multilayer wiring board according to claim 14, wherein the resin film is made of a flexible material. 25. The multilayer wiring board according to claim 14, wherein the resin film is made of a rigid material. 26. The resin film is made of a flexible material, 11, 18, 19,
20. A method for manufacturing a base material for multilayer wiring according to any one of 20 and 21. 27. The resin film according to claim 11, 18, 19, or 20, wherein the resin film is made of a rigid material.
22. The method for manufacturing a base material for multilayer wiring according to any one of 21.