JP2010067697A - Method for manufacturing printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten manufacturing time of a substrate, to reduce the number of processes and to achieve high accuracy by forming a circuit pattern on a substrate by a simple process having no liquid layer process without using a photomask, a resist film, a silk print board, and so on. <P>SOLUTION: An etching mask resin film 4 having a peelable adhesive layer 6 is stuck to the surface of a substrate 1 obtained by sticking a conductive metallic thin film 2 to insulating resin 3. Ultraviolet laser light 7 is converged on the etching mask resin film 4 and convergence points of ultraviolet laser light 7 are scanned along the periphery 8 of a portion to be etched and removed on the metallic thin film 2 corresponding to a desired printed wiring pattern. The etching mask resin film 4 corresponding to the portion to be etched is cut and removed up until arrival at the metallic thin film 2 to peel and remove the etching mask resin film 4 of the portion to be etched and prepare an etching mask. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a method for forming an etching mask for forming a circuit pattern in a printed wiring board.

Conventionally, a printed wiring board is manufactured by adhering a copper wire thin film such as copper to the entire surface of a resin substrate and etching away unnecessary portions to create a circuit pattern. As a method for producing an etching mask for a circuit pattern, for example, a photographic method is known. The circuit pattern is formed as follows.

First, a necessary circuit pattern is designed, and the pattern is printed on a transparent resin film using a precise printer to create an exposure mask. There is also a method of cutting out the mask using a cutter. Next, a metal thin film made of a conductive metal material such as copper is uniformly attached to the resin substrate, and through holes for attaching electronic components, etc. as necessary, and through holes for imparting conductivity to both sides of the substrate are provided. Open. Next, a photosensitive resin film is uniformly deposited on the metal thin film, and an exposure mask is adhered onto the metal thin film, and the exposure resin is exposed to visible light or ultraviolet rays, and the photosensitive resin film at the etching site is removed by development. Create an etching mask. Finally, a desired circuit pattern is formed on the resin substrate by immersing in an etching solution and etching an unnecessary metal thin film on the resin substrate (see Patent Document 1).

For low-precision and low-resolution circuit patterns, a silk mask is created according to the circuit pattern, and a metal thin film made of a conductive metal material such as copper is uniformly attached to the resin substrate. A through-hole is formed to provide a through-hole for attachment and conductivity on both sides of the substrate. Next, an etching resist ink is printed on the metal thin film using a silk mask to create an etching mask. Finally, a desired circuit pattern is formed on the resin substrate by immersing in an etching solution and etching an unnecessary metal thin film on the resin substrate (see Patent Document 2).

In addition, a method of creating an etching mask by drawing directly on a photosensitive resin film using a laser beam without using an exposure mask (see Patent Document 3), converting wiring pattern data into wiring data for optical modeling, A substrate having a conductive film on the surface is submerged in the photocurable resin liquid surface, and the photocurable resin liquid is cured by irradiating laser light toward the photocurable resin liquid surface based on wiring data for optical modeling. In this method, an etching resist is formed on the surface of the substrate, and the etching resist is removed after etching the conductive film on the surface of the substrate (Patent Document 4). A thin film layer is deposited on the insulating base slope, and at least one of the thin film layers There has been proposed a method (Patent Document 5) in which a layer is exposed with an ultraviolet laser beam to directly draw and expose a photoresist film deposited on an insulating base slope.
Japanese Patent Laid-Open No. 05-10205 JP-A-11-307923 JP-A-9-52497 JP 2000-59005 A JP 2000-114533 A

In the case where a highly accurate printed wiring board is produced by these manufacturing methods proposed in Patent Document 1 and Patent Document 2, a photosensitive resin film or a photomask film is indispensable for any of these methods. These methods have the following drawbacks.
(A) It is necessary to once create a photomask, and the process becomes longer.
(B) The photosensitive resin film is expensive, and it is necessary to use it on the entire surface of the substrate even if the etching pattern is very small in the fine pattern.
(C) The exposure process requires a dedicated room for exclusive illumination that blocks external light and uses an optical filter.
(D) Since the thermal expansion coefficients of the mask and the substrate are different, accuracy is deteriorated unless temperature and humidity are strictly managed in the management and process. Moreover, since the exposure process dislikes dust, a clean room is essential.
(E) Patterning with an aspect ratio of 1 or more is difficult because of exposure characteristics. If the photosensitive resin film is not thinned, it is difficult to form a fine pattern. In this case, the durability of the etching mask is lowered, and there is a limit to the miniaturization of the pattern.

In the method of irradiating a laser beam focused on a photosensitive resin film without using a photomask according to Patent Document 3, it is not necessary to manufacture a photomask and management of the photomask is unnecessary. Problems in using photosensitive resin, such as use, the necessity of managing ambient light in the exposure process, the need for dust removal, and the need for a development process, have not been solved.

The method according to Patent Document 4 requires a liquid layer process using a photocurable resin liquid, uses a large amount of an expensive photocurable resin liquid, and scans and irradiates an entire large area to create a mask. It is necessary and it is very disadvantageous for the construction of large patterns.

The method according to Patent Document 5 requires a photoresist development step, which necessitates a liquid layer process. Also, as in Patent Document 4, it is necessary to scan and irradiate the entire large area in order to create a mask. It is very disadvantageous for the pattern composition.

The present invention solves these problems of the prior art, and does not use a photosensitive resin, photomask, photoresist, etc., and prints by forming an etching mask by a simple process that does not have a liquid layer process. An object of the present invention is to provide a printed wiring board manufacturing method capable of manufacturing a wiring board by a simple method.

In order to achieve this object, in the present invention, in the printed wiring slope manufacturing method, a photosensitive resin is not used in the process of forming an etching mask on a substrate in which a conductive metal thin film is bonded on an insulating resin. A resin film highly resistant to the etching solution is used. The thickness of the film is not particularly considered, and is selected based on ease of handling and high resistance.

In the configuration of the present invention, an etching mask resin film having a peelable adhesive layer is bonded on a substrate having a conductive metal thin film bonded on an insulating resin, and ultraviolet laser light is focused on the etching mask resin film. The etching mask resin film is cut and removed until it reaches the metal thin film by scanning the convergence point of the ultraviolet laser light along the periphery of the portion where the metal thin film is etched away corresponding to a desired printed wiring pattern. Then, the etching mask resin film is peeled and removed from the portion to be etched to create an etching mask.
According to this configuration, an etching mask is formed by direct drawing on an etching mask resin film without using a photosensitive resin, a photomask, a photoresist, etc., so that an expensive photosensitive resin and an exposure mask are not required. A highly accurate pattern can be easily formed. In addition, a mask with an aspect ratio of 1 or more can be formed, and a fine pattern can be created.
Further, an etching mask can be formed by a simple dry process that does not use a liquid resin process that does not require a photosensitive resin, a photomask, a photoresist, or the like and does not require a development process.

In addition, an etching mask resin film having a peelable adhesive layer is adhered on a substrate having a conductive metal thin film adhered on an insulating resin, and ultraviolet laser light is converged on the etching mask resin film to obtain a desired print. The entire portion where the metal thin film is removed by etching corresponding to the wiring pattern is scanned by removing the etching mask resin film until reaching the metal thin film by scanning the convergence point of the ultraviolet laser beam with the convergence spot width. A part of the etching mask resin film is peeled and removed to form an etching mask. In this case, it is possible to scan with the convergence spot width by scanning a plurality of times over the entire portion where the convergence point of the ultraviolet laser beam is removed by etching.

The etching mask resin is selected from any one of polyester, polyimide, polypropylene, vinyl chloride, polyethylene terephthalate (PET), vinyl chloride, an organic material containing a benzene nucleus or a naphthalene nucleus. Further, the adhesive layer is selected from any one of acrylic, silicon, and synthetic rubber adhesive materials. These etching mask resins are highly resistant to the etching solution, and the thickness of the etching mask resin film does not need to be particularly considered. Therefore, the etching mask resin film can be selected with ease of handling and high durability.

The ultraviolet laser is a 266 nm pulse laser that is the fourth harmonic of a Q-switched Nd-YAG or Nd-YVO ₄ infrared laser, and the etching mask resin can process the pulse energy of the pulse laser, and the metal thin film cannot be processed. Set to a possible level.

According to the present invention, since a printed wiring circuit is formed by forming an etching mask directly on an etching mask resin film without using a photosensitive resin, a photomask, a photoresist, etc., an expensive photosensitive resin is used. In addition to eliminating the need for an exposure mask, it is possible to easily form a highly accurate pattern.
In addition, a mask with an aspect ratio of 1 or more can be formed, and a fine pattern can be created. Further, the etching mask resin is highly resistant to the etching solution, and the thickness of the etching mask resin film does not need to be considered in particular. Therefore, the etching mask resin film can be selected with ease of handling and high durability.
Further, an etching mask can be formed by a simple dry process that does not use a liquid resin process that does not require a photosensitive resin, a photomask, a photoresist, and the like, and that does not require development processing.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 2 shows an embodiment of a laser scanning optical system used in the method for producing a printed wiring board according to the present invention. The laser 11 is an ultraviolet laser light source, for example, a laser that uses 266 nm, which is the fourth harmonic of an Nd-YVO ₄ infrared laser, and its output beam 12 is guided by a folding mirror optical system 13 and is Y-axis galvano Scanning is performed by the scanner optical system 14 and the X-axis galvano scanner optical system 15, and the substrate 17 is irradiated by the fθ lens 16. Since the scanning range of the Y-axis galvano scanner optical system 14 and the X-axis galvano scanner optical system 15 is not wide, the substrate 17 is moved by a stage (not shown) to connect the scanning range.

FIG. 3 is a block diagram showing a procedure for forming a desired circuit pattern for laser drawing in order to etch away the metal thin film on the insulating resin corresponding to the desired printed wiring pattern in the present invention. First, a desired circuit pattern is designed using CAD, and a CAD drawing is created using CAD data as a file 21 in the DXF format. Only the drawing vector code 22 is extracted from the file data in the DXF format, and interpolation calculation is performed in accordance with the drawing to create the interpolation data 23. This data is passed through the D / A converter 24 to control the X and Y galvano scanner axes of the Y-axis galvano scanner optical system 14 and the X-axis galvano scanner optical system 15 shown in FIG. / OFF control signal 25 is created. A desired circuit pattern is drawn by moving the substrate 17 in FIG. 2 by laser drawing on the X and Y galvano scanner axis control signals and the drawing laser ON / OFF control signal 25 while moving on the stage.

FIG. 1 is a cross-sectional side view showing an example of a process of forming an etching mask by laser direct drawing using the laser scanning optical system of FIG. 2 and the procedure for forming the desired circuit pattern of FIG. 3 for laser drawing. It is.

In FIG. 1A, a substrate 1 is obtained by attaching a copper foil 2 to a polyimide base film 3. As shown in FIG. 1B on the substrate 1, as an etching mask resin film 4, an existing plating mask film using a silicone adhesive as an adhesive layer 6 and a polyester resin 5 as a resin layer, for example, Sumitomo Adhere 851A manufactured by 3M. As the etching mask resin, in addition to polyester, any of organic materials including polyimide, polypropylene, vinyl chloride, polyethylene terephthalate (PET), vinyl chloride, benzene nucleus, or naphthalene nucleus can be used. In particular, most engineering plastics containing benzene nuclei can be used.

Next, as shown in FIG. 1 (c), the laser light 11 to 266 nm ultraviolet laser light 7 is applied to the etching mask resin film 4 on the etching mask resin film 4 side of the substrate 1 to which the etching mask resin film 4 is bonded. The portion of the copper foil 2 to be etched away at the position corresponding to the desired printed wiring pattern while controlling the control signal applied to the Y-axis galvano scanner optical system 14 and the X-axis galvano scanner optical system 15 according to the CAD pattern By scanning along the periphery of the etching mask, the etching mask resin film 4 around the site where the copper foil 2 that is the irradiated site 8 of the 266 nm ultraviolet laser light 7 is to be removed by etching is evaporated. Since the etched portion is always a closed figure, the 266 nm ultraviolet laser light 7 is scanned in two dimensions along the XY axes of the Y-axis galvano scanner optical system 14 and the X-axis galvano scanner optical system 15 so as to trace the periphery of the etched portion. Scanning is performed by a converging optical system using a combination of the galvano scanner and the fθ lens 16. In this case, scanning may be repeated a plurality of times according to the thickness of the etching mask resin film 4 and the output of the 266 nm ultraviolet laser light 7.

At the time of laser irradiation, the pulse energy is controlled to process the resin film of the etching mask resin film 4, but it is necessary to set the conductive metal thin film 2 on the substrate 1 to a level that is not processed. In this example, the pulse energy of the 266 nm ultraviolet laser beam 7 was set to 15 μJ or less so that the copper foil 2 and the polyimide base film 3 of the substrate 1 were not damaged.

When all the scans are completed, as shown in FIG. 1D, the entire periphery 9 of the etching site on the substrate 1 is cut off. Then, the etching mask 10 was created by peeling and removing the etching mask resin film 4 from which the etching site was separated. By etching the substrate 1 on which the etching mask 10 is formed in this manner by a well-known etching method, a printed wiring board in which printed wiring or the like is formed on the substrate is manufactured.

By finely changing the signal gain to the two-dimensional galvano scanner on the XY axes, the processing pattern size can be finely adjusted. In particular, when drilling has been performed in advance, if a signal gain is determined by recognizing a guide pattern, highly accurate pattern matching is possible.

In the case of a fine pattern, the etching mask may be formed by evaporating and removing the film by scanning the entire etching portion with the convergent spot width of the ultraviolet laser light, not the periphery 9 of the etching portion of the etching mask resin film 4. it can. In addition, scanning with a desired convergence spot width can be performed by scanning a plurality of times. No photomask is required.

The ultraviolet laser used for pattern formation needs to evaporate and remove the engineering plastic used as the etching mask resin film 4, and a wavelength of 300 nm or less is essential. Laser light having a wavelength of 300 nm or more has a low absorptance relative to engineering plastics in general. Therefore, when laser light is irradiated, thermal processing is performed in which the temperature of the material increases. As a result, the etching mask resin film 4 is melted by the heat effect, and it is difficult to form a fine pattern.
On the other hand, at a wavelength of 300 nm or less, absorption directly occurs in the molecular bond constituting the etching mask resin, and a photolysis reaction occurs. Therefore, since heat generation is extremely small, the melting is small and a fine pattern can be formed. This is achieved by using 266 nm laser light, which is the fourth harmonic of the Q-switched Nd-YAG, Nd-YV _O 4 laser.

A KrF excimer laser beam having a similar wavelength and having a wavelength of 248 nm cannot be used in the present invention. Since the excimer laser has poor convergence, it is essential to use a mask for pattern exposure, which does not meet the object of the present invention in which no mask is used. Also, it is extremely difficult to create a pattern that only processes the periphery of the pattern.
Also, the carbon dioxide laser that is most often used for general laser processing can be processed by resin, but is heat processing due to temperature rise, and the resin is burned and removed. In this case, the influence of heat is large and the convergence spot is as large as about 100 μm, so that it cannot be used to create a fine pattern.

Sectional side view which shows an example of the process for carrying out the laser direct drawing of the method of forming the etching mask for forming a desired circuit pattern in the manufacturing method of the printed wiring board by this invention The conceptual diagram which shows the Example of the laser scanning optical system used for the manufacturing method of the printed wiring board by this invention The block diagram which shows the procedure for forming the desired circuit pattern for laser drawing in the manufacturing method of the printed wiring board by this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Copper foil 3 Polyimide base film 4 Etching mask resin film 5 Polyester resin 6 Adhesive layer 7 266 nm ultraviolet laser light 8 Irradiation site 9 Periphery of etching site 10 Etching mask 11 Laser 12 Output beam 13 Folding mirror optical system 14 Y-axis galvano Scanner optical system 15 X-axis galvano scanner optical system 16 fθ lens 17 Substrate 21 DXF format file 22 Drawing vector code 23 Interpolation data 24 D / A converter 25 ON / OFF control signal of drawing laser

Claims (6)

An etching mask resin film having a peelable adhesive layer is bonded on a substrate having a conductive metal thin film bonded on an insulating resin, and an ultraviolet laser beam is focused on the etching mask resin film to obtain a desired printed wiring pattern. The etching mask resin film is cut and removed until it reaches the metal thin film by scanning the convergence point of the ultraviolet laser beam along the periphery of the portion where the metal thin film is etched away corresponding to the etching of the portion to be etched A method for producing a printed wiring board, wherein an etching mask is prepared by peeling off a mask resin film. An etching mask resin film having a peelable adhesive layer is bonded on a substrate having a conductive metal thin film bonded on an insulating resin, and an ultraviolet laser beam is focused on the etching mask resin film to obtain a desired printed wiring pattern. The entire portion of the metal thin film to be etched away is scanned by removing the etching mask resin film until it reaches the metal thin film by scanning the convergence point of the ultraviolet laser beam with a convergence spot width, and etching the portion of the portion to be etched. A method for manufacturing a printed wiring board, comprising: removing an etching mask resin film to create an etching mask. 3. The method for manufacturing a printed wiring board according to claim 2, wherein scanning is performed with a convergent spot width by scanning a plurality of times over the entire portion where the convergence point of the ultraviolet laser beam is etched away. The etching mask resin is any one of organic materials containing polyester, polyimide, polypropylene, vinyl chloride, polyethylene terephthalate (PET), vinyl chloride, benzene nucleus or naphthalene nucleus. A method for producing a printed wiring board according to claim 1. The method for manufacturing a printed wiring board according to any one of claims 1 to 3, wherein the adhesive layer is any one of an acrylic-based, silicon-based, or synthetic rubber-based adhesive material. The ultraviolet laser is a 266 nm pulse laser that is the fourth harmonic of a Q-switched Nd-YAG or Nd-YVO ₄ infrared laser, and the etching mask resin can process the pulse energy of the pulse laser, and the metal thin film can be processed The method for manufacturing a printed wiring board according to any one of claims 1 to 3, wherein the level is set to an impossible level.