JP2015135933A - Multilayer wiring board and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that, in an inorganic multilayer board, circuit disconnection and insulation layer breakage or warpage may also easily occur in addition to a conduction defect of upper and lower conductive layers and it is necessary to remedy a high defect rate that may reach 30 to 40%.SOLUTION: A multilayer wiring board has a structure where conductive layers 1 are electrically connected with each other by an electrical conduction path 4 embedded into an insulation layer 3 that is positioned on the conductive layer 1, deeply to the side face thereof and penetrating the insulation layer 3 held between the upper and lower conductive layers 1. The three-dimensional structure of the multilayer wiring board is divided into thin layers by horizontal cross sections to generate 3D data. The multilayer wiring board is formed by printing, hardening and laminating the thin layers by a 3D printer using the 3D data. The electrical connection between the electrical conduction path 4 penetrating the insulation layer 3 and the conductive layer positioned at an upper side of the upper and lower positioning conductive layers 1 is formed by projecting the electrical conduction path 4 higher than a surface of the insulation layer 3 and bonding a protruding part of the electrical conduction path 4 while covering it with the conductive layer positioned at the upper side.

Description

  The present invention relates to a multilayer wiring board and a manufacturing method thereof, and more particularly to a multilayer wiring board manufactured using a 3D printer and a manufacturing method thereof.

Conventional types of multilayer wiring boards include organic (MLPCB), inorganic (LTCC), and hybrid systems in which organic and inorganic systems are mixed.
These conventional multilayer wiring boards are all mass-produced, and require a large investment in the equipment to be used. Furthermore, the manufacturing process is complicated, requires advanced technology, and is expensive. Had to be used. For this reason, the manufacturing cost becomes extremely high, and the fundamental problem that the manufacturing cost can be reduced only by the mass production method is included.
Therefore, this is a production method that cannot be applied to trial production and small-scale production.

Conventional manufacturing processes are common to both inorganic and organic systems. Formation of an insulating layer, formation of a conductive layer on the surface of the insulating layer, photolithography for the conductive layer, wiring circuit formation by etching, and upper and lower wiring circuits are electrically connected In order to make it conductive, an extremely fine hole with a diameter of several tens of μm is formed from the surface of the insulating layer to the lower wiring circuit, and a conductive material is filled in the hole by a method such as plating to electrically connect with the lower wiring circuit. Since it is a conduction method, it is extremely difficult to completely electrically connect the lower wiring circuit and the conductor filled in the hole.
For this reason, the failure rate due to conduction failure between the upper and lower conductive layers reaches 10%. In particular, in the inorganic multilayer substrate, in addition to the conduction failure of the upper and lower conductive layers, circuit disconnection, cracking and warping of the insulating layer are likely to occur, and the defect rate reaches 30 to 40%.

  Furthermore, the conventional manufacturing process has a problem that should be improved immediately from the viewpoint of protecting the global environment because any of the above-described processes consumes a large amount of chemicals, auxiliary materials, water, and the like.

  Furthermore, it takes 1 to 3 months for production. As a result, the production cost becomes high, and international competitiveness is lost in Japan, causing production companies to move overseas and outsource.

On the other hand, in order to improve the conventional complicated manufacturing method, a method in which the process is simplified and shortened has been developed. However, it has not yet been widely spread.
Representative examples include ALIVH (Patent Document 1) of Panasonic Corporation and B2it (Patent Document 2) of Dai Nippon Printing Co., Ltd.
In these methods, an insulating layer and a wiring circuit are stacked one layer at a time, and each time an insulating layer is sandwiched between the upper and lower wiring circuits, laser processing or photosensitive resin is used for each insulating layer. In this method, a hole having a diameter of about 100 μm is formed by a photolithography method or the like.
These methods are stacked one by one, and each time a via (through hole) is formed, electrical conduction is achieved with plating or conductive paste, and circuit formation is performed, so the number of layers increases as the number of layers increases However, it has the disadvantages of increasing the lead time and manufacturing cost, and increasing the defect rate, and it has not spread.

JP2013-89745A JP 2010-67835 A

  The present invention has been made in view of such problems, and its purpose is to produce a multilayer wiring board at a low cost in a short period of time even in low-volume production of various products, and disconnection of a wiring circuit, poor conduction between upper and lower insulating layers. It is an object of the present invention to provide a novel structure of a multilayer wiring board and a method for manufacturing the same that can solve the above-mentioned problems and greatly reduce the defect rate.

The present inventor conducts earnest research on the above-mentioned problems, and directly manufactures a multilayer substrate with a 3D printer without using a conventional multilayer substrate manufacturing method, i.e., circuit formation by etching, photolithography, drilling, hole filling, etc. As a result, the following knowledge was obtained.
That is, fine circuits, protrusions and pads can be made with the same accuracy as those manufactured by the conventional photolithography method. For example, R / S can be obtained with an accuracy of about 10 μm between lines, and the circuit It was found that it can be cured and sintered simultaneously with the lamination of thin layers and insulating thin layers. Furthermore, it was found that a multilayer substrate having performance equal to or better than that of the conventional manufacturing method can be manufactured, and further, the high product defect rate, which was the biggest drawback of the conventional manufacturing method, can be dramatically improved.
This invention is made | formed based on the above knowledge, The said subject of this invention can be solved by the following means.
In this specification, the conductive layer means a wiring circuit, pads and bumps electrically connected to the wiring circuit, and the like.

That is,
A multilayer wiring board in which a conductive layer and an insulating layer are formed by alternately laminating and bonding a plurality of layers, and the conductive layer is embedded in the insulating layer located on the conductive layer to the side surface. The upper and lower conductive layers are multi-layer wiring boards having a structure in which they are electrically connected to each other through an electrical conduction path that penetrates the insulating layer sandwiched between the upper and lower conductive layers,
The three-dimensional structure of the multilayer wiring board is divided into thin layers in a horizontal section to form 3D data, and using the 3D data, the thin layer is printed, cured, and laminated by a 3D printer,
Compared with conventional manufacturing methods, processes such as circuit formation by etching, photolithography, drilling, and hole filling can be omitted, and a product can be manufactured in a short time. In addition, expensive equipment, advanced technology, high-purity chemicals, and materials are not required, and the internal wiring density can be several times higher than the conventional density, and the number of layers to be stacked is super multi-layer printed wiring with 10 to 50 layers. It has been found that a board (MLPCB) can be produced.

Further, the electrical connection between the electrical conduction path penetrating the insulating layer and the conductive layer located above the conductive layer located above and below is such that the electrical conduction path is closer to the surface of the insulation layer. By projecting upward, the projecting portion of the electrical conduction path is covered with the conductive layer positioned above and joined to form a structure,
It has been found that the failure rate due to poor electrical conduction due to poor contact between the conductive layer and the electrical conduction path can be significantly reduced.
Furthermore, the electrical connection between the electrical conduction path and the conductive layer located below the conductive layer located above and below is performed by printing the electrical conduction path directly on the surface of the conductive layer and curing it. As a result, high-strength bonding is achieved, and electrical connection can be reliably achieved.
Therefore, the upper and lower ends of the electrical conduction path of the present invention can achieve a reliable electrical connection with the upper and lower conductive layers by the above-described structure, and can significantly reduce the failure rate due to electrical conduction failure. I found.

Then, when forming the conductive layer, the insulating layer on the upper and lower layers sandwiching the conductive layer, and the electric conduction path penetrating the upper insulating layer, the conductive layer and the electric conduction path are first cured. In addition, after the strength is developed, the upper insulating layer is cured, so that there is a possibility that a crack or the like occurs in the electrical conduction path due to shrinkage stress at the time of curing of the ink of the insulating layer and a conduction failure occurs. It has been found that the failure rate can be significantly reduced and the failure rate due to poor electrical continuity between the upper and lower wiring circuits and the disconnection of the wiring circuits can be significantly reduced.
The present invention has been made based on the above findings.

  The lower part of the electrical conduction path is formed by printing on the conductive layer, but the curing sequence of the electrical conduction path and the conductive layer may be simultaneous, or the electrical conduction path is first, or The conductive layer may be either first. Defects do not occur in the conductive layer and the electrical conduction path due to the order of curing.

  The term “covering” in claim 2 of the present specification means a state in which the conductive layer wraps and covers at least the protruding end surface of the electrical conduction path. Therefore, the side surface of the protruding electrical conduction path is joined in contact with the entire circumference or part of the electrical conduction path. In addition, since the protruding end surface of the electrical conduction path is wrapped and covered with the conductive layer, the height at which the electrical conduction path protrudes from the insulating layer is necessarily limited to a height less than the height of the conductive layer. Will be.

  In this specification, “curing” means that the printing ink used for the production of the multilayer wiring board of the present invention is an organic material, an inorganic material, and a curing means, for example, heat curing, reaction curing, photocuring. It means that the resin is cured to exhibit strength and bondability regardless of whether it is sintered and cured or other curing means. Therefore, it includes both adhesion of organic materials and sintering of inorganic materials.

  In order to carry out the method of the present invention, first, the design information of the wiring and pads of the multilayer wiring board is taken into 3D-CAD, the three-dimensional structure of this multilayer wiring board is divided into thin layers in a horizontal section, and converted into 3D data, Using this 3D data, a thin layer is printed, cured and laminated by a 3D printer to form a three-dimensional laminated structure.

There are no special restrictions on the thickness of each layer that is printed and stacked with a 3D printer, but the thinner the multilayer substrate, the thinner the thinner, so long as there is no problem with insulation and conductivity. preferable.
In the insulating layer, for example, an epoxy resin has a thickness of about 20 to 100 μm.
In a conductive layer, it is about 2-100 micrometers.

There is no particular restriction on the shape of the electrical conduction path, but a protruding shape is most preferable.
The protrusion may be a hollow shape or a solid shape, but the solid shape is the most easily formed by printing.

There are no particular restrictions on the choice of starting material when starting production of a multilayer substrate.
A copper-clad resin substrate may be used, or a normal resin substrate may be used.
Or you may start using a 3D printer from the beginning, without using a starting material.

When using a copper-clad resin substrate, first, the copper layer is etched to form a wiring circuit (in the present invention, indicated as a conductive layer).
An electrical conduction path for conduction with the upper layer is printed on the surface of the wiring circuit using ink for a 3D printer.
When a normal resin substrate is used, a wiring circuit is printed on the resin substrate, and an electrical conduction path for conduction with the upper layer is printed on the wiring circuit using ink for a 3D printer.

The printed electrical conduction path and wiring circuit are locally irradiated using a laser or the like, and are cured by heating.
Next, an insulating resin is printed so as to cover the wiring circuit.
The printed thickness of the insulating resin should be greater than the thickness of the wiring circuit so that the wiring circuit is embedded in the insulating resin and less than the height of the electrical conduction path. The tip should protrude from the insulating layer. The protruding height is set to a height less than the thickness of the wiring circuit.

  There are no particular restrictions on the printing method of the 3D printer. Any printing method can be selected as appropriate. For example, an ink jet method, a projection method, a hot melt lamination method, a powder firing method, and an optical modeling method can be appropriately selected.

  Next, laser irradiation or the like is performed to cure the epoxy resin.

  Next, in the same manner as described above, an electrical conduction path for conduction between the wiring circuit and the upper layer is formed in the insulating layer.

Conductive ink is baked on the wiring circuit and the electrical conduction path only by laser irradiation or the like.
In the subsequent steps, the same steps described above are repeated, and the layers are sequentially stacked.

  On the outermost surface of the insulating layer, a wire bonding (W / B) pad, a surface mounting (SMD) pad, and a flip chip mounting bump (protrusion) are formed, and then plated. In this specification, these pads and bumps are all expressed as conductive layers.

  In the prior art, it was difficult to manufacture wiring and wiring width (R / S) of 100 μm or less. In the present invention, it can be produced even if R / S is 10 μm or less, and a high-density wiring board can be produced.

  In the present invention, an important technique is that a 3D printer can easily print a wiring circuit, an electrical conduction path, and an insulating layer, and for this purpose, the composition of the ink is extremely important.

As a necessary condition, the adhesive strength between the insulating resin (ink) and the conductive resin (ink) is strong, and the conductive ink has high electrical conductivity after heat curing with a laser or the like.
The most preferable ink for conduction is preferably a mixture of Sn-Ag-Cu submicron particles having a particle size of 2 to 3 μm mixed with a cellulose-based thickener (vehicle) and kneaded.
After laser heating, it is necessary to formulate it so that it burns completely and no carbon or other organic residue remains.
Printability is also important. In the present invention, the accuracy of the wiring circuit printed by the 3D printer is 2 to 10 μm in width, and the circuit cross section can be printed in a rectangular parallelepiped. Incidentally, the cross section of the conventional screen printing method or photolithographic etching method has a trapezoidal shape, an inverted trapezoidal shape, an overhang shape, or a mushroom shape, causing a serious accident such as disconnection.

  As a metal material used for the circuit of the wiring board and the electrical conduction path between the upper and lower layers, Cu, Ag, Sn, Au, Pt, Pd, Ni, W, Mo, Mn, Bi, Pb, Al, In, Sb, Ti, It can be appropriately selected from simple metals such as Co and Cr and two or more kinds of these alloys.

The basis for selecting the conductive ink is determined by the function and characteristics of the substrate to be created.
For example, in the case of a PCB (resin printed circuit board), a resin having a very high melting point is not preferable due to the heat resistance of the resin.
Hi, laser irradiation technology has been developed locally, and the number of types of metal powder that can be used is increased compared to the conventional heating method.
Although these metal fine powders can be sprayed, melted and sintered by laser, it is preferable to mix these metal fine powders with some chemicals to make it easy to print with a 3D printer. A processing method is preferred.
Conductive layers (wiring circuits, pads, bumps) and electrical conduction paths can be formed by improving the cream solder technology used in conventional screen printing and printing by the ink jet method.

In the case of LTCC, the conductive ink used for the ceramic wiring board is preferably Cu, Ag, Ni, Co, or Ag—Pd paste ink.
The high-temperature firing type HTCC is preferably W, Mo-Mn paste ink.

  Next, in the case of PCB as the insulating resin, conventional epoxy, phenol, PET, fluororesin, ABS, urethane, polycarbonate, aramid resin, ABS, urethane, polycarbonate, aramid resin and the like are preferable.

As a form of use, a method of spraying these fine powders like electrostatic coating to heat, melt, and harden is possible, but it is difficult to create a uniform film thickness of 2 to 50 μm.
In the present invention, the method of using these resins in a liquid form that can be easily printed by a 3D printer has high film thickness management and workability.

The material of the insulating layer used for the production of the ceramic wiring board is Al ₂ O _{3 for} the alumina substrate, AlN for the AlN substrate, Si ₃ N ₄ based substrate, Si ₃ N ₄ as the main component, and others Add a glassy or inorganic oxide and make it easy to print with a 3D printer. Cellulose thickeners and surfactants are added for use.

  Moreover, W, Mo-Mn, Cu, Ni, Co, Ag, Ag-Pd, and a paste can be used as a conductive material for circuits and vertical conduction.

  A wiring circuit or an electrical conduction path is formed by printing by an inkjet method and locally heating by laser irradiation.

The pads and bumps on the surface printed and cured according to the present invention cannot be used with W / B or SMD as they are, so it is better to perform plating.
As solder for soldering an electronic component to a plated pad or the like, cream solder such as Sn-Ag-Cu, Sn, Sn-Ag-Cu-Bi, or a solder ball can be used.
On the other hand, it is better to apply plating of Ni / Au, Ni / Pd / Au, etc. to the pads and bumps for W / B.

Today, a method of performing W / B using a wire obtained by performing Pd plating on a Cu wire from an Au wire is changing.
A slightly thick plating of Ni / Au and Ni / Pd / Au is performed on the underlying pad or bump. As the plating method, electroplating is preferable as long as conduction is obtained. If continuity cannot be obtained, electroless Ni, Pd, Au is used.

Electronic components can be inserted and mounted between the insulating layers of the present invention as necessary.
By electrically connecting to the conductive layer existing between the layers of the multilayer wiring board of the present invention, a new function of the electronic component can be imparted to the multilayer wiring board of the present invention.
Electronic components include ICs, LSIs, resistors, capacitors, antennas, varistors, SAW filters, and the like.

The present invention has the following effects.
1. Man-hours such as photolithography, drilling, hole filling, plating, etc. required in the prior art can be largely omitted or reduced. (Significant reduction in production process and cost)
2 Awards for expensive equipment, advanced technology, expensive chemicals, components, water, etc. can be greatly reduced, and the burden on the environment can be reduced. (Energy saving and resource saving)
3 Anyone can easily produce a fine and highly accurate multilayer board.
4. Can produce a variety of products and small-scale production in a short period of time and provide a customized base.
5. The failure rate due to continuity failure and circuit disconnection can be greatly reduced.
6 The multilayer wiring board can be significantly reduced in size and thickness.

It is a schematic diagram for demonstrating this invention structure. It is another schematic diagram for demonstrating this invention structure. It is another schematic diagram for demonstrating this invention structure. It is a figure explaining another embodiment of a covering structure. It is a figure explaining the manufacturing process of this invention.

The structure of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view for explaining the structure of the present invention.
FIG. 2 is another schematic diagram for explaining the structure of the present invention.
FIG. 3 is another schematic diagram for explaining the structure of the present invention.

In the multilayer substrate of the present invention, the upper and lower insulating layers of the insulating layer 2 (lower) and the insulating layer 3 (upper) shown in FIG. 1, the upper and lower conductive layers 1 sandwiching the insulating layer, and the upper and lower insulating layers sandwiching the conductive layer, A unit structure of the multilayer substrate of the present invention is indicated by a combination of electrical conduction paths that penetrate through the insulating layer and are joined to the upper and lower conductive layers.
In the multilayer substrate of the present invention, a multilayer wiring board is constructed by stacking multiple unit structures.
In FIG. 1, the lowermost layer is the insulating layer 2 (lower), but the lowermost layer of the multilayer wiring board may be any of an insulating layer, a conductive layer, and an electrical conduction path. That is, when the lowermost layer is a conductive layer, the structure of FIG. 2 becomes the unit structure of the multilayer substrate of the present invention, and when the electrical conduction path is the lowermost layer, the structure of FIG. The upper and lower conductive layers 1 sandwiching the layers and the insulating layer, the upper and lower insulating layers sandwiching the conductive layer, and the combination in which there is an electrical conduction path that penetrates the insulating layer and is joined to the upper and lower conductive layers. is there. In the combination shown in FIG. 3, the lowermost electrical conduction path 4 is exposed to the outside, but a conductive layer (bump, pad) is joined thereto later.

  The structure of FIG. 1 is a structure obtained when a copper clad resin substrate or the like is mainly used as a start material, and the start material remains in the obtained multilayer wiring board. The structures of FIGS. This is a structure obtained mainly when a dummy plate is used as a starting material, and the dummy plate is peeled off from the obtained multilayer wiring board, and both cases are included in the present invention.

  As shown in FIGS. 1 to 3, the electrical conduction path 4 is laminated on the conductive layer 1, and the conductive layer 1 and the electrical conduction path 4 are both embedded in the insulating layer. The gap between the adjacent conductive layers 1 is also filled with the insulating layer 3.

Since the height of the electrical conduction path 4 is designed to be higher than the height of the insulating layer, even if embedded in the insulating layer, it has a structure that penetrates the insulating layer and protrudes outside. .
Further, the conductive layer 1 is laminated on the insulating layer 3, and the conductive layer 1 covers the electrical conduction path 4 protruding outward from the insulating layer 3. Therefore, the protruding height of the electrical conduction path 4 is less than the height (thickness) of the conductive layer 1.

When the upper end surface of the electrical conduction path 4 is the same height as the insulating layer 3, when the insulating layer 3 is printed, the ink oozes into the upper end surface of the electrical conduction path 4 and the upper end surface of the electrical conduction path 4. However, it may be covered with an insulating layer, and electrical conduction with the conductive layer may be hindered, resulting in poor conduction.
The purpose of making the height of the electrical conduction path 4 higher than the height of the insulating layer is to prevent conduction failure due to bleeding. Furthermore, in the unlikely event that printed ink swells on the side surface of the protruding portion of the electrical conduction path 4, the upper end surface of the electrical conduction path 4 is connected to the conductive layer so as not to cause poor conduction with the conductive layer. It is covered with.
In the present invention, the electric conduction path 4 protrudes above the insulating layer, and the upper end surface of the electric conduction path 4 is covered with the conductive layer. This ensures contact and bonding between the conduction path 4 and the conductive layer, and prevents conduction failure. These two means can be realized only by forming a three-dimensional structure by printing, curing and laminating thin layers with a 3D printer.

The structure for covering the electrical conduction path 4 in FIGS. 1 to 3 is a structure for wrapping the entire upper end surface of the electrical conduction path 4 and a part of the periphery of the protruding side surface. The protruding surface and the entire surface are embedded and covered.
In the present invention, any of the covering structures shown in FIGS. 1 and 4 may be selected. Any one may be selected as appropriate in consideration of the shape of the electrical conduction path 4, the surface area of the protruding portion, and the like.

The manufacturing process of the present invention will be described with reference to FIG.
FIG. 5 is an explanatory diagram in the case of manufacturing the multilayer wiring board having the unit structure shown in FIG.
The manufacturing process in the case of the unit structure of FIG. 2 and FIG. 3 also has the same order of stacking the insulating layer, the conductive layer, and the electrical conduction path, except that the lowermost layer is replaced with a conductive layer or an electrical conduction layer. Since the basic structure is basically the same, it will be represented in the description of FIG.

In the multilayer wiring board of the present invention, the unit structure is completed in the first to third steps of FIG.
The multilayer wiring board of the present invention is formed by stacking dozens of the unit structures.
Each step will be described in detail.
1st process A conductive layer is printed with a 3D printer on the surface of the insulating layer that has been previously cured, and an electrical conduction path is printed on the surface of the conductive layer.
Prior to the second step, the conductive layer and the electrical conduction path are cured.
The order of the curing treatment may be either first or simultaneous.

Second Step The printed conductive layer and the electrical conduction path are printed with an insulating ink using a 3D printer. At this time, printing is performed so that the insulating ink does not cover the upper part of the electrical conduction path. Also, ink is filled in the gap between the conductive layers.
The printed insulating layer ink is cured.
During the curing process, shrinkage occurs in the insulating layer ink. However, since the electrical conduction path and the conductive layer are already cured, the shrinkage stress causes cracks in the electrical conduction path or the conductive layer (wiring circuit). The probability of occurrence of a conduction failure due to disconnection is extremely low, and the failure rate due to an electrical conduction failure between the upper and lower wiring circuits and a disconnection of the wiring circuit can be significantly reduced.
This is the greatest feature of the method for producing the multilayer substrate of the present invention, “the printed layer of the conductive layer and the electrical conduction path are cured first, and the printed layer of the insulating layer is cured later”.

3rd process A conductive layer is printed and hardened by the structure which covers the electrical conduction path which protruded to the insulating layer.
As described above, the unit structure of the multilayer wiring board of the present invention is formed in the first to third steps.

The examples illustrate the invention.
In addition, a present Example is concretely demonstrated in order to make the meaning of this invention understand better, and of course, this invention is not limited only to this.

Example 1
Production of multilayer wiring boards (MLPCB)
A manufacturing method will be specifically described below, but it is needless to say that only the present embodiment does not limit the present invention.

Creation of 3D data 3D data was created based on the design information of the substrate having the three-dimensional internal wiring created by 3D-CAD, and input to the 3D printer.
In addition, the apparatus of Simet was used for 3D printer.
When the three-dimensional structure of the multilayer wiring board is divided into thin layers in a horizontal section, the insulating layer for each printing printed by a 3D printer, the printed thickness of the thin layer of the wiring circuit is 15 μm for the insulating layer, The thickness was set to 20 μm, and both the insulating layer and the thin layer of the wiring circuit had a thickness that could be formed by a single printing.
Since the electrical conduction path used for conduction with the upper layer needs to protrude outward from the insulating layer (15 μm thickness), the height was set to 20 μm. In other words, the height of the protrusion was embedded in the wiring circuit having a thickness of 20 μm by protruding 5 μm from the insulating layer.

The unit structure of the multilayer wiring board of the present example employs the structure shown in FIG. And the manufacturing process employ | adopted the process shown in FIG.

As the starting material, a commercially available A4 size double-sided copper-clad resin substrate was used, and in this example, only one side was used for sequential lamination.

First, the copper layer of the copper-clad substrate was etched to form a pad for standing a cylindrical copper protrusion for use in conduction with the internal wiring copper circuit and the upper layer on the surface of the resin substrate.
In this example, the resin substrate corresponds to the insulating layer (cured) in step 1 of FIG.
Note that the internal wiring copper circuit and the pad of this embodiment are collectively referred to as a conductive layer in this specification. The cylindrical copper protrusion is an electrical conduction path in the present specification.
The width of the internal wiring copper circuit was 20 μm, the thickness was 20 μm, the gap (R / S) between the internal wirings was 20 μm, and the cylindrical copper protrusion had a diameter of 20 μm and a height of 20 μm.
Next, on the internal wiring copper circuit and the pad for forming the protrusion, a cylindrical protrusion for electrical conduction with the upper internal wiring copper circuit is formed with a diameter of 20 μm, a height of 20 μm, and a distance from the adjacent copper protrusion of 20 μm. Formed.
It formed in the following process.

Using conductive ink (* 1), a protrusion was erected on the surface of the pad with a 3D printer.
Next, only the protrusions were locally heated with a laser and cured. The vehicle (adhesive) component contained in the ink was completely lost.
The conductivity (specific resistance) of the protrusion after curing was 1.780 × 10 −6 Ω · cm.
The conductivity (specific resistance) of pure copper was 1.724 × 10 ⁻⁶ Ω · cm ⁻¹ , and the conductivity (specific resistance) after curing of the projections of the present invention was almost the same as that of pure copper.

The composition of the conductive ink is as follows.
* 1 Composition: Composition in which phenol resin is mixed with commercially available copper paste (product of Fujikura Kasei Co., Ltd.).

Thereafter, an insulating ink (* 2) for 3D printer prepared from epoxy resin, glass powder, and vehicle was uniformly printed using a 3D printer at a place other than the copper protrusion. At that time, printing was performed so that the insulating printing ink did not cover the top of the protrusion. Insulating printing ink was printed with a printing thickness of 15 μm, a protrusion height of 20 μm, and a step of 5 μm.

The ink composition of * 2 is as follows.
* 2 Composition: Composition in which 70% epoxy resin, 20% glass powder having a particle diameter of 1 to 3 μm, 10% butyl cellosolve (buticello), etc. are mixed.

The printed layer of insulating ink was cured by irradiating a laser.

Next, on the surface of the insulating layer (printing layer of insulating ink), using conductive ink (* 1 composition), the width is 20 μm, the thickness is 20 μm, and the gap (R / S) between the internal wirings is A 20 μm internal wiring copper circuit was printed.
On the surface of the insulating layer, printing is performed so that the conductive ink is covered on the protrusion protruding 5 μm, and printing is performed so that the connection between the protrusion and the circuit is ensured, and then only the printed circuit part is heated with a laser. And cured.

On the surface of the internal wiring exposed to the outside, a cylindrical projection for conduction with the upper layer was erected with a 3D printer using conductive ink (* 1).
A protrusion having a diameter of 20 μm and a height of 20 μm was printed.

Only the protrusions were locally heated using a laser and cured.

In the subsequent steps, the above-described series of steps were repeated and sequentially laminated to produce a super multilayer printed wiring board (MLPCB) having 20 layers of internal wiring.

On the surface layer (outermost layer), pads and protrusions (bumps) for mounting various electronic components were printed with a 3D printer and cured.
The same conductive ink as the above * 1 was used as the printing ink.

For the wire bonding (W / B) and surface mounting (SMD), the surface layer pads and protrusions (bumps) were plated.

Two types of plating (Ni / Au plating and Ni / Pd / Au plating) were performed on the pad for W / B and the pad for soldering.

1. Pad plating process for W / B and soldering To remove copper circuit, copper protrusion (bump) oxide and remaining impurities formed with copper paste (conductive ink)
It was immersed in an acidic degreasing material composed of 20 g / L sulfuric acid, 10 g / L citric acid, and 0.1 g / L surfactant for 3 minutes at 50 ° C.
Copper oxides were removed, a red copper color appeared, and water repelling disappeared.

2. So-called soft etching was performed by immersing in an etching solution composed of 10 g / L of Na ₂ S ₂ O _{8 and} 10 g of sulfuric acid at 30 ° C. for 3 minutes.

3. In order to remove CuO produced on the copper surface, immersion treatment was performed at 30 ° C. for 2 minutes with 20 g / L of sulfuric acid.

4). It was immersed in a Pd active solution composed of PdCL ₂ 0.1 g / L and sulfuric acid 5 g / L at 20 ° C. for 2 minutes.

5. Plating was performed for 20 minutes at 30 g / L of NiSO _4, 20 g / L of NaH ₂ PO ₂ , 30 g / L of citric acid, pH 4.5, and a bath temperature of 85 ° C. Only the Cu circuit and the protrusions were plated with 4 μm of Ni.

6). Plating was performed for 10 minutes at KAu (CN) ₂ 1 g / L, citric acid 10 g / L, pH 4.5, and bath temperature 90 ° C.
Au was plated to 0.04 μm on Ni.

7). Electronic parts were mounted on the Ni / Au plated pads and protrusions (bumps).
Using a Ni / Au plated substrate, W / B strength and solder joint strength with respect to the pad were measured.
The results are shown in Table 1.

Ｗ／Ｂ強度の測定は、３０個のテストピースを用いて、２０ｇの力でワイヤーを引張って、何個、パッド部から剥がれたかで評価した。
表中、分子の数字は、３０個のテストピース中の剥がれた数を表す。

The measurement of W / B strength was evaluated by using 30 test pieces, pulling the wire with a force of 20 g, and how many pieces were peeled from the pad portion.
In the table, the number of molecules represents the number of peeled pieces in 30 test pieces.

The W / B strength and solder joint strength were almost the same as those of the conventional method.

Ni / Pd / Au plating process The substrate after electroless Ni plating was placed in an electroless Pd plating bath composed of PdCl _{2 2} g / L, ethylenediamine 20 g / L, EDTA 10 g / L, hydrazine 5 g / L, pH 9.0, Plate at 70 ° C. for 5 minutes.
Pd was plated by 0.2 μm.
Next, plating was performed at 90 ° C. for 2 minutes on an Au plating solution composed of KAu (CN) _{2 2} g / L, citric acid 10 g / L, and pH 4.5.
Au plating was plated by 0.001 μm.
Using this substrate, W / B and solder joint strength were measured.
The results are shown in Table 2.

半田接合強度の測定は、各々のパッドに半田付けをして引張り、パッドから半田が剥がれた時のｇ数で強度を評価した。数値は３０カ所の強度の平均値を示す。

The solder joint strength was measured by soldering each pad and pulling, and the strength was evaluated by the number of grams when the solder peeled off from the pad. A numerical value shows the average value of intensity | strength of 30 places.

The W / B strength and solder joint strength were almost the same as those of the conventional method.

From the results in Tables 1 and 2, the W / B strength and solder joint strength are almost the same as those of the conventional method even if the type of plating is changed, and the surface layer pad formed by the method of the present invention was formed by the conventional method. This means that the surface pad and its plating properties, adhesion strength (to the insulating layer), strength and the like are comparable.

Comparative Example A multilayer wiring board was prepared by the conventional technique described below.
1. The same double-sided copper-clad substrate as in FIG. 1 was used and only one side was used.
2. First, an epoxy resin paste was applied to the entire surface of the substrate with a target of 40 μm height (screen printing) and cured by heating.
3. A hole having a diameter of 100 μm was drilled in the cured epoxy resin layer with a laser in order to establish conduction with the underlying circuit. (Blind Via)
4). In order to fill the blind via with copper plating, the following steps were performed.

5. Usual etching, desmear, electroless copper plating, electrolytic copper plating (via fill), and then the copper plating surface was polished so as to be the same height as the insulating film (epoxy resin layer), and the via fill was completed.
6). In order to obtain adhesion strength between the insulating resin and the copper plating, the surface of the resin was roughened, and sensity san, activator, electroless copper and electrolytic copper plating were performed to form a copper plating layer having a thickness of 20 μm.
7). The copper plating layer was etched by photolithography to form a wiring circuit and a pad.
8). In the same step as (2), an epoxy resin was applied, dried and cured, and in the same step as (3), a hole for establishing conduction with the lower layer was drilled with a laser.
Steps 4, 5, 6, 7, and 8 were repeated, and the number of layers was increased by sequentially stacking.
As the amount of laminated water increased, the occurrence of poor conduction increased, and the number of laminated layers was limited to ten.
On the surface layer, a pad for W / B, a pad for soldering, and a bump for flip chip mounting were formed, and Ni / Au and Ni / Pd / Au plating were performed for W / B and soldering. .

The conventional method requires a lot of man-hours and takes a long time to manufacture.

  Table 3 shows a table comparing the number of layers that can be produced, the yield, the number of days required for production, and the production cost when the same wiring board is produced in this example and when the above-mentioned comparative example is preempted.

From the results shown in Table 3, it was found that the present invention is very advantageous in terms of the number of layers that can be produced, yield, production days, production costs, and the like.
Compared with the conventional manufacturing method, the present invention can omit steps such as circuit formation by etching, photolithography, hole making, hole filling and the like, and can reliably produce a good product in a short period of time. In addition, expensive equipment, advanced technology, high-purity chemicals, and materials are not required, and the internal wiring density can be easily manufactured with several times the density of the conventional wiring. A plate (MLPCB) can be manufactured, and it has been found that it is extremely effective in preventing the occurrence of poor conduction due to disconnection of the electrical conduction path and wiring circuit.

Example 2
A manufacturing process of an alumina ceramic package (HTCC) having a three-dimensional internal wiring structure having a fine internal wiring structure is as follows.

1 Design information of a ceramic wiring board having three-dimensional internal wiring was prepared by 3D-CAD, 3D data was created, and input to a 3D printer. The 3D printer used in this example used a method of extruding a muddy material from a nozzle of US Sunititas. It goes without saying that the 3D printer used in the present invention is not limited to this.

When the three-dimensional structure of the multilayer wiring board is divided into thin layers in a horizontal section, the insulating layer for each printing printed by a 3D printer, the printed thickness of the thin layer of the wiring circuit is 15 μm for the insulating layer, The thickness was set to 20 μm, and both the insulating layer and the thin layer of the wiring circuit had a thickness that could be formed by a single printing.

2 A wiring circuit and a pad using a 3D printer using a commercially available W paste on a green sheet prepared by mixing SiO ₂ , B ₂ O ₃ , PEG (polyethylene glycol), etc. with Al ₂ O ₃ as a main component. Printed.
The width of the wiring circuit was 20 μm, the interval between the wiring circuits was 20 μm, and the thickness of the wiring circuit was 20 μm.

3 The green sheet and the wiring circuit were simultaneously sintered using a laser in a reducing atmosphere (H2 + N2).

4 Next, columnar protrusions (diameter 20 μm, height 20 μm) for conduction with the upper layer wiring circuit are produced on the surface of the sintered wiring circuit with a 3D printer using the above-mentioned W paste, and the protrusions are formed with a laser. Sintered by heating.

5 The clay-like Al ₂ O ₃ slurry having the same component as the green sheet used in 2 above was printed without printing on the protrusions and covering the upper part of the protrusions, and an insulating layer between the upper and lower layers was produced. . The Al ₂ O ₃ slurry was printed with a printing thickness of 15 μm, a protrusion height of 20 μm, and a step of 5 μm.

6 The insulating layer was sintered with laser under the same conditions as 3 above.
7 At this point, the lower layer wiring circuit and the protrusions (upper and lower interlayer conduction pillars) were completely joined, and inspected for continuity defects and confirmed that there were no problems, and proceeded to the next step.

8 The above steps 2 and 3 were repeated on the sintered insulating layer to check the continuity, and this step was repeated to repeat the sequential lamination.

9 On the outermost layer surface, a pad for mounting electronic components and a pad for W / B were printed with a 3D printer using W paste and sintered.
10 W / B, pads for soldering, and bumps were plated with Ni / Au and Ni / Pd / Au by a known method to complete a multilayer ceramic IC package.
The completed multilayer substrate was free from cracks, warpage, and poor conduction.
In the method of the present invention, it was confirmed that a sound ceramic multilayer substrate without defects can be easily produced.

Comparative example (method according to the prior art)
The conventional method was manufactured in the following steps 1-6.
1 In the prior art, circuits and pads were formed by screen printing using W paste on a green sheet.
2 In the second layer, a hole for vertical conduction was punched on the same green sheet by punching, a circuit was printed with W paste, W paste was embedded in the punched portion, and used as a column for vertical conduction.
3 The third layer was formed in the same process as the second layer.
4 On the outermost layer, a W / B pad and a soldering pad were printed with W paste.
5 After successive lamination, the multilayer plates were superposed and then integrally sintered in a reducing atmosphere.
6 After sintering, plating was performed on the W / B pad and the soldering pad by a conventional method.

The biggest problem of the prior art is that when the green sheet is sintered, the volume shrinks by 20-30%, and at the time of shrinkage, the circuit breaks due to the difference in the expansion coefficient of the W paste used for the internal wiring, and the vertical conduction The column causes contact failure, and cracks and warpage of the substrate frequently occur, and the defect rate reaches 30 to 40%.
In this example, 20 pieces were produced, and nine defects including warpage and conduction failure occurred.
On the other hand, in the present invention, disconnection and contact failure can be checked sequentially at the time of stacking, and since sintering is performed for each layer stack, there is no warping or cracking of the substrate, and the defect rate is 0%.

Example 3
The superiority of the present invention is proved by comparing the number of defective insulation and disconnection between the manufacturing method according to the present invention and the conventional manufacturing method.
That is, ML-PCB was manufactured with the same specifications.
The first board used was a commercially available copper-clad double-sided board (A4 size).
The thickness of the copper plate was 20 μm, only one side was used, and a terminal for continuity test was produced by etching.
The vertical conduction protrusions were laminated with a diameter of 20 μm, a height of 20 μm, and 10 layers.
The number of projections is 200, and the projections of each layer are butted and joined, and the specific resistance is measured between the first layer terminals (projections) and the tenth layer terminals (projections) to evaluate the presence or absence of insulation or disconnection. did.
The multilayer substrate of the present invention was produced by the method of Example 1.
A conventional substrate was produced by the method of Comparative Example 1 of Example 1.
The results are shown in Table 4.

導通テストの条件：下層と上層間の抵抗を測定し、２００個の突起の平均値を示す。
耐湿サイクルの条件：９０〜６０％の湿度の中で２５℃×１０Ｈｒ、６５℃×１４Ｈｒを１サイクルとして、１０サイクル繰り返した。
断線：下層と上層間で全く電流が流れない時を断線とみなした。数字は、２００箇所測定した時の断線箇所の数。

Conditions for continuity test: The resistance between the lower layer and the upper layer is measured, and the average value of 200 protrusions is shown.
Conditions of moisture resistance cycle: 10 cycles were repeated with 25 ° C. × 10 Hr and 65 ° C. × 14 Hr as one cycle in a humidity of 90-60%.
Disconnection: When no current flows between the lower layer and the upper layer, it was considered as a disconnection. The number is the number of disconnection points when 200 points are measured.

  From the results in Table 4, the present invention has a smaller specific resistance than the conventional method and no disconnection.

In the conventional method, the reason why the specific resistance increases and the disconnection rate increases is considered to be as follows.
That is, the biggest problem in manufacturing the conventional method is a method of burning the epoxy resin until it reaches the underlying copper circuit using a laser in the drilling process.
In this method, a resin combustion residue or incompletely burned resin remains on the copper surface. In addition, the resin melts around the hole to form a film on the copper surface, and it is difficult to remove and confirm in the next desmear and etching processes. Eventually, in order to perform electrolysis or electroless copper plating on the copper surface where these residues remain, it can be inferred that the contact resistance naturally increases and the frequency of disconnection also increases.
Moreover, the shape of the hole opened by the laser has various shapes such as a trapezoid, an inverted trapezoid and an overhang. It seems that the reason why the defect rate is high is that the shape is not uniform.

On the other hand, according to the present invention, no resin (insulator) is present around the protrusion when the protrusion for vertical conduction is formed. Resins and the like do not flow onto the protrusions during curing and baking.
Therefore, the present invention has no cause for disconnection or insulation failure.
Further, as is clear from the results of the accelerated deterioration test (humidity cycle test), the superiority and inferiority become clearer.
The reason why there is no conduction failure even after the accelerated deterioration test and the resistance change is remarkably smaller than that of the conventional method is that the protrusions of the present invention are integrated by bonding the protrusions between the upper layer and the lower layer. It can be inferred that

Example 4
The superiority of the present invention is proved by comparing insulation failure, disconnection, and substrate warpage between the manufacturing method according to the present invention and the conventional manufacturing method. That is, HTCC was manufactured with the same specifications.

The insulating layer mainly composed of Al2O3 has a thickness of 30 μm, and the vertical conduction protrusions have a cylindrical shape with a diameter of 30 μm and a height of 30 μm.
The number of layers was 10. The number of projections was 200, and the projections of each layer were butted and joined, and the specific resistance between the lower layer and the upper layer was measured to measure insulation failure and disconnection.
The warpage and cracking of the substrate were evaluated visually.
The production of the present invention was produced by the same method as that of Example 2. Further, the conventional method was prepared by the method of the comparative example of Example 2.
The results are shown in Table 5.

導通テストの条件：下層と上層間の抵抗を測定し、２００個の突起の平均値を示す。
耐湿サイクルの条件：９０〜６０％の湿度の中で２５℃×１０Ｈｒ、６５℃×１４Ｈｒを１サイクルとして、１０サイクル繰り返した。
断線：下層と上層間で全く電流が流れない時を断線とみなした。数字は、２００箇所測定した時の断線箇所の数。

Conditions for continuity test: The resistance between the lower layer and the upper layer is measured, and the average value of 200 protrusions is shown.
Conditions of moisture resistance cycle: 10 cycles were repeated with 25 ° C. × 10 Hr and 65 ° C. × 14 Hr as one cycle in a humidity of 90-60%.
Disconnection: When no current flows between the lower layer and the upper layer, it was considered as a disconnection. The number is the number of disconnection points when 200 points are measured.

  From the results shown in Table 5, although the present invention has no disconnection even after the accelerated deterioration test (humidity cycle test), it has been proved that the conventional method has an extremely high disconnection rate.

The cause is considered to be as follows.
That is, in the conventional method, since it is integrally molded and fired, the shrinkage of 30 to 40% in volume ratio is unavoidable as a fate when firing ceramics. This is due to the disconnection of the internal wiring circuit and the disconnection of the upper and lower conductive protrusions. And the biggest cause of poor contact. Therefore, it is inevitable that a defect rate of 20 to 40% occurs in the conventional manufacturing method.
On the other hand, in the production method of the present invention, circuit formation and protrusion formation are first performed on a green sheet using W paste, and then only the circuit and protrusion portions are locally heated and fired with a laser. Thereafter, the insulating ceramic is printed and fired. Furthermore, since the present invention is a method of firing, checking and laminating one layer at a time, it is originally a technique that does not cause cracks, warpage, disconnection, or the like.

Example 5
Example 1 of producing a double-sided multilayer wiring board using a 3D printer from the beginning without using a commercially available copper-clad resin substrate. First, a glass plate having a size A4 and a thickness of 2 mm was prepared.
2. Using the same copper paste as in Example 1, 300 columnar protrusions with a diameter of 20 μm and a height of 20 μm are printed on the glass bumps and pads on one side using the same copper paste as in Example 1, and the portions are heated with a laser. And cured.
This protrusion serves as a bump or pad that becomes the starting point when the multilayer wiring board is laminated on the opposite surface.
3. Thereafter, an epoxy resin-based insulating resin was printed at a place other than the protrusion.
At that time, printing was performed so that the resin did not cover the top of the protrusion.
The thickness of the resin was 15 μm, the height of the protrusion was 20 μm, and the step was designed to be 5 μm for printing.
4). The resin was heated and cured with a laser.
5. Next, using the same copper paste as in 2), a wiring circuit having a width of 20 μm and a height of 20 μm was printed on the surface of the resin.
Printing was performed so that the copper paste was covered on the protrusion formed in 2), and the protrusion and the circuit were printed so as to ensure conduction, and then only the printed circuit portion was heated and cured using a laser. .
6). Next, 300 columnar protrusions having a diameter of 20 μm and a height of 20 μm were printed on the surface of the circuit portion on the surface of the circuit portion using the copper paste ink used in 2) in order to establish conduction between the upper and lower layers. Thereafter, only the protrusions were heated and cured with a laser.
In the same manner as in 7.3), an epoxy resin was printed on portions other than the columnar protrusions, and heated and cured. In this case as well, the work was performed while confirming whether or not the resin was covered on the upper part of the protrusion by a continuity test.
The steps of 8.6) to 7) were repeated to produce a multilayer wiring board with 20 layers on one side.
9. Bumps for flip chip (diameter 20 μm, height 20 μm) were formed on the outermost surface, and heated and cured with a laser.
10. The produced multilayer wiring board was heated at 150 ° C. for 3 hours to sufficiently cure the resin, circuit, and protrusions.
11. Next, the glass plate used first was removed from the multilayer wiring board.
On the back side of the obtained multilayer wiring board, the end face of the protrusion embedded in the resin was exposed.
This part becomes the back pad. Using the pad portion on the back surface as a starting point, the formation of protrusions and the printing of the insulating resin were repeated to produce a multilayer wiring board with a total of 40 layers on the back and front surfaces, and electroless plating was performed by the method of Example 1. .
12 The W / B strength, soldering strength, and the like were the same as those in Example 1, and were equivalent to those produced by the conventional method.

Example 6
Example 1 in which electronic components (circuit elements such as resistors and coils) are formed between both surfaces of a multilayer wiring board. A glass plate having a size of A4 and a thickness of 2 mm was prepared.
2. A bump, a circuit, and a pad were printed by an ink jet method using the commercially available W paste used in Example 2 at a position to become one side of the glass plate, a bump, a circuit, and a pad.
3. The W printing part was heated and sintered using a laser in a reducing atmosphere (H ₂ + N ₂ ).
4). Next, columnar protrusions (diameter 20 μm, height 20 μm) for conduction with the upper layer were erected on the circuit portion using the W paste.
The protrusion was heated and sintered by the method of 3).
The number of protrusions was 20/2 cm ² .
5. In order not to cover the same components as the green sheet used in Example 2 on the protrusions, printing was performed at a low height (15 μm), an insulating layer between upper and lower layers was formed, and sintered in the same process as 3) above. .
6). At this point, it was confirmed that the underlying circuit and the protrusions were completely joined and conducted.
7). Circuits and pads were printed on the insulating layer using W paste.
Circuits and pads are structured to be connected to the upper and lower layers through protrusions.
In the step 3), the pad and the circuit were sintered.
8). The resistance was then printed.
The resistor was designed to be conductive with the pad.
The resistance component is composed of 45% by mass of Ni fine powder, 45% by mass of Cr fine powder, 5% by mass of SiO _{2, and} 5% by mass of B ₂ O ₃ , and is made into a clay by adding water to form a comb. Printed on, heated and sintered with a laser.
9. Further, protrusions were raised on the circuit in the same process as in 4).
10. An insulating layer was formed in the same step as 5).
11. Pads and circuits were printed in the same process as 7 above.
12 Next, create a varistor between the layers. A fine powder of ZnO + SiC + ZnO—BiO ₃ , water, and nitrocellulose were mixed, and a slurry was printed between the circuit and the pad by an inkjet method, and designed to be electrically connected to the circuit.
Sintered using a laser.
The characteristics were checked and the performance was confirmed.
14 Protrusions were raised and sintered in the same process as 9 above.
15. An insulating layer was prepared and sintered in the same process as in 5.
16. A pad for mounting and a bump for flip chip mounting were formed on the outermost surface and sintered.
17. Ni-Au plating was applied to the pads and bumps.
18. The glass substrate was removed and the same process was repeated on the opposite side, and the outermost layer was plated. A double-sided multilayer wiring board having electronic components mounted between so-called layers was obtained.

Example 7
Embodiment 1 In which existing electronic parts (circuit elements such as resistors and coils) are formed between both surfaces of a multilayer wiring board. A glass plate having a size of A4 and a thickness of 2 mm was prepared.
2. Bumps, circuits, and pads were printed on the glass plate on one side, bumps, circuits, and pads using the conductive paste used in Example 1, and heated and cured with a laser.
3. Insulating resin was printed by the method of Example 1. At that time, the bumps, circuits, and pads were printed so as not to cover the insulating resin, and were heated and cured.
4). 200 protrusions having a diameter of 20 μm and a height of 20 μm were erected on the circuit portion and the pad portion.
5. The insulating resin was printed and cured at a height of 15 μm by the same method as 3) above. At that time, printing was performed with care so that the insulating resin did not cover the protrusions, and heating and curing were performed.
6). A ready-made SAW filter was soldered to the protruding protrusion.
The used solder is a mass ratio of Ag: Cu: Sn = 3.0: 0.5: 96.5, and 50% by mass of these fine powders of 0.1 to 2.0 μ, butyl cellosolve 10 1% by mass, 10% by mass of methylcellulose, and 30% by mass of water are mixed well to make it easy to print with a 3D printer.
7). Furthermore, a commercially available ceramic resistor was joined to another protrusion, and an antenna formed on a resin was mounted on another protrusion.
8). Protrusions having a height of 20 μm and a diameter of 20 μm were raised at the remaining protrusions and the openings of the circuit not covered with the insulating resin.
9. Insulating resin was printed in the same step as 3).
10. This operation was repeated to produce a multilayer wiring board having 20 layers on one side.
11. On the outermost layer, bumps and pads were formed so that semiconductors and electronic components could be mounted.
12 The glass substrate was removed from the obtained multilayer wiring board, and the same process was repeated on the opposite side, and the outermost layer was plated. A double-sided multilayer wiring board having electronic components mounted between so-called layers was obtained.

Examples 6 and 7 revealed the following.
In other words, it has been found that by making off-the-shelf ICs and electronic components between the layers, the thickness of the substrate can be greatly reduced, the outermost layer space is widened, and there is room for mounting other electronic components.
It has been found that the present invention can make a great contribution to the reduction in the thickness and size of electronic components.

  INDUSTRIAL APPLICABILITY The present invention contributes significantly to the reduction of manufacturing cost and the time required for manufacturing in the field of production of a large variety of multi-layer substrates on which semiconductors are mounted, and is an industrially extremely useful invention. In addition, it can greatly contribute to the miniaturization of electronic parts.

1 Conductive layer 2 Insulating layer (bottom)
3 Insulating layer (top) 4 Electrical conduction path

Claims (10)

A multilayer wiring board in which a conductive layer and an insulating layer are formed by alternately laminating and bonding a plurality of layers, and the conductive layer is embedded in the insulating layer located on the conductive layer to the side surface. The upper and lower conductive layers are multi-layer wiring boards having a structure in which they are electrically connected to each other through an electrical conduction path that penetrates the insulating layer sandwiched between the upper and lower conductive layers,
The three-dimensional structure of the multilayer wiring board is divided into thin layers in a horizontal section to form 3D data, and the thin layers are printed, cured and laminated by a 3D printer using the 3D data. A multilayer wiring board.   The electrical connection between the electrical conduction path that penetrates the insulating layer and the conductive layer that is located above the conductive layer located above and below makes the electrical conduction path protrude above the surface of the insulation layer, 2. The multilayer wiring board according to claim 1, wherein the protruding portion of the electrical conduction path is covered with a conductive layer positioned above and joined.   The multilayer wiring board according to claim 1, wherein the electrical conduction path has a conductive protrusion structure.   The conductive layer and the electrical conduction path are formed using a conductive ink, and the insulating thin layer is formed using an insulating ink, printed with a 3D printer, and then cured. 2. The multilayer wiring board according to item 1.   The conductive ink is one or a kind selected from Cu, Ag, Au, Pt, Pd, Ni, Co, Mn, Mo, W, Sn, Pb, Bi, Al, In, Sb, Ti, and Cr. The multilayer wiring board according to claim 4, wherein the multilayer wiring board is mainly composed of an alloy or a mixture of the above components.   The insulating ink is mainly composed of an organic insulating material powder, an inorganic insulating material powder, or an insulating material obtained by mixing an organic powder and an inorganic powder, and the organic insulating material powder is: , Epoxy, aramid, ABS, polycarbonate, phenol, urethane, fluorine, polyamide, acrylic, RET, or a mixture of two or more resin powders, and the inorganic insulating material powder is The ceramic powder according to claim 4, which is a mixture of one or more ceramic powders selected from alumina, aluminum nitride, silicon carbide, silica, boron oxide, silicon nitride, glass, glass fiber, and carbon nanotube. Multilayer wiring board.   A multilayer wiring board obtained by plating the conductive layer on the surface of the multilayer wiring board according to any one of claims 1 to 6.   The multilayer wiring board which mounted the electronic component on the surface of the multilayer wiring board of any one of Claims 1-7.   A multilayer wiring board comprising a circuit element or an integrated circuit mounted between the insulating layers of the multilayer wiring board according to claim 1.   A conductive layer of the multilayer wiring board according to any one of claims 1 to 9, an insulating layer on two upper and lower layers sandwiching the conductive layer, and an electrical conduction path penetrating the insulating layer on the upper side are formed. The method for producing a multilayer wiring board is characterized in that the conductive layer and the electrical conduction path are first cured, and then the insulating layer on the conductive layer is cured.

Images