JPH06164105A - Method for forming conductive circuit on surface of molded item and part with conductive circuit formed thereon - Google Patents

Abstract

PURPOSE:To provide a molded part having a desired thickness conductive circuit by forming a specific thickness metal thin film on the surface of a synthetic resin molded product and directing a laser beam to a part of the thin film to remove a metal thin film in the other part than a conductor circuit part and then applying electroplating to the metal thin film of a circuit pattern. CONSTITUTION:After activating the surface of a metal adhesive molded product, it is dipped into chemical copper plating solution to apply chemical copper plating to its surface by 0.2 to 2mum thick and clean and dry it. Next, its surface is exposed to a laser beam and a copper thin film in the other part then a circuit forming part is removed, thereby forming a circuit pattern 3. Next, electroplating is applied to the molded product in which the circuit pattern is formed to obtain a product with a circuit formed having a conductive circuit 4 in which a copper film in the circuit part has a desired thickness.

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.

[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 kinds of materials having different plating properties, and the difference in plating property between the circuit forming part and other parts is used. There is a SKW method or a PCK method in which a circuit part is selectively plated to form a metal circuit. However, since these methods require two molding steps, they are not only complicated and uneconomical. It is difficult to improve the adhesiveness of the interface between the two kinds of resins, which may cause a problem due to, for example, invasion of the plating solution or residual. On the other hand, in the conventional circuit forming method using a photoresist, there are many steps such as resist coating, circuit pattern exposure, pattern development, copper etching, and resist stripping, which is not only complicated but also the surface of a three-dimensional molded product. When a three-dimensional conductive circuit is to be formed, a certain degree of circuit can be formed by projection exposure with parallel light, but 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 is conceivable in which the conductive circuit is removed and used as it is. This method does not require double molding or use of a resist and is extremely simple. However, in this method, the thickness of the conductive metal layer is used as a conductive circuit. A relatively thick layer (eg 10 μm)
Above), and when the unnecessary portion of the metal layer is removed by laser light, it is necessary to increase the output of laser light, so that the synthetic resin molding of the base is damaged and the appearance shape is significantly impaired. In addition, there is a problem in that the synthetic resin is carbonized to impair the insulating property.

[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. Regarding the method of forming a conductive circuit by a detailed examination to solve the above problems, as a result of irradiating a laser beam with a metal layer which is previously applied to the surface of the synthetic resin molded article to a specific thickness or less, By lowering the output and selectively removing the unnecessary metal layer, a circuit pattern can be formed without damaging the underlying resin.After that, a metal layer of the desired thickness is applied by electroplating on the pattern to give an appearance. The inventors have found that a desired conductive circuit can be formed relatively easily without impairing the shape, the insulating property, etc., and have reached the present invention. That is, in the present invention, in forming a conductive circuit on the surface of a synthetic resin molded product, chemical plating, sputtering, vacuum deposition, ion plating, transfer method or conductive agent coating is previously performed on the surface of the synthetic resin molded product capable of metal coating. The thickness is 0.2 to 2 after metal coating by any of
By forming a metal thin film of μm, and then irradiating a part of the surface of the thin film with laser light, leaving the metal thin film in the part that becomes the conductive circuit part, and removing the metal thin film in the part other than the conductive circuit part A method for forming a conductive circuit on the surface of a molded article, which comprises forming a thin film circuit pattern and then performing electroplating on the metal thin film of the circuit pattern to form a conductive circuit having a desired thickness. And a conductive circuit forming component manufactured by the above method.

The method of the present invention will be described step by step with reference to the drawings. The material of the base molded product used in the present invention may be either a thermoplastic resin or a thermosetting resin as long as it is a synthetic resin material capable of firmly adhering a metal thin film,
Considering that such a molded product is later subjected to severe processing such as soldering, it is desirable that the molded product has high heat resistance and excellent mechanical strength, and in terms of mass production, a thermoplastic resin that can be injection molded. Is preferred. For example,
Aromatic polyesters, polyamides, polyacetals, polyphenylene sulfides, polysulfones, polyphenylene oxides, polyimides, polyether ketones, polyarylates and compositions thereof, and the like, particularly high melting point, high strength, high rigidity, molding processability, etc. Therefore, liquid crystalline polymers (for example, liquid crystalline polyester, 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 formed by injection molding or the like, and in order to improve the adhesion of the metal thin film on its surface, chemical etching with acid, alkali, etc., or physical surface such as corona discharge, plasma treatment, etc. Processing may be performed.

Next, a metal coating process is performed on the surface of this molded product to form a metal thin film (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 other hand, if it is too thin, the workability of electroplating when forming a metal layer having a sufficient thickness as a conductive circuit by electroplating in the final step 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 0.2 to 2 μm, 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 comparatively weak output without causing damage to the base molded product, and to the extent necessary for electroplating for the final circuit formation. Is preferable because it maintains the conductivity.
As a method for forming such a metal thin film, chemical plating,
Any conventionally known method such as sputtering, vacuum deposition, ion plating, transfer method, conductive agent coating, etc. may be used, but chemical plating (electroless plating), sputtering, ion plating is required to form a uniform metal thin film. Vacuum deposition is suitable.

Next, with respect to the molded product having a metal thin film formed on its surface (FIG. 2), the metal thin film in this portion is selectively scattered and removed by irradiating the portion other than the circuit forming portion with laser light whose output is appropriately adjusted. Then, a circuit pattern of the metal thin film is formed (FIG. 3). The laser light to be emitted has a wavelength in the infrared region such as a YAG laser or a carbon dioxide gas laser, and a predetermined circuit pattern is selectively emitted by a laser marker having an XY scanning mechanism controlled by a computer. . Also, when it is necessary to form a circuit in a complicated three-dimensional molded product, laser light should be guided in a three-dimensional direction by an optical fiber, prism, etc., and computer-controlled to accurately irradiate a predetermined area three-dimensionally. You can 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.

The molded product thus formed with the circuit pattern of the metal thin film may be used as it is as a circuit component if possible depending on the purpose of use, but in general, when it is used as a circuit component, in terms of its conductivity, Alternatively, the thin film circuit having a thickness of less than 2 μm as described above is often inconvenient in view of damage and breakage due to friction during use, and generally requires a thickness of at least 10 μm or more. Therefore, in the present invention, the circuit pattern is further electroplated and a metal layer is added to a desired thickness (for example, 10 to 100 μm) to form a final circuit (FIG. 4) of interest. .
A general electroplating method can be applied to the addition of the metal layer because the already formed circuit pattern has a conductivity that allows electroplating.

[0008]

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 a simple and accurate conductive circuit of the desired thickness can be obtained. It is possible to obtain a molded part having the above, which is economically advantageous.

[0009]

EXAMPLES Examples of the present invention will now be described with reference to the drawings, but the present invention is not limited thereto. Example 1 A three-dimensional molded product 1 obtained by injection molding using a metal-adhesive (chemical plating) resin composition mainly composed of liquid crystalline polyester (trade name "Vectra", manufactured by Polyplastics Co., Ltd.)
Was created (Fig. 1). Next, this is degreased, and after etching the almost entire surface with a KOH aqueous solution, H
After neutralizing with a Cl aqueous solution and washing, 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-75).
0, manufactured by Okuno Seiyaku Kogyo 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 chemically copper-plated.
The circuit pattern 3 was formed by irradiating the G laser 5 and removing the copper thin film other than the circuit formation part (FIG. 3). Next, a molded product with this circuit pattern (Fig. 3) is electroplated with copper to obtain a circuit-formed product (Fig. 4) having an accurate and three-dimensional conductive circuit 4 with a copper film thickness of 30 µm in the circuit part. Obtained. In this molded product, almost no damage was observed on the exposed resin background other than the circuit part.

Comparative Example 1 Except that the thickness of the chemical copper plating on the surface of the molded product was 5 μm,
In the same manner as in Example 1, a molded product having a copper thin film of 5 μm formed was prepared. An attempt was made to form a circuit pattern on this molded product by using the same laser light as in Example 1 with a laser light output of 0.6 W, but the laser light output with respect to the thin film thickness was too weak, and pattern formation was difficult. Further, when the output of the laser beam was increased successively, a circuit pattern could be formed, but an accurate pattern could not be obtained and the resin background was damaged.

Comparative Example 2 Chemical copper plating (thickness: 0.6 μm) was carried out by the same method as in Example 1.
m), electrolytic copper plating was performed as it was, and the entire surface of the molded product was once coated with a copper film having a thickness of 30 μm. Next, laser power of 5 to 15 is applied to this electroplated molded product.
When a W YAG laser was irradiated, the copper film could not be completely removed and a circuit pattern could not be formed.
Further, as a result of increasing the laser light output until the copper plating layer could be removed, the exposed resin background was found to be significantly damaged (carbonized) and could not be used as a circuit component.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a base molded product that is a three-dimensional circuit molded component as an example of the present invention.

FIG. 2 is a cross-sectional 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 cross-sectional view showing a state in which a chemical pattern is formed by removing a chemical copper thin film in a portion other than the circuit forming portion of the molded product plated with chemical copper shown in FIG. 2 by a YAG laser. .

FIG. 4 is a cross-sectional view showing a state in which a molded product having the circuit pattern shown in FIG. 3 is electroplated with copper to form a circuit made of a metal layer having a required thickness.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Base molded product 2 ... Copper thin film by chemical copper plating 3 ... Circuit pattern formed by laser light 4 ... Conductive circuit formed by electrolytic copper plating 5 ... Laser light

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[Procedure amendment]

[Submission date] February 14, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

The molded product thus formed with the circuit pattern of the metal thin film may be used as it is as a circuit component if possible depending on the purpose of use, but in general, when it is used as a circuit component, in terms of its conductivity, Alternatively, the thin film circuit having a thickness of less than 2 μm as described above is often inconvenient in view of damage and breakage due to friction during use, and generally requires a thickness of at least 10 μm or more. Therefore, in the present invention, the circuit pattern is further electroplated and a metal layer is added to a desired thickness (for example, 10 to 100 μm) to form a final circuit (FIG. 4) of interest. .
A general electroplating method can be applied to the addition of the metal layer because the already formed circuit pattern has a conductivity that allows electroplating. The molded product having the conductive circuit formed by the method of the present invention is used as various electric / electronic device parts. For example, an electronic element or the like is installed at a predetermined position, the terminal of the electronic element is connected to a predetermined portion of the conductive circuit, and further, if necessary, the conductive circuit and the electronic element may be entirely or partially made of a suitable resin. To form an integrated electronic component, and various electrical and electronic equipment components,
It is preferably used as a functional component for machinery.

Claims (3)

[Claims] 1. When forming a conductive circuit on the surface of a synthetic resin molded product, chemical plating, sputtering, vacuum deposition, ion plating, transfer method or conductive agent coating is applied to the surface of the synthetic resin molded product capable of metal coating in advance. To form a metal thin film having a thickness of 0.2 to 2 μm by irradiating a laser beam on a part of the surface of the thin film to remove the metal thin film in the part which becomes the conductive circuit part. After forming the circuit pattern of the metal thin film by removing the metal thin film in the portion other than the conductive circuit part, the metal thin film of the circuit pattern is further electroplated to form a conductive circuit of a desired thickness. A method for forming a conductive circuit on the surface of a molded article, which is characterized by the above. 2. The method for forming a conductive circuit on the surface of a molded product according to claim 1, wherein the molded product has a three-dimensional surface shape. 3. A conductive circuit forming component manufactured by the method according to claim 1.