JPH07193356A - Formation of circuit pattern using laser and circuit board - Google Patents

Abstract

PURPOSE:To provide a method of manufacturing efficiently a molded item, which is used as a circuit component in the field of an electrical apparatus, an electronic equipment and the like and has an accurate conductive circuit on the surface. CONSTITUTION:In a method wherein a metal thin film formed on the surface of a synthetic resin molded item is irradiated with laser beam, the metal thin film is removed to conduct the formation of a circuit pattern and a circuit is formed by electroplating, the thickness of the metal thin film is set in a thickness of 0.2 to 2.0mum and is the metal thin film formed on the surface of the molded item to remove the metal thin film in a width of 100 to 500mum is irradiated with the laser beam having a laser spot diameter of 50 to 500mum.

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 circuit pattern on a metal thin film formed on the surface of a synthetic resin molded product, which is used as a circuit component in the field of electric and electronic equipments, The present invention relates to a method for efficiently manufacturing a molded product having a conductive circuit.

[0002]

2. Description of the Related Art Conventionally, the problems to be solved by the invention
As a method of forming a circuit pattern by using a laser beam on the surface of a synthetic resin molded product, for example, a metal film having a sufficient thickness as a conductive circuit is previously formed on the surface of the molded product, and a metal film other than the conductive circuit is formed by a laser beam. A method in which the conductive circuit is directly removed by being scattered and removed by the method described in JP-A-64-833.
No. 91), but in this method, the thickness of the conductor metal layer is a relatively thick layer (for example, 10
It is necessary to increase the output of the laser light when removing unnecessary portions of the metal layer with the laser light, so that the synthetic resin molding of the base is damaged and the appearance shape is remarkably increased. However, there is a problem in that the insulation is obstructed, and the synthetic resin is carbonized to impair the insulating property. Therefore, a method has been considered in which a metal thin film is formed on the surface of the molded product, the metal thin film in a portion other than the conductive circuit portion is removed to form a circuit pattern, and electroplating is performed to form a conductive circuit. According to this method, since the output of the laser beam is reduced and irradiation is performed, the synthetic resin is not carbonized and there is no problem of insulation. However, conventionally, in this method, the removal width of the metal thin film by the laser beam is less than 100 μm, so When a conductive circuit is formed to a desired thickness by a subsequent electroplating process, plating may grow on the portion where the metal thin film has been removed, causing a problem that the conductive circuit is short-circuited.

[0003]

DISCLOSURE OF THE INVENTION The inventors of the present invention solve the problems of these conventional methods, and relate to a method of forming a circuit pattern on a molded product having a complicated shape with high precision by a simple method using laser light. As a result of a detailed study to solve the above problems, the metal thin film on the surface of the synthetic resin molded product was irradiated with laser light to be removed with a specific width, so that the conductive circuit was not short-circuited by the subsequent electroplating process. The inventors have found that a conductive circuit can be formed and have reached the present invention. That is, the present invention is a method for forming a circuit by electroplating by irradiating a metal thin film formed on the surface of a synthetic resin molded product with a laser beam to form a circuit pattern by removing the metal thin film. It is a circuit pattern forming method characterized by removing a metal thin film with a width of 100 to 500 μm by irradiating a laser beam having a laser spot diameter of up to 2.0 μm and a laser spot diameter of 50 to 500 μm.

The method of the present invention will be described below step by step. The material of the synthetic resin 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 molded product is later soldered. Considering that it is subjected to severe processing such as processing, it is desirable that it has high heat resistance and excellent mechanical strength, and in terms of mass production, a thermoplastic resin that is injection moldable is preferable. 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, etc., liquid crystalline polymers (eg, liquid crystalline polyester, polyester amide),
Polyarylene sulfide is particularly preferred, but not limited to. Further, in order to enhance the adhesion of the metal thin film, an appropriate substance such as an easily-etchable substance may be blended with the material if necessary. Synthetic resin molded products are
Although it is formed by injection molding or the like, in order to improve the adhesion of 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 performed.

Next, a metal coating process is performed on the surface of this molded product to form a metal thin film. 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 processability of electroplating is hindered in the step of forming a metal layer having a sufficient thickness as a conductive circuit by electroplating, which is not preferable. From this point of view, the thickness of the metal thin film applied to the surface of the substrate molded article is 0.2 to 2 μm, preferably 0.3 to
It is 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 film, any conventionally known method such as chemical plating, sputtering, vacuum deposition, ion plating, transfer method, conductive agent coating and the like may be used, but in order to form a uniform metal thin film. Chemical plating (electroless plating), sputtering, vacuum deposition, and ion plating are suitable.

Next, a synthetic resin molded article having a metal thin film formed on its surface is irradiated with a laser beam whose output and laser spot diameter are appropriately adjusted to the portion to be an insulating circuit or the contour line portion of the portion to be an insulating circuit. The metal thin film in the part is selectively removed. The spot diameter of the laser used here and the width of the metal thin film to be removed are particularly important. If the width of the metal thin film to be removed is too narrow, the problem of short-circuiting the conductive circuit portion due to electroplating in the next step is not preferable. Therefore, it is preferable that the width of the metal thin film to be removed is wide as long as it does not hinder the circuit formation. However, when using a laser beam with a laser spot diameter smaller than 50 μm, the metal thin film has a width wider than the spot diameter because the energy density is high. Although it is removed, it is impossible to remove a metal thin film having a sufficient width with one irradiation, and therefore the number of times of irradiation becomes too large and the laser irradiation time becomes long, resulting in poor productivity and uneconomical. But also. Also, the energy of the laser may deteriorate the resin. On the other hand, in the case of irradiating with a laser beam having a laser spot diameter larger than 500 μm, the energy required for removing the metal thin film cannot be secured because the energy density is low, and there is a problem that the metal thin film remains. From this viewpoint, the spot diameter of the laser beam used to remove the metal thin film is 50 to 500.
μm, preferably 150 to 250 μm. Also, if the width of the thin metal film to be removed is wider than 500 μm, laser light with a spot diameter of 500 μm is irradiated multiple times, and the outline of the insulating part is irradiated with laser light with a smaller spot diameter. The width of the metal thin film removed should be 500μ or less because the circuit accuracy is higher when the method described above is used.
From this point of view, the width of the metal thin film to be removed is 100-500 μm
And preferably 150 to 250 μm. The width within this range is preferable because electroplating does not short-circuit the conductive circuit, and the laser irradiation time is shortened to improve productivity. As described above, according to the present invention, by specifying the thickness of the metal thin film and the laser spot diameter, the synthetic resin molded article as the base is not damaged, and
A circuit pattern having a width of μm is formed, and the laser irradiation time is shortened by electroplating without short-circuiting the conductive circuit, thereby improving productivity.

The laser light for irradiating the metal thin film is Y
A predetermined circuit pattern such as an AG laser or a carbon dioxide laser is selectively irradiated by a laser marker having a scanning mechanism in XY directions controlled by a computer. If it is necessary to form a circuit in a complicated three-dimensional molded product, the 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 Or XYZ directions that move in synchronization with a laser marker having a scanning mechanism in XY directions and a computer,
It is also possible to irradiate three-dimensionally by combining a 5-axis table of rotation and inclination. 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. Further, since it is difficult to irradiate laser light while changing the spot diameter and varying the spot diameter within the same process, if you want to mix several removal widths of the metal thin film, move the Z axis to change the focus position of the laser. It can be performed by a method of displacing the laser to increase the laser spot diameter, or a method of irradiating the laser at a position where it partially overlaps a plurality of times.

Next, the synthetic resin molded product having a circuit pattern formed of a metal thin film may be used as it is as a circuit component if possible depending on the purpose of use. At the point, or at the point of damage and disconnection due to friction during use, etc.
Thin film circuits of less than m are often inconvenient and generally require a thickness of at least 10 μm or more. Therefore, in the present invention, the portion of the circuit pattern that becomes the conductive circuit is further electroplated to obtain a desired thickness (for example, 10
˜100 μm) with a metal layer to form the desired conductive circuit. 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.

Next, a metal layer is added to the conductive circuit to form an insulating circuit, or the synthetic resin molded product in which the chemical plating remains on the insulating portion is used as it is or, if necessary, by an etching solution for chemical plating, to isolate the insulating portion. The chemical plating remaining on the substrate is dissolved and removed to form a circuit board. A general metal etching solution (for example, iron chloride) may be used as the etching solution. Next, an electronic element is housed in a circuit board on which a conductive circuit is formed, and electrically connected by soldering, wire bonding, etc., and sealed to form an electronic component or an assembly of electronic components, and then the substrate is cut if necessary. Form the final electronic component.

[0010]

EFFECTS OF THE INVENTION According to the present invention, it is possible to avoid an obstacle to the appearance, shape, insulation and the like due to damage of a synthetic resin molded product when using a laser beam, and, in addition, during the electroplating process. You can avoid the short circuit of the conductive circuit,
A circuit board and an electronic component having a desired accurate conductive circuit can be obtained with a high yield rate by a simple method, which is economically advantageous.

[0011]

EXAMPLES Examples of the present invention will be shown below, but the present invention is not limited thereto.

Example 1 A three-dimensional molded product was obtained by injection molding using a metal adhesive (plating) resin composition mainly composed of liquid crystalline polyester (trade name "Vectra", manufactured by Polyplastics Co., Ltd.). Created. Next, this is degreased, and almost the entire surface is etched with a KOH aqueous solution, neutralized with an HCl aqueous solution, washed, and then washed with a catalyst (trade name "Catalyst A-3").
0 ", Okuno Seiyaku Kogyo Co., Ltd. to activate the surface, and then a chemical copper plating solution (trade name" OPC-750 ",
The surface of the molded product was dipped in Okuno Chemical Industries Co., Ltd., and the surface of the molded product was subjected to chemical copper plating with a thickness of 0.6 μm, thoroughly washed, and dried. Next, the surface of the molded product with chemical copper plating is irradiated with YAG laser light with a laser power of 0.5 W so that the laser spot diameter is 150 μm, and chemical copper plating is applied on the contour lines of the insulating circuit part and the insulating part. Was removed with a width of 150 μm to form a circuit pattern. Then
The molded product on which the circuit pattern was formed was subjected to electrolytic copper plating to obtain a molded product in which the thickness of the copper film in the conductive circuit portion was 30 μm and the chemical copper plating remained in the insulating portion. Next, the molded product with the chemical copper plating remaining on the insulating portion was immersed in an aqueous solution of iron (III) chloride to dissolve and remove the chemical copper plating to obtain a circuit board having an accurate and three-dimensional conductive circuit portion. Next, the film capacitor element is housed in this circuit board, the electrodes of the film capacitor element are electrically connected to the circuit of the circuit board, and the circuit board containing the film capacitor element is sealed after sealing with the sealing resin. A film capacitor was obtained by cutting.

Comparative Example 1 A three-dimensional molded article was obtained by injection molding using a metal adhesive (plating) resin composition mainly composed of liquid crystalline polyester (trade name "Vectra", manufactured by Polyplastics Co., Ltd.). A molded product was prepared and plated with chemical copper in the same manner as in Example 1. Next, a YAG laser beam with a laser power of 0.5 W is applied to the molded product whose surface is chemically copper-plated so that the laser spot diameter will be 40 μm, and the chemical copper plating on the contour line of the insulating circuit portion and the insulating portion will be performed. Width 60μ
A circuit pattern was formed by removing with m. Then, the molded product having the circuit pattern formed thereon was subjected to electrolytic copper plating to make the thickness of the copper film in the conductive circuit portion 30 μm, and only a molded product in which the conductive circuit was short-circuited was obtained.

Claims (6)

[Claims] 1. A method for forming a circuit by electroplating by irradiating a metal thin film formed on the surface of a synthetic resin molded product with laser light to remove the metal thin film to form a circuit pattern, wherein the metal thin film has a thickness of 0.2. A method for forming a circuit pattern, which comprises irradiating a laser beam having a laser spot diameter of 50 μm to 2.0 μm with a laser spot diameter of 50 to 500 μm to remove a metal thin film with a width of 100 to 500 μm. 2. The circuit pattern forming method according to claim 1, wherein the laser beam irradiation is performed by shifting the focal position of the laser so that the laser spot diameter is 50 to 500 μm. 3. The method for forming a circuit pattern according to claim 1, wherein the metal thin film is removed by irradiating the position where the laser is partially overlapped a plurality of times. 4. The circuit pattern forming method according to claim 1, wherein the synthetic resin molded product has a three-dimensional shape. 5. A circuit board on which a circuit is formed by electroplating a synthetic resin molded product on which a circuit pattern is formed by the method according to claim 1 and then flash etching if necessary. 6. An electronic device manufactured by accommodating an electronic element in the circuit board according to claim 5, electrically connecting and sealing an electrode of the electronic element and a circuit of the circuit board, and then cutting the board if necessary. parts.