JP2003179351A - Buildup multilayer wiring board and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a buildup multilayer wiring board in which the thickness of copper on a buildup surface layer is thin and on which a fine circuit can be formed. <P>SOLUTION: In the buildup multilayer wiring board, an interlayer via is bored by a laser, an umbrella-shaped protrusion of a conductor layer formed in a via opening is left, a conductive paste is filled into the via, and a plated layer does not exist on the conductor layer. The method of manufacturing the buildup multilayer wiring board comprises a process in which the interlayer via is formed by the laser and in which the umbrella-shaped protrusion of the conductor layer is formed in the via opening and a process in which the conductive paste is filled into the via. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a build-up multi-layer wiring board, and more particularly to a build-up multi-layer wiring board capable of forming a fine circuit by reducing the thickness of copper on the surface layer and a method for manufacturing the same.

[0002]

2. Description of the Related Art For mobile phones and information communication terminals, smaller and lighter products are preferred because of their intended use. On the other hand, the printed wiring boards used in the products are also focused on miniaturization and high density, and construction of elemental technologies is being considered. The technology for making printed wiring boards smaller and more dense requires a number of elemental technologies, but among these, the more important technology is transmitting signal lines and power sources on the printed wiring boards. It is important to consider the two points of the circuit (pattern) design routing technology and the circuit thinning technology.

The BVH structure of the build-up multi-layer wiring board is effective in the circuit routing technology in the design of the printed wiring board, and recently, the printed wiring board which requires miniaturization and high density like an information communication terminal. In many cases, build-up multilayer wiring boards are being used. Further, a BVH structure is often used for the purpose of increasing the density in a multi-pin array pad portion such as a BGA (ball grid array) mounting method or a CSP (chip size package) mounting method in which the mounting area is small. .

As a BVH structure for interlayer connection of a buildup multilayer wiring board, there is a method of forming an interlayer connection via by a laser drilling method. This method of forming vias for interlayer connection is a method of forming BVHs by a conformal method in which vias are first provided by laser irradiation and then copper plating for BVH is performed on the vias to obtain conductive connection between layers. However, since BVH of the conformal method performs copper plating for interlayer connection, the copper thickness of the build-up multilayer wiring board having BVH on the surface layer becomes thicker by the copper plating for BVH, and RCC (copper foil with resin) The total thickness of the material copper and copper plating is the copper thickness of the surface layer of the build-up multilayer wiring board. Therefore, in the circuit formation of the build-up multilayer wiring board that requires miniaturization and high density, the copper thickness of the surface layer becomes a problem, and it is difficult to form a fine circuit.

On the other hand, a small-sized and high-density build-up multilayer wiring board is realized by improving the thinning technology of the printed circuit. As a method of reducing the circuit width, it is effective to select a circuit forming method suitable for the required circuit width. For example, a circuit forming method called the subtractive method covers a copper foil on a printed wiring board with a resist for forming a circuit, performs exposure and development by using a photomask, and then creates a circuit by etching the copper foil. Is the way to do it. As a circuit forming method suitable for the circuit width in the subtractive method, a dry film resist method and an ED (electrodeposition coating) method are well known as typical method, and the circuit width required by selecting those method can be obtained. Can be formed.

The major difference between the two types of circuit forming methods is the sensitivity and resolution of the photoresist, which are greatly influenced by the difference in the material characteristics and the thickness of the resist. The resist thickness of the dry film resist method is around 40 μm,
As a result, L (line) / S (space) = 100/1
It is possible to form a circuit of about 00 μm.
The resist thickness of D method is about 6 μm, which allows L / S
It is possible to form a circuit of about 60/60 μm. As described above, in the conventional technique, when forming a fine circuit, it is important to select a circuit forming method that reaches the purpose.

Therefore, from the above, in order to miniaturize and increase the density of the printed wiring board, the build-up multilayer wiring board is used, and the BVH is used to arrange the circuits required in a small space in the circuit design. Then, the conventional way of thinking was to process with a circuit forming method capable of forming a fine circuit.

In the present invention, in order to form a fine circuit, in addition to the selection of the circuit forming method, it is focused on a portion where it is effective to reduce the thickness of copper in the circuit forming portion.
This will be described with reference to FIG. FIG. 3 shows a circuit cross section after the circuit is actually formed. The circuit width and the space between the circuits are the same, and the circuit shape obtained after the circuit is formed is shown by the thickness of copper. Since the thickness of the copper (2) is thin in FIG. 3A, the circuit width (FIG.
Since (b)) is obtained and the space between the circuits is sufficiently secured, the problem due to poor insulation does not occur. However, since the thickness of copper (2, 12) is large in FIG. 3C,
Since the required circuit cannot be formed in the circuit forming unit 10 and the space between the circuits is not sufficient, the problem of insulation failure caused by contacting the circuits is caused (FIG. 3D). Therefore, when forming a fine circuit as shown in FIG. 3, it is desirable that the thickness of copper be thin.

However, although the BVH structure of the build-up multi-layer wiring board has a feature of high density in circuit design, copper plating for interlayer connection is required to form the BVH structure, and therefore, as shown in FIG. As shown in d), the circuit portion other than the BVH is also copper-plated, and it is difficult to form a thin copper thickness required for forming a fine circuit. In addition, since the BVH itself cannot be made thinner than necessary in order to reliably form conduction between layers, it is difficult to reduce the thickness of the conventional BVH.
With the VH structure, it was difficult to reduce the copper thickness of the build-up multilayer wiring board.

Several methods are conceivable for the method of filling the laser drilling portion with the conductive paste, and the structures are shown in FIG. The structure of FIG. 4A is a state in which the via is filled with the conductive paste after laser drilling of the large window structure. In this structure, the copper plating for BVH can be omitted, but in a test such as a cold and high temperature circulation cycle (for example, -65 ° C 125 ° C) as a reliability test of the build-up multilayer wiring board, Since the insulating layer portion 3 in FIG. 4A repeatedly undergoes thermal expansion and contraction, stable conduction cannot be obtained at the contact portion between the copper and the conductive paste on the surface layer, and a problem occurs in the reliability test. Also, FIG.
In the structure of (b), stable conduction can be obtained because the conductive portion of copper and the conductive paste has plating on the via, but a problem occurs due to the thickness of copper during the circuit formation. Therefore, it is difficult to manufacture a BVH capable of reducing the thickness of copper in consideration of the reliability test of the build-up multilayer wiring board.

[0011]

The problem to be solved by the present invention based on the background described above is to produce a small-sized and high-density build-up multilayer wiring board by using the conventional B method.
A build-up multilayer wiring board capable of forming a fine circuit by devising a structure in which copper plating for BVH, which was necessary when manufacturing a VH, is omitted, and thinning the copper of the build-up surface layer, and the same It is to provide a manufacturing method.

[0012]

Means for Solving the Problems The present inventors have made various studies in order to achieve the above object. As a result, in order to omit the copper plating for forming the BVH and form the vias for interlayer connection, the build-up layer of the build-up multilayer wiring board is laser-drilled to form vias for interlayer connection. An umbrella-shaped protrusion (6 in FIG. 1 (b)) is formed on the substrate, and particularly preferably, a high-pressure injection type roughening device is used to gently bend the umbrella-shaped protrusion and then fill the via with conductive paste. However, in order to improve the reliability of the conductive connection between layers, it was found that the BVH structure (9 in FIG. 1 (e)) in which the umbrella-shaped protrusion is embedded in the conductive paste is effective, and the present invention is completed. I arrived.

That is, the present invention is a build-up multilayer wiring board in which conductor layers and insulating layers are alternately laminated, and the conductor layers formed in the openings of the vias by drilling the interlayer vias with a laser. The above object is achieved by a build-up multilayer wiring board characterized in that an umbrella-shaped protrusion remains, the via is filled with a conductive paste, and the conductor layer has no plating layer. .

In the build-up multilayer wiring board of the present invention, the umbrella-shaped protrusion of the conductor layer is gently bent toward the inner bottom portion of the via and is immersed in the conductive paste, which is stable. It is desirable for obtaining connection reliability.

Further, the present invention is a method for manufacturing a build-up multilayer wiring board in which conductor layers and insulating layers are alternately laminated, wherein an interlayer via is formed by laser processing, and the conductor layer is formed in the opening of the via. The above object is achieved by a method for manufacturing a build-up multilayer printed wiring board, which includes a step of forming an umbrella-shaped protrusion and a step of filling the via with a conductive paste.

In the method of the present invention, after the step of forming the umbrella-shaped protrusion, an abrasive is sprayed onto the umbrella-shaped protrusion using a high-pressure jet roughening device, and the umbrella-shaped protrusion is directed toward the inner bottom of the via. It is desirable to fold it.

In the method of the present invention, the interlayer vias are formed by laser processing by laser drilling through the copper foil by the copper direct method or by using the conformal mask method by laser drilling with a total laser energy of 30 mJ. It is desirable in forming the umbrella-shaped protrusion of the.

Wet blasting is particularly suitable as the high-pressure jet-type roughening device used in the method of the present invention, and the abrasive is sprayed at a spraying pressure of 0.2 to 0.4 MPa. Good results are obtained in gently bending toward the inner bottom.

In the method of the present invention, the filling of the conductive paste is preferably carried out by a vacuum printing machine using a printing mask, and the conductive filler contained in the conductive paste has an average particle diameter of 6 μm. The following are preferred.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to Table 1 and the drawings.

Table 1 compares the process of the present invention with the conventional process.
Shown in.

[0022]

[Table 1]

Among the steps (A) of the present invention in Table 1, the following steps will be outlined for each item. Process sequence: Laser drilling process sequence: High-pressure injection type roughening device Process sequence: Conductive paste filling

◎ Step Sequence: Laser Drilling In the laser drilling step of the present invention, the “copper direct method” and the “conformal mask method” are preferably used. The “copper direct method” is a laser drilling method in which the surface of the buildup layer in FIG. 5A is directly irradiated with laser. At this time, A- in Table 1
It is desirable that the copper surface of the build-up layer be physically or chemically polished as the laser pretreatment step to suppress the luster peculiar to the metal on the copper foil surface. For example, using a copper foil surface roughening agent "CZ8100" manufactured by MEC Co., Ltd.
As a suitable treatment, a degree of etching and a decrease in the metallic surface of the copper surface at the same time are removed. A carbon dioxide laser is used as a laser for directly irradiating the surface of the buildup layer, and a model preferably used is, for example, "ML605GTX (oscillator: 5
100 U) ". Further, it is preferable to appropriately adjust the laser energy of the first shot that pierces the copper foil and the second shot that burns the insulating layer portion by using a mask for squeezing a laser beam.

Further, in the laser drilling step, an umbrella-like protruding structure having a similar shape can be obtained by laser processing of the "conformal mask method". The "conformal mask method" is a method in which a window is opened in advance by copper foil etching at a position to be irradiated with laser and the laser is irradiated to the opening, as described in FIG. Specifically, there is a method in which a window having a shape smaller than the laser irradiation diameter is formed by etching at the center of the BVH formation portion of the build-up surface layer by circuit formation, and then a laser diameter larger than that window is irradiated to the window portion. More desirable. The energy of the irradiated laser burns the insulating portion of the build-up layer, and the structure obtained after the laser irradiation is as shown in FIG. 6C having an umbrella-shaped protrusion. A carbon dioxide gas laser is used as the laser used in the “conformal mask method”, and “ML605GTX (oscillator: 5100U)” manufactured by Mitsubishi Electric Corporation is preferably used. Further, it is preferable to irradiate with a laser diameter larger than that of the window portion of the build-up surface layer by using a mask for diaphragm of laser light. Further, in forming the umbrella-shaped protruding portion in the "conformal mask method", it is preferable to set a laser condition as a standard condition in which three shots are continuously irradiated.

◎ Step sequence: high-pressure jet-type roughening device The purpose of the high-pressure jet-type roughening device used in A- in Table 1 (A), which is the process of the present invention, is to provide an umbrella-shaped protrusion produced by laser processing. The main purpose is to gently bend the part. Wet blasting is preferably used as the high-pressure roughening treatment device. As the wet blast, for example, “Physical Fine Etcher: FR-66” manufactured by Macau Co., Ltd.
"3, Wet Blasting System" is mentioned as a suitable one, and the condition of use is a horizontal type device which is sprayed vertically to the printed circuit board, and the processing speed: 0.3 ~
2.7 M / min, air consumption: 8.0-12.0 m ³ /
Min, air pressure: 0.1-0.4MPa, abrasive: # 80
It is preferable that the standard condition is 0 to 2000. In addition, since the mixed liquid of water, the abrasive (slurry liquid), and the compressed air is sprayed perpendicularly to the umbrella-shaped protrusion when it is gently bent, the umbrella-shaped protrusion is bent evenly. It is preferable to use a method called a blast gun, which is a method of projecting from a jet port onto a workpiece, as standard conditions.

◎ Step Sequence: Filling of Conductive Paste It is preferable to use a vacuum printer for the filling method of the conductive paste in the present invention. As the vacuum printer, for example, "VE-500" manufactured by Toray Engineering Co., Ltd. is preferably used, and it is preferable to use the printing environment in a vacuum state by a driver vacuum pump. Further, it is preferable that the conductive paste for printing is used in a state where it is sufficiently defoamed before printing.

As the conductive paste used in the present invention, "hole filling DD paste" manufactured by Tatsuta Electric Wire Co., Ltd. is preferably used. A conductive paste containing an epoxy resin as a binder and a curing agent containing imidazole as a main component is preferably used. Silver coated copper powder is used as the metal filler, and the average particle size of the filler is preferably 2.5 μm.
The volume resistivity of the paste is 5 × 10
^-5 (Ωcm) is preferable.

[0029]

The present invention will be further described with reference to the following examples.

Example 1 FIG. 1 is a diagram showing a method for manufacturing a BVH having an umbrella-shaped protrusion, and the structure of the BVH is shown in FIG. 1 (e).
Further, FIG. 1 is a diagram showing circuit formation in the same layer.
VH (9 in FIG. 1E) and fine circuit forming portion (FIG. 1E)
It is expressed using (10) in (e). The present invention will be described below with reference to FIG. (1). The buildup layer 1 was stacked on the core substrate portion after the formation of the inner layer circuit 4 (see FIG. 1A). Here, RCC (copper foil with resin) is used as the buildup layer 1. (2). The surface of the build-up layer 1 in (1) above is subjected to CZ roughening treatment as a pretreatment for laser drilling, and then B
Laser processing was performed at the VH formation position by the copper direct method, and the via hole 5 for interlayer connection having the umbrella-shaped protruding portion 6 in the opening was formed (see FIG. 1B). After the laser processing is completed, combustion products remain at the bottom of the via 5, so the residue was removed in the desmear process. (3). After the umbrella-shaped protrusion 6 of (2) was created, the substrate surface was processed by high-pressure jetting using wet blasting to form a gently-folded umbrella-shaped protrusion 7 (see FIG. 1C). (4). Using a vacuum printer, the conductive paste was filled in the vias 5 created in (3) above and heat-cured to create a BVH having umbrella-shaped protrusions 7 (see FIG. 1D). (5). B having the umbrella-shaped protrusion 7 created in (4) above
A circuit of a build-up multilayer wiring board having VH on the surface layer was formed (see FIG. 1E). The copper thickness of the surface layer of the build-up multilayer wiring board produced in the order of steps according to the present invention becomes thin because the copper plating step is omitted, and R
The surface layer circuit was formed in the state of only 12 μm of the CC copper foil.

Comparative Example 1 FIG. 2 shows a method for forming BVH by the conventional method shown in Table 1 above, and the final step shows circuit formation. Further, as in FIG. 1, it is expressed by using the BVH (13 in FIG. 2E) and the fine circuit forming portion (10 in FIG. 2E). The conventional method will be described below with reference to FIG. (1). The buildup layer 1 was stacked on the core substrate portion after the formation of the inner layer circuit (see FIG. 2A). here,
RCC (copper foil with resin) is used as the buildup layer 1. (2). The surface of the build-up layer 1 in (1) above was used as a pre-treatment for laser drilling, and the window portion 11 for BVH drilling was created in the etching step (FIG. 2 (b)).
reference). (3). Laser irradiation was performed on the window portion 11 in the above (2), and the via holes 5 for interlayer connection were drilled (see FIG. 2C). After the laser processing is completed, combustion products remain at the bottom of the via 5, so the residue was removed in the desmear process. (4). After forming the via 5 of (3), BVH plating 12 for interlayer connection was performed in the order of chemical copper plating and electrolytic copper plating in the plating process (see FIG. 2D). (5). The circuit of the build-up multilayer wiring board prepared in (4) above was formed (see FIG. 2E). The thickness of copper on the surface layer of the build-up multilayer wiring board created in the above process sequence is 12 μm for RCC copper foil and BV.
The copper plating for H becomes 20 μm, and the total copper thickness is 3
It was 2 μm.

Test Example 1 In order to clarify the difference in circuit formability due to the difference in copper thickness, an ED (electrodeposition coating) method was used as a circuit forming method.
The build-up multilayer wiring board made by the conventional BVH structure and the build-up multilayer wiring board made by the present invention are formed into circuits with the respective circuit widths shown in Table 2, and a good product of the fine circuit pattern portion is obtained. The numbers were compared. The results are shown in Table 2. According to the test results, when the circuit width is reduced, the number of non-defective products of the build-up multilayer wiring board created by the conventional BVH structure decreases, but the build-up multilayer wiring board of the present invention has a defective circuit width of 50 μm.
It has been clarified that the number of non-defective products in the fine circuit pattern portion can be improved without generating any m. In addition, when classifying defects in circuit formation, short-circuit defects in which circuits contact due to insufficient etching between minute circuits,
Then, the copper on the circuit can be classified into an open system defect that causes defective conduction due to excessive etching. Comparing the defects shown in Table 2 by the classification, the conventional method cannot sufficiently etch the fine circuit pattern portion because the copper thickness is large, resulting in a large number of short-circuit defects (in this state. Is shown in FIG. 3). However, in the method of the present invention, the thickness of copper is thinner than that of the conventional method, so that the fine circuit pattern portion can be sufficiently etched, and as a result, the short-circuit system is eliminated. Therefore, it was confirmed from this test result that the present invention has an effect of improving the circuit formability of the fine circuit pattern portion.

[0033]

[Table 2]

Test Example 2 In the method of the present invention, an umbrella-shaped protrusion is formed by irradiating the surface layer of the build-up multilayer wiring board with a laser. At that time, the umbrella-shaped protrusion formed under the condition of laser energy is used. The structure is different. Therefore, in order to determine the conditions of laser energy for forming a suitable umbrella-shaped protrusion, a comparative test was conducted under the conditions shown in Table 3 for each of the "copper direct method" and the "conformal mask method". The results are shown in Table 3. As a result obtained from Table 3, particularly good umbrella-like protruding structure having a length of about 30 μm when the total laser energy is 30 mJ in both the “copper direct method” and the “conformal mask method” It became clear that

[0035]

[Table 3]

Test Example 3 In the method of the present invention, the surface of the build-up multilayer wiring board is roughened by using a wet blast (high pressure jet type roughening device) on the umbrella-shaped protrusion obtained by laser processing. , The umbrella-shaped protrusion is gently bent by the roughening pressure.
When the via is filled with the conductive paste, the gently-folded umbrella-shaped protrusion is embedded in the conductive paste, and the embedded portion is from the first layer of the build-up multilayer wiring board. It shows the role of conducting electricity to the second layer. Therefore, the length of the umbrella-shaped protrusion and the gently bent angle are important for supporting conduction. As for the former and the length of the umbrella-shaped projection, as shown in Test Example 2, the examination of the conditions of the laser energy is effective, but the angle of the latter-shaped umbrella-shaped projection is roughened in the wet blast of this section. The examination of conditions will be greatly involved as an effect. Therefore, the conditions of the injection pressure of the wet blast were examined, and the effective conditions for gently bending the umbrella-shaped protrusion were examined under various conditions shown in Table 4 and compared. The results are shown in Table 4. By the way, regarding the angle when bending the umbrella-shaped protrusion, it is a good condition to bend at a more right angle from the stability of connection reliability, and the bent angle is expressed as a negative value, and the larger the number, the better the result. means. From the test results, it was clarified that the injection pressure of 0.2 MPa to 0.4 MPa is suitable as a condition for favorably bending the umbrella-shaped protrusion.

[0037]

[Table 4]

Test Example 4 Under the conditions shown in Table 5, a study was conducted to fill the conductive paste into the vias for interlayer connection obtained by laser processing. A printing method was adopted as the filling method, and in order to fill the conductive paste without generating voids in the via, the printing method and the presence or absence of a printing mask were examined. The conductive paste is filled in the interlayer connection via in the present invention,
When a bubble is caught in the via because it supports conduction between layers, the bubble may cause an increase in conduction resistance value. Therefore, when air bubbles were caught in the via, the via was identified as a defective product, and the number was recorded together with good vias in which the air bubbles were not entrained after the printing was completed. The results are shown in Table 5. From the test results, it is clear that the printing method under normal pressure generated many defects, but printing in a vacuum state was satisfactorily performed, and all defective products disappeared by using a printing mask. Became.

[0039]

[Table 5]

Test Example 5 In order to clarify the relationship between the average particle size of the conductive filler used in the conductive paste for filling the vias for interlayer connection and the bubbles generated in the vias, the results are shown in Table 6. The test was conducted using a conductor filler having an average particle diameter of 2.5 to 7.5 μm. For comparison, when air bubbles were caught in the via, the via was classified as a defective product, and the number was recorded together with good vias in which the air bubbles were not caught in the state after printing was completed. The results are shown in Table 6. From the test results, it has been clarified that when the average particle size of the conductive filler is 6.0 μm or less, the printing can be performed well, and all the bubble defects inherent in the via are eliminated.

[0041]

[Table 6]

[0042]

EFFECT OF THE INVENTION BV having an umbrella-shaped protrusion in the present invention
The H structure (9 in FIG. 1E) retains the effective function of the conventional BVH for connecting the conduction between layers, while maintaining the conventional BVH.
Since copper plating for BVH used when forming the H structure can be omitted, according to the present invention, the thickness of copper on the surface layer of the build-up multilayer wiring board becomes thin, resulting in easy circuit formation, and particularly It is possible to provide a build-up multilayer wiring board excellent in fine circuit formability.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional process explanatory view showing an example of manufacturing a build-up multilayer wiring board by the method of the present invention.

2A to 2C are schematic cross-sectional process explanatory views showing an example of manufacturing a build-up multilayer wiring board by a conventional method.

FIG. 3 is a schematic cross-sectional explanatory view showing a fine circuit formation state due to a difference in copper thickness.

FIG. 4 is a schematic cross-sectional explanatory view showing BVH after filling with a conductive paste.

FIG. 5 is a schematic cross-sectional explanatory view showing a via forming method by a copper direct method.

FIG. 6 is a schematic cross-sectional explanatory view showing a method of forming a via by a conformal mask method.

[Explanation of symbols]

1: Build-up layer 2: Copper foil (RCC) 3: Insulation layer 4: Inner layer circuit section 5: Via for interlayer connection 6: Umbrella-shaped protrusion 7: Gently bent umbrella-shaped protrusion 8: Conductive paste 9: BVH having an umbrella-shaped protrusion 10: Fine circuit forming part 11: Window section 12: Copper plating 13: Conventional BVH 14: Photo mask 15: Photoresist 16: Surface roughening 17: Laser

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05K 3/00 H05K 3/00 JN 3/40 3/40 K (72) Inventor Kazutaka Morita Isesaki Gunma Prefecture 174-1, Naganuma-cho, Japan F-Term in Japan CMK Corporation (reference) 5E317 AA24 BB01 BB12 CC22 CC25 CD31 CD32 GG14 5E346 AA01 AA12 AA15 AA32 AA43 BB01 BB16 CC02 CC08 CC32 DD02 DD12 DD32 EE06 EE07 FF18GG28 H1524 GG15 H24

Claims (10)

[Claims] 1. A build-up multilayer wiring board in which conductor layers and insulating layers are alternately laminated, wherein an umbrella-shaped protrusion of a conductor layer formed in an opening of the via by drilling an interlayer via by a laser. And the via is filled with a conductive paste, and the conductor layer has no plating layer. 2. The build-up multilayer wiring according to claim 1, wherein the umbrella-shaped protruding portion of the conductor layer is gently bent toward the inner bottom portion of the via and is immersed in the conductive paste. substrate. 3. A method of manufacturing a build-up multilayer wiring board, wherein conductor layers and insulating layers are alternately laminated, wherein an interlayer via is formed by laser processing, and an umbrella-shaped protrusion of the conductor layer is formed in the opening of the via. And a step of filling the via with a conductive paste, the method for manufacturing a build-up multilayer printed wiring board. 4. After the step of forming the umbrella-shaped protrusion,
4. The build-up multilayer printed wiring according to claim 3, further comprising a step of spraying an abrasive material onto the umbrella-shaped protrusion using a high-pressure jet roughening device and bending the umbrella-shaped protrusion toward the inner bottom of the via. Substrate manufacturing method. 5. The method of manufacturing a build-up multilayer printed wiring board according to claim 3, wherein the interlayer via is formed by the laser processing by a copper direct method. 6. The method for manufacturing a build-up multilayer printed wiring board according to claim 3, wherein the interlayer vias are formed by the laser processing by a conformal mask method. 7. The total laser energy in the laser processing is 30 mJ.
7. The method for manufacturing a buildup multilayer printed wiring board according to any one of items 1 to 6. 8. The spraying of the abrasive by the high-pressure jet-type roughening device is performed by using wet blast, and the jet pressure is 0.2.
The method for manufacturing a buildup multilayer printed wiring board according to claim 3, wherein the buildup multilayer printed wiring board is manufactured at a pressure of 0.4 MPa to 0.4 MPa. 9. The build-up multilayer printed wiring board according to claim 3, wherein the conductive paste is filled with a vacuum printing machine using a printing mask. Production method. 10. The conductive filler of the conductive paste has an average particle diameter of 6 μm or less.
10. The method for manufacturing a build-up multilayer printed wiring board according to any one of items 1 to 9.