JPH08148809A - Circuit forming method and conductor circuit forming component - Google Patents

Abstract

PURPOSE: To comparatively easily form individually independent desired conduc tor circuit without deteriorating external appearance, configuration, and insula tion, by forming a metal layer on a thin metal film in a conductor circuit part by chemical plating, peeling an electrodeposition resist, and eliminating the thin metal film in the insulating part by using etching solution. CONSTITUTION: On the surface of a synthetic resin molded object capable of metal coating, an initial thin metal layer whose thickness is in the ranged of 0.1-2μm is formed previously by a motal coating process wherein one out of the following is used: chemical plating, sputtering, vacuum deposition, ion plating, transferring method, and conductive material coating. The contour line of a conductor circuit part 4 on the thin film surface is irradiated with a laser beam, and the thin metal film 2 is eliminated. After the conductor circuit part 4 is surrounded by an insulating closed circuit, and coating material or resist 6 is stuck on the insulating part by an electrodeposition method, a second metal layer 7 is formed on the coductor circuit part by chemical plating. The coating material or the resist 6 is eliminated, the thin metal film in the insulating part is eliminated, and a circuit 7 having a desired thickness is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a conductive circuit on the surface of a synthetic resin molded product, which is used as a circuit component in the field of electric and electronic equipment and has a precise conductive circuit on the surface. The present invention relates to a method for efficiently manufacturing a product, particularly a molded product having an independent circuit.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
As a method of forming a circuit on the surface of a synthetic resin molded product,
For example, double molding is performed using two types of resin materials having different plating properties, and the circuit part is selectively plated by utilizing the difference in plating property between the circuit forming part and other parts to form a metal circuit. SKW method, PCK method, etc., but these methods require two molding steps, which is not only complicated and uneconomical, but also difficult to improve the adhesion between two resin interfaces. In this case, for example, there may be a problem due to infiltration of plating liquid, residual, and the like. On the other hand, in the conventional circuit formation method using a photoresist, there are complicated steps such as circuit pattern exposure and pattern development in a dark room, and a three-dimensional conductive circuit is formed on the surface of a molded product having a three-dimensional shape. In this case, although some circuits can be formed by projection exposure with parallel light, there is a problem in accuracy and there is a limit depending on the three-dimensional shape of the substrate. Further, in recent years, a circuit forming method using a laser beam is being developed. For example, a metal film having a sufficient thickness as a conductive circuit is previously formed on the surface of a molded product, and the metal film other than the conductive circuit is scattered by the laser beam. A method of removing the conductive circuit as it is (JP-A-64
-83391 gazette) is considered, and according to this method, there is no need for double molding or use of resist, which is extremely simple.
In this method, it is necessary to make the thickness of the conductor metal layer to be a relatively thick layer (for example, 10 μm or more) having sufficient conductivity as a circuit, and to remove unnecessary portions of the metal layer with laser light, Since it is necessary to increase the output, there is a problem that the underlying synthetic resin molded product is damaged and the appearance shape thereof is significantly impaired, and the synthetic resin is carbonized to impair the insulating property. In addition, a method of forming a metal thin film on the surface of a molded product, removing the metal thin film in a portion other than the conductive circuit portion to form a circuit pattern, and performing electroplating to form a conductive circuit (JP-A-6-164105) is disclosed. It is conceivable that according to this method, the output of the laser beam is reduced and the synthetic resin is not carbonized because there is no problem of insulation. However, in this method, a metal layer is added by electroplating. It is necessary to provide a contact for plating or to electrically connect all the conductive circuit parts. In this case, the former is considerably difficult, the productivity is inferior and economically disadvantageous when this method is used, and the latter is difficult to form an independent circuit.

[0003]

The inventors of the present invention have solved the problems of these conventional methods, and have utilized a method for forming a circuit with high precision even in a molded product having a complicated shape by a simple method, particularly using laser light. As a result of a detailed study to solve the above problems with respect to a method of forming a conductive circuit by using a laser beam as a thin film layer in which the metal layer previously provided on the surface of the synthetic resin molded article is a specific thickness or less By irradiating on the contour line, the output of the laser beam is reduced to remove the unnecessary metal layer, and the circuit pattern can be formed in a short time without damaging the underlying resin, and the electrodeposition resist is applied on the insulating portion. After that, by applying a metal layer to the metal thin film of the conductive circuit portion by chemical plating, then peeling the electrodeposition resist and removing the metal thin film of the insulating portion with an etching solution, the appearance,
The inventors have found that desired independent conductive circuits can be formed relatively easily without impairing the shape and the insulating property, and have reached the present invention. That is, in the present invention, when forming a conductive circuit on the surface of a synthetic resin molded product, chemical plating, spattering, vacuum deposition, ion plating, transfer method and conductive agent coating are previously performed on the surface of the synthetic resin molded product capable of metal coating. The thickness is 0.1 to 2 after metal coating by any one of
An initial metal thin film layer in the range of μm is formed, and then the metal thin film is removed by irradiating the outline of the conductive circuit portion on the surface of the thin film with a laser beam to surround the conductive circuit portion with an insulating closed circuit, and the insulating portion is electrically charged. After applying the paint or resist by the coating method, a second metal layer is applied to the conductive circuit part by chemical plating, then the paint or resist is removed, and the metal thin film in the insulating part is removed by flash etching to obtain a desired thickness. And a conductive circuit forming component manufactured by the above method.

Hereinafter, the method of the present invention will be described step by step with reference to the accompanying drawings. The material of the base molded product used in the present invention may be either a thermoplastic resin or a thermosetting resin material as long as it is a synthetic resin capable of firmly adhering a metal thin film, but such a molded product is later soldered. In consideration of being subjected to severe treatment such as, a resin having high heat resistance and excellent mechanical strength is desirable, and a thermoplastic resin capable of injection molding is preferable from the viewpoint of mass production. Examples thereof include aromatic polyesters, polyamides, polyacetals, polyarylene sulfides, polysulfones, polyphenylene oxides, polyimides, polyetherketones, polyarylates and compositions thereof, particularly high melting point, high strength, high rigidity, From the viewpoint of molding processability and the like, liquid crystalline polymers (for example, liquid crystalline polyester and liquid crystalline polyester amide) and polyarylene sulfide are particularly preferable, but not limited thereto. Moreover, in order to enhance the adhesion of the metal thin film, an appropriate substance may be added to the material, if necessary.

The base molded product (FIG. 1) is molded by injection molding or the like. Further, in order to improve the adhesion to the metal thin film on the surface, chemical etching with acid, alkali or the like, or physical surface treatment such as corona discharge or plasma treatment may be further performed. Next, a metal coating process is performed on the surface of this molded product to form an initial metal thin film layer (FIG. 2). The thickness of the metal thin film provided here is particularly important. If it is too thick, a laser beam with a strong output is required for forming a circuit pattern by a laser beam in the next step, which causes damage to the base molded article as described above. Therefore, it is not preferable. On the contrary, if it is too thin, electricity does not flow in the step of applying the paint or the etching resist by the electrodeposition method, and the application by the electrodeposition method becomes impossible, which is not preferable. From this point of view, the thickness of the metal thin film applied to the surface of the base molded article is 0.1 to 2 μm.
Range, and preferably 0.3 to 1 μm. If the thickness is within such a range, the circuit pattern formation by the laser beam can be accurately performed with a relatively weak output without causing damage to the base molded product, and the coating or etching resist can be uniformly applied in the coating step by the electrodeposition method. It is suitable because it can be applied. As a method for forming such a metal thin film, any conventionally known method such as chemical plating (electroless plating), sputtering, vacuum deposition, ion plating, transfer method, and conductive agent coating may be used, but a uniform metal thin film may be formed. Chemical plating, sputtering,
Vacuum deposition and ion plating are suitable.

Next, with respect to a molded product (FIG. 2) having a metal thin film formed on the surface thereof, the metal thin film in this portion is selectively scattered by irradiating the contour line portion of the conductive circuit portion with laser light whose output is appropriately adjusted. By removing the conductive circuit portion, a circuit pattern of a metal thin film whose conductive circuit portion is surrounded by an insulating closed circuit is formed (FIG. 3). A big difference from the conventional method in this step is that since a portion which becomes a conductive circuit is surrounded by an insulating closed circuit, it is possible to form an electrically independent circuit as shown in FIG. . In the conventional method, in this case, it was necessary to provide a contact for plating for each independent conductive circuit. Therefore, in the conventional method, the width of the conductive circuit or the width between the conductive circuits is restricted to some extent by the size of the contact. On the other hand, since the method of the present invention has no contact portion, it does not have the limitation of the conventional method and can form a more precise circuit. The laser light to be emitted here is a laser having an infrared wavelength such as a YAG laser or a carbon dioxide gas laser, and a predetermined circuit pattern is controlled by a computer controlled X-ray.
Irradiation is selectively performed by a laser marker having a Y-direction scanning mechanism. Also, when it is necessary to form a circuit in a complicated three-dimensional molded product, a laser beam is used as an optical fiber,
It is possible to accurately irradiate a predetermined area three-dimensionally by computer control by guiding the light in a three-dimensional direction by a prism or the like. Alternatively, it is possible to irradiate three-dimensionally by combining a laser marker having a scanning mechanism in the XY directions and a five-axis table in the XYZ directions, rotation, and tilt that move in synchronization with a computer. Further, according to this method, the creation and modification of the pattern can be easily performed only by changing the drawing program in the laser irradiation area. Next, a paint or etching resist is applied to the insulating portion of the molded product in which the circuit pattern of the metal thin film in which the conductive circuit portion is surrounded by the insulating closed circuit is formed (FIG. 4). Here, since the conductive circuit portion is surrounded by the insulating closed circuit, the paint or etching resist is selectively applied to the insulating portion by the electrodeposition method used in the present invention. This process is very different from the conventional method, in which the circuit portion is exposed and the insulating portion is protected so that only the circuit portion is deposited by chemical plating in the next step. Further, the paint and etching resist applied by the electrodeposition method used here can withstand the chemical plating in the next step,
Any material can be used as long as it can be easily peeled off at the time of peeling the resist and is a hydrophobic material that repels the catalyst provided as necessary. Next, regarding the molded product in which the insulating portion is coated with a resist by the electrodeposition method, a catalyst is applied to the conductive circuit portion if necessary, and then the conductive circuit portion is immersed in a chemical plating solution to chemically plate the conductive circuit portion to form a second metal. Apply layers (Figure 5). The metal of this chemical plating may be the same metal as the metal of the initial metal thin film layer, but in order to remove the initial metal thin film layer more efficiently in the subsequent flash etching step,
It is preferable to use a metal having a higher etching resistance to the etching solution than the initial metal thin film layer. Considering the smoothness of the conductive surface when it finally becomes a circuit and a sufficient thickness when removing the initial metal thin film layer by flash etching, the thickness of this second metal layer is 10 μm or more. preferable. Next, the paint or resist is peeled off from the molded product subjected to chemical plating (FIG. 6), and the metal thin film in the insulating portion is dissolved and removed by flash etching to form a conductive circuit pattern (FIG. 7). Since the metal thin film of the insulating portion is thinner than the thickness of the metal layer of the circuit pattern, it is possible to form only the circuit pattern due to the difference in the thickness. The solution used for the flash etching may be any solution as long as it can dissolve the metal thin film, but in general, an iron (III) chloride aqueous solution is preferable, and a sodium persulfate aqueous solution is more preferable. Although the thickness of the metal layer of the final circuit is almost dependent on the thickness of the second metal layer, flash etching is performed in terms of conductivity or damage / disconnection due to friction during use. It is preferable that there is a thickness of 10 μm or more later.

[0007]

According to the present invention, there is no need for complicated composite molding unlike the SKW method and the PCK method, and the complicated steps in the dark room such as circuit pattern exposure and development unlike when using a photoresist. Is unnecessary, and the appearance, shape, and insulation properties due to damage to the base molded product when using laser light can be avoided, and efficient formation is possible even when an independent circuit exists. It is possible and economically advantageous.

[0008]

Embodiments of the present invention will be described below with reference to the accompanying drawings, but the present invention is not limited thereto. Example 1 A three-dimensional molded product 1 was prepared by injection molding using a metal adhesive (plating) resin composition mainly composed of liquid crystalline polyester (trade name "Vectra", manufactured by Polyplastics Co., Ltd.). (Figure 1). Next, this is degreased, and almost the entire surface is etched with a KOH aqueous solution.
After being neutralized with an aqueous solution and washed, a catalyst (trade name "Catalyst A-30", manufactured by Okuno Chemical Industries Co., Ltd.) is applied to activate the surface, and then a chemical copper plating solution (trade name " OPC-7
50 ", manufactured by Okuno Chemical Industries Co., Ltd.), and the surface of the molded product was subjected to chemical copper plating 2 having a thickness of 0.6 μm, thoroughly washed, and dried (FIG. 2). Next, a YA with a laser power of 0.5 W was applied to the molded product (Fig. 2) whose surface was plated with chemical copper.
By irradiating the G laser 3 vertically to remove the chemical copper plating on the contour line of the conductive circuit portion, the conductive circuit portion 4 is removed.
And the insulating part 5 was formed (FIG. 3). Next, after the electrodeposition resist 6 is applied to the insulating portion 5 of the molded product (FIG. 3) on which the conductive circuit portion 4 is formed (FIG. 4), the catalyst (trade name “Anipack CTS”, Ebara Eugelite Co., Ltd.) The surface of the conductive circuit portion 4 by activating the surface by applying a catalyst to the conductive circuit portion 4 and then immersing it in a chemical nickel plating solution (trade name “Top Nicoron”, manufactured by Okuno Chemical Industries Co., Ltd.) 4 was subjected to chemical nickel plating 7 having a thickness of 3 μm and washed well (FIG. 5). Next, a molded product (FIG. 5) in which the conductive circuit portion 4 is subjected to chemical nickel plating 7 is immersed in an alkaline aqueous solution, and the electrodeposition resist 6 applied to the insulating portion 5 is peeled off (FIG. 6). A circuit-formed article having an accurate and three-dimensional conductive circuit portion in which the chemical copper plating 2 on the insulating portion 5 is dissolved and removed so that the chemical nickel plating 7 remains only on the conductive circuit portion 4 (Fig. 7) was obtained.

[Brief description of drawings]

1A and 1B are views showing a base molded product that is a molded product of a three-dimensional circuit as an example of the present invention, in which FIG. 1A is a top view and FIG. 1B is a side view.

FIG. 2 is a top view showing a state where the surface of the base molded article shown in FIG. 1 is subjected to chemical copper plating and a copper thin film is applied.

FIG. 3 is a top view showing a state where a chemical pattern is formed by removing a chemical copper thin film on a contour line of a circuit portion of a molded product plated with chemical copper shown in FIG. 2 by a YAG laser.

4 is a top view showing a state in which an electrodeposition resist is applied to an insulating portion of a molded product having the circuit pattern shown in FIG.

5 is a top view showing a state in which a conductive circuit portion of a molded product obtained by applying an electrodeposition resist to the insulating portion shown in FIG. 4 is subjected to chemical nickel plating.

FIG. 6 is a top view showing a state in which the electrodeposition resist of the insulating portion of the molded product in which the conductive circuit portion shown in FIG. 5 is subjected to chemical nickel plating is peeled off.

7 is a top view showing a state in which a molded product from which the electrodeposition resist in the insulating portion shown in FIG. 6 has been peeled off is subjected to flash etching to remove the chemical copper plating film in the insulating portion to form a circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base molded product 2 ... Copper thin film by chemical copper plating 3 ... Laser light 4 ... Conductive circuit portion formed by laser light 5 ... Insulating portion formed by laser light 6 ... Electrodeposition resist 7 ... Nickel by chemical nickel plating film

Claims (5)

[Claims] 1. When forming a conductive circuit on the surface of a synthetic resin molded product, chemical plating, spattering, vacuum deposition, ion plating, transfer method, and conductive agent coating are previously performed on the surface of the synthetic resin molded product that can be coated with metal. To form a metal thin film having a thickness in the range of 0.1 to 2 μm by irradiating a laser beam on the contour line of the conductive circuit portion on the surface of the thin film to form a metal thin film. After removing and enclosing the conductive circuit part with an insulating closed circuit, applying a paint or resist to the insulating part by the electrodeposition method, applying a second metal layer to the conductive circuit part by chemical plating, and then removing the paint or resist Then, the metal thin film of the insulating portion is removed by flash etching to form a circuit having a desired thickness. 2. The circuit forming method according to claim 1, wherein an independent circuit is present in the conductive circuit formed on the surface of the synthetic resin molded product. 3. The circuit forming method according to claim 1, wherein the metal of the second metal layer is different from the metal of the initial metal thin film layer. 4. The circuit forming method according to claim 1, wherein the synthetic resin molded product has a three-dimensional surface shape. 5. A conductive circuit forming component manufactured by the method according to claim 1.