JP3770968B2 - Circuit formation method using laser - Google Patents

Description

【００１３】
実施例９
液晶性ポリエステル（商品名「ベクトラ」、ポリプラスチックス（株）製）を主体とする金属密着性（メッキ性）樹脂組成物を用いて射出成形により立体的な成形品１を作成した（図１）。次いでこれを脱脂し、ＫＯＨ水溶液にてその表面のほぼ全面をエッチング処理した後、ＨＣｌ水溶液にて中和、洗浄後、触媒を付与して表面を活性化し後、奥野製薬工業（株）製の無電解化学銅メッキ液ＯＰＣ−７５０のＡ液及びＢ液の混合溶液にチオ尿素６ｐｐｍを配合した化学銅メッキ液に浸漬して、表面に厚さ0.5 μｍの化学銅メッキの金属薄膜２を形成し、よく洗浄した後、乾燥した（図２）。
この表面の明度（Ｌ値）は23.76 であった。
次いで、この化学銅メッキを形成した成形品に、レーザー出力が0.7 ＷのＹＡＧレーザー光４を照射して、導電回路部分以外の不要部分の化学銅メッキを除去することにより、導電回路パターン５を形成した（図４）。
その後、この導電回路パターン５を形成した成形品の導電回路パターン部分に、厚さ10μｍの電気銅メッキを施し、洗浄後、乾燥し、正確で立体的な導電回路部分６を有する回路形成品（図５）を得た。
上記の工程で50個の回路形成品を製造し、その良品率を測定した結果を表２に示す。
実施例１０
金属薄膜の厚さを変えた以外は実施例９と同様にして回路形成品を製造し、同様の測定を行った。
結果を表２に示す。
【００１４】
【表２】

【図面の簡単な説明】
【図１】図１は、本発明の一例として立体回路成形部品となる基体成形品の斜視図である。
【図２】図２は、図１に示す基体成形品の表面に化学銅メッキを施し、銅薄膜を形成した状態を示す斜視図である。
【図３】図３は、図２に示す銅薄膜を形成した成形品を加熱し、銅薄膜表面に明度（Ｌ値）が40以下の酸化物を形成させた状態を示す斜視図である。
【図４】図４は、成形品の導電回路部分以外の銅薄膜をＹＡＧレーザーにより除去し、導電回路パターンを形成した状態を示す斜視図である。
【図５】図５は、図４に示す導電回路パターンを形成した成形品の導電回路部分に電気銅メッキを施し、回路を形成した状態を示す斜視図である。
【符号の説明】
１・・・基体成形品
２・・・化学金属メッキによる金属薄膜
３・・・明度（Ｌ値）が40以下に変化した金属
４・・・レーザー光
５・・・レーザー光により形成された導電回路パターン
６・・・電気銅メッキにより形成された導電回路[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for forming a conductive circuit on the surface of a synthetic resin molded product, and efficiently produces a molded product having an accurate conductive circuit on the surface, which is used as a circuit component in the field of electrical and electronic equipment. For the method.
[0002]
[Prior art and problems to be solved by the invention]
Currently, as a method of forming a circuit using laser light, a metal film having a sufficient thickness as a conductive circuit is formed on the surface of the molded product in advance, and the metal film other than the conductive circuit is scattered and removed by laser light. A method of forming a conductive circuit (Japanese Patent Laid-Open No. 64-83391) has been considered, but according to this method, the thickness of the conductive metal layer is set to a relatively thick layer (for example, 10 μm) so that the conductivity as a circuit is sufficient. Therefore, when removing unnecessary parts of the metal layer with laser light, it is necessary to increase the output of the laser light, resulting in damage to the underlying synthetic resin molded product. There are problems such as remarkably hindering the external shape of the formed circuit, and carbonizing the synthetic resin to hinder insulation.
Further, there is a method (Japanese Patent Laid-Open No. 6-164105) in which a metal thin film is formed on the surface of a molded product, a metal thin film 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, the laser light output is lowered to irradiate, so the synthetic resin is not carbonized and there is no problem with insulation, but the laser light output is lowered, so the thickness of the metal thin film is reduced. Due to the variation, the metal thin film may not be partially removed and may remain, resulting in a new problem that the conductive circuit is short-circuited.
[0003]
[Means for Solving the Problems]
As a result of studying in detail a method for forming a conductive circuit with high precision using a laser beam on a molded product having a complicated shape by a simple method, the present inventors have solved the above-mentioned problems of the conventional method. As a metal thin film formed on the surface of the metal, a specific one having a surface lightness (L value) of 40 or less is used, and by performing laser processing, the metal thin film does not remain due to variations in the thickness of the metal thin film. The inventors have found that the circuit can be formed without short-circuiting, and have completed the present invention .
That is, the present invention relates to a method of performing circuit formation by removing a metal thin film formed on the surface of a synthetic resin molded article with a laser beam, and the surface brightness (L value) obtained from an electroless copper plating solution containing an organic sulfur compound. ) Is a circuit forming method using a laser, characterized by performing laser processing using a metal thin film of 40 or less.
[0004]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the method of the present invention will be described step by step with reference to the drawings.
The material of the synthetic resin molded product (substrate molded product) used in the present invention may be either a thermoplastic resin material or a thermosetting resin material as long as it is a synthetic resin capable of firmly attaching a metal thin film. Considering that the molded product will undergo severe processing such as soldering later, it is desirable to have a high heat resistance and excellent mechanical strength. preferable. Examples include aromatic polyesters, polyamides, polyacetals, polyarylene sulfides, polysulfones, polyphenylene oxides, polyimides, polyether ketones, polyarylates and compositions thereof, and the lightness (L value) of the metal thin film surface. A thermoplastic resin having a heat distortion temperature of 200 ° C. or higher is preferable from the viewpoint of heat treatment to make it 40 or less, and in particular, from the viewpoint of high melting point, high strength, high rigidity, molding processability, etc. Polyesteramide) and polyarylene sulfide are particularly suitable, but not limited thereto. Moreover, in order to improve the adhesiveness of a metal thin film, you may mix | blend a suitable substance with the material as needed.
The base molded product 1 (FIG. 1) is molded by injection molding or the like, and in order to improve the adhesion of the metal thin film on the surface, further chemical etching with acid, alkali, etc., or physical such as corona discharge, plasma treatment, etc. Surface treatment may be performed.
[0005]
Next, a metal coating process is performed on the surface of the molded product to form a metal thin film 2 (FIG. 2).
If the thickness of the metal thin film 2 applied here is too thick, a strong laser beam is required for forming a circuit pattern by the laser beam in the next process, and as described above, the base molded article 1 is damaged. Therefore, it is not preferable. On the other hand, if it is too thin, electricity for plating does not flow in the metal layer adding step by electroplating in a later step, which is not preferable. From this standpoint, the thickness of the metal thin film 2 applied to the surface of the base molded article 1 is suitably in the range of about 0.1 to 2 μm, more preferably 0.3 to 1 μm. A thickness within such a range is preferable because circuit pattern formation by laser light can be accurately performed with relatively weak output without causing damage to the base molded article 1.
As a method for forming the metal thin film 2, any conventionally known method such as chemical plating, sputtering, vacuum deposition, ion plating, transfer method, and conductive agent coating may be used. However, in order to form a uniform metal thin film 2. For this, chemical plating (electroless plating), sputtering, vacuum deposition, or ion plating is suitable.
In addition, the metal used here may be any metal as long as it is a metal that changes to dark brown due to a chemical reaction or the like, as described later, such as copper, silver, nickel, etc. Copper is preferred for forming.
Here, if the lightness (L value) of the surface of the metal thin film is 40 or less, more preferably 30 or less, laser processing may be performed as it is. For example, when an organic sulfur compound is added to the electroless copper plating solution, the lightness (L value) of the surface of the deposited copper thin film is 40 or less, so that laser processing can be performed as it is. Here, examples of the organic sulfur compound include thiols such as 2-mercaptobenzimidazole, disulfides such as dimethyl disulfide, sulfides such as 1,2-bis (2-hydroxyethylthio) ethane, thioacetone and thiourea. Examples include thioketones, sulfoniums such as 1-ethylthiazolium chloride, and sulfolanes such as sulfolane, and one or more of these can be used.
When the lightness (L value) of the electroless plating surface exceeds 40, the lightness (L value) of the surface of the metal thin film 2 of the base molded product 1 (FIG. 2) having the metal thin film 2 formed on the surface is 40. What is necessary is just to change to a dark color so that it may become the following (FIG. 3).
The brightness in the present invention is an L value measured with a color difference meter.
As a method for changing the lightness (L value) of the metal thin film surface to 40 or less, a chemical reaction is suitable, and specifically, a known method such as oxidation or sulfuration, and any method suitable for the metal can be used. For example, in the case of a copper thin film, a method of forming a dark oxide on the surface of the thin film by oxidation by heating is simple and suitable. The setting of the heating temperature here is important, and the metal thin film 2 is difficult to be oxidized at a low temperature, and conversely, a problem such as deformation occurs in the base resin molded product at a high temperature. From this standpoint, the heating temperature when the metal thin film is oxidized by heating is suitably 100 to 200 ° C, preferably 140 to 200 ° C, and the heating time is suitably 0.5 to 3 hours.
[0006]
In general, laser processing of metal and synthetic resin is processed with a laser with a lower output of synthetic resin, so it is necessary to process with a laser with the lowest possible output to prevent damage to the synthetic resin in the base part. is there. In the present invention, if the lightness (L value) of the color difference meter is set to 40 or less, the absorption of the laser beam to the metal thin film increases, and the unnecessary portion of the metal thin film is formed by a low-power laser that does not damage the synthetic resin. It has been found that a conductive circuit that is completely removed and does not short-circuit can be formed. In other words, if the lightness (L value) of the color difference meter is greater than 40, the absorption of the laser beam with respect to the metal thin film deteriorates, and it must be processed with a high-power laser. In some cases, such as carbonization of carbon dioxide may occur, which is not preferable.
[0007]
Next, by irradiating the unnecessary part other than the conductive circuit part with the laser beam 4 whose output is appropriately adjusted, for the molded article (FIG. 3) on which the metal thin film having the surface brightness (L value) of 40 or less is formed, Only the metal thin film 2 in this portion is selectively scattered and removed to form a conductive circuit pattern 5 of the metal thin film 2 (FIG. 4).
Here, the laser beam 4 to be irradiated may be any laser as long as it can remove the chemically reacted metal thin film, but considering the removal performance of the metal thin film, a YAG laser having a wavelength in the infrared region, A carbon dioxide laser or the like is preferable.
Such a laser selectively irradiates a preset circuit pattern with a laser marker having a scanning mechanism in XY directions controlled by a computer. In addition, when it is necessary to form a circuit in a complicated three-dimensional molded product, the laser beam 4 can be guided in a three-dimensional direction by an optical fiber, a prism, etc., and a predetermined area can be accurately irradiated by computer control. . Alternatively, three-dimensional irradiation can be performed by combining a laser marker having a scanning mechanism in the XY directions and a table of five axes in the XYZ directions, rotation, and tilt that move in synchronization with a computer. Further, according to this method, there is an advantage that pattern creation and correction can be easily performed only by changing a laser irradiation region drawing program.
[0008]
Thereafter, the conductive circuit portion of the circuit pattern 5 formed by removing unnecessary portions of the metal thin film 2 having a surface brightness (L value) of 40 or less is further electroplated to obtain a desired thickness (for example, 10 to 10). 100 μm) is added with a metal layer to form the desired conductive circuit 6 (FIG. 5). If the thickness of the metal layer is 10 μm or more, there is no problem of electrical conductivity or damage disconnection due to friction during use, and it is not necessary to make it thicker than necessary. good.
The metal thin film 2 having a lightness (L value) of 40 or less due to the compound 3 such as an oxide is not particularly good in the adhesion of the metal layer 6 formed by electroplating on the metal thin film 2, so that the metal is obtained by electroplating. As a pretreatment for forming the layer 6, it is desirable to remove the metal thin film surface layer. As the method, any known method may be used, but a method of dissolving and removing the surface layer by immersing the molded article in an acid such as hydrochloric acid or sulfuric acid is convenient.
[0009]
【The invention's effect】
According to the present invention, it is possible to avoid adverse effects on appearance, shape, insulation, etc. due to damage of a synthetic resin molded product due to the use of laser light, and metal thin films due to variations in metal thin film thickness Therefore, there is no short circuit of the conductive circuit, and the processing condition width is wide, so that the mass productivity is excellent, and a conductive circuit component having an accurate conductive circuit of a desired thickness can be obtained by a simple method, This is also advantageous.
[0010]
【Example】
Hereinafter, examples of the present invention will be described with reference to the drawings, but the present invention is not limited thereto. The lightness (L value) is determined by a color difference meter (“Z-300A” manufactured by Nippon Denshoku Industries Co., Ltd.) using a 30φ projection lens so that it is not affected by external light. It is the value obtained by measuring the plating surface. The following Examples 1 to 8 are shown for reference.
Example 1
A three-dimensional molded article 1 was prepared by injection molding using a metal adhesive (plating property) resin composition mainly composed of liquid crystalline polyester (trade name “Vectra”, manufactured by Polyplastics Co., Ltd.) (FIG. 1). ). Next, this was degreased and the entire surface was etched with an aqueous KOH solution, neutralized with an aqueous HCl solution, washed, and then given a catalyst to activate the surface, then a chemical copper plating solution (Okuno Pharmaceutical Co., Ltd.) It was immersed in OPC-750 manufactured by Co., Ltd., a mixed solution of A liquid, B liquid and C liquid) to form a chemical copper-plated metal thin film 2 having a thickness of 0.3 μm on the surface, washed well, and then dried. (FIG. 2).
Next, when the molded product (FIG. 2) whose surface was chemically copper-plated was heated at 120 ° C. for 1 hour, the chemical copper-plated surface caused a chemical reaction and changed to dark brown oxide 3 (FIG. 3). The lightness (L value) of this surface was 26.23.
Next, the molded product with the discolored surface of the chemical copper plating is irradiated with a YAG laser beam 4 having a laser output of 0.4 W to remove the unnecessary portion of the chemical copper plating other than the conductive circuit portion. 5 was formed (FIG. 4).
Thereafter, the molded article on which the conductive circuit pattern 5 is formed is immersed in a 5% aqueous sulfuric acid solution, and the discolored oxide on the surface is dissolved and removed. Then, the conductive circuit pattern portion is subjected to electrolytic copper plating with a thickness of 10 μm, After washing, drying was performed to obtain a circuit-formed product (FIG. 5) having an accurate and three-dimensional conductive circuit portion 6.
Table 1 shows the results of manufacturing 50 circuit-formed products by the above process and measuring the yield rate.
[0011]
Examples 2-8, Comparative Examples 1-6
The thickness of the metal thin film, the heating temperature when forming a dark compound (oxide) on the surface of the metal thin film, the brightness of the surface of the molded product formed as a result, and the removal of unnecessary parts other than the conductive circuit part A circuit-formed product was produced in the same manner as in Example 1 except that the laser output of the laser beam was changed as shown in Table 1, and the same measurement was performed.
The results are shown in Table 1.
[0012]
[Table 1]

[0013]
Example 9
A three-dimensional molded article 1 was prepared by injection molding using a metal adhesive (plating property) resin composition mainly composed of liquid crystalline polyester (trade name “Vectra”, manufactured by Polyplastics Co., Ltd.) (FIG. 1). ). Next, this was degreased and the entire surface of the surface was etched with an aqueous KOH solution, neutralized with an aqueous HCl solution, washed, activated with a catalyst, and then manufactured by Okuno Pharmaceutical Co., Ltd. Electroless chemical copper plating solution OPC-750 solution A and B solution mixed with chemical copper plating solution containing 6ppm thiourea to form 0.5μm thick chemical copper plating metal thin film 2 on the surface After washing well, it was dried (FIG. 2).
The lightness (L value) of this surface was 23.76.
Next, the molded product formed with the chemical copper plating is irradiated with YAG laser light 4 having a laser output of 0.7 W to remove unnecessary portions of the chemical copper plating other than the conductive circuit portion, thereby forming the conductive circuit pattern 5. Formed (FIG. 4).
Thereafter, the conductive circuit pattern portion of the molded product on which the conductive circuit pattern 5 is formed is subjected to electrolytic copper plating with a thickness of 10 μm, washed and dried, and a circuit-formed product having an accurate and three-dimensional conductive circuit portion 6 ( Fig. 5) was obtained.
Table 2 shows the results of manufacturing 50 circuit-formed products by the above process and measuring the yield rate.
Example 10
A circuit-formed product was produced in the same manner as in Example 9 except that the thickness of the metal thin film was changed, and the same measurement was performed.
The results are shown in Table 2.
[0014]
[Table 2]

[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a perspective view of a base molded product that becomes a three-dimensional circuit molded component as an example of the present invention.
FIG. 2 is a perspective view showing a state in which a surface of the base molded product shown in FIG. 1 is subjected to chemical copper plating to form a copper thin film.
FIG. 3 is a perspective view showing a state in which a molded product on which the copper thin film shown in FIG. 2 is formed is heated to form an oxide having a lightness (L value) of 40 or less on the surface of the copper thin film.
FIG. 4 is a perspective view showing a state in which a conductive circuit pattern is formed by removing a copper thin film other than a conductive circuit portion of a molded product with a YAG laser.
5 is a perspective view showing a state in which a circuit is formed by applying electrolytic copper plating to a conductive circuit portion of a molded product on which the conductive circuit pattern shown in FIG. 4 is formed. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Base-molded article 2 ... Metal thin film 3 by chemical metal plating 3 ... Metal whose brightness (L value) has changed to 40 or less 4 ... Laser beam 5 ... Conductivity formed by laser beam Circuit pattern 6: conductive circuit formed by electrolytic copper plating

Claims (4)

In a method of forming a circuit by removing a metal thin film formed on the surface of a synthetic resin molded product with a laser beam, the surface brightness (L value) obtained from an electroless copper plating solution containing an organic sulfur compound is 40 or less. A method of forming a circuit using a laser, characterized by performing laser processing using a metal thin film. 2. The circuit forming method according to claim 1, wherein the organic sulfur compound is one or more selected from thiols, disulfides, sulfides, thioketones, sulfoniums, and sulfolanes . 3. The circuit forming method according to claim 1, wherein laser processing is performed with a YAG laser . The circuit forming method according to claim 1, wherein the synthetic resin molded product has a three-dimensional shape.

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