JPH05192958A - Manufacture of composite molded product - Google Patents

Abstract

PURPOSE:To obviate masking of the rear face before electroless plating in the manufacturing method of a plastic composite molded product with a metal pattern only on its surface formed by electroless plating. CONSTITUTION:A primary molded body 11 constituted by an easy plating material 2 is fixed in a mold 12 in a manner of moving in the specified direction only, and energizing force is applied from one direction of the inner face of the mold to bring the primary molded body into contact with the inner face on the opposite side, and a second plating-resistant molding material 3 is filled in the mold. Then, the primary molded body 11 is brought into contact with the inner face on the opposite side of the mold 12 by the injection pressure, and a second molded body is molded in a manner that the outer face of the primary molded body 11 on the side of being not in contact with the mold 12 is coated with the second plastic molding material 3. A metal layer is formed by electroless plating on a section of the surface of a composite molded product where the primary molded body is exposed.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a method for producing a composite molded article,
In particular, the present invention relates to a method for producing a plastic composite molded article having a patterned metal layer on the surface and a method for producing a composite molded article having an exposed portion of the primary molded body on only one surface.

[0002]

2. Description of the Related Art A plastic molded article having a patterned metal layer used as an electric circuit pattern or the like on its surface, for example, MCB (molded circuit board), MWB (molded)
wiring board), MID (molded interconnection dev)
Ice) is drawing attention as it meets various requirements such as weight reduction, space saving, and cost reduction.

For producing a plastic molded article having a patterned metal layer on the surface, there has been hitherto been known, for example, in JP-A-63-
As described in JP-A No. 50-20482 and JP-A No. 1-207989, a primary molded product corresponding to a skeleton is formed of a plastic material that is easily electroless plated (hereinafter referred to as an easily-platable material). 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 molded product that does not require plating. A method of plating an exposed portion of a conductive material is usually used.

For example, as shown in FIG. 3A, first, a primary molded body 31 having a convex portion 31a having a flat top and a concave portion 31b between the convex portions 31a is formed of an easily plateable material 32. Then, in the secondary molding die 33 for accommodating the primary molded body 31, the concave portions 31b on both front and back surfaces of the primary molded body 31 are formed.
By injecting the hard-to-plate material 34 into the cavity in the mold 33 containing the, a secondary molded product 35 having a cross section as shown in FIG. 3B is formed. In the secondary molded product 35,
The recess 31b described above is filled with the plating-resistant material 34. The mold 33 is removed, and the primary molded body 31 of the secondary molded product 35 is removed.
When the electroless plating is performed after roughening the exposed surface 31c as shown in FIG. 3 (C), as shown in FIG. 3 (D), the protrusion 31a of the primary molded body 31 is formed. The metal layer 36 is formed only on the surface of the corresponding exposed portion 31c of the easily plated material 32 of the secondary molded product 35. Thus, a plastic composite molded product (plastic two-shot substrate) 37 having a metal pattern is obtained.

[0005]

However, in the conventional method as described above, in order to stably hold the primary molded body in the cavity of the secondary molding die, convex portions are provided on both front and back surfaces thereof. There was a need. As a result, a metal layer is also formed on the back surface by electroless plating. It may be inconvenient if there is a metal portion on the back surface. In that case, it is necessary to mask the back surface with a plating resist material before electroless plating. This increases the number of steps and reduces productivity.

Therefore, an object of the present invention is to realize a method for producing a plastic composite molded article having a metal pattern formed by electroless plating only on the front surface, which does not require masking the back surface before electroless plating. It is in.

Another object of the present invention is to realize a method for producing a composite molded article which has an exposed portion of the primary molded body only on the front surface and has a rear surface composed of only the secondary molded body.

[0008]

The present invention realizes a method for producing a plastic molded product having a metal pattern formed only by electroless plating on the front surface without the need to mask the back surface before electroless plating. , A primary molded body made of an easily-platable material is fixed at a predetermined position in the mold for secondary molding so that it can be moved only in a predetermined direction, and one side of the inner surface of the mold is fixed in this predetermined direction. A predetermined biasing force is applied to the primary molded body to displace it to bring the primary molded body into close contact with the inner surface on the opposite side of the mold, and the hard-to-plate second plastic molding material is injected into the space inside the mold at a predetermined injection pressure. Filling, releasing the action of the above-mentioned urging force on the primary molded body, the primary molded body is brought into close contact with the inner surface on the opposite side of the mold by the injection pressure,
The secondary molded body is formed such that the outer surface of the primary molded body facing one inner surface (the side not in close contact with the mold) of the mold is covered with the second plastic molding material. In this way, a composite molded body is formed by combining the primary molded body and the secondary molded body, and the patterned metal is formed by electroless plating on the exposed portion of the primary molded body composed of the easily-platable material on the surface of the composite molded body. Form the layers.

To apply a biasing force to the primary molded body,
It is advantageous to use an elastic member such as a spring. If the elastic extension force of an elastic member such as a spring is applied to the primary molded body via a rigid body that contacts the primary molded body, for example, a pin, the primary molded body is brought into close contact during injection molding of the secondary molded body. When the secondary molding material (difficult to plate) is injected into the mold from the gate located on the side opposite to the surface on which the secondary molding material is filled, the static pressure of the secondary molding material that fills the cavity around the primary molding acts on the pins. Since the elastic member is compressed and the pins and the like are separated from the primary molded body, the action of the biasing force on the primary molded body is released,
Instead, the injection pressure causes the primary compact to come into close contact with the inner surface of the opposite mold.

The biasing force to the primary molded body may be applied by an electromagnetic solenoid or fluid pressure.

The mold used for the secondary molding in the method for producing a composite molded article according to the present invention is such that the primary molded body is fixed inside so as to be movable only in a predetermined direction, and one of the inner surfaces is fixed to the predetermined shape. A predetermined biasing force that displaces in the direction is applied to the primary molded body to bring the primary molded body into close contact with the inner surface on the opposite side of the mold, and the injection of the second plastic molding material causes the action of the biasing force on the primary molded body. Unraveling, bringing the primary compact into close contact with the inner surface on the opposite side of the mold by injection pressure, and so that the outer surface of the primary compact facing the side not in contact with the mold is covered with the second plastic molding material, It must be constructed so that it can be filled with a second plastic molding material to form a secondary molding.

The primary molding material requires rigidity, dimensional stability, and heat resistance because the primary molding forms the skeleton of the final molded product and functions as a core during secondary molding. Since it must be considered, it is usually selected from among so-called engineering plastics. For example, polycarbonate, polyamide, polyetherimide,
Polysulfone, polyether sulfone, polyphenylene sulfide, polyethylene terephthalate, polyether ketone and polyether ether ketone are preferred. A liquid crystal polymer such as Novacurate (trade name), Vectra (trade name), or a thermosetting resin such as a phenol resin, an epoxy resin, or a diallyl phthalate resin may be used. A filler such as glass fiber, potassium titanate fiber, or calcium carbonate may be added to these resins.

The secondary molding material, like the primary molding material,
These materials can be selected, but the molding temperature is preferably lower than that of the primary molding material.

In order to form a patterned metal layer on the surface of the primary molding, when an easily-platable material is used as the primary molding material, is it amorphous or has a relatively low molecular weight and is easily roughened? Use is made of one that is easily attacked by a specific solvent or chemical, or one that is added with a catalyst containing a noble metal compound such as palladium, gold or silver.

Electroless plating is used to form a metal layer on the exposed surface of the primary molded body on the surface of the composite molded body. The electroless plating comprises a step of roughening the exposed surface of the easily-platable material and, if necessary, applying a catalyst composed of a compound of a noble metal such as palladium, gold or silver, and a step of applying plating. ..

The surface of the primary molding (easy-plating) material is generally pretreated so as to have sufficient adhesion to the plating layer. First, stains such as a release agent, grease, and dust adhering to a molded product are removed with an alkaline cleaner, a surfactant, an organic solvent and the like. Then, if necessary, after treating with N, N-dimethylformamide, etc., chromic acid / sulfuric acid, calcium hydroxide, hydrofluoric acid / nitric acid, acidic ammonium fluoride /
The surface is roughened using an etching solution such as nitric acid.

In order to selectively form a metal layer on the outer surface of the primary molding material, a method of adding a plating catalyst to the primary molding material in advance, a method of selectively roughening the primary molding material,
And there is a combination of both. Examples of the electroless plating catalyst added in advance to the primary molding material include metals of Group VIII and Group IB of the Periodic Table, for example, nickel, platinum, palladium, rhodium, iridium, gold, silver, copper, or compounds such as salts. An oxide can be used. A specific example is palladium chloride. The selective roughening of the primary molding material is possible, for example, by using a solvent that causes the primary molding material to swell but not the secondary molding material.

Instead of previously adding a catalyst for electroless plating to the primary molding material, a step of applying a catalyst may be added after the surface roughening. The catalyst is applied by 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 roughen the secondary molding material. A method of depositing palladium on the surface and a sensitizing-activating method, that is, metal pattern formation of a secondary molding material in which a strong reducing agent such as stannous chloride, hydrazine chloride, hypophosphorous acid is roughened After adsorbing on the part, 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. In some cases, nickel and gold are electrolessly plated on copper. When the metal layer is used as a wiring portion of an electric circuit pattern, generally, a copper layer or a layer of nickel, gold, solder or the like is formed alone or in combination on the copper layer. A metal layer of the same or different type may be further formed on the electroless plated layer by ordinary electroplating using this layer as a conductor (for example, an electroplated nickel layer on the electroless plated copper layer). This method is useful when a sufficient thickness of the metal layer cannot be obtained by electroless plating.

By selectively forming a metal layer on the exposed surface of the easily-platable primary molding material, a patterned metal layer is formed on the surface of the composite molded article according to the shape of the exposed portion of the primary molding material. To be done.

The method for producing a composite molded article of the present invention is useful in addition to the case where the metal layer is selectively formed on the exposed surface of the primary molding material. For example, it can be used for the purpose of selectively coloring the exposed surface of the primary molding material by forming the primary molding material with a material that is easily colored and the secondary molding material with a material that is difficult to be colored. Hereinafter, the present invention will be described in more detail with reference to Examples.

[0022]

EXAMPLE 1 An example of a composite plastic molded product having a metal pattern manufactured according to the present invention is shown in FIG. In the plastic composite molded article 1, the concave portions 2b between the convex portions 2a of the primary molding material 2 are filled with the secondary molding material 3, and the metal layer 4 is formed on the surface of the exposed portion of the convex portions 2a of the primary molding material 2. It was formed. The primary molding material 2 is a polyethersulfone containing 0.1% by weight of palladium and 20% by weight of glass fiber as a catalyst for electroless plating.
rsulfone), the secondary molding material 3 is 30% by weight of glass fiber.
Added polyphenylene sulfide
e).

The plastic composite molded article 1 is manufactured by the following method. A primary molding material 11 having a cross section shown in FIG. 2 (A) is injection-molded by a conventional method using a polyether sulfone containing a palladium catalyst and glass fiber as the primary molding material 2. The injection molding temperature was 380 ° C and the mold temperature was 150 ° C. The primary molded body 11 is formed with a convex portion 2a and a concave portion 2b.

Next, as shown in FIG. 2B, the primary molded body 11 is inserted into the cavity 12a of the die 12. On the lower surface of the mold 12, three pins 13 (one of which is not shown) that can freely move back and forth within a predetermined range are provided, and when the mold 12 is clamped, the pins 13 are the lower surface of the primary molded body 11. Abut. A tapered surface 13 a is formed on the side surface of the head of the pin 13. Since the pin 13 is biased in the forward direction by the spring 14, the primary molded body 11 is pushed upward, and the upper surface of the convex portion 2a of the primary molded body 11 comes into close contact with the inner surface of the upper portion of the mold 12. The pin 13 also acts as a positioning means for the primary molded body 11 with respect to the mold 12. As a secondary molding material 3 from a gate (not shown) provided under the mold 12,
Polyphenylene sulfide added with glass fiber is injected, and as shown in FIG.
Fill the cavity 12a containing b. When the filling is continued at a predetermined injection pressure, the static pressure of the secondary molding material 3 causes the tapered surface 1
A downward force acts on 3a, and the pin 13 is pushed down against the biasing force of the spring 14, and as shown in FIG. Molding material 3
Is filled. As a result, a secondary molded product 15 shown in FIG. 1 (A) is obtained (in the present invention, the recess formed in the primary molded body and the portion formed of the secondary molding material filled in the back surface are referred to as the secondary molded body, A composite molded product composed of a primary molded product and a secondary molded product is called a secondary molded product). Injection molding temperature is 300
The mold temperature was 100 ° C. The secondary molded product 15 has an exposed portion 2c of the primary molded body (material).

The outer surface of the secondary molded product 15 was degreased by a conventional method and immersed in N, N-dimethylformamide for 2 minutes.
The exposed portion 2c of the primary molding material was roughened as shown in FIG. 1 (B) by immersing it in a chromic acid / sulfuric acid etching solution at a temperature of 60 ° C. for 4 minutes for etching. After washing with water, electroless copper plating was performed by a conventional method to deposit copper as the metal layer 4 to a thickness of 30 μm. In this way, FIG.
A plastic molded product 1 having a cross section shown in (C) is obtained.

[0026]

According to the method of manufacturing a plastic molded product of the present invention, it is not necessary to mask the back surface before plating when manufacturing a plastic molded product having a metal pattern only on the front surface. Therefore, the number of steps is reduced and the manufacturing cost of the molded product is reduced.

Further, according to the method for producing a plastic molded article of the present invention, the exposed portion of the primary molded body is provided only on the surface,
It is possible to easily manufacture a plastic molded product whose back surface is composed of only the secondary molded product.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a method for producing a composite plastic molded product having a metal pattern according to the present invention.

FIG. 2 is a sectional view showing an embodiment of a method for manufacturing a composite plastic molded product according to the present invention.

FIG. 3 is a cross-sectional view showing a conventional method for manufacturing a composite plastic molded product having a metal pattern.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Plastic composite molded product 2a Convex part of primary molding material 2b Recessed part of primary molding material 2c Exposed part of primary molding material 3 Secondary molding material 4 Metal layer 11 Primary molding 12 Mold 12a Mold cavity 13 Pin 13a Taper Surface 14 Spring 15 Secondary Molded Product 31 Primary Molded Body 31a Projection 31b Recess 31c Exposed Part of Primary Molded Body 32 Easy Plating Material 33 Secondary Molding Mold 34 Difficult Plating Material 35 Secondary Molded Product 36 Metal Layer 37 Plastic composite molded products

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takanobu Ishibashi 5-1-1 Hidakacho, Hitachi City, Ibaraki Pref., Electric Wire Research Laboratory, Hitachi Cable, Ltd. (72) Inventor Toshiyuki Oaku 5-chome, Hidakacho, Hitachi City, Ibaraki Prefecture 1st-1 Hitachi Cable Co., Ltd. Electric Cable Research Laboratory (72) Inventor Hideki Asano 5-1-1 Hidakacho, Hitachi City, Ibaraki Prefecture Hitachi Cable Electric Cable Co., Ltd.

Claims (3)

[Claims] 1. A primary molded body composed of a first plastic molding material which is easily electroless plated, and a secondary molded body composed of a second plastic molding material which is difficult to electroless plate. In the method of producing a composite molded article having a patterned metal layer on the surface, a composite molded article constituted by combining, on the exposed portion of the primary molded body on the surface, a metal layer is formed by electroless plating, The primary molded body is fixed inside the mold for secondary molding so as to be movable only in a predetermined direction, and the primary molded body is displaced from one of the inner surfaces of the mold in the predetermined direction. A biasing force is applied to bring the primary molded body into close contact with the inner surface of the mold opposite to the one inner surface, and the space in the mold is filled with the second plastic molding material at a predetermined injection pressure, For primary moldings While releasing the action of the biasing force, the primary molding is brought into close contact with the inner surface of the mold on the opposite side by the injection pressure, and the outer surface of the primary molding facing the one inner surface of the mold is the first As covered by the second plastic molding material,
A method for producing a composite molded article, which comprises forming the secondary molded body. 2. The predetermined urging force is an extension force of a predetermined strength of an elastic body, and the filling of the second plastic molding material is performed by the predetermined strength against the elastic body based on the injection pressure. 2. The method for producing a composite molded article according to claim 1, wherein a compressive force larger than the elongation force of the ridge is generated. 3. The predetermined biasing force is applied to the primary molded body via a rigid body that is in contact with the primary molded body, and the injection pressure causes the compressive force to the elastic body via the rigid body. The method for producing a composite molded article according to claim 2, wherein the contact between the rigid body and the primary molded body is released.