JPH04332190A - Composite molded product of synthetic resin having patterned metal layer and electromagnetic wave shield - Google Patents

Abstract

PURPOSE:To realize a synthetic resin composite molded product having patterned metal layer and electromagnetic wave shield which do not require to use a plated resist, complicated design of the dies for double molding and procedures such as attachment of metal films and ensures excellent mechanical strength. CONSTITUTION:A synthetic resin composite molded product comprises a metal plate 1 having through holes 2, a first molded body of synthetic resin 3, which does not suitable for electroless plating, filling the through holes 2 and having a groove 3b corresponding to a circuit pattern at the external surface thereof, a second molded body of synthetic resin 4, which is suitable for electroless plating, filling the groove 3b and a patterned metal layer 5 formed on the external surface 4a of the second synthetic resin.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a synthetic resin composite molded product having a patterned metal layer and an electromagnetic wave shield, particularly a synthetic resin composite molded product having a patterned metal layer on the outer surface and an electromagnetic wave shield such as a metal plate. , relates to a synthetic resin composite molded product having a patterned metal layer and electromagnetic shielding.

0002

[Prior Art] In manufacturing methods for synthetic resin molded products having a circuit pattern on the surface, such as wiring boards, methods such as transfer and screen printing have often been used to form the circuit pattern. Since this method is wasteful and costly, a method of forming a patterned metal layer by electroless plating on the surface of a synthetic resin suitable for adhering metals has come to be used. Electroless plating must be performed selectively on areas where a metal layer is required. One method is to perform electroless plating by covering the surface of the synthetic resin in areas that do not require electroless plating with a plating resist.

[0003] Furthermore, as described in JP-A-63-50482 and JP-A-1-207989, a two-step molding method of synthetic resin by injection molding is used, and the surface of the molded product is coated with electroless plating. By primary molding a synthetic resin that can be easily applied, and using this as a skeleton, secondary molding is performed using a resin that is difficult to electroless plate, and electroless plating is applied to the surface of the exposed part of the primary mold. A method has been developed to obtain a predetermined circuit pattern. For the primary molding, for example, a synthetic resin containing a noble metal that serves as a catalyst for electroless plating is used.

This method will be explained with reference to FIG. First, Figure 3
As shown in (A), a convex portion 31a having a flat top;
A primary molded body 31 having a concave portion 31b therebetween is formed of an easily plated material 32, and then a mold including the concave portion 31b of the primary molded body 31 is placed in a mold for secondary molding (not shown). By injecting a material 33 that is difficult to plate into the inner cavity, a secondary molded product 34 having a cross section as shown in FIG. 3(B) is formed. In the secondary molded product 34, the above recess 3
1b is filled with a material 33 that is difficult to plate. After removing the mold and roughening the surface 31c of the secondary molded product 34 where the primary molded body 31 is exposed as shown in FIG. 3(C),
When electroless plating is performed, the metal layer 35 is formed only on the exposed portion 31c of the primary molded body 31 made of the easily plated material 32, as shown in FIG. 3(D). In this way, the plastic composite molded product 3 with the metal pattern
6 is obtained.

[0005] In recent years, electromagnetic interference has been increasing with the increase in electronic devices, so recently, emphasis has been placed on electromagnetic wave shielding of wiring boards, and one way to do this is to use composite molded metal and synthetic resin. has been done. For example, Figure 4
As shown in (A), a metal plate 1 with through holes 2 is placed in a mold 4.
1, and injection molding of synthetic resin 42 is performed. Since the coefficient of thermal expansion of synthetic resin is larger than that of metal, the stress generated due to the difference in coefficient of thermal expansion during the cooling process of the synthetic resin 42 causes
A synthetic resin 42 is fixed to the metal plate 1. And Figure 4 (
As shown in B), the surface of the synthetic resin 42 is partially subjected to electroless plating using a plating resist (not shown),
A metal layer 43 is formed in a pattern.

Another method for electromagnetic shielding of a wiring board is to attach a metal film to the back surface of the wiring board.

[0007]

[Problems to be Solved by the Invention] However, in order to form a patterned metal layer by electroless plating on the surface of a synthetic resin composite-molded with a metal plate as described above, it is necessary to Must be pre-coated with plating resist. The metal plate also needs to be coated with plating resist at least around the synthetic resin. It takes a lot of effort to remove these plating resists after electroless plating.

[0008] On the surface of the composite molded product of metal plate and synthetic resin,
As a method of forming a patterned metal layer without using a plating resist, it is also possible to apply the above two-step molding method to molding of synthetic resin. However, according to this method,
First, a composite of metal and synthetic resin is formed through primary molding, and then secondary molded resin is added to it, so the material that is combined with the metal plate is primarily the primary molded resin, which is a resin that is easy to electroless plate. Therefore, in order to isolate the circuit pattern on the surface from the metal plate, the design of the compact and therefore the mold becomes quite complex.

The method of attaching a metal film to the back surface of a wiring board for electromagnetic shielding requires time and effort to attach the metal film, which increases the cost of electronic equipment. Furthermore, it does not have the same mechanical strength as a composite molded product of a metal plate and a synthetic resin.

Therefore, an object of the present invention is to provide a synthetic resin composite molding having a patterned metal layer and electromagnetic shielding, which does not require the use of a plating resist or the complicated design of a mold for two-step molding. It is to realize the product.

Another object of the present invention is to realize a synthetic resin composite molded product having a patterned metal layer and electromagnetic wave shielding, which does not require the labor of pasting a metal film and has excellent mechanical strength. There is a particular thing.

0012

[Means for Solving the Problems] According to the present invention, there is no need to use a plating resist, no need for complicated design of a mold for two-step molding, and no need for labor such as pasting a metal film. In order to realize a synthetic resin composite molded product that has a patterned metal layer and electromagnetic shielding, and has excellent mechanical strength, it is possible to create a synthetic resin composite molded product that has a patterned metal layer and electromagnetic shielding. and a first synthetic resin molded body made of a first synthetic resin unsuitable for electroless plating (hereinafter referred to as difficult-to-plating resin), which has grooves on its outer surface having a pattern corresponding to a predetermined circuit pattern. , a second synthetic resin molded body made of a second synthetic resin suitable for electroless plating (hereinafter referred to as easy-plating resin) filled in the groove, and an outer surface of the second synthetic resin molded body. A composite molded product of synthetic resin and metal having a patterned metal layer on its surface was constructed so as to be composed of the formed patterned metal layer.

[0013] The type of metal constituting the metal plate etc. can be selected depending on the intended shielding of electromagnetic waves. For example, a highly conductive metal such as copper or aluminum is used for electrostatic shielding, a magnetic metal such as iron is used for electromagnetic shielding, and a composite of these is used for both shields. The size and shape of the through hole are selected depending on the required mechanical strength, electromagnetic wave shielding effect, ease of injection molding of synthetic resin, etc. Metal molded objects such as metal plates are
It can be easily formed into a required shape by plastic working such as rolling or drawing.

[0014] The hard-to-plate resin used in primary molding is required to have rigidity, dimensional stability, and heat resistance, as the primary molded product functions as a core during secondary molding, and electrical properties must also be taken into account. Therefore, it is usually selected from among so-called engineering plastics. For example, polycarbonate, polyetherimide, polysulfone, polyethersulfone, and polyphenylene sulfide are preferred. Alternatively, thermosetting resins such as phenol resin, epoxy resin, diallyl phthalate resin, etc. may be used. Fillers such as glass fiber, potassium titanate fiber, calcium carbonate, etc. may be added to these resins.

[0015] As the easy-plating resin used for secondary molding, the same kind of resin as the difficult-plating resin can be used, but in order to selectively form a patterned metal layer on the surface, the resin is lower than the difficult-plating resin. Is it easy to roughen the surface due to molecular weight?
Use materials that are easily attacked by specific solvents, chemicals, etc., or materials to which catalysts containing noble metals such as palladium, gold, and silver are added. Further, it is preferable that the molding temperature of the easily plated resin is lower than that of the difficultly plated resin from the viewpoint of preventing deformation of the difficultly plated resin.

[0016] The grooves on the surface of the primary composite molded body filled with the easily plated resin are not limited to bottomed grooves, but may be holes that pass through a through hole of a metal plate or the like and penetrate to the opposite surface. . A reverse taper may be provided on the wall surface of the groove. The reverse taper is within a range that does not cause difficulty in primary forming, and is generally preferably 0.1 to 1%. This prevents the easy-plating resin from peeling off and falling off from the difficult-plating resin later even if the adhesion between the difficult-to-plating resin and the easy-plating resin is slightly poor.

[0017] This groove may be formed at the same time as the primary molding, but it may also be formed by machining such as cutting on the primary molded body after the primary molding. Part of the groove may be formed during primary molding, and the remaining part may be formed by processing after primary molding.

In the secondary molding, injection molding can be used as usual to inject the easily plated resin into the grooves of the difficult to plate resin.

Since it is necessary to form a patterned metal layer on the surface of the easily plated resin, the resin is amorphous or has a relatively low molecular weight compared to the hard to plate resin, is easily roughened, or is prepared using a specific solvent, It is preferable to use a material that is easily attacked by chemicals. It is advantageous to use a catalyst to which a noble metal catalyst such as palladium, gold, or silver is added, since it is not necessary to apply a catalyst before electroless plating.

[0020] Electroless plating is used to form a metal layer on the exposed portion of the easily plateable resin on the surface of the secondary composite molded body. Before performing electroless plating, if necessary, a pretreatment of imparting a noble metal catalyst such as palladium, gold, or silver may be performed.

[0021] To roughen the exposed surface of the easily plated resin of the secondary composite molded article, the mold release adhering to the outer surface of the molded article is usually first removed using an alkaline cleaner, a surfactant, an organic solvent, etc. Remove dirt such as chemicals, oil, and dirt. Next, after processing with N,N-dimethylformamide, etc. as necessary, the surface is roughened using an etching solution such as chromic acid/sulfuric acid, calcium hydroxide, hydrofluoric acid/nitric acid, acidic ammonium fluoride/nitric acid, etc. do. Such surface roughening treatment makes it possible to obtain sufficient adhesive strength between the plated layer and the plated layer.

It is preferable to use a synthetic resin to which a plating catalyst has been added in advance as the easily plated resin in order to selectively form a metal layer on the outer surface of the synthetic resin. The electroless plating catalysts to be added include Groups VIII and I of the periodic table.
Elements and compounds of Group B metals, such as copper, silver, gold, nickel, platinum, palladium, rhodium, iridium, or salts and oxides thereof, can be used.

Instead of adding a catalyst for electroless plating in advance, a step of applying a catalyst to the surface may be added after surface roughening. The method for applying the catalyst is the catalyst-accelerator method, in which the resin is immersed in a mixed catalyst solution containing metals such as palladium and tin, and then activated with an acid such as hydrochloric acid or oxalic acid to roughen the surface of the easily plated resin. A method of precipitating palladium etc. on the surface, and a sensitizing-activating method, that is, stannous chloride, hydrazine chloride,
There is a method in which a strong reducing agent such as hypophosphorous acid is adsorbed onto a desired portion of a roughened easily plated resin, and then the resin is immersed in a catalyst solution containing noble metal ions such as palladium or gold to precipitate the noble metal.

After the pretreatment, plating with copper, nickel, etc. is performed using an electroless plating (chemical plating) method. In some cases, copper is electrolessly plated with nickel and then gold. When a metal layer is used as a wiring part of an electric circuit pattern, generally a copper layer or a layer of nickel, gold, solder, etc., alone or in combination, is formed on the copper layer. On the electroless plated layer, a layer of the same or different metal may be further formed by ordinary electroplating using this layer as a conductor (for example, an electroplated nickel layer on an electroless plated copper layer). This method is useful when sufficient thickness of the metal layer cannot be obtained by electroless plating.

The composite molded article of the present invention is useful as a wiring board having electromagnetic shielding.

[0026]

[Effect] The hard-to-plate resin filled into the through holes provided in the metal plate during the first composite molding has a higher coefficient of thermal expansion than the metal, so during the cooling process it contracts more than the metal and becomes stressed. This causes the difficult-to-plating resin to be fixed to a metal plate or the like. Then, grooves are formed in a predetermined pattern on the outer surface, and the grooves are filled with an easily plated resin, so that a patterned metal layer is formed on the surface of this portion by electroless plating. In this way, the easily plated resin was filled in the grooves on the outer surface of the hard to plate resin, and a patterned metal layer was formed on the surface of the easily plated resin.
A composite molded body of metal and two types of synthetic resins is formed. This composite molded body has two metal parts: a metal plate partially embedded inside the synthetic resin, and a patterned metal layer formed on the outer surface of the synthetic resin. The former serves as an electromagnetic wave shield, and the latter is used as a circuit pattern (wiring section).

[0027]

[Examples] Hereinafter, examples will be shown to provide a more specific explanation of the present invention. [Example 1] An example of a composite molded product according to the present invention is shown in Fig. 1 (E
). In FIG. 1(E), a metal plate 1 has a rising portion 1a and a through hole 2, and a hard-to-plating resin 3 is formed so as to close the through hole 2. There is a groove 3b on the upper surface of the difficult-to-plating resin 3, which is filled with the easy-to-plating resin 4, and its outer surface is covered with a metal layer 5. Difficult to plate resin 3 is polyphenylene sulfide containing 30% by weight of glass fiber as a filler.
The easy-plating resin 4 is polyether sulfone (p
olyethersulfone).

The composite molded article 13 shown in FIG. 1(E) is manufactured in the following manner in the order shown in FIG. 1(A) and below. As shown in FIG. 1(A), a metal plate 1 having a through hole 2
is fixed in a mold 6 having a convex portion 6a on the inner surface, and injection molding of the hard-to-plating resin 3 into the cavity 6b of the mold 6 shows that the hard-to-plating resin 3 has no part in the mold, as shown in FIG. 1(B). A groove 3b is formed corresponding to the convex portion 6a on the inner surface of 6. The primary composite molded product 11 is a composite molded product composed of a metal plate 1 and a resin 3 that is difficult to plate. The surface of the hard-to-plating resin 3 other than the groove 3b is designated as 3a. As shown in FIG. 1(C), the primary composite molded product 11 is fixed in the mold 7, and the easily plated resin 4 is
is filled into the groove 3b by injection molding to obtain the secondary composite molded product 12 shown in FIG. 1(D). When electroless plating is performed after performing the necessary pretreatment, a metal layer 5 is formed on the outer surface 4a of the easily plated resin 4 filled in the groove 3b, and the surface becomes as shown in FIG. 1(E). Composite molded product 13 having a metal layer 5 in part
is obtained.

The manufacturing process of the composite molded article 13 is shown in a perspective view in FIG. FIG. 2(A) shows a metal plate 1 having a through hole 2. As shown in FIG. FIG. 2(B) shows a primary composite molded product 11 composed of a metal plate 1 and a hard-to-plating resin 3 (corresponding to FIG. 1(B)). FIG. 2(C) shows a secondary composite molded product 12 in which the easy-plating resin 4 is filled into the grooves 3b (see FIG. 2(B)) of the difficult-plating resin 3 (corresponding to FIG. 1(D)). . FIG. 2(D) shows a composite molded product 13 having a patterned metal layer 5 (FIG. 1(D)).
Corresponds to E). Figures 1 (B), (D), and (E) are shown in Figure 2 (B).
), (C), and (D) along the cutting line I-I. If mechanical strength is not required, the through hole 2 may be made wider.

[Example 2] As the difficult-to-plating resin 3, polyether sulfone (po
The manufacturing method was the same as in Example 1 except that lyethersulfone was used.

[0033]

Effects of the Invention The synthetic resin composite molded product having a patterned metal layer and electromagnetic wave shielding according to the present invention can form a patterned metal layer without using a plating resist, and can reduce the complexity of the mold for two-step molding. No special design is required. Also,
It does not require the effort of attaching a metal film to provide electromagnetic shielding. Since it is a composite molded product of metal and synthetic resin, it has excellent mechanical strength.

According to the method of manufacturing a synthetic resin composite molded product having a patterned metal layer and electromagnetic shielding according to the present invention, it is not necessary to use a plating resist to form the patterned metal layer, and there is no need to use a plating resist for forming the patterned metal layer. Does not require complicated mold design. Further, it does not require the effort of attaching a metal film to provide electromagnetic shielding. In addition, a synthetic resin composite molded product having a patterned metal layer and electromagnetic wave shielding and having excellent mechanical strength can be manufactured.

[Brief explanation of the drawing]

1A to 1E are cross-sectional views showing an embodiment of a synthetic resin composite molded product having a patterned metal layer and electromagnetic shielding according to the present invention, and a method for manufacturing the same.

FIGS. 2A to 2D are perspective views showing the manufacturing process of the composite molded article of the present invention.

3A to 3D are cross-sectional views showing a conventional method for manufacturing a synthetic resin composite molded product having a patterned metal layer.

FIG. 4 is a sectional view showing a conventional synthetic resin composite molded product having a metal layer and electromagnetic shielding.

[Explanation of symbols]

1 Metal plate 1a Metal plate rising portion 2 Through hole 3 Difficult to plate resin 3a Surface 3b of the portion of the difficult to plate resin other than the groove
Groove 4 Easy-plating resin 5 Metal layer 6 Mold 6a Convex portion 6b on the inner surface of the mold Cavity 7 Mold 11 Primary composite molded product 12 Secondary composite molded product 13 Composite molded product 31 Primary molded product 31a Convex portion 31b of primary molded product Primary molding Recessed portion 31c of the body Surface 32 where the primary molded product is exposed
Easy to plate material 33 Difficult to plate material 34 Secondary molded product 35 Metal layer 36 Plastic composite molded product 41 Mold 42 Synthetic resin 43 Metal layer

Claims (1)

[Claims] 1. A first metal body not suitable for electroless plating, comprising a metal body having at least one through hole, and a groove filled to close the through hole and having a pattern corresponding to a predetermined circuit pattern. a first synthetic resin molded body made of a synthetic resin; a second synthetic resin molded body filled in the groove pattern and made of a second synthetic resin suitable for electroless plating; and the second synthetic resin molded body. A synthetic resin composite molded product having a patterned metal layer and electromagnetic wave shielding, characterized in that it consists of a patterned metal layer formed by electroless plating on the outer surface of the body.