JP5327107B2 - Printed wiring board substrate, printed wiring board, and printed wiring board manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for a printed wiring board, which has no size limit since an expensive vacuum facility is not required for the manufacturing the same, does not use an organic adhesive, has high density and high performance, and is sufficiently thinned by using various kinds of base materials without being limited from the quality of the base materials, and also to provide a printed wiring board using the substrate and a method for producing the printed wiring board. <P>SOLUTION: The substrate 1 for a printed wiring board includes: an insulative base material 10; and a conductive layer for covering the surface of the base material 10. The base material 10 has a through-hole 11 penetrating through the base material 10, and the conductive layer includes a conductive ink layer 20 containing metal particles for covering the entire surface of an inner hole of the through-hole 11 and both the front and rear surfaces of the base material 10. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a printed wiring board substrate, a printed wiring board, and a method for manufacturing a printed wiring board.

Conventionally, a printed wiring board substrate, that is, a printed wiring board substrate, is generally a method of bonding a heat-resistant polymer film and a copper foil with an organic adhesive, or coating a resin solution on a copper foil surface, drying, etc. Thus, the heat-resistant polymer film film is produced by a method of laminating.
For this reason, when producing a double-sided printed wiring board, after producing a through-hole, a desmear process is performed, electroless plating and electrolytic plating are performed, and resist formation and etching are performed.
In recent years, there has been an increasing demand for higher density and higher performance of printed wiring boards.
A printed wiring board substrate that does not have an organic adhesive layer and has a sufficiently thin conductive layer (copper foil layer) is required as a printed wiring board substrate that satisfies the demands for higher density and higher performance. It has been.
In response to the above requirements for a printed wiring board substrate, for example, JP-A-9-136378 discloses a copper thin film substrate in which a copper thin layer is laminated on a heat-resistant polymer film without using an adhesive. . In this copper thin film substrate, a copper thin film layer is formed as a first layer on the surface of a heat-resistant insulating base material using a sputtering method, and a copper thick film layer is formed thereon as a second layer using an electroplating method. ing.
Japanese Patent Application Laid-Open No. 6-120640 discloses a method for manufacturing a flexible printed wiring board capable of mounting components at high density.

JP-A-9-136378 JP-A-6-120640

The copper thin film substrate described in Patent Document 1 is a substrate that meets the requirements for high-density, high-performance printed wiring, in that an organic adhesive is not used, and the conductive layer (copper foil layer) can be thinned. I can say that.
On the other hand, since the first layer is formed using the sputtering method, vacuum equipment is required, and equipment costs such as construction, maintenance, and operation of the equipment increase. Moreover, all of supply of the base material to be used, thin film formation, base material storage, etc. must be handled in a vacuum. In addition, there is a problem that there is a limit in increasing the size of the substrate in terms of equipment.
Moreover, in the manufacturing method of the flexible printed wiring board of the said patent document 2, it can be said that it is a printed wiring board which meets the request | requirement of a high density and high performance printed wiring in the point which can shorten a terminal space | interval.
On the other hand, since the thickness of the wiring circuit is the sum of the thickness of the original copper clad laminate and the thickness of the plating layer, the wiring circuit becomes thick, making it difficult to produce a high-density and high-performance wiring circuit. There is a problem that there is.

  Therefore, the present invention solves the above-mentioned problems in the prior art, does not require expensive vacuum equipment for production, and thus is not subject to size limitations, uses no organic adhesive, and is made of a base material. It is an object of the present invention to provide a printed wiring board substrate, a printed wiring board, and a method for manufacturing the printed wiring board that can achieve high density, high performance, and sufficient thinning using various base materials without being limited to .

The printed wiring board substrate of the present invention is a printed wiring board substrate comprising an insulating base material and a conductive layer covering the surface of the base material, the base material penetrating the base material. A first conductive layer having a through hole, and the conductive layer is made of a conductive ink containing metal particles covering the entire surface of the inner hole of the through hole and the front and back surfaces of the substrate, and the first conductive layer The first feature is that the second conductive layer is formed of a plating layer laminated thereon, and the plating layer is formed by electroless plating and electrolytic plating .

According to the first feature of the present invention, the printed wiring board substrate is a printed wiring board substrate comprising an insulating base material and a conductive layer covering the surface of the base material. The material has a through-hole penetrating the base material, and the conductive layer is made of a conductive ink containing metal particles covering the entire inner surface of the through-hole and the front and back surfaces of the base material . Since the conductive layer and the second conductive layer made of a plating layer laminated on the first conductive layer, and the plating layer is formed by electroless plating and electrolytic plating , first, sputtering, etc. There is no need for expensive vacuum equipment required for physical vapor deposition. Therefore, the size of the printed wiring board substrate (mainly for the double-sided printed wiring board) is not limited by the vacuum equipment.
In addition, the conductive layer can be formed on the substrate without using an organic adhesive .

Moreover, since the 1st conductive layer is comprised as a layer containing a metal particle, the board | substrate for printed wiring boards using various base materials can be provided, without being restrict | limited to the material of a base material.

In addition, since the first conductive layer is formed of a conductive ink containing metal particles, it is possible to provide a printed wiring board substrate suitable for forming a high-density, high-performance printed wiring having a sufficiently thin conductive layer. it can.

Further, the conductive layer is formed by a first conductive layer made of conductive ink containing metal particles and a second conductive layer made of a plating layer laminated on the first conductive layer, so that a sufficiently thin layer is formed. For a printed wiring board suitable for forming a high-density, high-performance printed wiring having a sufficiently thin conductive layer having a conductive layer comprising a first conductive layer and a second conductive layer adjusted to the required thickness by plating A substrate can be provided.

In addition , since the plating layer is formed by electroless plating and electrolytic plating , the first conductive layer made of conductive ink containing metal particles can be made thin. Therefore, the amount of ink can be saved, and the printed wiring board substrate can be reduced in cost.

In the printed wiring board substrate of the present invention, in addition to the first feature of the present invention, the first conductive layer is made of a conductive ink containing metal particles having a particle diameter of 1 to 500 nm . It has 2 features.

According to the second feature of the present invention, in addition to the function and effect of the first feature of the present invention, the first conductive layer is made of a conductive ink containing metal particles having a particle diameter of 1 to 500 nm. Therefore, a dense and uniform thin layer can be stably formed on the insulating substrate without unevenness. Therefore, it is possible to provide a printed wiring board substrate having a thin layer suitable for obtaining fine printed wiring and a conductive layer having no defect.

In addition to the first or second feature of the present invention described above, the printed wiring board substrate of the present invention is a metal ion formed by an action of a reducing agent in an aqueous solution in which the metal particles include a complexing agent and a dispersing agent. The third feature is that the particles are obtained by a liquid phase reduction method for reducing the amount of sucrose.

According to the third aspect of the present invention, in addition to the function and effect of the first or second aspect of the present invention, in the aqueous solution in which the metal particles include a complexing agent and a dispersing agent, Since the particles are obtained by a liquid phase reduction method that reduces metal ions by working, an apparatus for obtaining particles is relatively simple compared to the gas phase method, leading to cost reduction. Also, mass production is easy and easy to get. Furthermore, there is an advantage that the particle diameter can be made relatively uniform by stirring in an aqueous solution.

The printed circuit board substrate of the present invention, in addition to the first to third any one of the features of the present invention, the fourth, wherein the metal particles are particles obtained by titanium redox process It is said.

According to the fourth aspect of the present invention, in addition to the function and effect of any one of the first to third aspects of the present invention, the metal particles are particles obtained by a titanium redox method. The particle size can be surely and easily adjusted to 1 nm to 500 nm, and the first conductive layer made of the conductive ink is formed as a uniform particle having a small number of defects and having a uniform shape with a round shape. Can be finished in a thin layer. Therefore, a conductive layer suitable for forming fine printed wiring can be obtained.

Moreover, the printed wiring board substrate of the present invention includes, in addition to any one of the first to fourth features of the present invention, Ni, Cr between the insulating base material and the first conductive layer. The fifth feature is that an intervening layer composed of one or more elements of Ti, Si, or more is present.

According to the fifth aspect of the present invention, in addition to the function and effect of any one of the first to fourth aspects of the present invention, a gap between the insulating base material and the first conductive layer is provided. , Ni, Cr, Ti, Si, an intervening layer made of one or more elements is present, so that the intervening layer is formed of a conductive ink on the insulating base material. It becomes a base when laminating and adhesion can be improved.

Moreover, the printed wiring board of this invention makes it 6th to manufacture using the board | substrate for printed wiring boards as described in any one of the said 1st- 5th of this invention.

According to the sixth aspect of the present invention, since the printed wiring board is manufactured using the printed wiring board substrate according to any one of the first to fifth aspects of the present invention, an expensive vacuum is provided. No equipment is required, and the demand for high-density, high-performance printed wiring with a thin conductive layer can be satisfied.

In the printed wiring board of the present invention, in addition to the sixth feature of the present invention, the second conductive layer is patterned by a semi-additive method using a resist with the first conductive layer as a base. This is the seventh feature.

According to the seventh aspect of the present invention, in addition to the function and effect of the sixth aspect of the present invention, the second conductive layer is a semi-additive method using a resist with the first conductive layer as a base. Thus, a higher density printed wiring board can be provided.

In addition, the printed wiring board manufacturing method of the present invention includes a through-hole forming step for forming a through hole in an insulating base material, and an insulating base material in which a through hole is formed after the through-hole forming step. Conductive ink application step for applying conductive ink containing metal particles dispersed in solvent, heat treatment step for performing heat treatment after the conductive ink application step , and electroless plating for performing electroless plating after the heat treatment step Etching after the plating step, the electroplating step of performing electrolytic copper plating after the electroless plating step, the resist pattern forming step of forming a resist pattern after the electrolytic plating step, and the resist pattern forming step An eighth feature is that it includes at least an etching process .

According to the eighth aspect of the present invention, the printed wiring board manufacturing method includes a through hole forming step of forming a through hole in an insulating base material, and the through hole is formed after the through hole forming step. A conductive ink application step of applying a conductive ink containing metal particles dispersed in a solvent to an insulating base material ; a heat treatment step of performing a heat treatment after the conductive ink application step ; and An electroless plating step for performing electroless plating, an electroplating step for performing electrolytic copper plating after the electroless plating step, a resist pattern forming step for forming a resist pattern after the electroplating step, and the resist after the pattern forming step, and an etching step for etching since at least provided by a through hole forming step, a through hole on an insulating substrate It can be formed.
Also, the conductive ink application step can apply the conductive ink containing metal particles to the insulating base material in which the through holes are formed.
In addition, the heat treatment process can remove unnecessary organic substances in the conductive ink to securely fix the metal particles on the insulating substrate, and form a conductive ink layer on the surface of the insulating substrate. it can be.

In addition, the electroless plating step can form a plating layer on the conductive ink layer without requiring energization.
Moreover, the plating layer which consists of copper can be formed on the plating layer formed by the electroless-plating process by the electroplating process.
Moreover, a resist pattern can be formed by a resist pattern formation process.
Further, an unnecessary conductive layer can be removed by an etching process.
Therefore, the thickness of the printed wiring board (mainly double-sided printed wiring board) can be reduced, and a high-density, high-performance printed wiring board can be obtained.

Also printed wiring board, since prepared by coating and heat treatment and the plating of the conductive ink is being, it is possible to eliminate the need for expensive vacuum equipment, also producing a printed wiring board without using an organic adhesive. Further, there is an advantage that various base materials can be used without being limited by the material of the base material .

Of course, by using nano-order metal particles, a sufficiently dense and uniform conductive ink can be applied, and a plating layer can be formed thereon, producing a dense and uniform printed wiring board without defects. be able to.

Furthermore, the conductive ink layer can be made thin by forming the plating layer in the electroless plating process and the electrolytic plating process . Therefore, the amount of ink can be saved and the cost can be reduced.

In addition, the printed wiring board manufacturing method of the present invention includes a through-hole forming step for forming a through hole in an insulating base material, and an insulating base material in which a through hole is formed after the through-hole forming step. Conductive ink application step for applying conductive ink containing metal particles dispersed in solvent, heat treatment step for performing heat treatment after the conductive ink application step, and electroless plating for performing electroless plating after the heat treatment step A plating step, a resist pattern forming step for forming a resist pattern after the electroless plating step, an electrolytic plating step for performing electrolytic copper plating after the resist pattern forming step, and the resist after the electrolytic plating step A resist pattern peeling step for peeling off the resist pattern formed in the pattern forming step, and a resist pattern after the resist pattern peeling step. That at least and a conductive ink layer removing step of removing the conductive ink layer exposed by the pattern peeling process is characterized ninth.

According to the ninth feature of the present invention, the printed wiring board manufacturing method includes a through hole forming step of forming a through hole in an insulating base material, and the through hole is formed after the through hole forming step. A conductive ink application step of applying a conductive ink containing metal particles dispersed in a solvent to an insulating base material; a heat treatment step of performing a heat treatment after the conductive ink application step; and An electroless plating step for performing electroless plating, a resist pattern forming step for forming a resist pattern after the electroless plating step, an electrolytic plating step for performing electrolytic copper plating after the resist pattern forming step, After the electrolytic plating step, a resist pattern peeling step for peeling the resist pattern formed in the resist pattern forming step, and the resist pattern peeling Since the process includes at least a conductive ink layer removing process for removing the conductive ink layer exposed by the resist pattern peeling process, the through hole is formed in the insulating base material by the through hole forming process. Can do.
Also, the conductive ink application step can apply the conductive ink containing metal particles to the insulating base material in which the through holes are formed.
In addition, the heat treatment process can remove unnecessary organic substances in the conductive ink to securely fix the metal particles on the insulating substrate, and form a conductive ink layer on the surface of the insulating substrate. can do.
In addition, the electroless plating step can form a plating layer on the conductive ink layer without requiring energization.
Moreover, a resist pattern can be formed by a resist pattern formation process.
Moreover, the plating layer which consists of copper can be formed according to an electroplating process. Moreover, a resist pattern can be peeled by a resist pattern peeling process. Further, the conductive ink layer exposed in the resist pattern peeling step can be removed by the conductive ink layer removing step.
That is, a printed wiring board can be manufactured by a so-called semi-additive method, and a printed wiring board (mainly a double-sided printed wiring board) with higher density and higher performance can be obtained.
Further, since the printed wiring board is manufactured by applying conductive ink, heat treatment and plating, an expensive vacuum facility is not required, and the printed wiring board can be manufactured without using an organic adhesive. Further, there is an advantage that various base materials can be used without being limited by the material of the base material .

Of course, by using nano-order metal particles, a sufficiently dense and uniform conductive ink can be applied, and a plating layer can be formed thereon, producing a dense and uniform printed wiring board without defects. be able to.

Furthermore, the conductive ink layer can be made thin by forming the plating layer in the electroless plating process and the electrolytic plating process . Therefore, the amount of ink can be saved and the cost can be reduced.

According to the printed wiring board substrate of the present invention, no expensive vacuum equipment is required for manufacturing, and therefore, there is no size limitation, no organic adhesive is used, and the base material is limited. Accordingly, high-density and high-performance printed wiring (mainly double-sided printed wiring) can be made possible by using various base materials.
Further, according to the printed wiring board of the present invention, as in the case of the printed wiring board substrate described above, no vacuum equipment is required for production, and thus there is no size limitation, and no organic adhesive is used. In addition, high-density and high-performance printed wiring (mainly double-sided printed wiring) can be made possible without being limited by the material of the base material or the lower layer.
Further, according to the method for producing a printed wiring board of the present invention, an expensive vacuum facility is not required, and therefore, the size of the base material is not limited without being restricted in size and without using an organic adhesive. In addition, a printed wiring board (mainly a double-sided printed wiring board) having a thin, dense and homogeneous conductive layer suitable for forming a high-density, high-performance printed wiring can be manufactured.

BRIEF DESCRIPTION OF THE DRAWINGS It is a perspective view explaining the board | substrate for printed wiring boards which concerns on embodiment of this invention, (a) is a figure which shows the board | substrate for printed wiring boards provided with 1 layer of conductive layers on both front and back, (b) is 2 layers of conductive It is a figure which shows the board | substrate for printed wiring boards provided with a layer on both front and back surfaces. It is sectional drawing explaining the manufacturing method of the board | substrate for printed wiring boards which concerns on embodiment of this invention, and a printed wiring board. It is sectional drawing explaining the manufacturing method of the printed wiring board which concerns on embodiment of this invention. It is sectional drawing explaining the modification of the manufacturing method of the printed wiring board which concerns on embodiment of this invention. It is sectional drawing explaining the modification of the manufacturing method of the printed wiring board which concerns on embodiment of this invention. It is sectional drawing explaining the manufacturing method of the conventional printed wiring board. It is sectional drawing explaining the manufacturing method of the conventional printed wiring board.

  Embodiments of a printed wiring board substrate and a manufacturing method thereof, and a printed wiring board and a manufacturing method thereof according to the present invention will be described with reference to the following drawings to provide an understanding of the present invention. However, the following description is an embodiment of the present invention, and does not limit the contents described in the claims.

First, a printed wiring board substrate and a manufacturing method thereof, and a printed wiring board and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to FIGS.
First, a printed wiring board substrate 1 according to the present invention will be described with reference to FIG.
The printed wiring board substrate 1 is a printed wiring board substrate having a single conductive layer on both front and back surfaces, and has an insulating base material 10 made of a film or a sheet, and front and back surfaces of the insulating base material 10. The conductive ink layer 20 is covered.
As shown in FIG. 1A, the printed wiring board substrate 1 is provided with a through hole 11 that penetrates the insulating base material 10.
The number of through-holes 11 and the positions where they are formed are not limited to those in the present embodiment, and can be changed as appropriate.

The insulating substrate 10 is a base for laminating the conductive ink layer 20, and a thin one is used as a film and a thick one is used as a sheet.
Examples of the material for the insulating base 10 include flexible materials such as polyimide and polyester, paper phenol, paper epoxy, glass composite, glass epoxy, Teflon (registered trademark), rigid materials such as glass base, and hard materials. It is possible to use a rigid flexible material combined with a soft material.
In this embodiment, a polyimide film is used as the insulating base material 10.

The conductive ink layer 20 is a conductive layer that covers the entire inner surface of the through hole 11 formed on the insulating base material 10 and the front and back surfaces of the insulating base material 10. It is formed by applying a conductive ink containing metal particles to the surface of the substrate 10. By using a conductive ink coating layer, the front and back surfaces of the insulating substrate 10 can be easily covered with a conductive film without the need for vacuum equipment.
The conductive ink layer 20 includes a layer subjected to a heat treatment such as drying or baking after application of the conductive ink.
In short, the conductive ink can be laminated by applying it to the entire inner surface of the through hole 11 formed on the insulating base material 10 and the front and back surfaces of the insulating base material 10. Anything is acceptable.
In the present embodiment, a conductive ink is used that includes metal particles as a conductive substance that provides conductivity, a dispersant that disperses the metal particles, and a dispersion medium. By applying using such a conductive ink, a coating layer made of fine metal particles is laminated on the front and back surfaces of the insulating substrate 10.

As the metal particles constituting the conductive ink, one or more elements of Cu, Ag, Au, Pt, Pd, Ru, Sn, Ni, Fe, Co, Ti, and In can be used. However, Cu is preferably used because of its good conductivity, easy printed wiring processing, and economical cost.
In this embodiment, Cu is used.

  The size of the metal particles contained in the conductive ink is 1 to 500 nm. This particle size is significantly smaller than that for normal coating, and is suitable for obtaining a dense conductive thin film. When the particle diameter is less than 1 nm, the dispersibility and stability in the ink are not necessarily good, and the particles are too small, and it takes time to apply the coating for lamination. Moreover, when exceeding 500 nm, it is easy to precipitate and it becomes easy to produce an unevenness | corrugation when apply | coating. In consideration of dispersibility, stability, unevenness prevention and the like, the thickness is preferably 30 to 100 nm.

  The metal particles contained in the conductive ink can be obtained by a titanium redox method. Here, the titanium redox method is defined as “a method in which metal element ions are reduced by a redox action when trivalent Ti ions are oxidized into tetravalent ions to precipitate metal particles”. The metal particles obtained by the titanium redox method have a small particle size, are uniform, and can have a spherical or granular shape, so that the conductive ink layer 20 can be formed into a thin and dense layer. .

  In the present embodiment, the printed wiring board substrate 1 is configured as a printed wiring board substrate having a single conductive layer on both the front and back surfaces, but is not necessarily limited to such a configuration. For example, as shown in FIG. 1B, the conductive ink layer 20 is a first conductive layer, and a plating layer 30 as a second conductive layer is formed on the first conductive layer by an electrolytic plating process (so-called electroplating method). It is good also as a structure which makes the board | substrate 2 for printed wiring boards provided with two conductive layers on both front and back by laminating | stacking.

  Further, in order to increase the adhesion between the insulating base material 10 and the conductive ink layer 20, an intervening layer composed of one or more elements of Ni, Cr, Ti, and Si is provided. It may be configured to exist. These intervening layers can be obtained by, for example, subjecting a resinous insulating base material 10 such as polyimide to an alkali treatment to expose a functional group on the resin surface and allowing a metal acid to act on the functional group. Si can be obtained by subjecting the resinous insulating base material 10 to silane coupling treatment.

Next, a printed wiring board substrate and a manufacturing method thereof, and a printed wiring board and a manufacturing method thereof according to an embodiment of the present invention will be described with reference to FIGS.
The printed wiring board 3 according to the present invention is conductive by forming a plating layer on the entire surface of the inner hole of the through hole 11 formed on the printed wiring board substrate 1 and on the front and back surfaces of the printed wiring board substrate 1. This is a double-sided printed wiring board in which the ink layer 20 is a first conductive layer and the plating layer 30 is a second conductive layer.
The printed wiring board 3 is manufactured by a so-called subtractive method using the printed wiring board substrate 1 of the present invention.

  More specifically, referring to FIGS. 2 and 3, through hole forming step 100 for forming through hole 11 in insulating base material 10, and through hole 11 is formed after through hole forming step 100. A conductive ink application step 200 for applying a conductive ink containing metal particles dispersed in a solvent to the insulating base material 10, and a heat treatment step (not shown) for performing a heat treatment after the conductive ink application step 200 A plating process 300 for performing electrolytic copper plating after the heat treatment process, a resist pattern forming process 400 for forming a resist pattern after the plating process 300, and a wiring circuit for forming a wiring circuit after the resist pattern forming process 400 It is manufactured through the formation process 500.

First, referring to FIG. 2, in the through hole forming step 100, the through hole 11 is formed on the insulating base material 10 using drilling, laser processing, or the like.
Thereafter, the conductive ink application process 200 applies conductive ink containing metal particles to the entire surface of the inner hole of the through hole 11 and the front and back surfaces of the insulating substrate 10.
Next, in a heat treatment step (not shown), the metal particles in the applied conductive ink are fixed on the insulating substrate 10 as a metal layer. As a result, the conductive ink layer 20 containing metal particles to be a conductive layer is formed on the entire surface of the inner hole of the through hole 11 formed on the insulating base material 10 and on the front and back surfaces of the insulating base material 10. .
As described above, the printed wiring board substrate 1 including the one conductive layer shown in FIG.

Next, as shown in FIG. 2, the entire surface of the inner hole of the through hole 11 and the front and back surfaces of the insulating base material 10 are plated by an electroplating process (so-called electroplating method) using copper. Layer 30 is formed.
As a result, a conductive layer is formed in which the conductive ink layer 20 is the first conductive layer and the plating layer 30 stacked on the first conductive layer is the second conductive layer. That is, the printed wiring board substrate 2 having the two conductive layers shown in FIG.

Thereafter, as shown in FIGS. 2 and 3, in a resist pattern forming step 400, a resist pattern 42 is formed by performing exposure and development using a pattern mask 41 in a state where the resist 40 is laminated on the plating layer 30. Then, a portion to be a wiring pattern is covered.
Next, as shown in FIG. 3, an unnecessary conductive layer other than a portion to be a wiring pattern is removed by an etching process 510 of the wiring circuit forming process 500.
Thereafter, as shown in FIG. 3, the resist pattern 42 is stripped by a resist pattern stripping step 520 of the wiring circuit forming step 500.
Through the above steps, the printed wiring board 3 using the printed wiring board substrate 1 according to the present invention is manufactured.

In the present embodiment, the plating layer 30 is formed only by the electrolytic plating process (so-called electroplating method), but is not necessarily limited to such a configuration.
For example, it is good also as a structure provided with an electroless-plating process before an electroplating process.
By setting it as such a structure, the thickness of the conductive ink layer 20 which is a 1st conductive layer can be made thin. Accordingly, the printed wiring board substrate 1 and the printed wiring board 3 can save the ink amount and can reduce the cost.
The metal used for the electrolytic plating process is not limited to copper (Cu), and a metal having excellent conductivity such as silver (Ag) or gold (Au) may be used.
Moreover, the manufacturing method of the printed wiring board 3 using the board | substrate 1 for printed wiring boards of this invention is not limited to an above-described subtractive method. The printed wiring board 3 according to the present invention belongs to the printed wiring board 3 according to the present invention, in other words, including those by various other subtractive methods and other manufacturing methods.

  Hereinafter, the configuration and manufacturing method of the printed wiring board substrate 1 and the printed wiring board 3 will be described in more detail.

(Configuration of insulating base material)
As the insulating base material 10, a continuous material continuous in one direction can be used. Using a continuous material, the printed wiring board substrate 1 can be manufactured in a continuous process. The insulating base material 10 can be an independent piece having a predetermined size.
The materials used as the insulating base material 10 are as described above, such as an insulating rigid material and a flexible material, in addition to polyimide.
As the conductive ink, an ink containing fine metal particles as a conductive substance, a dispersant for dispersing the metal particles, and a dispersion medium is used.

The types and sizes of the metal particles dispersed in the conductive ink are as already described above in addition to using Cu particles of 1 to 500 nm.
Moreover, the manufacturing method of a metal particle includes the titanium redox method mentioned above, and the following manufacturing methods are possible.

(Method for producing metal particles)
The metal particles can be produced by a conventionally known method such as a high temperature treatment method called an impregnation method, a liquid phase reduction method, or a gas phase method.
In order to produce metal particles by the liquid phase reduction method, for example, in water, a water-soluble metal compound that is a source of metal ions forming the metal particles and a dispersant are dissolved, and a reducing agent is added. Preferably, the metal ion may be subjected to a reduction reaction for a certain time under stirring. Of course, when metal particles made of an alloy are produced by a liquid phase reduction method, two or more water-soluble metal compounds are used.
In the case of the liquid phase reduction method, the produced metal particles are spherical or granular in shape, have a sharp particle size distribution, and can be made into fine particles.
For example, in the case of Cu, the water-soluble metal compound that is the source of the metal ion is copper (II) nitrate [Cu (NO ₃ ) ₂ ], copper (II) sulfate pentahydrate [CuSO ₄ .5H _2. O]. In the case of Ag, silver nitrate (I) [AgNO ₃ ], silver methanesulfonate [CH ₃ SO ₃ Ag], and in the case of Au, tetrachloroaurate (III) acid tetrahydrate [HAuCl ₄ · 4H ₂ O], In the case of Ni, nickel chloride (II) hexahydrate [NiCl ₂ · 6H ₂ O] and nickel nitrate (II) hexahydrate [Ni (NO ₃ ) ₂ · 6H ₂ O] can be exemplified. For other metal particles, water-soluble compounds such as chlorides, nitric acid compounds and sulfuric acid compounds can be used.

(Reducing agent)
As a reducing agent when producing metal particles by the oxidation-reduction method, various reducing agents capable of reducing and precipitating metal ions in a liquid phase (aqueous solution) reaction system can be used. For example, sodium borohydride, sodium hypophosphite, hydrazine, transition metal ions such as trivalent titanium ions and divalent cobalt ions, reducing sugars such as ascorbic acid, glucose and fructose, ethylene glycol, glycerin, etc. A polyhydric alcohol can be mentioned. Among these, the titanium redox method described above is a method of reducing and precipitating metal ions by redox action when trivalent titanium ions are oxidized to tetravalent.

(Dispersant for conductive ink)
As the dispersant contained in the conductive ink, various dispersants having a molecular weight of 2000 to 30000 and capable of favorably dispersing the metal particles precipitated in the dispersion medium can be used. By using a dispersant having a molecular weight of 2000 to 30000, the metal particles can be well dispersed in the dispersion medium, and the resulting conductive ink layer 20 as the first conductive layer has a dense and defect-free film quality. Can be. If the molecular weight of the dispersant is less than 2000, the effect of preventing the aggregation of the metal particles and maintaining the dispersion may not be obtained sufficiently. As a result, the conductive layer laminated on the insulating base material 10 may be dense. There is a possibility that it cannot be made with few defects. When the molecular weight exceeds 30000, the bulk is too large, and in the heat treatment performed after the application of the conductive ink, the sintering of the metal particles is inhibited to generate voids, or the film quality of the conductive ink layer 20 is dense. Or the decomposition residue of the dispersant may lower the conductivity.
In addition, it is preferable that the dispersant does not contain sulfur, phosphorus, boron, halogen and alkali from the viewpoint of preventing the deterioration of parts.
Preferred dispersants are those having a molecular weight in the range of 2000 to 30000, having amine-based polymer dispersants such as polyethyleneimine and polyvinylpyrrolidone, and having a carboxylic acid group in the molecule such as polyacrylic acid and carboxymethylcellulose. Hydrocarbon polymer dispersant, poval (polyvinyl alcohol), styrene-maleic acid copolymer, olefin-maleic acid copolymer, or copolymer having a polyethyleneimine moiety and a polyethylene oxide moiety in one molecule And a polymeric dispersant having a polar group.
The dispersant can be added to the reaction system in the form of a solution dissolved in water or a water-soluble organic solvent.
It is preferable that the content rate of a dispersing agent is 1-60 weight part per 100 weight part of metal particles. When the content ratio of the dispersant is less than the above range, there is a possibility that the effect of preventing the aggregation by dispersing the metal particles around the metal particles in the conductive ink containing water is insufficient. When the above range is exceeded, during the baking heat treatment after the coating of the conductive ink, the excessive dispersant inhibits the baking including the sintering of the metal particles, thereby causing voids or reducing the denseness of the film quality. In addition, the decomposition residue of the polymer dispersant may remain in the conductive layer as an impurity, thereby reducing the conductivity of the printed wiring.

(Metallic particle size adjustment)
To adjust the particle size of the metal particles, adjust the type and blending ratio of the metal compound, dispersant, and reducing agent, and adjust the stirring speed, temperature, time, pH, etc. when the metal compound is reduced. That's fine.
For example, the pH of the reaction system is preferably 7 to 13 in order to obtain particles having a fine particle size as in the present invention.
In order to adjust the pH of the reaction system to 7 to 13, a pH adjusting agent can be used. As this pH adjuster, common acids and alkalis such as hydrochloric acid, sulfuric acid, sodium hydroxide and sodium carbonate are used. In particular, in order to prevent deterioration of peripheral members, alkali metals and alkaline earth metals, Nitric acid and ammonia which do not contain a halogen element such as chlorine and impurity elements such as sulfur, phosphorus and boron are preferable.
In the embodiment of the present invention, metal particles having a particle diameter in the range of 30 to 100 nm are used, but it is possible to use those having a particle diameter in the range of 1 to 500 nm as an allowable range.
Here, the particle diameter is represented by the center diameter D50 of the particle size distribution in the dispersion, and was measured using a Microtrac particle size distribution meter (UPA-150EX) manufactured by Nikkiso Co., Ltd.

(Adjustment of conductive ink)
The metal particles deposited in the liquid phase reaction system can be adjusted to a conductive ink using a powder once passed through processes such as separation, washing, drying, and crushing. In this case, powdered metal particles, water as a dispersion medium, a dispersant, and if necessary, a water-soluble organic solvent are blended at a predetermined ratio, and a conductive ink containing metal particles can do.
Preferably, the conductive ink is prepared using a liquid phase (aqueous solution) reaction system in which metal particles are deposited as a starting material.
That is, the liquid phase (aqueous solution) of the reaction system containing the precipitated metal particles is subjected to treatments such as ultrafiltration, centrifugation, washing with water, and electrodialysis to remove impurities, and if necessary, concentrated to remove water. Or, conversely, after adjusting the concentration of the metal particles by adding water, if necessary, a conductive ink containing the metal particles is prepared by blending a water-soluble organic solvent in a predetermined ratio. In this method, it is possible to prevent generation of coarse and irregular particles due to agglomeration during drying of the metal particles, and it is possible to obtain a conductive ink layer 20 that is a dense and uniform first conductive layer.

(Dispersion medium)
The ratio of water serving as a dispersion medium in the conductive ink is preferably 20 to 1900 parts by weight per 100 parts by weight of the metal particles. If the water content is less than the above range, the effect of dispersing the water-based dispersant sufficiently and dispersing the metal particles surrounded by the dispersant may be insufficient. Further, when the content ratio of water exceeds the above range, the metal particle ratio in the conductive ink is decreased, and a good coating layer having the necessary thickness and density cannot be formed on the surface of the insulating substrate 10. There is.

The organic solvent blended into the conductive ink as necessary can be various water-soluble organic solvents. Specific examples thereof include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol and tert-butyl alcohol, ketones such as acetone and methyl ethyl ketone, Examples thereof include polyhydric alcohols such as ethylene glycol and glycerin and other esters, and glycol ethers such as ethylene glycol monoethyl ether and diethylene glycol monobutyl ether.
The content ratio of the water-soluble organic solvent is preferably 30 to 900 parts by weight per 100 parts by weight of the metal particles. If the content ratio of the water-soluble organic solvent is less than the above range, the effect of adjusting the viscosity and vapor pressure of the dispersion due to the inclusion of the organic solvent may not be sufficiently obtained. When the above range is exceeded, there is a possibility that the effect of dispersing the metal particles in the conductive ink satisfactorily without causing aggregation by sufficiently swelling the dispersant with water.

(Application on insulating base material with conductive ink)
As a method of applying the conductive ink in which metal particles are dispersed on the insulating base material 10, a spin coating method, a spray coating method, a bar coating method, a die coating method, a slit coating method, a roll coating method, a dip coating method. It is possible to use a conventionally known coating method such as. Alternatively, it may be applied to only a part of the insulating base material 10 by screen printing, a dispenser or the like.
Drying after application. Thereafter, the process proceeds to heat treatment described later.

(Heat treatment of coating layer)
By heat-treating the conductive ink applied on the insulating base material 10, the conductive ink layer 20 fixed on the base material is obtained as a baked coating layer. The thickness of the conductive ink layer 20 is preferably 0.05 to 2 μm.
By heat treatment, the dispersant and other organic substances contained in the applied conductive ink are volatilized and decomposed by heat to remove them from the coating layer, and the remaining metal particles are in a sintered state or a stage before sintering. Then, they are firmly fixed on the insulating base material 10 as if they were in close contact with each other and solid-bonded.
The heat treatment may be performed in the air. Further, in order to prevent oxidation of the metal particles, it may be further fired in a reducing atmosphere after firing in the air. The firing temperature can be set to 700 ° C. or less from the viewpoint of suppressing the crystal grain size of the metal of the conductive ink layer 20 formed by the firing from becoming excessively large and the generation of voids.
Of course, the heat treatment is performed at a temperature of 500 ° C. or less in consideration of the heat resistance of the insulating base material 10 when the insulating base material 10 is an organic resin such as polyimide. The lower limit of the heat treatment temperature is preferably 150 ° C. or higher in consideration of the purpose of removing organic substances other than metal particles contained in the conductive ink from the coating layer.
Further, as the heat treatment atmosphere, considering that the metal particles to be laminated are extremely fine, in order to prevent the oxidation well, for example, the O ₂ concentration was decreased, for example, the O ₂ concentration was set to 1000 ppm or less. A non-oxidizing atmosphere can be obtained. Furthermore, for example, a reducing atmosphere can be obtained by containing hydrogen at a concentration lower than the lower explosion limit (3%).
This completes the process of forming the conductive ink layer 20 by applying the conductive ink onto the insulating substrate 10 and heat-treating the coating layer.

(Lamination of plating layer by plating process)
The plating layer 30 to be laminated on the conductive ink layer 20 is laminated by a plating process 300. Actually, it is performed by an electrolytic plating process (so-called electroplating method) using copper (Cu). In the present embodiment, since the conductive ink layer 20 as the first conductive layer is formed in the lower layer in advance, the plating layer 30 as the second conductive layer can be easily formed by electroplating.
By using the electrolytic plating process, it is possible to quickly stack up to a predetermined stacking thickness. In addition, there is an advantage that the thickness can be adjusted accurately for stacking. Moreover, the plating layer 30 obtained can be made into a homogeneous layer without defects.
The thickness of the plating layer 30 is set depending on what kind of printed circuit is produced, and the thickness is not particularly limited. However, as long as the purpose is to form a high-density and high-performance printed wiring, a conductive layer of, for example, 1 to several tens of microns can be formed as a thickness that enables the formation of such a high-density wiring.
The relationship between the thickness of the conductive ink layer 20 that is the first conductive layer and the plating layer 30 that is the second conductive layer is that the conductive ink layer 20 that is the first conductive layer makes the surface of the insulating substrate 10 conductive. Thus, it serves as a base formation necessary for the formation of the plating layer 30 as the second conductive layer, and as long as the front and back surfaces of the insulating base material 10 are reliably covered, it is sufficient that the thickness is thin. It is. On the other hand, the plating layer 30 requires a thickness necessary for forming a printed wiring. Therefore, the thickness of the plating layer 30 can be considered as the thickness of the entire conductive layer.
The electroplating step (so-called electroplating method) can be performed using a conventionally known electroplating bath and selecting appropriate conditions so that an electroplated layer having a predetermined thickness can be quickly formed without defects.
In the present embodiment, the conductive ink layer 20 that is the first conductive layer is made of Cu as the conductive layer of the printed wiring board substrate 1. When the plating layer 30 as the second conductive layer is made of Cu, the conductive ink layer 20 is preferably Cu, but other metals having good adhesion with Cu can also be adopted. . Of course, when the cost and the like are not considered, the conductive ink layer 20 and the plating layer 30 are not necessarily made of Cu, and the conductive ink layer 20 adheres to the insulating substrate 10 and the plating layer 30. The plating layer 30 can be made of a metal having excellent conductivity.

  As described above, in order to improve the adhesion between the insulating substrate 10 and the conductive ink layer 20 as the first conductive layer, any one or more of Ni, Cr, Ti, and Si is previously used. An intervening layer made of these elements may be present. In this case, the step of forming the intervening layer is entered as a preliminary treatment. In this pretreatment, for example, a resinous insulating base material 10 such as polyimide is subjected to an alkali treatment to expose a functional group on the resin surface, and a metal acid of the above-described metal element is allowed to act on the functional group. Get. The Si intervening layer can be obtained by subjecting the resinous insulating base material 10 to a silane coupling treatment.

  As described above, according to the printed wiring board 3 using the printed wiring board substrate 1 according to the present invention and the manufacturing method thereof, the vacuum equipment is more expensive to manufacture than the conventional double-sided printed wiring board and manufacturing method thereof. Is not necessary, and the equipment cost can be reduced, the manufacturing efficiency is good, and the size is not limited. In addition, desmear treatment is not required, and various substrates can be used without using organic adhesives and without being restricted by the material of the substrate, enabling high density, high performance, and sufficiently thin conductive layers. It can be. Further, the etching can be performed with high accuracy during the etching process. (So-called etching sagging can be prevented.) Mass production of a high-density, high-performance double-sided printed wiring board can be realized.

That is, as shown in FIGS. 6 and 7, the conventional double-sided printed wiring board 5 has a copper-clad structure in which a conductive layer 50 is formed by laminating copper thin films on the front and back surfaces of an insulating base material 10 by sputtering. After forming the through-hole 11 by the through-hole formation process 100 using the multilayer substrate 4, the desmear process is performed, and the plating layer 30 is formed by performing the electroless plating process and the electrolytic plating process by the plating process 300. In general, those manufactured through a resist pattern forming process 400 and a wiring circuit forming process 500 are used.
Therefore, vacuum equipment for performing the sputtering method is required, and equipment costs such as construction, maintenance and operation of equipment are high. In addition, all of the supply of the insulating base material 10 to be used, the formation of the thin film, the storage of the insulating base material 10 must be handled in a vacuum, and a desmear treatment is required after the formation of the through-holes 11, so that the production efficiency However, there is a limit to increasing the size of the insulating base material 10.
Further, since the thickness of the wiring circuit is the sum of the thickness of the original copper-clad laminate 4 and the thickness of the plating layer 30, the wiring circuit becomes thick and it is difficult to produce a high-density and high-performance wiring circuit. At the same time, it was difficult to perform etching accurately during the etching process (so-called etching sagging occurred).

Next, with reference to FIG. 4 and FIG. 5, the modification of the manufacturing method of the printed wiring board based on this invention is demonstrated.
In this modification, the printed wiring board 3 is manufactured by the semi-additive method using the printed wiring board substrate 1. Other configurations are the same as those of the above-described embodiment of the present invention. The same member and the same function are given the same number, and the following description is omitted.

First, referring to FIG. 4, through hole forming process 100 forms through hole 11 in insulating base material 10 using drilling, laser processing, or the like.
Next, in a conductive ink application process 200, a conductive ink containing metal particles is applied to the entire surface of the inner hole of the through hole 11 and the front and back surfaces of the insulating substrate 10.
Thereafter, the metal particles in the applied conductive ink are fixed on the insulating substrate 10 as a metal layer by a heat treatment step (not shown). Thereby, the conductive ink layer 20 containing the metal particles to be the conductive layer is formed on the front and back surfaces of the insulating base material 10.
Thus, the printed wiring board substrate 1 is manufactured as shown in FIG.

Next, as shown in FIG. 4, the resist pattern forming step 400 exposes the resist 40 on the front and back surfaces of the printed wiring board substrate 1 and exposes and develops the pattern mask 41. As shown in FIG. 5, a resist pattern 42 is formed to cover the portion other than the portion to be the wiring pattern.
Next, a plating layer 30 is formed by an electroplating process (so-called electroplating method) using copper (Cu) in a portion to be a wiring pattern by the plating process 300.
As a result, a conductive layer is formed in which the conductive ink layer 20 is the first conductive layer, and the plating layer 30 laminated on the first conductive layer is the second conductive layer. That is, using the conductive ink layer 20 as the first conductive layer as a base, the plating layer 30 as the second conductive layer is patterned by a semi-additive method using the resist 40.

Thereafter, as shown in FIG. 5, the resist pattern 42 is stripped by a resist pattern stripping step 520 of the wiring circuit forming step 500.
Next, as shown in FIG. 5, the conductive ink layer 20 exposed in the resist pattern peeling step 520 is removed by the etching step 510 of the wiring circuit forming step 500.
Through the above steps, the printed wiring board 3 using the printed wiring board substrate 1 according to this modification is manufactured.
In addition, in this modification, before the resist pattern formation process 400, the structure provided with the electroless-plating process which coat | covers the whole surface of the inner hole of the through-hole 11, and the front and back surfaces of the insulating base material 10 with an electroless-plating layer. It is good.
By setting it as such a structure, the thickness of the conductive ink layer 20 which is a 1st conductive layer can be made thin. Accordingly, the printed wiring board substrate 1 and the printed wiring board 3 can save the ink amount and can reduce the cost.

  A conductive ink having a copper concentration of 8% by weight, in which copper particles having a particle diameter of 40 nm are dispersed using water as a solvent, is prepared, and this is a polyimide film (Kapton EN) which is an insulating substrate in which through holes are formed. This was applied to the entire surface and the front and back surfaces of the inner hole of and dried at 60 ° C. for 10 minutes in the air. Further, heat treatment was performed at 250 ° C. for 30 minutes in a nitrogen atmosphere (oxygen concentration: 100 ppm). The resistance value of the conductive ink layer obtained at this time was 40 μΩcm. Further, by performing copper electroplating on the front and back surfaces of the conductive ink layer, a printed wiring board substrate having a thickness of 12 μm was obtained.

  The heat treatment was performed in the same manner as in Example 1 except that 3% hydrogen and 97% nitrogen were used. The resistance value of the conductive ink layer obtained at this time was 10 μΩcm. Furthermore, the board | substrate for printed wiring boards with a thickness of 12 micrometers was obtained by electroplating copper on a conductive ink layer.

  According to the present invention, a high-density, high-performance printed wiring board substrate (mainly for a double-sided printed wiring board) and a printed wiring board (mainly a double-sided printed wiring board) can be manufactured at low cost without the need for vacuum equipment. Can be provided well, and has high industrial applicability in the field of printed wiring.

DESCRIPTION OF SYMBOLS 1 Printed wiring board board | substrate 2 Printed wiring board board | substrate 3 Printed wiring board 4 Copper-clad laminated board 5 Double-sided printed wiring board 10 Base material 11 Through hole 20 Conductive ink layer 30 Plating layer 40 Resist 41 Pattern mask 42 Resist pattern 50 Conductivity Layer 100 Through-hole formation process 200 Conductive ink application process 300 Plating process 400 Resist pattern formation process 500 Wiring circuit formation process 510 Etching process 520 Resist pattern peeling process

Claims (9)

A printed wiring board substrate comprising an insulating base material and a conductive layer covering the surface of the base material, wherein the base material has a through hole penetrating the base material, and the conductive layer is A first conductive layer made of a conductive ink containing metal particles covering the whole surface of the inner hole of the through hole and the front and back surfaces of the base material, and a plating layer laminated on the first conductive layer. A printed wiring board substrate comprising a second conductive layer, wherein the plating layer is formed by electroless plating and electrolytic plating . 2. The printed wiring board substrate according to claim 1, wherein the first conductive layer is made of a conductive ink containing metal particles having a particle diameter of 1 to 500 nm . In aqueous solution the metal particles comprise a complexing agent and dispersant, according to claim 1 or 2, characterized in that the particles obtained by a liquid phase reduction method for reducing the metal ions by the action of a reducing agent Printed wiring board substrate. The printed wiring board substrate according to any one of claims 1 to 3, wherein the metal particles are particles obtained by a titanium redox method . 2. An intervening layer made of one or more elements of Ni, Cr, Ti, and Si is present between the insulating substrate and the first conductive layer. The printed wiring board board | substrate of any one of -4. The printed wiring board manufactured using the board | substrate for printed wiring boards of any one of Claims 1-5 . The printed wiring board according to claim 6, wherein the second conductive layer is patterned by a semi-additive method using a resist with the first conductive layer as a base . A through hole forming step for forming a through hole in an insulating base material, and a conductive ink containing metal particles dispersed in a solvent on the insulating base material in which the through hole is formed after the through hole forming step. A conductive ink coating step to be applied, a heat treatment step of performing a heat treatment after the conductive ink coating step, an electroless plating step of performing electroless plating after the heat treatment step, and after the electroless plating step, An electrolytic plating process for performing electrolytic copper plating, a resist pattern forming process for forming a resist pattern after the electrolytic plating process, and an etching process for performing etching after the resist pattern forming process are provided. Manufacturing method of printed wiring board . A through hole forming step for forming a through hole in an insulating base material, and a conductive ink containing metal particles dispersed in a solvent on the insulating base material in which the through hole is formed after the through hole forming step. A conductive ink coating step to be applied, a heat treatment step of performing a heat treatment after the conductive ink coating step, an electroless plating step of performing electroless plating after the heat treatment step, and after the electroless plating step, A resist pattern forming step for forming a resist pattern, an electrolytic plating step for performing electrolytic copper plating after the resist pattern forming step, and a resist pattern formed in the resist pattern forming step after the electrolytic plating step is peeled off Resist pattern peeling step and conductivity exposed by the resist pattern peeling step after the resist pattern peeling step Method for manufacturing a printed wiring board, characterized in that it comprises at least a conductive ink layer removing step of removing the ink layer.

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