JPH05283842A - Manufacture of plastic molding having patterned metal layer - Google Patents

Abstract

PURPOSE:To enable the manufacture of a three-dimensional plastic molding having a micropatterned metal layer by using a liquid photoresist as the etching resist. CONSTITUTION:A molding 1 is formed from a molding material, degreased from the whole outer face, and then dipped in a chromic/sulfuric etchant to coarsen the face. After rinsing, electroless copper plating is conducted to precipitate copper as a metal layer 4. After soft etching and rinsing are conducted with a 10% persulfuric soda + 5% sulfuric solution, a positive type photoresist is applied by dipping. At this time, it is used by dilution so that viscosity may be 15cps. It is exposed to light by using an ultrahigh pressure mercury vapor lamp after drying, developed, rinsed, postbaked, and etched with a ferrous chloride etchant. Finally, it is dipped in peeling solution to peel off the resist, resulting in completion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a plastic molded product such as a casing, a circuit board, a circuit component, a connector, an electromagnetic shield component, etc., the surface of which is partially covered with metal by plating or the like.

[0002]

2. Description of the Related Art Recently, what is called an injection molded circuit board (hereinafter referred to as MCB) and an injection molded circuit component (hereinafter referred to as MID) in which an electric circuit pattern is provided on the surface of a plastic molded product brings downsizing and cost reduction. Is expected to be. This is, for example, in JP-A-63-50.
As described in Japanese Patent Application Laid-Open No. 482 and Japanese Patent Application Laid-Open No. 1-207989, a metal pattern is formed on a three-dimensional surface, and it is not limited to a lithographic plate like a conventional printed wiring board and can be applied to any shape. Is a feature.

The manufacturing method described in the above publication is called a two-time molding method and is a plastic material (hereinafter referred to as an easily-platable material) that can be easily electroless plated to form a primary molded product corresponding to a skeleton. After that, a plastic material that is difficult to electrolessly plate (hereinafter referred to as a hard-to-plate material) is injected into the outer surface of the primary formed product that does not require plating. A method of plating the exposed portion of the conductive material is usually used.

For example, a metal pattern 4 as shown in FIG.
A method of manufacturing the plastic molded product 40 having 4 on the surface will be described. 5A to 5C are cutting lines X- of FIG.
Corresponds to the X cross section. First, in FIG. 5A, the primary molded body 20 is molded from the easily-platable material 2. Primary compact 2
0 has a concave portion 21 between convex portions 22 whose tops are flat,
Further, it has a hole 25 penetrating the back surface. Then, in the mold for secondary molding that accommodates the primary molded body 20 with the convex surface 22 of the primary molded body 20 as the outer surface, the difficult-plating material 3 is injected into the concave portion 21 and the surface 23 on the opposite side. Figure 5
A secondary molded product 30 having a cross section as shown in (B) is formed. In the secondary molded product 30, the recess 21 and the back surface described above are filled with the non-plating material 3, and the surface of the projection 22 and the hole 25 are exposed. When the surface of the secondary molded product 30 is plated, a plastic molded product 40 having a metal pattern 44 on the surface is manufactured as shown in FIG. 5 (C). The metal layer 44 is formed only on the exposed surface of the easily-platable material 2 (the convex portion of the primary molded body 20 and the hole 25). Thus, the plastic molded product 40 having the metal pattern 44 as shown in FIG. 4 can be obtained. In this case, the pattern width and spacing are determined by injection molding.

Further, there is a "resistless printing" full addit method which is found in JP-A-61-113295. This is a method in which a photosensitive catalyst is applied to the entire surface of which the adhesion has been improved, the catalyst is printed in a specific pattern by exposure to ultraviolet light, and then a metal layer is formed on that portion by electroless plating. Since this method uses a photographic method, it can be made finer than the former.

[0006]

On the other hand, in the conventional printed board, miniaturization is rapidly progressing and the printed wiring board has a size of 0.2 m.
m or less is also generalized, and 0.1 mm or less is required. Under such circumstances, miniaturization is being demanded also in MCB and MID.

However, in the above-mentioned double molding method, the pattern width interval is 0.4 mm because it is formed by injection molding.

In addition, since the "resistless printing" full additive method uses a photographic method, further miniaturization can be achieved.
There are problems such as the resolution of the photosensitive catalyst and the lateral growth of plating due to resistless and abnormal deposition.
Is the limit.

Therefore, the molded product also requires a manufacturing method using the photoresist method. However, the existing photoresist method cannot be applied to a three-dimensional shape because both the plating resist and the etching resist are for flat plates.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a method for producing a plastic molded product having a fine patterned metal layer on a three-dimensional plastic molded product.

[0011]

SUMMARY OF THE INVENTION The gist of the present invention is that a circuit is formed by an etching method using a liquid photoresist and an electrodeposition resist which can be applied to a three-dimensional shape as an etching resist, As a result, a method for producing a plastic molded product having a finely patterned metal layer on a three-dimensional plastic molded product is made possible.

That is, the above-mentioned object of the present invention is to form a patterned metal layer by molding a plastic molded article, roughening the surface and applying a metal plating layer thereon, and forming a patterned metal layer by a photoresist method. In the method for producing a plastic molded product having, a plastic molded product having a patterned metal layer, characterized in that the plastic molded product has a three-dimensional structure with an uneven plating material as a component and a liquid photoresist is used as the etching resist. Method of manufacturing goods.

In a method for producing a plastic molded article having a patterned metal layer in which a plastic molded article is molded, the surface is roughened, a metal plating layer is applied thereon, and a patterned metal layer is formed by a photoresist method, This is achieved by a method for producing a plastic molded product having a patterned metal layer, which is characterized in that an electrodeposition resist is used as the etching resist.

In the present invention, the easy plating material means a plastic material which can be easily electroless plated. The easily platable material is selected according to the rigidity and dimensional stability required for the molded product and the heat resistance and electrical characteristics, but so-called engineering plastic is usually suitable. For example, polycarbonate, ABS resin, polyetherimide, polysulfone, polyethersulfone, polyphenylene sulfide liquid crystal polymer and the like are preferable. Alternatively, a thermosetting resin such as phenol resin, epoxy resin or diallyl phthalate resin may be used. A filler such as glass fiber, potassium titanate fiber, or calcium carbonate may be added to these resins. Since a metal layer is formed on the surface, it is easily attacked by a specific solvent, chemicals, etc. and is likely to be roughened, and a low molecular weight component may be added to the above resin, or a rubber component such as butadiene rubber may be added. In addition, palladium that serves as a catalyst for performing electroless plating,
In some cases, precious metals such as gold and silver are added.

Molding of the plastic molded article in the present invention is carried out by processing such as injection molding, compression molding, extrusion molding and cutting depending on the material.

The roughening of the surface of the plastic molded product in the present invention requires roughening of the surface of the molded product in order to give a sufficient adhesion of the metal layer to the molded product. First, stains such as a release agent and oil adhered to a molded product are removed with an alkaline cleaner, a surfactant, an organic solvent and the like. Next, the surface is roughened using an etching solution such as chromic acid / sulfuric acid, potassium hydroxide, hydrofluoric acid / nitric acid, and ammonium acid fluoride / nitric acid.

When a catalyst is added to the plastic material in advance, the plating process is started as it is.

The catalyst used here is VI of the 5th column of the periodic table.
Compounds of Group II metals, such as halides, are preferred. A specific example is palladium chloride.

When the catalyst is not applied in advance, a pretreatment step of applying the catalyst may be added after the surface roughening. As a method of applying a catalyst, a catalyst-accelerator method, that is, after immersing in a mixed catalyst solution of a metal such as palladium or tin, it is activated with an acid such as hydrochloric acid or oxalic acid to give a roughened surface of the secondary molding material. On the metal pattern forming part of the secondary molding material roughened with a strong reducing agent such as stannous chloride, hydrazine chloride, hypophosphorous acid, etc. After the adsorption, there is a method of precipitating the noble metal by immersing it in a catalyst solution containing noble metal ions such as palladium and gold.

After the pretreatment, copper, nickel or the like is plated by electroless (chemical) plating.

When a metal layer is used as a wiring portion of an electric circuit pattern, a copper layer is generally formed.

It should be noted that the first plating is electroless plating of 5 μm.
Of course, it does not matter if a thinning of m or less is performed and then a predetermined thickness is formed by electroplating.

Next, a circuit pattern is formed by etching. First, an etching resist is applied.

As the etching resist in the present invention, a screen printing method, a dry film method (photosensitive) is generally used, and also in the case of the molded product, it can be used when the coating portion is limited to a flat surface. However, it cannot be applied to a three-dimensional shape having irregularities, and a liquid photoresist is required. Liquid photoresists include, for example, weak alkaline development type (former) and solvent development type (latter) as found in PER-20 series and PER10 series made by Taiyo Ink. It is necessary to use properly depending on the influence. Also, Tokyo Chemical's PMER-N type, PME
As seen in the RP type, there are a negative type (the former) and a positive type (the latter). Generally, a positive type is suitable when there are many recesses (including through holes), but this is not always the case.

This is because in the case of non-uniformity, the resolution for exposure differs depending on the location, making it impossible to draw a pattern having uniform pattern width intervals.

Generally, there are a roll coater method, a dip method, a spray method, a Wheeler method (spinner method), an electrostatic coating method, etc., and it is necessary to use them properly depending on the shape. If the shape of the plastic molded product is complicated, the dip method, spray method, or electrostatic coating method is suitable. It is necessary to adjust the viscosity of each resist with a predetermined diluting liquid according to the shape of the plastic molded product and the coating method, and apply the resist as uniformly as possible. Further, it may be applied thinly at several times instead of being thick at a time.

If the shape of the plastic molded product becomes complicated, it becomes difficult to apply even the liquid photoresist evenly due to liquid dripping, liquid retention in the concave portion, liquid crevice at the edge portion, and the like. In such a case, electrodeposition resist (photosensitive) is suitable.

Like the liquid photoresist, the electrodeposition resist has a positive type (the former) and a negative type (the latter) as seen in Nippon Paint P-1000 and N-100. As with the liquid photoresist, generally, the positive type is suitable when there are many recesses. For this resist, a method of electrically depositing and coating in a solution is used, which is similar to electroplating called electroplating. This is a substrate (molded product with plating)
There is an anion type electrodeposition (alkaline development type) using as an anode and a cation type electrodeposition (acid development type) using a substrate as a cathode.
Any one may be used as long as it does not affect the developability of the molded article substrate.

Liquid sagging like the liquid photoresist,
It is possible to apply thinly and evenly without worrying about liquid retention or liquid squeezing. However, it should be noted that the potential may be different and the film thickness may be different for a sharp corner (both unevenness). For this reason, it is desirable to add R to the corner portion as much as possible. If possible, R = 1.0 mm or more should be provided, but 0.5 mm is also effective. It should be noted that the addition of this R is effective against liquid retention and liquid crevice even in a liquid photoresist. This is also effective for uniform throwing power to the corners of the plating film when electroplating. Further, it is effective for the contact property of the photomask at the time of exposure.

In the case of the electrodeposition resist, unlike the liquid resist, it can be selectively applied to the portion where the metal layer is provided, which is also advantageous in the final process of removing the resist.

Before applying the resist, a pretreatment for removing rust, stains and the like on the surface of the metal layer and imparting adhesive strength to the resist may be applied to any of the resists. After coating, exposure to development is performed under predetermined conditions to draw a pattern. Further, it is etched with ferric chloride or cupric chloride to form a circuit pattern, and finally the resist is peeled off. After this, if necessary, apply solder resist,
Finish the product by plating nickel, gold, tin, etc.

The molded product is not limited to the plastic material as long as the surface can be roughened and the metal layer can be formed, and may be ceramic or metal coated with an insulating material.

[0033]

EXAMPLE Example 1 The shapes and pattern products shown in FIGS. 1 and 2 were prepared by the following method, and the minimum pattern width and interval of the mask were 0.13 mm. First, a molded product was prepared by injection molding using a polyether sulfone for electroless plating (manufactured by ICI Japan Co., Ltd., Pixtrix PES3608GL20) as a molding material. At this time, the injection molding temperature was 360 ° C and the mold temperature was 150 ° C.

Next, the entire outer surface of the molded product 1 was degreased by a conventional method, immersed in N, N-dimethylformamide for 2 minutes, and then immersed in a chromic acid / sulfuric acid etching solution at a temperature of 60 ° C. for 4 minutes to roughen the surface. Was made. After washing with water, electroless copper plating was performed by a conventional method to deposit copper as a metal layer to a thickness of 30 μm.

Next, as a pretreatment for resist coating, after performing soft etching with a solution of 10% sodium persulfate + 5% sulfuric acid and washing with water, a positive type photoresist (manufactured by Tokyo Ohka Kogyo Co., Ltd.) PMER.P.D40S is formed by a dipping method. It was applied so that the film thickness would be about 6 μm. At this time, dedicated diluent PD
Was diluted to a viscosity of 15 cps. 9
After drying at 0 ℃ for 30 minutes, use an ultra-high pressure mercury lamp to 300
It was exposed at mJ / cm ² , developed with PI-S for 2 minutes, washed with water, post-baked at 120 ° C. for 10 minutes, and then etched with a ferric chloride etching solution. Finally, the resist was peeled off by immersing it in the stripping solution PS at 60 ° C. for 2 minutes.

(Example-2) The procedure of Example-1 was the same except that the spray method was used.

(Embodiment 3) In Embodiment 2, as shown in FIG.
b was rounded with R = 1.0 mm. Everything else was the same.

Example-4 A positive type electrodeposition resist (photosensitive) was used as the etching resist in Example-1.
Nippon Paint P-1000 was applied to a thickness of about 7 μm by the electrodeposition method. The electrodeposition condition was 50 mA / dm in the solution.
² minutes for 2 minutes. After washing with water, drying at 100 ° C x 5 minutes, exposure with a metal halide lamp at 350 mJ / cm ² , and spraying 1% sodium metasilicate at 30 ° C x 2
Minutes of development. Further, etching was performed with a ferric chloride etching solution to form a pattern, and then 5% sodium metasilicate was sprayed at 50 ° C. for 2 minutes to peel off the resist.

All other conditions were the same as in Example-1.

(Example-5) In Example-4, Example-
As in the case of 3, the corners 1a and 1b of the molded product 1 are R = 1.0.
A roundness of mm was added. Further, the bottom surface, which does not require pattern formation, was masked with a Teflon adhesive tape to prevent roughening of the base material, plating and resist coating. Others were exactly the same as in Example-4.

(Example-6) In Example-4, 50% by weight of an inorganic filler was used as the molding material instead of the polyether sulfone.
A "plating grade" liquid crystal polymer (Vectra C. 810, manufactured by Polyplastics Co., Ltd.) containing

The molding conditions were an injection molding temperature of 330 ° C. and a mold temperature of 100 ° C.

Degreasing treatment was carried out in the same manner as in polyethersulfone and then 50 ° C. × 60 in 50% potassium hydroxide solution.
The surface was roughened by immersion for a minute. After washing with water, a catalyst was applied by the catalyst-accelerator method and then a 30 μm copper layer was formed by electroless plating.

Others were the same as in Example-4.

(Example-7) In Example-4, electroplating was used together with the formation of the copper layer. First, electroless plating is applied to a thickness of 5 μm, and then electroplating is applied to a thickness of 25 μm.
Finally, a thickness of 30 μm was formed. All other examples
Same as 4.

(Example-8) Example-3 in Example-7
R = 1.0m at corners 1a and 1b of molded product 1
Rounded m. Everything else was the same as in Example 7.

(Comparative Example-1) In Example-1, a heat-drying type etching resist (X-37 manufactured by Taiyo Ink Mfg. Co., Ltd.) was applied to the resist by screen printing and pattern drawing was performed. Dry at 60 ℃ for 15 minutes and then 100
After carrying out at 7 ° C. for 7 minutes, it was etched with a ferric chloride etching solution in the same manner as in Example-1 to form a pattern. The resist was stripped using 3% NaOH at 40 ° C.

Others are the same as in Example 1.

(Comparative Example 2) In the photosensitive catalyst solution described in JP-A-61-113295 having the following composition after the same molding and pretreatment (roughening) as in Example 1 were carried out. Soak at 50 ° C.

Photosensitive catalyst solution composition: sulfitol 220 g / l 2,6-anthraquinone disulphonic acid 16 g / l disodium salt copper (II) 8 g / l copper (II) bromide 0.5 g / l nonyl Phenoxypolyethoxy ethanol 2.0 g / l Fluoroboric acid Soak in a pH of 3.75 and dry at 50 ° C. for 5 minutes to obtain a radiosensitized coating on the substrate material.

Next, after exposing with a high pressure mercury lamp to obtain copper nuclei, a developer 1 (formaldehyde 1.3 cm / l, PH containing ethylene dinitrilotetraacetate 0.1 mol / l) was used.
It is immersed in a container (12.5 container) for 5 minutes and further in developer 2 (developer 1 from which formaldehyde has been removed) for 5 minutes, followed by washing with water to perform pattern printing with copper nuclei.

After this, a copper layer was formed to a thickness of 30 μm by the electroless plating so as to cover the printed area. No resist was used in this comparative example.

(Comparative Example 3) Polyether sulfone (PES360) was used for the easily plateable resin, which was prepared by the conventional method described in JP-A-63-50482.
8GL20), primary molding was performed, and then secondary molding was attempted using polyphenylene sulfide containing 30% glass fiber (Ube Kogyo GR-6) as the non-plating resin. However, the pattern width is 0.1 for both primary molding and secondary molding.
5 mm and the interval of 0.15 mm could not be molded.

Table 1 shows the quality of pattern formation and the resist releasability of each portion of the plastic moldings obtained in each of the examples and the comparative examples by a five-level evaluation. The larger the number, the better the characteristic of the item in question (meaning the middle of 4.5 grade).

Each of the examples of the present invention shows that it is possible to form a fine pattern which is impossible or almost impossible in the comparative example.

[0056]

[Table 1]

[0057]

Industrial Applicability According to the method for producing a plastic molded article having a patterned metal layer of the present invention, a three-dimensional plastic molded article having irregularities having a metal layer of a fine pattern of 0.2 mm or less, which has been impossible in the past, is produced. be able to.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a plastic molded product having a patterned metal layer of the present invention.

2 is a cross-sectional view of the embodiment of FIG.

FIG. 3 is a cross-sectional view in which R is added to 1a and 1b in FIG.

FIG. 4 is a plan view showing an example of a plastic molded product having a patterned metal layer according to a conventional method.

5 is a cross-sectional view (A), (B) showing the manufacturing process of the plastic molded product having the patterned metal layer of FIG.
(C).

[Explanation of symbols]

1, 40 Plastic molded product having patterned metal layer 1A to 1D Surface of plastic molded product having patterned metal layer 1a Corner part (convex) 1b 〃 (concave) 1c Hole 2 Easy-platable material 20 Primary molded product 21 Primary Recessed part of molded body 22 Convex part of primary molded body 25 Hole 3 Difficult-to-plate material 30 Secondary molded product 33 Surface of hard-to-plate material 4,44 Surface of metal layer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideki Asano Inventor Hideki Asano 5-1-1 Hidakacho, Hitachi City, Ibaraki Hitachi Power Systems Laboratory

Claims (2)

[Claims] 1. A method for producing a plastic molded product having a patterned metal layer in which a plastic molded product is molded, the surface is roughened, a metal plating layer is applied thereon, and a patterned metal layer is formed by a photoresist method. 2. The method for producing a plastic molded product having a patterned metal layer, wherein the plastic molded product has a three-dimensional structure having an unevenness with an easily plated material as a component, and a liquid photoresist is used as the etching resist. 2. A method for producing a plastic molded product having a patterned metal layer in which a plastic molded product is molded, the surface is roughened, a metal plating layer is applied thereon, and a patterned metal layer is formed by a photoresist method. 2. A method for producing a plastic molded article having a patterned metal layer, wherein an electrodeposition resist is used as the etching resist.