JPH1018080A - Formation of metallic conductive layer on surface of fluorine plastic body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which decreases the number of stages, facilitates stage maintenance and reduces a production cost as a method for formation of a metallic conductive layer on the surface of a body. SOLUTION: (1) The surface of the fluorine plastic body, for example, tetrafluoroethylene resin, subjected to a degreasing treatment is first subjected to an activation treatment by an immersion treatment in a sodium metal- naphthalene complex soln., etc., as an activation treatment stage S1. (2) Next, a conductive coating material, for example, a silver conductive coating material contg. conductive particles consisting of silver is applied on the surface of the fluorine plastic body subjected to the activation treatment and is dried to form a ground surface conductive layer as a conductive coating material applying and drying stage S2. (3)) Next, the surface of the ground surface conductive layer is subjected to copper plating by a copper electroplating treatment using a plating liquid of, for example, copper sulfate, to form a copper plating conductive layer, by which the metallic conductive layer is formed on the surface of the fluorine plastic body, as an electroplating stage S3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a metal conductive layer on the surface of a fluororesin body. More particularly, the present invention relates to a method for forming a metal conductive layer on the surface of a fluororesin used for a member such as a coaxial cable or an electric circuit board for high frequency use.

[0002]

2. Description of the Related Art Fluororesins having a low dielectric constant are used for insulating members such as coaxial cables and electric circuit boards which require excellent high-frequency performance. However, since fluororesins have chemically stable properties, it is quite difficult to form a metal conductive layer having strong adhesion on the surface thereof. Therefore, after modifying the surface of the fluororesin body, the underlying metal conductive layer is formed thin by electroless plating, and then a thick metal conductive layer such as copper is formed on the underlying metal conductive layer by electroplating. Was.

A conventional method of forming a metal conductive layer on the surface of a fluororesin body, that is, a method of forming a metal conductive layer on the surface of a fluororesin body by a chemical surface modification method and a plating method will be described with reference to FIG.
Each step will be described with reference to the flowchart of FIG. In addition,
In the flow chart 5, the description of the degreasing of the surface of the fluororesin body with alcohol or the like and the washing process as a post-treatment of each step is removed.

(1) First, as an activation processing step T1,
The surface of the degreased fluororesin body is activated by immersion in a metal sodium-naphthalene complex solution or the like. (2) Next, as a pre-treatment step T2 before electroless plating of the activated fluorine resin body, first, the activated fluorine-based body surface is charged to minus (-) by a conditioner treatment. Next, in the pre-dipping treatment, the treatment liquid of the conditioner treatment is prevented from being mixed into the catalyzing treatment liquid of the next step. Next, as a catalyzing step for depositing a catalytic metal on the surface of the fluororesin body before electroless plating, first, Pd ⁺⁺ and Sn ⁺⁺ are adsorbed in a colloidal state on the surface of the fluororesin body by an activating process. Next, in accelerator treatment, stannous chloride (SnCl ₂₎
Redox reaction of palladium chloride (PDC1 ₂₎ and
By ^{[Sn ++ + Pd ++ → Sn ++++} + Pd 0 ], Pd
⁺⁺ is reduced and precipitated on the surface of the fluororesin body as metal Pd.

[0005] Through the above pretreatment step T2, the fluororesin body on which the metal Pd is reduced and deposited on the surface is subjected to the electroless plating step T2.
3 is introduced. (3) In the electroless plating step T3, nickel plating is applied to the surface of the fluorine resin body on which the metal Pd is deposited by, for example, electroless nickel plating to provide a base metal plating layer. (4) Next, as an electroplating step T4, copper plating is performed on the electroless nickel plating layer by, for example, an electrolytic copper plating process using a copper sulfate plating solution to provide a copper plating layer. Through the above steps, a metal plating conductive layer is formed on the surface of the fluororesin body.

[0006]

As described above, in the conventional method, many steps were required to form a metal conductive layer on the surface of the fluororesin body. In particular, since the pretreatment step T2 preceding the electroless plating step T3 involves a chemical adsorption reaction step of precipitating a catalytic metal on the surface of the fluororesin body before the electroless plating, a series of steps involved in this is required. However, it has been difficult to control the solution under stable conditions in each step. For this reason, there has been a problem that the production cost increases and the product yield decreases due to the occurrence of defects.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned various problems of the prior art, and has a small number of processes, easy process management, and further reduces manufacturing costs.
An object of the present invention is to provide a method for forming a metal conductive layer on the surface of a fluororesin body.

[0008]

According to a first aspect of the present invention, there is provided an activation step of activating a surface of a fluororesin body, and applying a metal-based conductive coating on the surface of the activated fluororesin body. A fluororesin body having a conductive paint application and drying step of applying and drying to form a base metal conductive layer, and an electroplating step of forming a copper plating layer on the formed base metal conductive layer by electroplating Provided is a method for forming a metal conductive layer on a surface.

According to a second aspect of the present invention, the conductive particles of the metal-based conductive coating are formed on a surface of a fluororesin body made of any one of gold, silver, copper, nickel and aluminum. A method for forming a layer is provided.

[0010] In a third aspect, the present invention provides the method according to the above, wherein the activation treatment is performed by immersing a metal sodium-naphthalene complex solution.
Provided is a method for forming a metal conductive layer on the surface of a fluororesin body, which is a sputter etching treatment, an excimer laser irradiation treatment, a plasma treatment or a combination thereof.

According to a fourth aspect of the present invention, there is provided the present invention, wherein the fluororesin body is a coated fluororesin body provided on the outer periphery of a center conductor, and the surface of the fluororesin body from which the high-frequency coaxial cable is manufactured in each of the above steps. To provide a method for forming a metal conductive layer on a substrate.

According to a fifth aspect of the present invention, there is provided the present invention, wherein the fluororesin body is a resin body constituting a substrate, and a metal conductive layer is formed on the surface of the fluororesin body on which a low dielectric constant printed circuit board is manufactured in each of the steps. A method of forming is provided.

Examples of the fluororesin include a tetrafluoroethylene resin (PTFE), a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), and a tetrafluoroethylene-hexafluoropropylene copolymer resin ( FEP) or a single fluororesin such as tetrafluoroethylene-ethylene copolymer resin (ETFE) can be used.

As the metal-based conductive paint, the gold,
Examples thereof include particles in which conductive particles such as silver are uniformly dispersed and mixed in a binder such as an acrylic resin, an epoxy resin, or a PVC resin. Specific examples include Silvest P-248 and P-255 (trade names, manufactured by Tokuri Kagaku Kenkyusho Co., Ltd.) and DD Paste AE1300 (trade name, manufactured by Tatsuta Electric Wire Co., Ltd.). In addition, it is not preferable that the conductive particles are carbon-based conductive paints made of carbon black, graphite, or the like, because the electrical characteristics are poor. In addition, a metal-based conductive adhesive can be used in addition to the metal-based conductive paint.

[0015]

In the method for forming a metal conductive layer on the surface of a fluororesin according to the first aspect of the present invention, an activation step S1 for activating the surface of the fluororesin and a step of activating the surface of the activated fluororesin are performed. A conductive paint application and drying step S2 of applying and drying a conductive paint to form a base metal conductive layer (hereinafter abbreviated as a base conductive layer); and forming a copper on the formed base conductive layer by electroplating. Since the metal conductive layer is formed on the surface of the fluororesin body by the electroplating step S3 for forming the plating layer, the number of steps is small and the method for forming the metal conductive layer is efficient.

Since the base metal conductive layer is formed by applying and drying (including curing) a conductive paint, the adhesion to the surface of the fluororesin body is improved, and several tens to several tens by electroplating in the next step. A copper plating layer having a thickness of 100 microns can be easily formed. In the formation of the underlying conductive layer,
Since only a very simple process of applying and drying the conductive paint is required, a series of pretreatment steps such as a conventional chemisorption reaction step is not required, and liquid management in the step is not required. As a result, the manufacturing cost is drastically reduced, the product quality is stabilized, and the yield is improved.

In the method for forming a metal conductive layer on the surface of a fluororesin body according to a second aspect of the present invention, the conductive particles of the conductive paint are made of any one of gold, silver, copper, nickel and aluminum. Therefore, the obtained underlying conductive layer has good conductivity.

In the method for forming a metal conductive layer on the surface of a fluororesin body according to a third aspect of the present invention, the activation treatment is performed by immersing a metal sodium-naphthalene complex solution, sputter etching, excimer laser irradiation, plasma treatment. Alternatively, because of the combination thereof, the activation of the surface of the fluororesin body can be favorably performed, and the adhesion to the underlying conductive layer is improved.

According to a fourth aspect of the present invention, in the method for forming a metal conductive layer on the surface of a fluororesin body, the fluororesin body is a coated fluororesin body provided on the outer periphery of a center conductor. Since the coaxial cable for high frequency is manufactured, a coaxial cable for high frequency with good characteristics can be efficiently obtained.

In the method for forming a metal conductive layer on the surface of a fluororesin body according to a fifth aspect of the present invention, the fluororesin body is a fluororesin body constituting a substrate, and a low dielectric constant printed circuit board is formed by each of the steps. Since it is manufactured, a low dielectric constant printed circuit board having good characteristics can be efficiently obtained.

[0021]

EXAMPLES The method of forming a metal conductive layer on the surface of a fluororesin body of the present invention will be described in detail with reference to examples. In addition,
The present invention is not limited to this embodiment. Example 1 Example 1 will be described with reference to a flow chart 1 for explaining a method for forming a metal conductive layer on the surface of a fluororesin body of the present invention. In FIG. 1, the descriptions of the degreasing of the surface of the fluororesin body with alcohol and the like and the washing process as a post-treatment of each step are removed.

(1) First, as an activation processing step S1,
The surface of the degreased fluororesin body, for example, the surface of a tetrafluoroethylene resin (PTFE) is activated by immersion treatment with a metal sodium-naphthalene complex solution. (2) Next, as a conductive paint application and drying step S2, a conductive paint, for example, a silver-based conductive paint in which conductive particles are made of silver is applied and dried on the surface of the activated fluororesin body, and dried. A conductive layer is formed. (3) Next, as an electroplating step S3, copper plating is performed on the underlying conductive layer by, for example, electrolytic copper plating using a copper sulfate plating solution to form a copper-plated conductive layer. Through the above steps, a metal conductive layer is formed on the surface of the fluororesin body.

Embodiment 2 Next, an embodiment of a high-frequency coaxial cable to which the method of the present invention is applied will be described with reference to FIG. 1 and a sectional view 2 of the high-frequency coaxial cable. As center conductor 1, wire diameter 0.
A 203 m silver-plated copper-coated steel wire is extruded and coated with a tetrafluoroethylene resin (PTFE) as a fluorine resin body 2 to have an outer diameter of 0.1 mm.
A 66 mm fluororesin wire 3 was used. After passing the wire 3 through an alcohol solution to remove fats and oils on the surface, as an activation treatment step S1, a metal sodium-naphthalene complex solution at a liquid temperature of 10 ° C. [trade name of Junkosha Co., Ltd .: [Tetra etch] for 1 minute to perform a surface activation treatment, and then washed with water. Subsequently, a conductive paint application and drying step S
As an example 2, the activated fluororesin wire 3 was replaced with a silver-based conductive paint [trade name: Sylvest P-248 (62% silver, 11% binder, 26% solvent) manufactured by Tokurika Kagaku Kenkyusho]] After passing through the inside for 0.1 minute, the excess paint is squeezed out by felt, and the conductive paint is uniformly applied to the surface of the PTFE coating of the wire 3 and subsequently dried at 100 ° C. for 1 minute to obtain a coated surface. Then, an underlying conductive layer 4 having a thickness of 3 μm was formed. Subsequently, as an electroplating step S3, the resultant was introduced into a copper sulfate plating solution at a liquid temperature of 25 ° C., and electroplated with copper at a current density of 4 A / dm ² for 120 minutes to form a 100 μm thick copper plate. The conductive layer 5 was formed and then washed with water to obtain a high-frequency coaxial cable 6.

Embodiment 3 Next, an embodiment of a low dielectric printed circuit board to which the method of the present invention is applied will be described with reference to FIG. 1 and a sectional view 3 showing a main part of the printed circuit board. As the fluororesin body 11, a 150 mm × 150 mm × 1 mm thick PTFE substrate provided with a through hole at a predetermined position is used. After removing fats and oils on the surface of the PTFE substrate 11 in an alcohol solution, activation is performed. As a treatment step S1, a surface activation treatment is performed by immersing in a metal sodium naphthalene complex solution at a liquid temperature of 10 ° C. for 1 minute,
Then, it was washed with water. Subsequently, conductive paint application and drying process S
As No. 2, the activated PTFE substrate 11 was immersed in the same silver-based conductive paint as in Example 10 for 10 seconds, pulled up, and dried at 100 ° C. for 2 minutes to form a 3 μm thick base on the surface. The conductive layer 12 was formed. Subsequently, as an electroplating step S3, copper electroplating was performed for 45 minutes in a copper sulfate plating solution at the same solution temperature of 25 ° C. as in Example 2 at a current density of 5 A / dm ² , and the underlying conductive layer 12 was formed. 15 on
A copper-plated conductive layer 13 having a thickness of μm was formed and then washed with water.

Next, although not shown, resist coating → prebaking → exposure →
A wiring pattern is formed on both surfaces and through holes 14 of the PTFE substrate 11 on which the copper-plated conductive layer 13 is formed by a photofabrication method including a step of development → cleaning → post bake → etching → resist stripping, and a low dielectric constant print is performed. Substrate 15 was obtained.

Embodiment 4 Next, another embodiment of a low dielectric printed circuit board to which the method of the present invention is applied will be described with reference to FIG. 1 and a schematic diagram 4 for explaining a low dielectric constant printed circuit board. FIG. 4A is a cross-sectional view showing a state in which a wiring pattern is formed on a fluororesin substrate by a pressure screen printing method, and a pattern 22 'made of a conductive paint d using a squeegee s and a patterning screen p. Is formed by printing. FIG. 1B is a perspective view showing a fluororesin substrate on which an underlying conductive layer is formed, and FIG. 1C is a low dielectric constant printed circuit board on which a copper plating conductive layer is formed on the underlying conductive layer. FIG.

The same PTFE substrate 21 as in the third embodiment was used, and the same steps as in the third embodiment were performed up to the activation processing step S1. Next, as a conductive paint application and drying step S2, first, as shown in FIG. 4 (a), the same conductive paint d as in Example 2 is applied to the surface of the activated PTFE plate 21 by a pressure screen screen printing method. Then, a wiring pattern 22 'was printed and applied, followed by drying at 100 ° C. for 2 minutes to form a base conductive layer 22 having a thickness of 10 μm as shown in FIG. 4B. Subsequently, as an electroplating step S3, copper electroplating was performed in the same copper sulfate plating solution at a solution temperature of 25 ° C. at a current density of 5 A / dm ² for 30 minutes in the same manner as in Example 2, and FIG.
As shown in FIG. 7, a copper plating conductive layer 23 having a thickness of 15 μm was formed on the underlying conductive layer 22 and then washed with water to obtain a low dielectric constant printed circuit board 25.

Comparative Example Comparative Example 1 Comparative Example 1 will be described with reference to the flow chart 5 and the sectional view 2 of the coaxial cable. Using the fluororesin wire 3 having the same structure as that of the second embodiment, the electroless nickel plating layer of the underlying conductive layer 4 was reduced to 0.1 by the activation process T1, the pretreatment process T2, and the electroless plating process T3 shown in FIG.
It was formed to a thickness of μm. Next, an electroplating step T4 was performed under exactly the same processing conditions as in Example 2 to form a copper-plated conductive layer 5 having a thickness of 100 μm, followed by washing with water to obtain a high-frequency coaxial cable 6. The activation processing step T1 is exactly the same as the activation processing step S1 of the second embodiment.

With respect to Example 2 and Comparative Example 1, the thickness of the underlying conductive layer, the processing time from the surface activation treatment to the formation of the underlying conductive layer, the controllability of the processing solution, and the attenuation characteristic of the high-frequency coaxial cable were tested. The results are shown in Table 1 below.

[0030]

[Table 1]

As is clear from Table 1 above, according to the present invention, the time required for forming the underlying conductive layer on the surface of the fluororesin body is shorter than that of the conventional method, and the controllability of the processing solution is excellent. Further, the high-frequency coaxial cable obtained by the present invention has good attenuation characteristics in a frequency region up to 2.0 GHz used for mobile communication and the like.

[0032]

According to the method for forming a metal conductive layer on the surface of a fluororesin body of the present invention, the formation of the underlying conductive layer requires a series of chemical adsorption reactions required before the electroless plating step of the conventional method. This eliminates the need for a pre-treatment step, and requires only a very simple step. As a result, the processing time has been reduced from hundreds to several tenths, and the burden of liquid management has been reduced, resulting in drastic reductions in manufacturing costs, stable product quality, and high yields. Also improved. Further, the high-frequency coaxial cable according to the method of the present invention can obtain transmission characteristics equivalent to those of the conventional method up to about 2 GHz used for mobile communication. In addition, the low-permittivity printed circuit board according to the method of the present invention can have excellent high-frequency characteristics because the resistance of the underlying conductive layer hardly contributes due to the skin effect. Therefore, the present invention is extremely effective especially in the production of high-frequency coaxial cables and low dielectric constant printed circuit boards,
The effect that contributes to the industry is extremely large.

[Brief description of the drawings]

FIG. 1 is a flowchart showing a method for forming a metal conductive layer on the surface of a fluororesin body of the present invention.

FIG. 2 is a sectional view showing a high-frequency coaxial cable according to a second embodiment of the present invention. (Also used for explaining comparative examples)

FIG. 3 is a sectional view showing a main part of a low dielectric constant printed circuit board according to a third embodiment of the present invention.

FIG. 4 is a schematic diagram for explaining a low dielectric constant printed circuit board according to Example 4 of the present invention. FIG. 3A is a cross-sectional view showing a state in which a wiring pattern is formed on a fluororesin substrate by a pressure screen printing method. (B) is a perspective view showing a fluororesin substrate on which a base conductive layer is formed. (C) is a sectional view showing a low dielectric constant printed circuit board in which a copper-plated conductive layer is formed on a base conductive layer.

FIG. 5 is a flowchart showing a conventional method for forming a metal conductive layer on the surface of a fluororesin body.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 center conductor 2 fluororesin body 3 fluororesin wire 4,12,22 underlying conductive layer 5,13,23 electrolytic copper plating layer 6 high-frequency coaxial cable 11,21 fluororesin substrate 14 through hole 15 25 low dielectric constant printed circuit board 22 ′ Pattern d conductive paint p patterning screen s squeegee

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical indication location H05K 1/09 H05K 1/09 C 3/24 7511-4E 3/24 A

Claims (5)

[Claims] An activation process for activating the surface of a fluororesin body, and a conductive process for applying a metal conductive paint on the surface of the activated fluororesin body and drying to form a base metal conductive layer. A method for forming a metal conductive layer on a surface of a fluororesin body, comprising: a step of applying and drying a paint; and an electroplating step of forming a copper plating layer on the formed underlying metal conductive layer by an electroplating method. 2. The conductive particles of the metal-based conductive paint,
2. The method for forming a metal conductive layer on the surface of a fluororesin body according to claim 1, comprising a metal particle of any one of gold, silver, copper, nickel and aluminum. 3. The activation treatment includes a metal sodium-naphthalene complex solution immersion treatment, a sputter etching treatment,
3. The method for forming a metal conductive layer on a surface of a fluororesin body according to claim 1, wherein the method is an excimer laser irradiation treatment, a plasma treatment, or a combination thereof. 4. The high-frequency coaxial cable according to claim 1, wherein the fluororesin body is a coated fluororesin body provided on an outer periphery of a center conductor, and a high-frequency coaxial cable is manufactured in each of the steps. The method for forming a metal conductive layer on the surface of a fluororesin body according to the above. 5. The fluororesin according to claim 1, wherein the fluororesin body is a fluororesin body constituting a substrate, and a low-dielectric-constant printed circuit board is manufactured by each of the steps. A method for forming a metal conductive layer on a body surface.