JP2006310455A - Method of forming conductive circuit on inner wall of transparent hollow body - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately and quickly form a fine conductive circuit of high density on the inner wall of a hollow body. <P>SOLUTION: A copper film 2 having thickness of 0.3 μm is formed on an inner wall 11a of a cylindrical hollow body 1 which is injection molded with cycloolefin polymer of a transparent synthetic resin by a high frequency ion plating method. Then, laser beam is irradiated from the rear side of the copper film 2 so that it passes through the wall thickness from the outside of the hollow body 1, so other non-circuits 2b are removed except for a conductive circuit 2a which comes to be a spiral antenna. Since the conductive circuit 2a is covered with the hollow body 1 itself, no protective cover is required to prevent flaw, corrosion, or sticking of conductive substance, resulting in a lower cost and a smaller size. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for forming an antenna made of a spiral conductive circuit on the inner wall of a cylindrical transparent hollow body, for example.

Electronic devices such as mobile phones are increasingly required to have multiple functions and miniaturization, and accordingly, electric circuits used for electronic devices are also required to be smaller and higher in density. As one of the methods for forming such a minute and high-density electric circuit, a metal thin film is already formed on the outer surface of the insulator, and this metal thin film is irradiated with laser light to remove only the circuit portion. Thus, means for forming a conductive circuit has been proposed (see, for example, Patent Documents 1 to 3).
JP-A-6-164105 (pages 1 to 4, FIG. 4) JP-A-7-66531 (pages 1 to 4, FIG. 3) Japanese Patent Laid-Open No. 7-66532 (pages 1 to 5, FIG. 3)

  By the way, such a minute and high-density electric circuit loses its electrical function even if slight trauma, corrosion, or adhesion of a conductive material occurs. However, since all of the above-described means are to form the circuit portion on the outer surface of the insulator, in order to prevent such damage, corrosion, or adhesion of conductive materials, the formed electric circuit is further modified. It is necessary to cover with a protective cover. However, providing such a protective cover on the electric circuit increases the amount of labor and the outer size, so when trying to reduce the cost and size of electric parts and circuits as much as possible, It becomes a big obstacle. Therefore, a means for accurately and quickly forming a minute and high-density electric circuit that does not require such a protective cover or the like is desired.

  Therefore, an object of the present invention is to provide a method for accurately and quickly forming a minute and high-density conductive circuit on the inner wall of a hollow body.

  If the conductive circuit can be formed on the inner wall of the transparent hollow body as described above, the conductive circuit is covered by the hollow body itself and is not exposed to the outside, so that it is possible to prevent external damage, corrosion, or adhesion of a conductive substance. Therefore, it is not necessary to provide a protective cover or the like. Therefore, as a result of repeated experiments, the present inventor formed a conductive metal film on the inner wall of the transparent hollow body, and applied a laser to the conductive metal film so as to pass through the transparent hollow body from the outside of the transparent hollow body. It has been found that a conductive circuit can be formed on the inner wall of the transparent hollow body by selectively irradiating light.

  That is, the characteristics of the method for forming a conductive circuit on the inner wall of the transparent hollow body according to the present invention include a step of forming a conductive metal film on the inner wall of the hollow body made of an insulating transparent material, and the hollow body from the outside of the hollow body. And irradiating the conductive metal film with laser light so as to pass through the body, and removing the conductive metal film while leaving a circuit portion.

Here, the “insulating transparent material” means any transparent material that can form a conductive metal film and can transmit a laser beam, such as transparent glass, quartz, and transparent. Synthetic resin is applicable. Further, the “hollow body” means that the inside is a cavity, and a part of the cavity is open to the outside, and the shape and size are not limited. For example, a cylindrical body having both ends opened, and a container shape having one end opened and the other end closed are applicable. The “inner wall of the hollow body” means an inner surface of a cavity formed in the hollow body. "Conductive metal film" means a film made of all conductive metals capable of forming a film on the above-described insulating transparent material, such as copper, nickel, gold, silver, etc. formed by chemical plating or vapor deposition plating, Or the metal film of these alloys corresponds. The “laser” is preferably a continuous transmission type, and corresponds to YAG, CO ₂ , Ar laser, or the like.

  When the number of circuit portions is small, most of the conductive metal film that becomes a non-circuit portion must be removed with laser light while leaving the small number of circuit portions, and the work efficiency is extremely deteriorated. Therefore, in order to solve such a problem, another feature of the method for forming a conductive circuit on the inner wall of the transparent hollow body according to the present invention is that the boundary between the circuit portion and the non-circuit portion is irradiated with laser light, and this boundary is formed. By removing the conductive metal film of the part, the circuit part and the non-circuit part are separated by an insulating passage. Then, the electroplating is performed by charging the cathode to the circuit portion of the conductive metal film, thereby increasing the thickness by laminating the plating only on the circuit portion, and then immersing it in an etching solution, so that the electroplating is not applied. It is an object to form a conductive circuit by removing only the conductive metal film that forms the non-circuit portion and leaving only the circuit portion whose thickness is increased by the lamination of plating.

  That is, another feature of the method for forming a conductive circuit on the inner wall of the transparent hollow body according to the present invention is the step of forming a conductive metal film on the inner wall of the hollow body made of an insulating transparent material and the outside of the hollow body. A step of irradiating the conductive metal film with laser light so as to pass through the hollow body to remove the conductive metal film at a boundary portion separating the circuit portion and the non-circuit portion; and The present invention includes a step of performing electroplating by energizing the circuit portion and a step of removing the non-circuit portion of the conductive metal film by etching.

  Here, the “boundary part separating the circuit part and the non-circuit part” means that the conductive metal film formed on the inner wall of the hollow body includes a circuit part that becomes a conductive circuit and a non-circuit part that does not become a conductive circuit. , Which means a boundary such as a line or a band that separates from each other so as not to be electrically energized. Including critical boundaries. In such a case, if the cathode is charged to the circuit portion during the electrolytic plating, the non-circuit portion is insulated from the circuit portion, and therefore, the electroplating can be performed only on the circuit portion.

  The insulating transparent material is a transparent synthetic resin, and is preferably made of any one of polyetherimide, polyethersulfone, polyimide, polyamide, polycarbonate, cycloolefin polymer, polyethylene terephthalate, or acrylic. Further, the conductive metal film is preferably formed by any one of chemical plating, sputtering, vacuum deposition, or ion plating.

  As described above, if a conductive circuit can be formed on the inner wall of the transparent hollow body, the conductive circuit is covered by the hollow body itself, so that no protective cover is provided to prevent damage, corrosion, or adhesion of conductive materials. Etc., and the cost can be reduced and the size can be reduced. In addition, the conductive metal film formed on the inner wall of the transparent hollow body is irradiated with laser light, the circuit portion and the non-circuit portion are separated by an insulating passage, and only this circuit portion is energized for electrolytic plating. By removing only the conductive metal film that forms the non-circuit portion that is not electroplated by etching or the like, the conductive metal film that forms the non-circuit portion is removed even when the area of the non-circuit portion is large. Work efficiency can be greatly improved.

  In addition, since an electric circuit can be precisely formed on the inner periphery of the cylinder member or the like, an electronic device such as an encoder configured by inserting a rotor, a slider, or the like on the inner periphery of the cylinder member or the like can be reduced in size and reduced. Cost can be reduced. Furthermore, if a spiral antenna circuit can be formed on the inner wall of a hollow cylindrical member made of a transparent material, it is possible to easily insert a light-emitting element for incoming notification of a mobile phone into the hollow cylindrical member and incorporate it. Thus, the portable antenna can be further reduced in size.

  As an example of a method of forming a conductive circuit on the inner wall of a transparent hollow body according to the present invention with reference to FIGS. 1 to 2, a spiral-shaped inner wall of a cylindrical transparent hollow body is used as an antenna for a mobile phone. A case where a conductive circuit is formed will be described. As shown in FIG. 1A, first, a hollow body 1 made of an insulating transparent material is formed. The hollow body 1 has a cylindrical shape having a through hole 11 in the center, and is manufactured by injection molding a cycloolefin polymer which is a transparent synthetic resin. The wall thickness between the outer shape and the inner diameter of the hollow body 1 is 2 mm.

  Next, the hollow body 1 is degreased and washed, and as shown in FIG. 1B, the inner wall 11a of the through hole 11 of the hollow body 1 is thickened as a conductive metal film by high-frequency ion plating. A 0.3 μm-thick copper film 2 is formed. The thickness of the copper film 2 may be 0.1 to 2 μm.

  Next, as shown in FIG. 1 (C), a laser beam is irradiated from the back side of the copper film 2 so as to pass through a wall thickness of 2 mm from the outside of the hollow body 1 to form a spiral antenna. The other non-circuit part 2b is removed leaving the conductive circuit part 2a. As the laser 3, a YAG laser is used.

  The laser 3 is fixed and moved in the axial direction while rotating the cylindrical hollow body 1, and the other non-circuit portions 2b are sequentially removed while leaving the conductive circuit portion 2a serving as a spiral antenna. Further, if the focal position of the laser beam of the laser 3 is set in front of the copper film 2, that is, within the wall thickness of the hollow body 1, the synthetic resin of the hollow body may be heated and foamed, so the focal position is It is desirable to set the position passing through the copper film, that is, outside the wall thickness of the hollow body.

  It is also effective to perform electrolytic copper plating on the conductive circuit portion 2a and increase the thickness of the conductive circuit portion to enhance the strength, durability, and the like.

  Next, another method of forming a conductive circuit used as a spiral antenna on the inner wall of a cylindrical transparent hollow body will be described with reference to FIG. First, as shown in FIG. 2A, a cylindrical hollow body 101 having a through hole 111 at the center is injection-molded using a cycloolefin polymer, which is a transparent synthetic resin, in the same manner as described above. Then, the hollow body 101 is degreased and washed, and as shown in FIG. 2B, the inner wall 111a of the through hole 111 of the hollow body has a thickness of 0. 5 mm as a conductive metal film by high-frequency ion plating. A 3 μm thick copper film 102 is formed.

  Next, as shown in FIG. 2 (C), a laser beam is irradiated from the back side of the copper film 102 so as to pass through a wall thickness of 2 mm from the outside of the hollow body 101 to form a spiral antenna. The spiral boundary portion 102c that separates the circuit portion 102a from the surrounding non-circuit portion 102b is removed. The laser 103 is fixed and moved in the axial direction while rotating the cylindrical hollow body 101 to remove the spiral boundary portion 102c. The laser 103 uses a YAG laser.

  Next, as shown in FIG. 2D, electrolytic copper plating is performed using the conductive circuit portion 102a as a cathode, and a copper film 104 having a thickness of 10 to 100 μm is laminated on the circuit portion. When this electrolytic copper plating is performed, the surrounding non-circuit portion 102b is insulated by the spiral boundary portion 102c. Therefore, the non-circuit portion is not copper-plated, and the above-described high-frequency ion plating method is used. The formed copper film is 0.3 μm thick. Here, a known technique can be used for the electrolytic copper plating.

  Next, as shown in FIG. 2E, the 0.3 μm-thick copper film forming the non-circuit portion 102b is removed by etching. In this etching, since the copper film 104 having a thickness of 10 to 100 μm is laminated on the conductive circuit portion 102a by electrolytic copper plating, the copper film is not removed and a spiral antenna is formed. .

  As described above, the hollow bodies 1 and 101 can be made of a transparent synthetic resin such as polyetherimide, polyethersulfone, polyimide, polyamide, polycarbonate, cycloolefin polymer, polyethylene terephthalate, or acrylic. The wall thickness of the hollow bodies 1 and 101 is not limited to 2 mm described above, and may be less than 2 mm or thicker than 2 mm. When the wall thickness is made thicker than 2 mm, it is theoretically possible to increase the wall thickness up to the distance between the laser θ lens and the focal depth. However, if the wall thickness becomes too thick, Laser light diffuses and it becomes difficult to precisely shape the circuit portion. Therefore, when the circuit part is precisely formed, it is advantageous that the wall thickness is thin.

  As described above, the copper films 2 and 102 formed on the inner walls of the hollow bodies 1 and 101 are not limited to ion plating, and well-known chemical plating, sputtering, vacuum deposition, or the like can be used. Further, the conductive metal film is not limited to the copper films 2 and 102, and other conductive metal films such as nickel and solder can be used.

As described above, the lasers 3 and 103 are not limited to YAG lasers, and CO ₂ or Ar lasers can be used. Conditions such as the output of the lasers 3 and 103, the depth of focus, the beam diameter, or the processing speed are as follows: the type of laser, the material, shape, and wall thickness of the hollow bodies 1 and 101, and the conductive metal film removed by the laser. Depending on the type, thickness, and area, the hollow body itself may be set in a range where no alteration or bubbles occur.

[Example 1]
A copper film having a thickness of 0.3 μm was formed on one surface of a 2 mm-thick plate material made of a cycloolefin polymer, which is a transparent synthetic resin, by high-frequency ion plating. Next, YAG laser light was passed through the plate material having a thickness of 2 mm from the back surface of the plate material, and the copper film was irradiated to remove the copper film. It was confirmed that the copper film can be removed without causing any alteration or bubbles in the cycloolefin polymer itself. The processing conditions are as follows.
1. Laser used: Toshiba Corporation, model name “LAY-724DU-6CA”
2. Output (W): 26.0 (A) QSW 6 KHz (Optical power meter measurement)
3. Depth of focus: 296.3 mm from Fθ lens
4). Beam diameter: 120 μm
5. Processing speed: 370 mm / sec

[Example 2]
Using a cycloolefin polymer which is a transparent synthetic resin, a cylindrical hollow body having an outer diameter of 10 mm, an inner diameter of 6 mm, and a length of 30 mm was injection molded. A copper film having a thickness of 0.3 μm was formed on the inner wall of the cylindrical hollow body by high frequency ion plating. Next, from the outside of the hollow body, YAG laser light was passed through the wall thickness of 2 mm of the hollow body to irradiate the copper film, thereby removing the copper film. It was confirmed that the copper film can be removed without causing any alteration or bubbles in the cycloolefin polymer itself. The processing conditions were set to be the same as those in [Example 1] described above.

  The method for forming a conductive circuit on the inner wall of a transparent hollow body according to the present invention can form a precise conductive circuit accurately and quickly on the inner wall of a hollow body such as a variety of transparent synthetic resins. The present invention can be widely used in industries such as electronic devices that are required to have higher density and cost reduction.

It is process drawing which forms a conductive circuit in the inner wall of a cylindrical hollow body. It is another process drawing which forms a conductive circuit in the inner wall of a cylindrical hollow body.

Explanation of symbols

1, 101 Hollow body 11, 111 Through hole 11a, 111a Inner wall 2, 102 Copper film (conductive metal film)
2a, 102a Circuit part 2b, 102b Non-circuit part 102c Boundary part 3, 103 Laser 104 Copper film (electrolytic plating)

Claims (4)

Forming a conductive metal film on the inner wall of the hollow body made of an insulating transparent material;
A step of irradiating the conductive metal film with laser light from the outside of the hollow body so as to pass through the hollow body, and removing the conductive metal film leaving a circuit portion. A method of forming a conductive circuit on the inner wall of a hollow body. Forming a conductive metal film on the inner wall of the hollow body made of an insulating transparent material;
Irradiating the conductive metal film with laser light so as to pass through the hollow body from the outside of the hollow body, and removing the conductive metal film at a boundary portion separating the circuit portion and the non-circuit portion;
Performing electrolytic plating on the circuit portion of the conductive metal film;
And a step of removing the non-circuit portion of the conductive metal film by etching. A method for forming a conductive circuit on the inner wall of a transparent hollow body.       3. The insulating transparent material according to claim 1, wherein the insulating transparent material is a transparent synthetic resin, and is any one of polyetherimide, polyethersulfone, polyimide, polyamide, polycarbonate, cycloolefin polymer, polyethylene terephthalate, or acrylic. A method for forming a conductive circuit on the inner wall of a transparent hollow body, comprising:       4. The conductive metal film according to claim 1, wherein the conductive metal film is formed on the inner wall of the transparent hollow body by any one of chemical plating, sputtering, vacuum deposition, or ion plating. Method for forming a sex circuit.