JPH1187925A - Manufacture of multilayered circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve reliability and operability by forming a columnar conductive element of conductive polymer thick film paste at a conductor formed on a board, covering its periphery with an insulating layer, and exposing a head of the columnar element embedded in the covered insulating layer by mechanical polishing for forming a conductor. SOLUTION: A conductor circuit 2 is formed on a board 1 by using prior art. Then, a columnar conductive element 10 is formed by using conductive polymer thick film paste. The paste is obtained by dispersing a polymer (resin) binder. Then, a conductive element is formed by forming a film in a predetermined size at a predetermined place by printing, and then curing it. Furthermore, since solid resin is dissolved in solvent to be used for binder, the columnar element 10 having high reliability can be formed. The element 10 can be freely extended or contracted in X, Y and Z directions, air gap is scarcely formed in the element, and residual stress is scarcely retained. Thus, the element 10 having high reliability is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method of manufacturing a multilayer wiring board, and more particularly to a method of manufacturing a so-called build-up multilayer wiring board in which conductive circuits and insulating layers are alternately laminated.

[0002]

2. Description of the Related Art In recent years, there has been a remarkable progress in high-density wiring technology for electronic component mounting substrates due to demands for higher performance and smaller size of electronic communication devices. In particular, due to the high integration of semiconductor elements, the increase in the number of terminals, and the miniaturization of electronic components, the development of multilayer wiring boards in which wiring circuits are formed in multiple layers for the purpose of increasing the density of printed wiring boards has been rapidly advancing. . Conventionally,
As a multilayer wiring board, for example, a multilayer wiring board in which a plurality of circuit boards on which an inner layer circuit is formed is laminated with a prepreg as an insulating layer, and then heat-pressed and integrated, and the layers are connected to each other by plating through holes to conduct electricity. Was common.

However, in this method of manufacturing a multilayer wiring board, the number of through-holes for interlayer connection increases as the number of layers increases and the density increases, and the area for passing a conductor circuit is reduced. It has become difficult to form circuits and increase the density. As a multilayer wiring board that can solve such problems, we have developed a build-up multilayer wiring board in which conductive circuits and insulating layers are alternately laminated and only those parts that require interlayer connection are connected with via holes (blind through holes). Was done. High-density circuits are possible with the build-up method multilayer wiring board.

[0004] The manufacturing process of the build-up method multilayer wiring board is as follows.
Generally, it comprises the steps shown in FIG. (1) a step of forming a conductor circuit 2 on a substrate 1, (2) a step of forming an interlayer insulating layer 3 on a conductor 2 of a substrate, (3)
Forming a via hole 4 at a predetermined position of the interlayer insulating layer 3 by light or heat; and (4) a via hole 4
Forming a metal conductor 6 on the interlayer insulating layer on which is formed by means such as vapor deposition and plating.

When a photosensitive resin is used for the interlayer insulating layer in this method, high insulation, high glass transition temperature, high heat resistance, low water absorption, and low dielectric constant required for the insulating layer while imparting photosensitivity are provided. However, it is difficult to design a resin that satisfies low dielectric loss and the like. In addition, it is also difficult to design a resin that retains the property that the unirradiated portion can be removed by development using a solvent or an aqueous alkali solution as a developing solution, while at the same time having chemical resistance such as desmear resistance and plating solution resistance. I have a problem.

On the other hand, when a thermosetting resin is used for the interlayer insulating layer, a via hole is opened by irradiating a laser beam. However, in a heat mode laser, a part of the resin is carbonized.
In the case of the laser remaining in the bottom of the via hole or in the photon mode laser, the inorganic filler or the like in the insulating layer remains as it is, so that the formation of the conductor in the subsequent process is incomplete and the connection reliability has many problems.

Further, in this method, it is difficult to determine whether or not all the via holes have a desired shape at the stage when the via holes are opened. As an improvement of this method, a method of obtaining an electrical connection by embedding a conductive polymer thick film paste instead of obtaining an electrical connection of a via hole by the above-described means such as vapor deposition and plating has been studied. ing. This is shown in (5) to (7) of FIG. This is after the step of opening a via hole in the conventional process (Fig. 1 (3)).
(5) A step of embedding the conductive polymer thick film paste 5 in the via hole 4 by screen printing or the like and curing the paste to form a conductor, and (6) a step of removing the head of the conductor by mechanical polishing. And (7) forming a conductor 6 over the entire mechanically polished surface.

However, according to this method, the diameter is several
It is necessary to ensure that a paste consisting of metal powder and a resin binder is buried in a via hole with a depth of several tens of microns, which is not more than 00 microns, to ensure high conductivity without bubbles and cracks and connection reliability. It is very difficult, the yield is poor, and practical application is delayed. As a method of solving such a problem of the conventional method of manufacturing a multilayer wiring board by a build-up method, a via-post type build-up wiring board has been proposed. This is a process as shown in FIG.

(1) A step of forming a conductive circuit 2 on a substrate 1, (2) A photosensitive resin 7 (dry film resist, photoresist) is applied and dried on the substrate, and exposed through a predetermined mask. And (3) forming a columnar metal block 9 called a via post in the hole 8 from which the photosensitive resin has been removed by development, by means of electroplating or the like, and (4) photosensitizing. Removing and removing the conductive resin 7,
(5) a step of applying and curing the thermosetting resin 31 over the entire surface of the substrate so as to cover the via posts 9; and (6) performing mechanical polishing to expose the top of the via posts buried in the thermosetting resin 31. (7) a step of forming the metal conductor 6 on the interlayer insulating layer on which the via posts 9 are formed by means such as vapor deposition and plating;

And the like. Since this via post type build-up wiring board makes electrical connection points first,
The feature is that the interlayer connection reliability is very high.
However, there is a problem that formation of via posts requires a very large number of steps, which increases material costs and lowers yield, so that significant cost increases cannot be avoided.

[0011]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a method of manufacturing a multilayer wiring board having highly reliable conductive via holes with excellent workability. is there.

[0012]

Means for Solving the Problems In order to achieve the above object, the present inventors have conducted intensive studies on a process for producing a multilayer wiring board, and as a result, a conductive polymer thick film paste was previously used on a conductive circuit. The present inventors have found that the above-mentioned problems can be solved by forming a columnar conductor by using this method, and have completed the present invention. That is, the present invention provides (1) a step of forming a conductor circuit on a substrate, (2) a step of forming a columnar conductor on a conductor of the substrate using a conductive polymer thick film paste,
(3) a step of covering the periphery of the columnar conductor with an insulating layer;
High reliability is obtained by a method for manufacturing a multilayer substrate, comprising: (4) a step of exposing the head of a columnar conductor buried by an insulating layer by mechanical polishing; and (5) a step of forming a conductor on the mechanically polished surface. To provide a multilayer wiring board with excellent workability.

Hereinafter, the present invention will be described in detail according to the method for manufacturing a multilayer wiring board according to the present invention (see FIG. 3). The first step (FIG. 3A) of forming the conductive circuit 2 on the substrate 1 can use a conventionally known technique. Generally, a glass-epoxy laminate is widely used as the substrate 1, but a paper-phenol laminate, an aramid laminate, a bismaleimide laminate, a polyimide substrate, a metal core substrate, or the like may be used. The conductive circuit 2 is generally obtained by leaving a copper foil bonded to the substrate 1 as a predetermined pattern by applying photolithography technology. Instead of the copper foil, a copper thin film formed by vapor deposition, electroless and / or electrolytic plating, or a conductive metal thin film other than copper may be used. Also, a conductive thick film obtained by printing a conductive paste by a method such as screen printing and curing the conductive paste may be used.

In the present invention, before entering the next second step, as shown in FIG. 3A, the step between the wiring circuit and the base material is filled with an insulating layer 32A in advance and smoothed ( (Planarization) structure and then steps (2 ′) to (5 ′) can be adopted.

As a second step (FIG. 3B), the conductor 2
On top of this, a columnar conductor 1 is formed using a conductive polymer thick film paste.
0 is formed. The conductive polymer thick film paste is obtained by dispersing conductive particles in a polymer (resin) binder.
After forming a film with a predetermined size in a predetermined place by printing,
This is cured to form a conductor. Generally, as a printing means, other printing methods can be adopted as long as fine screen printing can be performed. Here, as the conductive particles, any one of gold, silver, copper, nickel, carbon, graphite and the like can be used, and in consideration of conductivity, stability, cost, etc., copper powder or silver is generally used. Plated copper powder is used.

Further, epoxy resin as a binder,
Various thermosetting resins such as a phenol resin, a melamine resin, and a thermosetting acrylic resin are used alone or in combination. Further, in consideration of the solubility of the resin and the printing workability, these thermosetting resins can be used after being diluted with an organic solvent, a plasticizer, or the like. As described above, a method of embedding a via hole with a conductive polymer thick film paste has been considered as one of the conventional methods for manufacturing a multilayer wiring board. It is an undetermined condition that the molecular thick film paste 5 is solvent-free. This is because heat treatment (for example,
(Heat curing of interlayer insulation layer, soldering during component mounting, heating in pressure cooker test, heat resistance test, heat cycle test, etc.), foaming and blistering occur due to evaporation of the solvent, and connection reliability is impaired. This is because

On the other hand, the conductive polymer thick film paste 10 used in the method of the present invention does not have this limitation. This is because as is clear from FIGS. 3 (2) and (2 ′),
In the present invention, the conductive polymer thick film paste is printed in a columnar shape and is thermally cured. However, the columnar body 10 is in an open state, so that the solvent can be easily diffused during the thermal curing and can be performed reliably. Because. As a result, a phenol resin, a melamine resin, a curable acrylic resin, or the like, which is relatively difficult to eliminate the solvent, can be used as the conductive polymer thick film paste resin of the present invention.

Further, even when an epoxy resin is used, not only bisphenol A and bisphenol F type liquid resins but also solid resins such as novolak epoxy and various polyfunctional epoxy resins can be dissolved in a solvent and used as a binder. As a result, a highly reliable columnar conductor 1
0 can be formed. In addition, even if the solvent is not used, a certain degree of shrinkage of the thermosetting resin is inevitable during curing.Therefore, when the via holes are filled with the conductive polymer thick film paste, voids are generated or internal stress is generated. According to the present invention, the columnar body can be freely contracted in the X and Y directions and the Z direction even though there is a possibility that the columnar body will remain. Can be In this step, it is also a major feature of the present invention that it is easy to visually inspect or check with a checker whether or not the predetermined conductive columnar conductor 10 having a predetermined size and a predetermined size is completed. In addition, compared to the prior art shown in FIG. 2 in which the columnar conductor is formed by electrolytic copper plating by heavy casting, the method of the present invention is a very simple process of screen printing and thermosetting, so that the product yield is high. And the cost can be significantly reduced.

As a third step (FIG. 3C), the periphery of the columnar conductor 10 is covered with an insulating layer 32. Here, for the insulating layer 32, a photocurable or / and thermosetting resin composition is used. The material design of the insulating layer 32 is easier than that of the insulating layer 32 used as an interlayer insulating layer in a conventional build-up method of manufacturing a multilayer wiring board. That is, when the photosensitive resin is used as the insulating layer 32 in the present invention, the entire surface of the insulating layer 32 is irradiated with light and cured, so that the insulating layer 32 has high insulating properties and high glass transition temperature required while having photosensitivity. It is only necessary to design a resin that satisfies high heat resistance, low water absorption, low dielectric constant, low dielectric loss, etc., and since a development process is unnecessary, it is easy to combine desmear resistance, plating solution resistance, etc. . The photosensitive resin used in the present invention contains a photosensitive resin, a photopolymerization catalyst, and a filler, and is diluted with a photosensitive monomer or an organic solvent as necessary to form a paste, and is subjected to screen printing, dip coating, and spray coating. , Curtain coating,
It is applied by centrifugal application. After the application, it is dried if necessary and cured by light irradiation. It is also possible to improve the physical properties of the insulating layer 32 by performing B-stage by photoreaction and performing mechanical polishing in the next step at this stage, and then performing photocuring or thermal curing.

On the other hand, when a thermosetting resin is used for the interlayer insulating layer 32, there is little restriction on the type of the resin and the selection of the filler, and many thermosetting resins and functional fillers are selected as the interlayer insulating film. Can be used. The thermosetting resin used in the present invention includes epoxy resin, phenol resin, xylene resin, melamine resin, urea resin, benzoguanamine resin, bismaleimide resin, polyamide resin, polyimide resin, thermosetting polyphenylene ether resin, thermosetting acrylic Various thermosetting resins such as resins are used alone or in combination. If necessary, a filler or a curing catalyst is added. These are diluted with an organic solvent and applied as a paste.

The coating method includes screen printing, dip coating, spray coating, curtain coating, centrifugal coating and the like. After the application, the coating is dried and cured as needed. The curing reaction can be controlled to achieve the B stage. At this stage, mechanical polishing in the next step is performed, and then thermal curing is further performed to improve various physical properties of the insulating layer 32. In this step, a method of performing photo-curing and / or thermo-curing after forming a photo-curing and / or thermo-curing insulating resin around the columnar conductor 10 by a screen printing technique, or a photosensitive insulating material is used. A method may be used in which after the entire surface is applied, after exposure and development through a mask that does not irradiate light only to the columnar conductor 10, photocuring and / or thermal curing are performed again.

The fourth step (FIG. 3D) is a step of exposing the head of the columnar conductor 10 buried by the insulating layer by mechanical polishing to make it planar (planarization). As a method of mechanical polishing, buff polishing is generally used. In the buff polishing, the polishing roughness and the polishing amount can be adjusted by selecting the abrasive, adjusting the polishing pressure, and adjusting the substrate transfer speed. The fifth step (FIG. 3 (5)) is a step of forming the conductor 6 on the mechanically polished surface. This step employs means such as vapor deposition, plating, and printing of a conductive paste, similarly to the steps performed in the conventional method. Generally,
It is used as a desmear treatment in a through-hole, is subjected to etching with permanganate, is then subjected to electroless copper plating, and then lacks electrolytic copper plating to form a conductive layer 6 on the entire surface of the substrate. By repeating the steps (1) to (5), the multilayer wiring board of the present invention is manufactured.

The method for manufacturing a multilayer wiring board according to the present invention has the following features. 1) Via-holes are previously formed in conductive pillars (pillar conductors)
By introducing the step of forming the via hole, the electrical connectivity of the via hole can be reliably ensured. 2) The columnar conductor can be easily manufactured in a short time by a simple and familiar technique such as screen printing and heat curing. 3) As the columnar conductor, generally used widely used conductive polymer thick film paste (PTF, poIymer)
Thick Film) can be used. This conductive PT
The F paste does not necessarily need to be a solventless type. 4) At the stage when the columnar conductor is formed, it can be easily inspected whether the conductor is as designed. 5) Various materials can be applied as an interlayer insulating material serving as an electrical insulator supporting the columnar conductor, as compared with a conventional method. 6) A dry film or a resist ink can be used for forming an insulating layer. The resist ink does not necessarily need to be solventless.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a multilayer wiring board according to the present invention is shown in the following examples. It goes without saying that the present invention is not limited to these examples. Further, the unit symbol “part” indicating the ratio in the examples indicates part by weight.

(Example 1) 1) Copper paste (abbreviated as PTF-C-1) 100 parts of 2% silver-coated copper powder, phenol resin (solid content: 7)
8 parts of a 0% butyl carbitol acetate solution) and 1 part of a dispersant were mixed and kneaded using a three-roll mill to obtain a viscosity of 60%.
A copper paste of 0PS (poise) was obtained. Butyl carbitol was used for viscosity adjustment. 2) Next, a copper paste PTF-C-1 is screen-printed at a predetermined position on the wiring of a printed wiring board obtained by photo-etching the surface of a copper-clad laminate (copper foil thickness 12 μm) by an ordinary method. Was printed. For screen printing,
A columnar body having a diameter of 150 μm was prepared by using a screen plate of 350 mesh stainless steel and an emulsion thickness of 20 μm. The printed wiring board with the copper paste pillars
After drying at 30 ° C. for 30 minutes, it was thermally cured at 150 ° C. for 30 minutes to obtain a columnar conductor (height: about 25 μm).

3) Insulating paste (abbreviated as PTF-I-1) 75 parts of 50% acrylate of cresol novolak epoxy resin, 5 parts of dipentaerythritol hexaacrylate, epoxy resin (Epicoat 100, manufactured by Yuka Shell)
7) 20 parts, photopolymerization initiator (Circa Geigy, Irgacure 651) 5 parts, thermosetting catalyst (Shikoku Chemicals, 2P4)
MHZ) 5 parts, Silica (Crystalite, Tatsumori) 40
After mixing 20 parts of butyl cellosolve acetate,
The mixture was kneaded with three rolls and adjusted to a viscosity of 600 ps. 4) An insulating paste PTF-I-1 was printed on the entire surface of the printed circuit board on which the columnar conductor was formed using a screen printing plate having a tetron thickness of 120 mesh and an emulsion thickness of 20 μm.
Dry at 0 ° C for 30 minutes, dry film thickness about 27μm (on copper foil)
Was formed. 5) Next, after performing 500 mJ / cm ² whole surface exposure with a high pressure mercury lamp, heat treatment was performed at 100 ° C. for 1 hour.

6) The surface of the printed wiring board is polished using a buffing polisher to expose the heads of the columnar conductors, which are cured products of the copper paste PTF-C-1, and the insulating paste PT
The same level (planarization) as the FI-1 film surface was obtained. 7) The printed wiring board having the flattened insulating film is surface-roughened by chromate treatment according to a conventional method, then neutralized, washed with water, chemically copper-plated, and electrolytically copper-plated to a uniform thickness of 20 μm. After forming a conductor of
C. for 2 hours. The heat treatment of the insulating layer proceeds by this annealing treatment. 8) Next, the conductor was etched by photoetching in a conventional manner to form a circuit.

Example 2 1) Copper paste (abbreviated as PTF-C-2) After mixing 85 parts of copper powder, 20 parts of a phenol resin (70% butyl carbitol acetate solution with a solid content of 70%), and 1 part of a dispersant, The mixture was kneaded using three rolls to obtain a copper paste having a viscosity of 700 PS. Butyl carbitol was used for viscosity adjustment. 2) Next, a copper paste PTF-C-2 was screen-printed at a predetermined position on the wiring of a printed wiring board obtained by photoetching the surface of a copper-clad laminate (copper foil thickness 12 μm) by a conventional method. Was printed. For screen printing,
A columnar body having a diameter of 150 μm was prepared using a metal mask (stainless steel plate having a thickness of 50 μm). The printed wiring board on which the copper paste pillars are printed is dried at 80 ° C. for 30 minutes and then dried at 150 ° C.
It was heat-cured for 60 minutes to form a columnar conductor (about 45 μm in height). 3) Insulating paste (abbreviated as PTF-I-2) Cresol novolak epoxy resin (Dainippon Ink,
N-680 solid content 70% butyl cellosolve solution) 30
Part, epoxy resin (made by Yuka Shell, Epicoat 100
1. 20 parts of a 70% butyl cellosolve solution in solid content), 10 parts of an epoxy resin (manufactured by Yuka Shell, Epicoat 828),
5 parts of thermosetting catalyst (manufactured by Nippon Kayaku, Kayahard AS), 20 parts of silica (crystallite, Tatsumori), 10 parts of calcium carbonate, 5 parts of talc, butyl cellosolve acetate 2
After mixing 0 parts, kneading with 3 rolls and viscosity of 300ps
Was adjusted.

4) A 100-mesh tetron plate, an emulsion thickness of 15 μm, is formed on the entire surface of the printed circuit board on which the columnar conductors are formed.
The insulating paste PTF-I-2 was printed twice using a screen printing plate of No. 1, dried at 80 ° C. for 30 minutes, and then
Heat treatment was performed at 0 ° C. for 30 minutes to form an insulating layer having a dry film thickness of about 47 μm (on the copper foil). 5) polishing the surface of the printed wiring board using a buffing machine,
The head of the columnar conductor, which was a cured product of the copper paste PTF-C-2, was exposed and leveled with the surface of the insulating paste PTF-I-2. 6) After the surface of the printed wiring board having the flattened insulating film is roughened by chromate treatment, neutralization is performed according to a conventional method.
After washing with water, the surface was chemically copper-plated and electrolytic copper-plated to form a uniform 20 μm conductor, and then annealed at 150 ° C. for 2 hours. 7) Next, the conductor was etched by photoetching in a conventional manner to form a circuit.

Example 3 PTF-C as copper paste
PTF-C-3 is used instead of
A printed wiring board was produced in the same manner as in Example 2 except that the column-shaped conductor was obtained by thermosetting at 2 ° C. for 2 hours. The copper paste (PTF-C-3) used in this example was prepared as follows. 90 parts of silver-coated copper powder, 7 parts of epoxy resin (manufactured by Yuka Shell, Epicoat 806L), 3 parts of epoxy diluent (manufactured by Asahi Denka, Glycidol ED502), 2.5 parts of epoxy curing agent (manufactured by Ajinomoto, Amicure PN23), After mixing 0.5 part of a dispersing agent (Disp. PN160, manufactured by Toho Chemical Co., Ltd.), the mixture was kneaded using three rolls to obtain a copper paste having a viscosity of 700 PS.

(Example 4) The copper paste (PTF-C-2) described in Example 2 was applied to a copper-clad laminate (copper foil having a thickness of 12).
μm) was printed by screen printing at a predetermined position on the wiring of a printed wiring board obtained by photoetching the surface by a conventional method. For screen printing, a stainless steel mesh of 350 mesh and an emulsion thickness of 20 μm was used.
Was prepared. The printed wiring board on which the copper paste column was printed was dried at 80 ° C. for 30 minutes, and then heat-cured at 150 ° C. for 80 minutes to obtain a columnar conductor (about 25 μm in height). Then, a screen printing plate in which the insulating paste (PTF-I-2) described in Example 2 (provided that the viscosity of the paste was 600 poise) was masked with a 350 mesh stainless steel (emulsion thickness: 20 μm) at the columnar portion. Print using 80
After drying at 30 ° C. for 30 minutes, heat treatment was performed at 150 ° C. for 30 minutes to form an insulating layer having a dry film thickness of about 23 μm (on the copper foil). Thereafter, the surface of the printed wiring board was polished using a buffing polisher so that the head of the columnar conductor, which was a cured product of the copper paste PTF-C-2, was leveled with the coating surface of the insulating paste PTF-I-2. . After the surface of the printed wiring board having the flattened insulating film is roughened by chromate treatment, neutralized and washed with water according to a conventional method, and then the surface is subjected to chemical copper plating and electrolytic copper plating. After uniformly forming a 20 μm conductor, annealing was performed at 150 ° C. for 2 hours. Then, the conductor was etched by photoetching in a conventional manner to form a circuit.

Fifth Embodiment In the first embodiment, instead of exposing the entire surface with a high-pressure mercury lamp, 500 mm is applied through a photomask having a pattern for shielding a portion corresponding to the columnar body.
A multi-layer wiring board was obtained in the same manner as in Example 1 except that exposure was performed at mJ / cm ² , development was performed with a chlorocene solution, and heat treatment was performed at 100 ° C. for 1 hour.

Example 6 1) An insulating paste PTF-I was screen-printed on the entire surface of a printed wiring board obtained by photo-etching the surface of a copper-clad laminate (copper foil thickness 16 μm) by a conventional method. -2
Was printed. The printing was performed using a screen printing plate having a 150 mesh Tetron and an emulsion thickness of 15 μm.
For 30 minutes to form an insulating layer having a dry film thickness of about 18 μm (on the base material). 2) The surface of the insulating layer was polished using a buffing machine to expose the copper foil surface, and then heat-treated at 150 ° C. for 30 minutes. 3) A columnar conductor was formed at a predetermined position on the copper foil as follows. That is, the copper paste PTF-C-3 was screen-printed (using a screen plate of stainless steel 350 mesh and an emulsion thickness of 20 μm) to a diameter of 150 μm.
m columnar bodies were produced. The printed wiring board on which the copper paste column was printed was heated at 80 ° C. for 15 minutes, and then heat-cured at 150 ° C. for 60 minutes to obtain a columnar conductor (about 20 μm in height).

4) Further, an insulating paste PTF-I-2 was printed on the surface by screen printing. For printing, a screen printing plate having a Tetron 120 mesh and an emulsion thickness of 25 μm was used. After printing, it was dried at 80 ° C. for 30 minutes to form an insulating layer having a dry film thickness of about 28 μm (on the copper foil). 5) Next, the surface of the insulating layer is polished using a buffing machine,
After exposing the surface of the columnar conductor, heat treatment was performed at 150 ° C. for 30 minutes. 6) The printed wiring board having the flattened insulating film is surface-roughened by chromate treatment according to a conventional method, then neutralized, washed with water, chemically copper-plated, and electrolytically copper-plated to a uniform thickness of 20 μm. After forming a conductor of
C. for 2 hours. The heat treatment of the insulating layer proceeds by this annealing treatment. 7) Next, the conductor was etched by photoetching in a conventional manner to form a circuit.

(Embodiment 7) The connection reliability of a blind through hole of the present invention in which a columnar conductor was previously formed on a conductive circuit by using a conductive polymer thick film paste was evaluated by MIL-ST.
D-202F Thermal Shock Test Method 107G, C
As a result of evaluation at condition C (−65 ° C. to + 200 ° C.), each of the samples produced in Examples 1 to 6 was 1
As a result of the test up to 00 cycles, no disconnection occurred.

[0036]

As described above, according to the method of the present invention, a highly reliable build-up multilayer wiring board can be manufactured at a low cost, which greatly contributes industrially.

[Brief description of the drawings]

FIG. 1 shows a conventional method for manufacturing a multilayer wiring board.

FIG. 2 shows a conventional method for manufacturing an improved multilayer wiring board.

FIG. 3 is a method for manufacturing a multilayer wiring board according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base material 2 Conductor circuit 3 Interlayer insulating layer 4 Via hole 5 Conductive polymer thick film 6 Metal conductor 7 Photosensitive resin 8 Hole 9 Via post 10 Columnar conductor 31 Insulating layer 32 Insulating layer 32A Insulating layer 32B Insulating layer

Claims (4)

[Claims] 1. A method of manufacturing a multilayer wiring board having via holes, wherein a conductive circuit and an insulating layer are laminated in multiple layers, (1) a step of forming a conductive circuit on a substrate, and (2)
A step of forming a columnar conductor using a conductive polymer thick film paste on a conductor of a substrate; (3) a step of coating the periphery of the columnar conductor with an insulating layer; and (4) a columnar conductive layer buried by the insulating layer. A method of manufacturing a multilayer substrate, comprising: a step of exposing a head of a body by mechanical polishing; and (5) a step of forming a conductor on a mechanically polished surface. 2. The method according to claim 1, wherein the conductive polymer thick film paste contains a conductive metal powder and a thermosetting resin as essential components. 3. The method for manufacturing a multilayer substrate according to claim 1, wherein the conductive polymer thick film paste is formed into a column by screen printing, and is thermally cured to form a columnar conductor. 4. The method according to claim 1, wherein the insulating layer is a photocurable and / or thermosetting resin composition.