JP2011258646A - Substrate for printed wiring board and method for manufacturing substrate for printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for a printed wiring board, capable of being formed without using a sputtering device, and a method for manufacturing the substrate for a printed wiring board.SOLUTION: The substrate 1 for a printed wiring board includes: an insulating base material; a first conductive layer 21 laminated on the insulating base material 10; and a second conductive layer 24 laminated on the first conductive layer 21. The first conductive layer 21 is formed of conductive particles 22A. Surface treatment for increasing a coupling force between the conductive particles 22A and the insulating base material 10 is performed on the laminated surface 10A of the insulating base material 10 on a side where the first conductive layer 21 is laminated.

Description

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

  In recent years, there has been an increasing demand for higher density of printed wiring boards. Accordingly, a technique for reducing the thickness of the conductive layer of the printed wiring board substrate as a base material of the printed wiring board has been developed. A technique described in Patent Document 1 is known as such a technique. In the technique of Patent Document 1, a first conductive layer is formed on an insulating substrate by a sputtering method. Next, a second conductive layer is formed on the first conductive layer by electroplating.

JP-A-9-136378

  However, since the sputtering method is used in the method for manufacturing a printed wiring board substrate, a large initial equipment cost is required to start manufacturing the substrate, and as a result, the printed wiring board substrate becomes expensive.

  This invention is made | formed in view of such a situation, The objective is providing the manufacturing method of the board | substrate for printed wiring boards which can be formed without using a sputtering device, and the board | substrate for printed wiring boards. There is.

In the following, means for achieving the above object and its effects are described.
(1) The invention described in claim 1 includes an insulating base material, a first conductive layer laminated on the insulating base material, and a second conductive layer laminated on the first conductive layer. In the substrate for a wiring board, the first conductive layer is formed of conductive particles, and the laminated surface of the insulating base on the side where the first conductive layer is laminated includes the conductive particles and the insulating group. The gist is that surface treatment is performed to increase the bonding strength with the material.

  According to this invention, since the first conductive layer is formed by stacking conductive particles, the first conductive layer can be formed without using a sputtering apparatus. The laminated surface of the insulating base material is subjected to surface treatment, and the bonding force of the laminated surface of the insulating base material to the conductive particles is increased, so that the layer composed of the first conductive layer and the second conductive layer is insulated. The force necessary for peeling from the conductive substrate, that is, the peel strength can be increased.

  (2) The invention according to claim 2 is that in the printed wiring board substrate according to claim 1, a conductor-binding functional group that binds to the conductor particles is introduced into the laminated surface. It is a summary.

  The conductor particles are in contact with the laminated surface of the insulating substrate. When the bonding force between the conductor particles and the molecules constituting the laminated surface is small, the conductor particles are separated from the molecules with a small force, and thus the adhesive strength between the first conductive layer and the insulating substrate is lowered. In this invention, since the conductor binding functional group is introduced into the laminated surface and the conductor particles and the conductor binding functional group are bonded to each other, the adhesive force between the first conductive layer and the insulating substrate can be increased. .

  (3) The invention according to claim 3 is the printed wiring board substrate according to claim 2, wherein the conductor particles are metal particles and the conductor-binding functional group contains oxygen. .

  The bond strength between oxygen atoms and metal particles is greater than the bond strength between carbon atoms and metal particles. For this reason, since the adhesive force between the conductor particles and the insulating base material can be increased by introducing the conductor-binding functional group containing oxygen into the laminated surface of the insulating base material, the first conductive layer is insulated from the first conductive layer. The peel strength from the conductive substrate can be increased.

  (4) The invention according to claim 4 is the printed wiring board substrate according to claim 2 or 3, wherein the conductor-binding functional group is at least one selected from the group consisting of a carbonyl group, a carboxyl group, and a hydroxyl group. The gist is that it is one.

  (5) The invention according to claim 5 is the printed wiring board substrate according to any one of claims 2 to 4, wherein the conductor particles are metal particles, and oxygen of carbon relative to carbon in the laminated surface is obtained. The gist is that the ratio is 0.25 or more in molar ratio.

  When the ratio of oxygen to carbon on the laminated surface is less than 0.25 in terms of molar ratio, the peel strength between the first conductor layer and the insulating base material becomes smaller than the practically required value. According to this invention, in order to make the ratio of oxygen to carbon in the laminated surface a molar ratio of 0.25 or more, the peel strength between the first conductor layer and the insulating base material is not less than a practically required value. can do.

  (6) The invention according to claim 6 is the printed wiring board substrate according to any one of claims 1 to 5, wherein the first conductive layer is a conductive ink containing the conductive particles. The gist is that it is formed by coating.

  (7) The gist of the invention according to claim 7 is that, in the printed wiring board substrate according to any one of claims 1 to 6, the particles of the conductor particles are 1 nm or more and 500 nm or less. Yes.

  If the conductor particles are less than 1 nm, they are very likely to aggregate and difficult to handle. When the particle diameter of the conductor particles is larger than 500 nm, the gap between the conductor particles becomes excessive. In this invention, since the first conductive layer is formed of conductor particles having a particle diameter of 1 nm or more and 500 nm or less, than when forming the same layer using a particle diameter of less than 1 nm or more than 500 nm, It can be a dense layer.

  (8) The invention according to claim 8 is a print including an insulating base material, a first conductive layer laminated on the insulating base material, and a second conductive layer laminated on the first conductive layer. In the method for manufacturing a substrate for a wiring board, a surface treatment step of performing a surface treatment for increasing the bonding force between the laminated surface and the first conductive layer on the laminated surface of the insulating base material, and after the surface treatment step A first conductive layer forming step of forming a first conductive layer by applying a conductive ink containing conductive particles to the laminated surface; and after the first conductive layer forming step, It includes a second conductive layer forming step of forming a second conductive layer thereon.

  According to this invention, the first conductive layer is formed by applying the conductive ink to the laminated surface after the surface treatment step. That is, the first conductive layer can be formed without using a sputtering apparatus. Moreover, since the laminated surface of the insulating base material is surface-treated before forming the first conductive layer on the insulating base material, the adhesive force of the first conductive layer to the insulating base material can be increased.

  (9) The invention according to claim 9 is a print including an insulating base, a first conductive layer laminated on the insulating base, and a second conductive layer laminated on the first conductive layer. In the method for manufacturing a substrate for a wiring board, by applying a surface treatment process for surface-treating the laminated surface of the insulating base material and a conductive ink containing conductive particles to the laminated surface after the surface treatment process. A first conductive layer forming step of forming a first conductive layer; and an electroless plating step of forming an electroless plating layer on the first conductive layer by performing electroless plating after the first conductive layer forming step; And a second conductive layer forming step of forming a second conductive layer on the first conductive layer after the electroless plating step.

  According to this invention, electroless plating is performed after the first conductive layer forming step to form the electroless plated layer on the first conductive layer. Thereby, since the space | gap part of conductor particles produced when a 1st conductive layer is formed can be filled up with the plating metal of electroless plating, a 1st conductive layer can be made dense.

  (10) The invention according to claim 10 is the method for manufacturing a printed wiring board substrate according to claim 8 or 9, wherein in the surface treatment, a contact angle between the laminated surface and the conductive ink is used as a reference value. The summary is as follows.

  When the conductive ink is applied to an insulating substrate having no wettability, the layer thickness of the conductive ink becomes uneven. According to this invention, since the contact angle between the laminated surface and the conductive ink is set to a reference value or less, the conductive ink layer having a uniform thickness can be formed on the insulating substrate.

(11) The invention according to claim 11 is the gist of the printed wiring board substrate manufacturing method according to claim 10, wherein the reference value is less than 60 degrees.
When the contact angle between the insulating substrate and the conductive ink is 60 degrees or more, spots occur in the layer thickness of the conductive ink. According to this invention, since the contact angle between the insulating substrate and the conductive ink is less than 60 degrees, the conductive ink layer having a uniform thickness can be formed on the insulating substrate.

  (12) The invention according to claim 12 is the method for producing a printed wiring board substrate according to any one of claims 8 to 11, wherein in the surface treatment, the conductor particles are formed on the laminated surface. The gist is to introduce a conductor-binding functional group to be bonded.

  Some printed wiring board substrates contain functional groups that bind to conductive particles. When a layer of conductive particles is formed on such a printed wiring board substrate, the conductive particles and functional groups are bonded. In the present invention, a conductor-bound functional group is newly introduced regardless of whether the printed wiring board substrate has a functional group. Thereby, the ratio of the conductor particle couple | bonded with the conductor coupling | bonding functional group in a lamination | stacking surface increases. As a result, the adhesive force between the first conductive layer and the insulating substrate can be increased.

  (13) The invention according to claim 13 is the method for manufacturing a printed wiring board substrate according to any one of claims 8 to 12, wherein the first conductive layer forming step is electrically conductive on the laminated surface. An application step of applying ink; an evaporation step of evaporating the medium of the conductive ink after the application step; and a heat treatment step of heat-treating a conductor contained in the conductive ink after the evaporation step. It is a summary.

  According to this invention, the conductive ink contained in the conductive ink is heat-treated by evaporating the medium of the conductive ink. For this reason, the conductor particles can be fixed to the insulating substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the board | substrate for printed wiring boards which has a conductive layer which can be formed without using a sputtering device, and the manufacturing method of the board | substrate for printed wiring boards can be provided.

Sectional drawing which shows the board | substrate for printed wiring boards of one Embodiment of this invention to a cross-sectional structure. About the insulating base material of the same embodiment, (A) is a cross-sectional view showing the cross-sectional structure of a conductive ink applied to an insulating base material that has not been surface-treated, and (B) is a surface-treated insulating base material. Sectional drawing which shows the cross-section of what applied the conductive ink to the material. The flowchart which shows the procedure of the manufacturing method of the board | substrate about the board | substrate for printed wiring boards of the embodiment. The schematic diagram which shows typically the measuring method of the peeling strength about the board | substrate for printed wiring boards of the embodiment. The table | surface which compared the manufacturing conditions and the characteristic of the board | substrate for printed wiring boards of an Example, and the board | substrate for printed wiring boards of a comparative example.

An embodiment of a printed wiring board substrate of the present invention will be described with reference to FIG.
<Printed wiring board substrate>
The printed wiring board substrate 1 includes an insulating base material 10, a first conductive layer 21 formed on one surface of the insulating base material 10, and a second conductive layer stacked on the first conductive layer 21. 24. Hereinafter, the layer including the first conductive layer 21 and the second conductive layer 24 is referred to as a conductive layer 20.

  The insulating base material 10 is formed of an insulating plate material or an insulating film. For example, examples of the plate material include a paper phenol plate and a paper epoxy plate. A polyimide film is mentioned as a film.

  Conductor-binding functional groups are formed on the laminated surface 10 </ b> A that adheres to the first conductive layer 21 in the insulating substrate 10. The conductor-binding functional group is chemically bonded to the conductor particles 22A. The conductor-binding functional group is a functional group containing oxygen, and examples thereof include a carbonyl group, a carboxyl group, and a hydroxyl group. These functional groups containing oxygen also have a function of reducing the contact angle between the conductive ink 30 and the laminated surface 10A. The composition ratio of oxygen to carbon (hereinafter referred to as “oxygen / carbon composition ratio”) on the laminated surface 10A of the insulating substrate 10 is set to a reference value or more. The reference value is set based on the minimum value allowed as the peel strength at which the conductive layer 20 peels from the insulating substrate 10. In this embodiment, the reference value is 0.25 in terms of molar ratio.

  The first conductive layer 21 includes a conductive particle layer 22 formed of conductive particles 22A and an electroless plating layer 23 formed by an electroless plating method. The diameter of the conductor particles 22A (hereinafter “particle diameter”) is in the range of 1 to 500 nm. The layer thickness of the conductor particle layer 22 is in the range of 0.001 to 0.5 μm. Examples of the conductor particles 22A include Cu, Ag, Au, Pt, Pd, Ru, Sn, Ni, Fe, Co, Ti, In metal particles, or carbon particles.

  In addition, although the particle diameter of 22 A of conductor particle | grains is 1-500 nm, it is preferable to make the particle diameter into the range of 30-100 nm. In this case, the layer thickness of the conductor particle layer 22 becomes uniform as compared with the conductor particle 22A having a particle diameter in the range of 1 to 500 nm.

  The electroless plating layer 23 fills the gaps between the conductor particles 22 </ b> A and smoothes the surface of the conductor particle layer 22. The thickness of the electroless plating layer 23 is set to be within 1 μm with the laminated surface 10A of the insulating base material 10 as a reference surface. Examples of the electroless plating material include Cu, Ag, and Ni. When the conductor particles 22A are copper particles, Cu or Ni is preferable from the viewpoint of adhesion to the copper particles.

  The second conductive layer 24 is formed by electroplating such as Cu, Ag, Au. The layer thickness of the second conductive layer 24 is made larger than the layer thickness of the first conductive layer 21. For example, the layer thickness of the second conductive layer 24 is set to 12 μm with the laminated surface 10A of the insulating base material 10 as a reference surface. This layer thickness is appropriately set depending on the printed wiring board substrate.

<Manufacturing method of printed wiring board substrate>
With reference to FIG. 2 and FIG. 3, the manufacturing method of the board | substrate for printed wiring boards of this invention is demonstrated.

  As the insulating substrate 10, a continuous material wound around a roll or a plate material having a predetermined size is used. When a continuous material is used, each process is performed in a state where a part of the continuous material is pulled out from the roll. When a plate material is used, each process is performed by automatically conveying the plate material.

  First, as shown in FIG. 3, in step S100, the surface treatment of the insulating base material 10 is performed. As a surface treatment method, plasma treatment for forming a conductor-bonded functional group on the insulating base material 10 by plasma and alkali treatment for forming the conductor-bound functional group by immersing the insulating base material 10 in an alkaline aqueous solution And so on. Further, corona treatment that modifies the surface of the object by corona discharge, UV treatment that modifies the surface of the object by ultraviolet light, and the like are also included. Examples of the plasma treatment include argon plasma for modifying the surface of the object under an argon atmosphere and oxygen plasma for modifying the surface of the object under an oxygen atmosphere.

By the surface treatment, the contact angle between the surface of the insulating substrate 10 and water (hereinafter referred to as “water contact angle”) is 60 ° or less, and the oxygen / carbon composition ratio of the surface of the insulating substrate 10 is 0.25. That's it.
With reference to FIG. 2, changes in the surface structure of the insulating base material 10 before and after the surface treatment of the base material are shown. By subjecting the insulating base material 10 to plasma treatment or alkali treatment, polymer molecules on the surface of the insulating base material 10 are destroyed, decomposed, and cut to remove some carbon, or the same destruction, decomposition, and cutting. In this process, oxygen is introduced into the surface. This increases the proportion of the composition such as carboxyl group or carbonyl group.

  FIG. 2A is a schematic diagram schematically showing a state when the water-soluble conductive ink 30 is applied to the insulating base material 10 which is not surface-treated. When the insulating base material 10 is not surface-treated, even if the water-soluble conductive ink 30 is applied to the whole base material 10, the same ink is aggregated due to surface tension, so that the same ink is applied. And uncoated portions are formed.

  FIG. 2B is a schematic diagram schematically showing a state when the water-soluble conductive ink 30 is applied to the surface-treated insulating base material 10. When the insulating base material 10 is surface-treated, the contact angle of the insulating base material 10 with respect to water is reduced to improve the wettability, so that the insulating base material 10 has a uniform thickness over the entire surface. Conductive ink 30 is applied.

Next, the first conductive layer 21 is formed on the insulating substrate 10.
In the first conductive layer 21 forming step (first conductive layer forming step), a coating step of applying the conductive ink 30 to the insulating substrate 10, a drying step of the conductive ink 30, and the conductor particles 22A are provided. A heat treatment step for sintering and an electroless plating step for forming the electroless plating layer 23 are included.

  The conductive ink 30 includes metal particles as the conductor particles 22A, a solvent, and a dispersant that disperses the metal particles in the solvent. For example, water is used as the solvent. Besides water, a volatile solvent such as ethanol or a mixture of water and a volatile solvent can be used.

  The size of the metal particles is such that the particle diameter is 1 to 500 nm as described above. When the particle diameter is smaller than 1 nm, the metal particles are not uniformly dispersed in the conductive ink 30. Further, when the particle diameter is larger than 500 nm, due to the large mass of the individual metal particles, spots of the ink after applying the conductive ink 30 to the insulating substrate 10 are likely to occur. For this reason, the range of the particle diameter of the metal particles is set to the above range.

  The metal particles are formed by a titanium reduction method. The titanium reduction method is a method in which metal ions dissolved in a solvent are precipitated by oxidation of Ti ions. Thereby, granular metal particles are formed.

  The dispersant disperses the conductor particles 22A in a solvent. For example, a dispersant having a molecular weight of 2000 to 100,000 is used. When a dispersant having a molecular weight of less than 2000 is used, the conductor particles 22A may not be uniformly dispersed in the solvent. If a dispersant having a molecular weight greater than 100,000 is used, it may remain between the conductive particles 22A even after the conductive ink 30 is dried, and the bonding between the conductive particles 22A in the subsequent heat treatment step may be hindered. .

  Examples of the dispersant include amine-based polymer dispersants such as polyethyleneimine and polyvinylpyrrolidone, and hydrocarbon-based polymer dispersants having a carboxylic acid group in the molecule such as polyacrylic acid and carboxymethylcellulose. It is done.

  In the application step in step S110, the conductive ink 30 is applied to the insulating substrate 10 by a roller. The application method is not limited to the roller coating method. For example, methods such as spin coating, spray coating, bar coating, die coating, slit coating, and dip coating can be used.

  In the drying process in step S120, water contained in the conductive ink 30 is evaporated. For example, it is held for a predetermined time in an environment of atmospheric pressure and 60 ° C. As a result, the water of the conductive ink 30 evaporates, and the metal particles become a thin layer and remain on the insulating substrate 10.

  In the heat treatment step in step S130, the metal particles are sintered and organic substances other than the metal particles (hereinafter referred to as “residual organic substances”) are removed. Examples of the residual organic material include a dispersant contained in the conductive ink 30. The heat treatment is performed in an atmosphere that suppresses oxidation of the metal particles. For example, heat treatment is performed at an oxygen concentration of 1000 ppm. Also, heat treatment can be performed in a reducing atmosphere, for example, in a hydrogen atmosphere. However, the hydrogen concentration is less than the hydrogen explosion lower limit concentration.

  By the way, when the heat treatment is performed at a temperature higher than the heat resistant temperature of the insulating base material 10, the insulating base material 10 is deformed. For this reason, the heat treatment temperature is set in consideration of the heat resistant temperature of the insulating base material 10. For example, when a polyimide film is used as the insulating substrate 10, the heat treatment is performed at a temperature of 500 ° C. or less. Further, since it is necessary to remove the residual organic matter, the heat treatment temperature is set to a temperature higher than 150 ° C., which is the lower limit temperature at which the residual organic matter is decomposed and removed. For the above reasons, the heat treatment temperature is set to a temperature range of 150 ° C to 500 ° C.

Thus, the conductor particle layer 22 is formed by the processes from step S110 to step S130. The layer thickness of the first conductive layer 21 is 0.1 μm.
In the electroless plating in step S140, the gaps between the conductor particles 22A formed during sintering are filled with plating metal. Further, a dense electroless plating layer 23 is formed on the surface of the conductor particle layer 22 by the same electroless plating.

  Next, in step S150 (second conductive layer forming step), the second conductive layer 24 is formed on the electroless plating layer 23 by electroplating. Since the second conductive layer 24 is formed on the flat electroless plating layer 23, the surface of the second conductive layer 24 is also flat. The layer thickness of the second conductive layer 24 is set according to the use of the printed wiring board substrate 1.

Next, an example of the printed wiring board substrate 1 will be described.
<Example 1>
(material)
-As the insulating base material 10, a polyimide film (product name Kapton (registered trademark) EN-S) is used.
The conductive ink 30 is adjusted so that the solvent is water and copper particles having a particle diameter of 50 nm are dispersed with a dispersant to have a copper concentration of 3% by mass.
(Production conditions)
-Plasma treatment is performed for 30 minutes in a nitrogen gas atmosphere on the polyimide film.
After the plasma treatment, the conductive ink 30 is applied to the surface of the polyimide film with a roller. The coating thickness of the conductive ink 30 is set so that the layer thickness of the conductive particle layer 22 becomes 0.1 μm after the ink is heat-treated. After applying the conductive ink 30, it is dried at 60 ° C. for 10 minutes under atmospheric pressure conditions.
-About the polyimide film after a drying process, it heat-processes for 30 minutes at 400 degreeC in nitrogen atmosphere (oxygen concentration of 100 ppm or less).
-After the heat treatment step, electroless plating of copper is performed on the surface of the conductive particle layer so as to have a thickness of 0.1 μm.
-After electroless-plating process, copper electroplating is performed and the layer thickness of copper plating (2nd conductive layer 24) shall be 12 micrometers.
(Sample measurement method)
-The contact angle of water with respect to the polyimide film which performed plasma treatment is measured with a contact angle meter (DM-301 of Kyowa Interface Science).
The composition ratio of oxygen / carbon on the surface of the polyimide film subjected to the plasma treatment is measured by X-ray photoelectron spectroscopy.
-The peeling strength between a polyimide film and electroconductivity is measured with the following method. In FIG. 4, the schematic diagram of the measuring method of peeling strength is shown. A sample prepared under the above manufacturing conditions is left at 150 ° C. under atmospheric pressure (hereinafter “high temperature treatment”). Thereafter, the sample is fixed to the base with the polyimide film side facing down. Next, a part between the polyimide film and the conductive layer 20 is peeled off, and a grip portion 20A for peeling the conductive layer 20 from the polyimide film is provided. Then, the peeling strength at that time is measured while pulling the grip portion 20A in the peeling direction X at a pulling speed of 50 mm / min. Note that the peeling direction indicates a direction from the portion where the conductive layer 20 is peeled from the polyimide film to the portion where it is not peeled on a plane parallel to the sample.
(result)
-The contact angle of water with respect to the polyimide film after surface treatment was 55 degrees.
The composition ratio of oxygen / carbon on the surface of the polyimide film after the surface treatment was 0.25.
The peel strength of the printed wiring board substrate 1 after the high temperature treatment was 6.8 N / cm.

<Example 2>
(Material) The same material as in Example 1 was used.
(Production conditions)
-It replaced with the plasma treatment of Example 1, and performed the surface treatment of the polyimide film by argon treatment. Specifically, the polyimide film is subjected to plasma treatment for 30 minutes in an argon gas atmosphere.
Steps after the surface treatment step, that is, application of the conductive ink 30, drying of the ink, heat treatment of the ink, electroless plating, and electroplating were performed under the same conditions as in Example 1.
(Sample measurement method)
The contact angle of water with respect to the polyimide film, the oxygen / carbon composition ratio on the surface of the polyimide film, and the peel strength were measured in the same manner as in Example 1.
(result)
-The contact angle of water with respect to the polyimide film after surface treatment was 60 degrees.
The composition ratio of oxygen / carbon on the surface of the polyimide film after the surface treatment was 0.27.
-The peel strength of the printed wiring board substrate 1 after the high temperature treatment was 6.5 N / cm.

<Example 3>
(Material) The same material as in Example 1 was used.
(Production conditions)
-It replaced with the plasma treatment of Example 1, and performed the surface treatment of the polyimide film by the alkali treatment. Specifically, the polyimide film was immersed in an aqueous sodium hydroxide solution (concentration 5 mol / l) for 3 minutes.
Steps after the surface treatment step, that is, application of the conductive ink 30, drying of the ink, heat treatment of the ink, electroless plating, and electroplating were performed under the same conditions as in Example 1.
(Sample measurement method)
The contact angle of water with respect to the polyimide film, the oxygen / carbon composition ratio on the surface of the polyimide film, and the peel strength were measured in the same manner as in Example 1.
(result)
-The contact angle of water with respect to the polyimide film after surface treatment was 54 degrees.
The composition ratio of oxygen / carbon on the surface of the polyimide film after the surface treatment was 0.40.
-The peel strength of the printed wiring board substrate 1 after the high-temperature treatment was 7.1 N / cm.

<Comparative example>
(Material) The same material as in Example 1 was used.
(Production conditions)
-The surface treatment of the polyimide film was not performed.
The conductive ink 30 is applied to the polyimide film by the same method as in Example 1.
(Sample measurement method)
The contact angle of water with respect to the polyimide film, the oxygen / carbon composition ratio on the surface of the polyimide film, and the peel strength were measured in the same manner as in Example 1.
(result)
-The contact angle of water with respect to the polyimide film was 80 °.
The composition ratio of oxygen / carbon on the surface of the polyimide film after the surface treatment was 0.18.
Since the uniform conductive ink 30 layer could not be formed on the polyimide film, the subsequent treatment could not be performed.

<Contrast between Example and Comparative Example>
With reference to FIG. 5, an Example and a comparative example are compared.
(1) A comparative example and Examples 1-3 are compared.

  In the comparative example, surface treatment is not performed on the polyimide film, while in Examples 1 to 3, plasma treatment or alkali treatment is performed on the polyimide film. The contact angle of water with the polyimide film of the comparative example was 80 °, and the conductive ink 30 could not be applied uniformly. On the other hand, the contact angle of water with respect to the polyimide films of Examples 1 to 3 subjected to surface treatment was 60 ° or less, and the conductive ink 30 could be uniformly applied.

  The gas used for plasma processing differs between Example 1 and Example 2. That is, while the plasma processing of Example 1 uses nitrogen gas, the plasma processing of Example 2 uses argon gas.

  Example 1 and Example 3 differ in the means of surface treatment for the polyimide film. That is, in Example 1, the surface treatment is performed by plasma treatment, whereas in Example 2, the surface treatment is performed by an alkaline aqueous solution.

  As for the oxygen / carbon composition ratio on the surface of the polyimide film after the surface treatment, the same ratio in Example 1, the same ratio in Example 2, and the same ratio in Example 3 are larger than the same ratio in the comparative example as 0.25. That's it. Further, regarding the peel strength of the printed wiring board substrate 1 after the high temperature treatment, the same strength in Example 1, the same strength in Example 2, and the same strength in Example 3 are 6.0 N / cm or more.

(2) Summary By setting the contact angle of the polyimide film and water to 60 ° or less, the conductive ink 30 can be uniformly applied to the polyimide film. Further, by setting the oxygen / carbon composition ratio of the polyimide film surface after the surface treatment to 0.25 or more, the peel strength of the printed wiring board substrate 1 after the high temperature treatment may be 6.0 N / cm or more. it can.

According to this embodiment, the following effects can be obtained.
(1) In the present embodiment, the first conductive layer 21 is formed of the conductor particles 22A, and the laminated surface 10A of the insulating base material 10 is a surface that increases the bonding force between the conductor particles 22A and the insulating base material 10 Processing is in progress.

  According to this configuration, since the first conductive layer 21 is formed by stacking the conductor particles 22A, the first conductive layer 21 can be formed without using a sputtering apparatus. Since the lamination surface 10A of the insulating substrate 10 is subjected to surface treatment, the bonding force of the lamination surface 10A of the insulating substrate 10 to the conductor particles 22A is increased. The force required to peel from 10, that is, the peel strength can be increased.

  (2) In the present embodiment, a conductor-binding functional group that is bonded to the conductor particles 22A is introduced into the laminated surface 10A. The conductor particles 22A are in contact with the laminated surface 10A of the insulating substrate 10. When the bonding force between the conductor particles 22A and the molecules constituting the laminated surface 10A is small, the conductor particles 22A are separated from the molecules with a small force, so that the adhesive strength between the first conductive layer 21 and the insulating substrate 10 is high. Lower. In this configuration, since the conductor binding functional group is introduced into the laminated surface 10A and the conductor particles 22A and the conductor binding functional group are bonded to each other, the adhesive force between the first conductive layer 21 and the insulating substrate 10 is increased. can do.

  (3) In the present embodiment, the conductor particles 22A are configured as metal particles. The conductor-binding functional group contains oxygen. In general, the bonding force between oxygen atoms and metal particles is larger than the bonding force between carbon atoms and metal particles. For this reason, since the bonding force between the conductive particles 22A and the insulating base material 10 can be increased by introducing the conductor-binding functional group containing oxygen into the laminated surface 10A of the insulating base material 10, the first The peel strength between the conductive layer 21 and the insulating substrate 10 can be increased.

  (4) In the present embodiment, the conductor particles 22A are configured as metal particles, and the ratio of oxygen to carbon in the stacked surface 10A is 0.25 or more in terms of a molar ratio. When the ratio of oxygen to carbon in the laminated surface 10A is less than 0.25 in terms of molar ratio, the peel strength between the first conductor layer and the insulating base material 10 is smaller than the practically required value. According to this configuration, since the ratio of oxygen to carbon in the laminated surface 10A is set to 0.25 or more in terms of molar ratio, the peel strength between the first conductor layer and the insulating substrate 10 is a practically required value. This can be done.

  (5) In the present embodiment, the size of the conductor particles 22A is 1 nm or more and 500 nm or less. When the particle diameter of the conductor particles 22A is larger than 500 nm, the gap between the conductor particles 22A becomes excessive. In the above configuration, since the first conductive layer 21 is formed by the conductive particles 22A having a particle diameter of 1 nm or more and 500 nm or less, when the same layer 21 is formed using a particle having a particle diameter of less than 1 nm or greater than 500 nm. Rather than a dense layer.

  (6) In the present embodiment, a surface treatment process for surface-treating the laminated surface 10A of the insulating substrate 10, and a first conductive material for forming the first conductive layer 21 by applying the conductive ink 30 to the laminated surface 10A. A layer forming step, an electroless plating step of forming the electroless plating layer 23 on the first conductive layer 21 by electroless plating, and a second of forming the second conductive layer 24 on the first conductive layer 21 A conductive layer forming step.

  According to this configuration, after the first conductive layer formation step, electroless plating is performed to form the electroless plating layer 23 on the first conductive layer 21. Thereby, since the space | gap part of conductor particle | grains 22A produced when the 1st conductive layer 21 is formed can be filled up with the electroless-plating metal, the 1st conductive layer 21 can be made dense.

  (7) In this embodiment, the contact angle between the laminated surface 10A and the conductive ink 30 is set to a reference value or less in the surface treatment. When the conductive ink 30 is applied to the insulating substrate 10 having no wettability, the layer thickness of the conductive ink 30 is uneven. According to this configuration, since the contact angle between the laminated surface 10A and the conductive ink 30 is set to a reference value or less, a conductive ink layer having a uniform thickness can be formed.

  (8) In the present embodiment, the contact angle between the laminated surface 10A and the conductive ink 30 is set to a value less than 60 degrees in the surface treatment. When the contact angle between the insulating substrate 10 and the conductive ink 30 is 60 degrees or more, unevenness occurs in the layer thickness of the conductive ink. According to the above configuration, since the contact angle between the insulating substrate 10 and the conductive ink 30 is set to a value less than 60 degrees, the conductive ink layer having a uniform thickness can be formed on the insulating substrate 10. .

  (9) In the present embodiment, in the surface treatment, a conductor-binding functional group that bonds to the conductor particles 22A is introduced into the laminated surface 10A. Some printed wiring board substrates 1 include functional groups that bind to the conductive particles 22A. When the layer of the conductor particles 22A is formed on such a printed wiring board substrate 1, the conductor particles 22A and the functional group are bonded. In this configuration, a conductor-bound functional group is newly introduced regardless of whether or not the printed wiring board substrate 1 has a functional group. This increases the proportion of the conductor particles 22A that are bonded to the conductor-binding functional group on the stacked surface 10A. As a result, the adhesive force between the first conductive layer 21 and the insulating substrate 10 can be increased.

  (10) In the present embodiment, the first conductive layer forming step in the method for manufacturing the printed wiring board substrate 1 includes the application step of applying the conductive ink 30 to the laminated surface 10A, and the conductive ink after this application step. An evaporation process for evaporating the medium 30 and a heat treatment process for heat-treating the conductor contained in the conductive ink 30 are included after the evaporation process.

  According to this configuration, the medium of the conductive ink 30 is evaporated, and the conductor contained in the conductive ink 30 is heat-treated. For this reason, the conductor particles 22 </ b> A can be fixed to the insulating substrate 10.

(Other embodiments)
In addition, the embodiment of the present invention is not limited to the embodiment shown in each of the above-described embodiments, and the embodiment can be modified as shown below, for example. Further, the following modifications are not applied only to the above-described embodiments, and different modifications can be combined with each other.

  In each of the above embodiments, after the conductive particle layer 22 is formed on the insulating base material 10, the electroless plating layer 23 is formed by performing electroless plating on the conductive particle layer 22, The formation of the electroless plating layer 23 may be omitted.

  In each of the above examples, the composition ratio of oxygen / carbon on the surface of the polyimide film after the surface treatment was set to 0.00 so that the peel strength of the printed wiring board substrate 1 after the high temperature treatment was 6.0 N / cm or more. 25 is set. That is, the oxygen / carbon composition ratio is used as an index of the peel strength of the printed wiring board substrate 1. For this reason, the ratio is appropriately changed depending on the required performance of the printed wiring board substrate 1.

  In each of the above embodiments, a polyimide film is used as the insulating substrate 10, but the present invention can also be applied to substrates other than the insulating substrate 10. Moreover, what applied this invention to the other base material has the same effect as the said Example.

  In each of the above examples, nitrogen plasma treatment, argon plasma treatment, and alkali treatment are cited as examples of surface treatment. However, a conductor-bound functional group may be introduced into the polyimide film by corona treatment or UV treatment. Can do. Thereby, the contact angle with respect to the water of the surface of the film can be made smaller than the contact angle of the film before processing, and the peel strength with respect to the film can be increased.

  In each of the above embodiments, examples of the conductor binding functional group to be introduced into the insulating base material 10 include a carbonyl group and a carboxyl group containing oxygen, but examples of the conductor binding functional group are limited to this. What is necessary is just to couple | bond with 22 A of conductor particle | grains.

  DESCRIPTION OF SYMBOLS 1 ... Board | substrate for printed wiring boards, 10 ... Insulating base material, 10A ... Laminated surface, 20 ... Conductive layer, 21 ... 1st conductive layer, 22 ... Conductor particle layer, 23 ... Electroless plating layer, 24 ... 2nd Conductive layer, 22A ... conductive particles, 30 ... conductive ink.

Claims (13)

In a printed wiring board substrate including an insulating base material, a first conductive layer laminated on the insulating base material, and a second conductive layer laminated on the first conductive layer,
The first conductive layer is formed of conductive particles;
The laminated surface of the insulating substrate on the side where the first conductive layer is laminated is subjected to a surface treatment for increasing the bonding force between the conductive particles and the insulating substrate. Printed wiring board substrate. In the printed wiring board substrate according to claim 1,
The printed wiring board substrate, wherein a conductor-binding functional group that binds to the conductor particles is introduced into the laminated surface. In the printed wiring board substrate according to claim 2,
The conductor particles are metal particles,
The printed circuit board substrate, wherein the conductor-binding functional group contains oxygen. In the printed wiring board substrate according to claim 2 or 3,
The printed wiring board substrate, wherein the conductor-binding functional group is at least one selected from the group consisting of a carbonyl group, a carboxyl group, and a hydroxyl group. In the printed wiring board substrate according to any one of claims 2 to 4,
The conductor particles are metal particles,
The ratio of oxygen to carbon in the laminated surface is 0.25 or more in terms of molar ratio. In the printed wiring board substrate according to any one of claims 1 to 5,
The printed circuit board substrate, wherein the first conductive layer is formed by applying a conductive ink containing the conductive particles. In the printed wiring board substrate according to any one of claims 1 to 6,
The printed wiring board substrate, wherein the conductor particles have a particle size of 1 nm to 500 nm. In a method for manufacturing a printed wiring board substrate, comprising: an insulating base material; a first conductive layer laminated on the insulating base material; and a second conductive layer laminated on the first conductive layer.
A surface treatment step for performing a surface treatment for increasing the bonding force between the laminated surface and the first conductive layer with respect to the laminated surface of the insulating substrate;
A first conductive layer forming step of forming a first conductive layer by applying a conductive ink containing conductive particles to the laminated surface after the surface treatment step;
A method for manufacturing a printed wiring board substrate, comprising: a second conductive layer forming step of forming a second conductive layer on the first conductive layer after the first conductive layer forming step. In a method for manufacturing a printed wiring board substrate, comprising: an insulating base material; a first conductive layer laminated on the insulating base material; and a second conductive layer laminated on the first conductive layer.
A surface treatment step for surface-treating the laminated surface of the insulating substrate;
A first conductive layer forming step of forming a first conductive layer by applying a conductive ink containing conductive particles on the laminated surface after the surface treatment step;
An electroless plating step of forming an electroless plating layer on the first conductive layer by performing electroless plating after the first conductive layer forming step;
And a second conductive layer forming step of forming a second conductive layer on the first conductive layer after the electroless plating step. A method for manufacturing a printed wiring board substrate, comprising: In the manufacturing method of the printed wiring board substrate according to claim 8 or 9,
In the surface treatment, a contact angle between the laminated surface and the conductive ink is set to a reference value or less. A method for manufacturing a printed wiring board substrate. In the manufacturing method of the printed wiring board substrate according to claim 10,
The said reference value is less than 60 degree | times. The manufacturing method of the board | substrate for printed wiring boards characterized by the above-mentioned. In the manufacturing method of the substrate for printed wiring boards as described in any one of Claims 8-11,
In the surface treatment, a conductor-binding functional group that binds to the conductor particles is introduced into the laminated surface. A method for manufacturing a printed wiring board substrate, comprising: In the manufacturing method of the printed wiring board board according to any one of claims 8 to 12,
The first conductive layer forming step includes an application step of applying conductive ink to the laminated surface, an evaporation step of evaporating a medium of the conductive ink after the application step, and the conductive ink after the evaporation step. A method for manufacturing a printed wiring board substrate, comprising: a heat treatment step of heat treating a conductor contained in the substrate.

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