JPH0476984A - Method for producing a three-dimensional molded product having a three-dimensional conductive circuit on its surface - Google Patents

Abstract

PURPOSE:To transfer a circuit pattern to the surface of a stereoscopic molded form by exposing through a photomask when a conductive circuit is formed on the form. CONSTITUTION:A photomask formed with a circuit pattern by feeding normal temperature curable epoxy resin mixed with fluorescent substance in a circuit pattern forming groove is formed. On the other hand, a circuit forming stereoscopic molded form is injection molded by using plating resin composition, and copper-plated on the entire surface. The photomask is engaged closely therewith, irradiated with an ultraviolet ray to expose the circuit pattern, developed, and exposed at the plated part except the circuit. The copper of the part is melted and removed. Thus, a metallic conductive circuit can be formed on the stereoscopic surface.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for accurately forming a three-dimensional conductive circuit on the surface of a three-dimensional molded product, and is used as a circuit component in the fields of electrical and electronic equipment. The present invention relates to a method for efficiently manufacturing a three-dimensional molded article having a three-dimensional conductive circuit on its surface.

[Prior art and its problems] Conventionally, methods for forming a three-dimensional circuit on the surface of a three-dimensional molded product include, for example, the SKW method using two types of materials with different adhesion properties to metals, or the PCK method. However, these methods require two molding steps, which are not only complicated and uneconomical, but also make it difficult to improve the adhesion between the two resin interfaces, requiring a high degree of airtightness. This is a problem in the case of pan-cages for electronic components and the like. In addition, due to poor adhesion between the two resins, the plating liquid that penetrated during the plating process may remain at the interface, which may later cause corrosion of the circuit metal and cause serious problems, so strict control of molding conditions is required. . Furthermore, with this method, there is a limit to the width of the circuit that can be formed, and at the same time, the clarity of the circuit edges is poor, and there are also problems with the accuracy and precision of the circuit.

On the other hand, there is a method in which a planar mask is used for a three-dimensional molded product made by one molding, and a three-dimensional circuit is formed on the three-dimensional surface by an additive method or a subtractive method, but in this method, the recesses of the molded product and the mask Because there is a gap between them, the circuit pattern drawn on the mask cannot be accurately projected onto the inner bottom or side surfaces of the recess, resulting in poor circuit edge accuracy. In this case, it was impossible to accurately transfer the circuit pattern on the mask.

[Means to solve the problem]

Therefore, the present inventors solved these problems by using an additive method or a subtractive method on the surface of a three-dimensional molded product that was molded in a single molding process without performing two-stage molding. As a result of intensive study on methods for forming three-dimensional circuit patterns, the present invention has been arrived at, and has made it possible to form highly accurate minute circuits.

That is, the present invention provides a method for forming a conductive circuit on the surface of a three-dimensional molded product by an additive method or a subtractive method. The circuit pattern is transferred to the surface of the three-dimensional molded product by fitting a photomask having a pattern of the same shape as the circuit pattern to be applied to the molded product and exposing it to light through the photomask,
This is a method for manufacturing a three-dimensional molded product having a three-dimensional conductive circuit on its surface.

The present invention is a material to which metal can be bonded by plating or the like. For example, a metal film is formed in advance on the surface of a three-dimensional substrate or component made by injection molding by a method suitable for the material, and then electrodeposited on this. A photoreactive etching resist is applied by painting or the like, and the circuit pattern is exposed through a three-dimensional (e.g., male) circuit pattern exposure photomask that accurately fits onto the surface of the three-dimensional molded product. However, this is a method for manufacturing a three-dimensional three-dimensional molded circuit, which is characterized in that the circuit is transferred and formed onto a three-dimensional molded article by a conventional semi-additive method or subtractive method. The sensitivity of the Unoting resist differs depending on whether the circuit pattern area and the non-pattern area transferred to the molded product using this method are exposed or not, and are distinguished from the exposed reaction area, so post-processing leaves a metal film only on the pattern area. This makes it possible to form a conductive circuit in the molded product.

The material of the three-dimensional molded product used here may be either thermoplastic resin or thermosetting resin, as long as it is a material that can adhere a strong metal film by plating, sputtering, or other methods. Considering that it will be subjected to severe processing such as soldering later, it is preferable to use a material with high heat resistance and excellent mechanical strength, and from the viewpoint of mass production, thermoplastic resin is preferable. Examples include aromatic polyester, polyamide, polyacetal, polyphenylene sulfide, polysulfone, polyphenylene oxide,
Polyimide, polyetherketone, polyarylate, etc. are preferred, but the material is not limited thereto.

Next, the shape of the photomask used in the present invention is such that at least the circuit forming part of the target molded product closely fits and joins, for example, the cavity of the mold used for molding the injection molded product. A mold with the same three-dimensional shape is preferable.

Such a shape may be formed by injection molding, vacuum forming, compression molding, casting, or other conventionally known molding methods for thermosetting resins or thermosetting resins, or may be formed by cutting.

Next, the material for forming the photomask of the present invention needs to be able to transmit exposure light, and in this respect, a transparent material is preferable, and it must be at least a semi-transparent material.

From this point of view, substrates used for photomasks include silicone resins, acrylic resins, epoxy resins, polycarbonate resins, polyester resins, polystyrene resins, etc., but there is no need to limit them to these as long as they are transparent. do not have. Moreover, glass can also be used.

Next, it is preferable that the material forming the photomask of the present invention allows irradiation light to be uniformly dispersed to each part of the three-dimensional surface, and for this purpose, it is preferable to mix an appropriate amount of a light dispersing agent in the photomask material.

Inorganic fine particles are generally used as the light dispersing material to be added to the photomask material for this purpose, such as metal fine particles such as aluminum, mica having a high refractive index, glass powder, glass peas, glass flakes, short glass fibers, etc. It is more preferable that these inorganic fine particles have their surfaces coated with a metallic film to make them bright.

Addition of such a light dispersing agent in an excessive amount will impede transparency, and therefore, although it depends on the substance, the amount of the light dispersing agent added is at most 10% by weight or less, and generally 5% by weight or less, based on the photomask substrate. The combination of such a light dispersing agent has the effect of reflecting or refracting light irradiated from the outside and dispersing it in any direction, and is effective in uniformly exposing the surface of the photomask at all angles. However, some photomask materials themselves have light dispersion properties, and there are cases where it is not necessary to include such a dispersant.

Next, the photomask forms a circuit pattern on its surface,
It is necessary to accurately block (or transmit) only that portion of the exposure to the molded product that fits with this, and distinguish it. Therefore, as a method for forming a circuit pattern on a photomask, the following method is used, for example, in accordance with the conventional additive method or subtractive method.

■ Method of using an emulsion This method uses a photographic emulsion that is used in conventional photomasks such as polyester film and glass, and applies it to a three-dimensional photomask by spraying, vapor deposition, electrostatic coating, etc. After drying, the circuit pattern to be formed is directly drawn using a laser beam, G-line, H-line, I-line, etc. of a high-pressure mercury lamp.

A circuit pattern can then be formed on the surface of a three-dimensional photomask by developing it.

■Dry plating method Using a metal mask, a circuit pattern is formed on the surface of a three-dimensional photomask using conventional methods such as vacuum evaporation, sputtering, and ion blasting. In this case, the patterned portion may be a thin film that does not transmit light. It doesn't require much adhesion.

■ Casting, injection molding, or cutting method Casting, injection molding, or cutting is performed to create a recess corresponding to the circuit pattern on the photomask surface, and resin or glass mixed with colored or fluorescent material is poured into the recess. After that, the surface is leveled to form a circuit pattern that does not transmit light such as ultraviolet rays. Note that the resin composition used at this time may be an epoxy resin or the like before curing.

By fitting the photomask created as described above to a three-dimensional molded product and exposing it to light, the circuit pattern on the surface of the photomask is accurately transferred to the three-dimensional molded product, and the reaction that coats the surface of the molded product is A yin and yang identification corresponding to a circuit pattern is formed on the molded article in response to the etching resist, and when this is converted into a metal film by a conventional method, a metal circuit is formed. Incidentally, regardless of whether the circuit pattern is a positive or negative image, it is possible to metalize the circuit portion using a suitable method.

〔Effect of the invention〕

According to the present invention, it is possible to accurately form a three-dimensional circuit on the surface of a three-dimensional molded product of any shape, and unlike those formed by two-stage molding, the circuit parts manufactured by this method are two-dimensional. Since there is no resin interface, there are no various problems caused by this, and since only one molding process is required, which is relatively costly, considerable cost reductions can be expected.

Furthermore, in terms of circuit width accuracy, the photomask is in complete contact with the exposed object, so even fine-line and dense circuits can be
It has the advantage of being able to pattern accurately and clearly and uniformly exposing even the sides parallel to the incident light.

〔Example〕

Examples of the present invention are shown below, but the present invention is not limited thereto.

Example 1 0.0% aluminum fine powder added to room temperature curable epoxy resin
The mixture was mixed uniformly at 1% by weight, and cast and cured into the shape shown in FIG. Next, this recessed part (circuit pattern forming groove) 2
A photomask with a circuit pattern was created by pouring a room-temperature curable epoxy resin mixed with a fluorescent substance into the photomask (Figure 2).

On the other hand, a three-dimensional molded product 4 for circuit formation shown in FIG.
It is injection molded using a metal-adhesive (plating property) resin composition mainly composed of
Electrodeposition type photoetching resist ([Sonne EDUV6
01 J (trade name, manufactured by Kansai Paint Co., Ltd.) was painted. The photomask shown in FIG. 2 was tightly fitted onto this as shown in FIG. 4, and ultraviolet rays were irradiated to expose the circuit pattern.

Next, the photomask was removed, and the circuit pattern was developed using a predetermined method to expose the plating area other than the circuit.

This was immersed in sodium persulfate to dissolve and remove the copper in areas other than the circuit, and was further washed with water to completely remove the adhering chemicals. In this way, a molded article (FIG. 5) having a metallic conductive circuit 5 accurately formed on its three-dimensional surface was obtained.

Example 2 A cylindrical object made of polycarbonate (which fits tightly into the circuit-forming molded part) was made (Fig. 6) with 0.05% by weight of fine aluminum powder evenly mixed therein, and an ion beam was applied to the side surface of this object. Metallic chromium was deposited by rating. Next, a negative-type etching resist ("Sonne EDUV376 J trade name, manufactured by Kansai Paint ■") was applied by electrodeposition, and after drying, the cylindrical photomask was rotated as shown in FIG. 7(a). A spiral laser beam was scanned from A to B to form a spiral exposure pattern on the photomask surface (Figure 7 (c)).Next, development was performed using a prescribed method to etch only the portion that would become the circuit pattern. The resist was left and the chromium was exposed.This was immersed in a 10% hydrochloric acid solution to dissolve the exposed chromium.Finally, the etching resist was removed by a prescribed alkaline treatment.
This was used as a photomask for forming a conductive circuit.

Next, a cylindrical molded product (Fig. 8) was made by injection molding using a metal-adhesive (plating) resin composition mainly composed of liquid crystal polymer (trade name "Vectra", manufactured by Polyplastics ■). This inner surface is fully plated with copper using a predetermined method, and then a positive photo-etching resist ([
Sonne EDUV601 J product name, manufactured by Kansai Paint ■)
was painted. After drying, it was closely fitted with the polycarbonate mold body photomask and irradiated with ultraviolet rays (FIG. 9). At this time, in order to increase exposure efficiency, a mirror 6 was placed under the photomask to utilize reflected light from below.

Next, the photomask was removed and developed using a predetermined method to remove the resist other than the circuit area, and then immersed in a ferric chloride solution to dissolve the exposed copper plating. Finally 3
% sodium hydroxide solution to remove the etching resist on the circuit section. In this way, a molded product (FIG. 10) in which a spiral conductive circuit was formed on the inner surface of a cylindrical molded product was obtained.

[Brief explanation of drawings]

FIG. 1 shows an example (Example 1) of the photomask shape (before circuit pattern formation) used in the present invention. FIG. 2 shows the shape of a circuit pattern formed on the photomask shown in FIG. FIG. 3 shows the shape of a three-dimensional molded product for forming a metal circuit. FIG. 4 shows an exposure process in which the photomask of FIG. 2 is fitted to the three-dimensional molded product of FIG. 3. FIG. 5 shows a molded product in which a metal circuit is formed on the surface of the three-dimensional molded product shown in FIG. FIG. 6 shows another example (Example 2) of the photomask shape (before circuit pattern formation) used in the present invention. 7A and 7B show a state in which a spiral circuit pattern is formed on the photomask of FIG. 6, and a photomask provided with a spiral circuit pattern. FIG. 8 shows the shape of a cylindrical three-dimensional molded product for forming a metal circuit. FIG. 9 shows an exposure process in which the photomask shown in FIG. 7(b) is fitted to the three-dimensional molded product shown in FIG. FIG. 10 shows a molded product in which a metal circuit is formed on the surface of the three-dimensional molded product shown in FIG. Molded products for photomasks Grooves for circuit pattern formation Three-dimensional molded products for circuit formation Metal conductive circuit mirrors

Claims (1)

[Claims] 1. When a conductive circuit is formed on the surface of a three-dimensional molded product by an additive method or a subtractive method, it has a three-dimensional shape that closely fits the molded product, is transparent or at least translucent, A surface characterized in that a photomask having a pattern of the same shape as a circuit pattern to be applied to a molded product is fitted onto the molded product, and the circuit pattern is transferred to the surface of the three-dimensional molded product by exposure through the photomask. A method for manufacturing a three-dimensional molded product having a three-dimensional conductive circuit. 2. The method for producing a three-dimensional molded article according to claim 1, wherein the material forming the photomask is composed of a composition containing a light dispersing agent. 3. The method for producing a three-dimensional molded article according to claim 2, wherein the light dispersing agent is inorganic fine particles. 4 The light dispersing agent is one or more inorganic fine powders selected from metal powder, mica powder, glass powder, glass beads, short glass fibers, and glass flakes, or fine particles having specular luster whose surfaces are coated with metal. The method for producing a three-dimensional molded article according to claim 2 or 3. 5 The substrate forming the photomask is silicone resin,
The method for producing a three-dimensional molded article according to any one of claims 1 to 4, wherein the material is an acrylic resin, an epoxy resin, a polycarbonate resin, a polyester resin, a polystyrene resin, or a glass. 6. The method for producing a three-dimensional molded article according to any one of claims 1 to 5, wherein the three-dimensional molded article is made of a thermoplastic resin or a thermosetting resin capable of forming a metal film.