JPH04259516A - Manufacture of plastic molded product - Google Patents

Abstract

PURPOSE:To improve electro-magnetic wave impediment without necessitating a molding process for conductive film. CONSTITUTION:A leading wire (insulated leading wire) 1 whose surface is electric-insulation-treated is arranged so that almost a fixed electric circuit pattern is obtained and shaped so that the same runs after a form of a molded product. Then either the same is fixed with an electric insulation material or the lead wire whose surface is electric-insulation-treated is arranged either on the top of an electrical insulating adhesive leafy matter or between the electrical insulating adhesive leafy matters so that almost a treated electric circuit pattern is formed. The same is shaped so that the same runs after almost a form of the molded product, made into a preform 11 and the preform 11 is molded integrally as an insert material by making use of a conductive molding material.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is directed to forming the electric circuit in order to shield electromagnetic waves emitted from a molded article having an electric circuit on the inner surface and/or inside the article or electromagnetic waves attempting to invade from the outside. The present invention relates to a method for producing a plastic molded product, in which a preform is made of a conductor wire whose surface is electrically insulated, and is integrally molded with a conductive molding material.

0002

[Prior Art] Electrical and electronic equipment such as communication equipment, control equipment, measuring instruments, and home appliances are becoming increasingly smaller, lighter, more multifunctional, and more compact. In addition to high integration, multi-layer and high-density wiring boards, and the use of flexible wiring boards, MCBs (MCBs) have electrical circuits formed on the surface and/or inside of the housings and parts of electrical and electronic equipment.
Molded Circuit Board), M
ID (Molded Interconnect
The introduction of molded products or three-dimensional circuit molded products is being actively considered for circuits called ``G Devices'' and the like.

[0003] Molding methods for these molded products with circuits include:
For electrical circuits for power supplies that carry relatively large currents, a method of insert molding a conductive metal sheet such as copper, aluminum, phosphor bronze, or 42 alloy by punching or etching with an electrically insulating molding material is a comparative example. For signal electrical circuits that carry a small current, thermal transfer of conductive ink, printing with a screen or pad, pasting of an electrically insulating film with an electrical circuit, and chemical plating are applied to the necessary parts of the casing made of electrically insulating molding material. There is a way to use it. There are several types of methods using chemical plating, for example, Nikkei Mechanical Magazine ('89.11.
According to A.P.E Process (APE No. 13)
Process), Additive Plate-n-
Etch Process), Maldon Add.
Mold'n Add Process
), Moldon Plate Technology (Mold'
n Plate Technology), Recessed Tracking Method (Recessed T
In addition, there are methods such as activating the plating catalyst with UV or laser. As mentioned above, there are many methods for molding molded products with circuits, but there are many methods that are suitable for producing small quantities of a wide variety of products, have a short turnaround time (TAT: time from order to delivery), and use inexpensive jigs and general-purpose tools. A method that can be molded using molding equipment has also been developed.

0004

[Problems to be Solved by the Invention] For electrical and electronic equipment including these molded products with circuits, various synthetic materials with features such as practical strength, durability, light weight, cost, decorativeness, productivity, etc. Resins are selected and used as appropriate depending on the purpose and conditions of use of electrical and electronic equipment, but general synthetic resins have chargeability and electromagnetic wave permeability in common, and the latter is particularly useful for cover covers for radar and radio wave detectors. It is suitable for such applications. However, electromagnetic waves from the outside may pass through a synthetic resin casing or the like and cause the electrical/electronic equipment concerned to malfunction. This phenomenon is caused by electromagnetic interference (Electromagnetic interference).
erference (hereinafter referred to as EMI), A
This can lead to noise from V-equipment, distorted images, computer malfunctions, and automatic control equipment going out of control. This EM
I: If appropriate electromagnetic shielding measures are not taken for the electrical/electronic equipment in question, this equipment itself can become a source of EMI. Therefore, when using electromagnetic wave-transparent synthetic resin for the housing of electric/electronic equipment, it is necessary to take measures to prevent EMI. Measures to prevent this EMI include applying conductive paint to the surface and/or inner surface of the synthetic resin molding, forming a conductive film by thermal spraying, plating, sputtering, etc. of metal, and applying conductive coatings such as metal or carbon to the synthetic resin molding material. Methods such as imparting conductivity to the molding material itself by kneading powdered substances, foil pieces, fibers, etc., and insert molding of metal or carbon fiber fabrics or metal sheets are known. Providing electrical conductivity in this way also prevents static electricity from being applied to the electric/electronic equipment, and prevents electrical shock from static electricity to the human body and
This also helps prevent functional deterioration and destruction of electronic equipment.

Among these EMI prevention measures, methods using conductive molding materials may reduce the appearance (transparency, surface smoothness, hue, etc.) of the molded product due to the conductivity imparting agent; The EMI shielding effect and reliability are excellent, and compared to when using conventional molding materials, only slight changes in molding conditions require special consideration in terms of the working environment, such as updating molding equipment or thermal spraying. There are some characteristics such as not. However, in the molding of a molded product with a circuit according to the conventional technology, the conductive molding material comes into direct contact with the above-mentioned electric circuit, leading to a short circuit of the electric circuit, and therefore cannot be put to practical use.

[0006] An object of the present invention is to provide a method for manufacturing plastic molded products that does not cause the above-mentioned problems.

[0007]

[Means for Solving the Problems] In view of the above-mentioned current situation, the inventors of the present invention have realized that, on the one hand, there is an increasing demand for smaller size, lighter weight, multifunctionality, and higher performance, and on the other hand, it is necessary to solve problems based on EMI. As a result of intensive research in order to respond immediately to trends in electrical and electronic equipment, we have found that plastic casings of electrical and electronic equipment, internal surfaces and/or parts of electrically insulated conductors can be used to meet the specified electrical requirements. After the circuit is formed and shaped, it is integrated using ordinary molding equipment and molding methods and a commonly used thermoplastic or thermosetting conductive molding material, thereby reducing the process of forming conductive films, etc. We have found a way to improve EMI without requiring it.

[0008] In the present invention, conductive wires whose surfaces are treated with an electrically insulating material are arranged in approximately a predetermined electrical circuit pattern,
After shaping to roughly follow the shape of the molded product, it is fixed with an electrically insulating material, or the top surface of an electrically insulating adhesive thin film (prepreg, etc.) or an electrically insulating adhesive thin film is fixed. In between, conducting wires with electrically insulated surfaces are arranged so as to roughly form a predetermined electrical circuit pattern, which is then shaped to roughly follow the shape of the molded product to form a preform, and then these are used as insert materials to conductively conductive wires. This invention relates to a method for manufacturing plastic molded products that are integrally molded using a plastic molding material.

In the present invention, the method for forming an electric circuit pattern involves arranging a conductive wire coated with an electrically insulating material so that only both terminal portions are at predetermined positions. At this time, it is not necessary to arrange the circuit strictly according to a predetermined electric circuit pattern.
Further, there is no problem even if the conducting wires contact or overlap. However, when shaping a molded article using a large number of conductive wires, it is preferable to avoid overlapping the conductive wires at the bending part as much as possible, and arrange them so that they are lined up on the same plane.

The thickness of the conducting wire to be used is selected depending on the magnitude of the current to be applied. In addition, the cross-sectional shape of the conducting wire is
A circle, a rectangular shape, etc. can be selected as appropriate. The conductor wires, which are generally arranged in a predetermined electric circuit pattern, are shaped to roughly follow the shape of the molded product. The shaping at this time does not have to be strictly in close contact with the mold, but as mentioned above, avoid overlapping the conductive wires at the bending part during shaping, and avoid placing them in other parts as well. It is desirable to avoid overlapping the conductor wires as much as possible so that they are flat, and to take care not to impede the smooth flow of the molding material during molding. In addition, it goes without saying that the area occupied by the electric circuit in the molded product should be determined by considering the EMI shielding effect of the conductive molding material, and consideration should be given to obtaining a thickness of the molding material that is effective for EMI shielding. do.

[0011] In order to fix the shaped conductor according to a predetermined electric circuit pattern, the plasticity of the conductor is used to preform it and then preheat it to an appropriate temperature. Adhere and solidify the powder coating using a fluid dip coating method, hot spray method, cascade method, etc., or expose the necessary parts by masking the electrically insulating powder material and adhere and solidify the powder material by thermal spraying. A preform is obtained by immersing it in a molten electrically insulating material, adhering it, and solidifying it. As needed,
Firing, hardening, etc. may be performed as post-treatment.

[0012]An alternative method of obtaining the aforementioned preform is as follows:
The conductive wires are arranged on the top surface of the electrically insulating adhesive thin film or between the electrically insulating adhesive thin films so as to form an approximately predetermined electrical circuit pattern, and are placed approximately in the shape of the molded article before or after curing. It can also be shaped using a mold, a Yaken mold, etc. so as to follow the shape. If necessary, it may be made into a preform through post-curing. An adhesive may be applied to the surface of the preform obtained as described above in order to ensure interfacial adhesion with a molding material used for sealing in a later step. This adhesive may be rubber-based, thermoplastic resin-based, or
It may be of any thermosetting resin type, and is not particularly limited.

[0013] In order to fix the preform in a predetermined position in the mold, appropriate dimensions and
Guide holes, protrusions, etc. of different shapes and numbers are provided, and guide bushes, recesses, etc. that match the guide holes, protrusions, etc. are provided on the surface of the corresponding mold. These preform positioning parts can be provided inside or outside the cavities of the pair of molds. For example, guide holes may be provided at the fixed portions of both terminals of the conducting wire, and at appropriate locations between the terminals of the conducting wire arranged in approximately a predetermined electric circuit pattern.
A guide hole may also be provided on the fixing plate provided to fix the arrangement of the conducting wires. In the latter case, especially when the preform is long and shear stress is applied to the preform by the molding material flowing inside the mold cavity when sealing with conductive molding material, the terminal portion of the conductor It is also effective in preventing defects from occurring.

The conductive molding material used to seal the preform as an insert material may be mainly composed of thermoplastic resin, thermosetting resin, etc., depending on the purpose and conditions of use of the molded product with circuitry. is used. Among these, thermoplastic resins include polyethylene, polypropylene, ABS, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polysulfone, polyamides, polyetherketone, polyamideimide, liquid crystal polymers, polyphenylene sulfide, etc., singly or in combination of two or more. used. On the other hand, as the thermosetting resin, phenol resin, unsaturated polyester resin, epoxy resin, polyurethane, polyimide, etc. are used alone or in combination of two or more.

[0015] In addition to the conductivity imparting agent, fillers, flame retardants, flexibilizing agents, coloring agents, reinforcing materials, etc. may be added to these thermoplastic resins, thermosetting resins, etc. as necessary. be able to. Furthermore, these conductive molding materials contain additives to improve the wettability of the matrix resin with fillers, flame retardants, flexibilizing agents, colorants, reinforcing materials, etc., and to improve the fluidity of the molding material. Additives and micro hollow spheres for weight reduction may be added.

[0016]

[Examples] Examples of the present invention will be described below. Example 1 As shown in Fig. 1, a conductor wire (manufactured by Hitachi Cable, trade name HBH-1, IMW, 0.1φ, 0 types of coating) was prepared by electrically insulating the surface of a copper wire with a diameter of 0.1 mm using polyimide varnish. After preparing the insulated conductor wire (hereinafter referred to as insulated conductor wire) 1, place the insulated conductor wire 1 avoiding the parts that will be the rib position 7 and the opening position 8 of the molded product, and connect both ends and two middle parts with strip-shaped prepreg. (Manufactured by Hitachi Chemical Mold, product name GN62NS, thickness 0.
34 mm) and placed on a hot plate at a temperature of 170°C with a pressure of 0.2
It was cured by heating and pressurizing at 9 MPa (3 kgf/cm2) for 120 minutes, and portions that would become guide holes 5 and 6 were cut at both ends of each strip-shaped prepreg.

Next, along the crease line 4, R (radius) 0.2
Bend it at right angles by mm, and then bend it to 120 to 1
1 in molten polyimide (manufactured by Nippon Polyimide, trade name Kerimide 1050) kept at a temperature of 30°C.
After soaking for a minute, the sample was taken out, left at room temperature for 10 minutes while removing residual drops, and then kept in a constant temperature bath at 205° C. for 5 hours for after-cure.

[0018] After this, the product was taken out of the thermostatic oven, left to cool to room temperature, and an adhesive (manufactured by ThreeBond, trade name: ThreeBond 1570) was applied to the entire surface to a thickness of 10 to 15 μm.
It was kept in a dryer at 00°C for 10 minutes. Furthermore, holes were drilled in the areas marked above, and guide holes 5 and 6 were formed in the terminal fixing plate 2 and the intermediate fixing plate 3, as shown in FIG.
A preform 11 as shown in FIG. 1 was obtained. In addition, in FIG. 2, 9 is solidified polyimide.

After the preform 11 is fixed by the insert material fixing protrusion (not shown) provided on the lower die of the molding die and the guide holes 5 and 6, the upper die is closed, and the insert material fixing protrusion (not shown) provided on the lower die of the molding die is closed. Carbon fiber reinforced polybutylene terephthalate (manufactured by Toray, trade name PBT1) is passed through the pin gate.
401T30, carbon fiber content 30% by weight) was injection molded. The molding equipment used at this time was Toshiba Machine's IS-
A 75S injection molding machine was used. The molding conditions were: mold temperature 65±5℃, cylinder temperature 235±10℃, injection pressure (
gauge pressure) 7.84 MPa (80 kgf/cm2),
The injection speed was 99%, the injection time was 3 seconds, and the cooling time was 9 seconds. Note that the thickness of the molded product was 3 mm. After demolding, the molded product was heat-treated in a constant temperature bath at 150° C. for 3 hours to obtain a plastic molded product.

There were no electrical defects such as disconnections in the 11 insulated conductive wires 1 inserted in the obtained plastic molded product and short circuits between the insulated conductive wires 1, and the EMI shielding effect was 40 dB under an electric field of 100 MHz. there were. Further, the volume resistivity of the surface of the plastic molded product was 100 Ωcm.

Example 2 As shown in FIG. 3, both ends of the same insulated conductor wire 1 as in Example 1 were fixed with terminal fixing plates 2 at a pitch of 1 mm. On the other hand, a glass paper base modified epoxy resin prepreg (manufactured by Hitachi Kasei Mold, product name GN6) was cut into the shape shown in Figure 3.
2NS, thickness 0.34 mm) on the top surface of the electrically insulating adhesive thin sheet 10, avoiding the parts that will be the rib position 7 and opening position 8 of the molded product, and insulating on the top surface of the crease line 4. After arranging the conductors so that they do not overlap, the temperature is 170℃.
1 at a pressure of 0.29 MPa (3 kgf/cm2) on a hot plate.
It was cured by heating and pressurizing for 20 minutes, and holes were formed at the rib position 7, the opening position 8, and the guide hole 5.

The cured prepreg material on which the insulated conductive wire 1 was placed and fixed in this way was heated to 80°C, and then cut along the crease line 4 with a radius of 0.2 mm using a Yagen mold held at 80°C.
A preform was obtained by bending. Next, an epoxy resin adhesive (manufactured by ThreeBond, trade name: ThreeBond 1570) is applied to the lower surface of this preform (the surface in contact with the molding material during molding) to a thickness of 10 to 15 μm.
It was kept in a dryer at 100°C for 10 minutes. This material is placed on the upper mold surface of a set of molds using the guide hole 5 of the terminal fixing plate 2 and a protrusion (not shown) provided on the mold so that the adhesive-applied surface faces downward. After positioning the mold using vacuum suction and clamping the mold, the mold was passed through the pin gate provided in the upper mold, and then the same molding material, molding conditions, and heat treatment process as in Example 1 were performed, and the mold was made to a thickness of 3 mm as in Example 1. A plastic molded product was obtained.

There were no electrical defects such as disconnection in the insulated conductor 1 inserted into the obtained plastic molded product or short circuit between the insulated conductors, and the EMI shielding effect was as low as 10 in the electric field.
It was 40 dB below 0 MHz. Further, the volume resistivity of the surface of the plastic molded product was 100 Ωcm.

Comparative Example 1 Except that the immersion step in molten polyimide in Example 1 was omitted and glass fiber reinforced polybutylene terephthalate (manufactured by Toray Industries, trade name: PBT1101G30, glass fiber content 30% by weight) was used as the molding material. A plastic molded product with a thickness of 3 mm was obtained through the same steps as in Example 1.

It was visually observed that the insulated conductive wires in the obtained plastic molded product were pressed against the wall of the opening and gathered together, and as a result of an electrical continuity test, 4 out of 11 insulated conductive wires
The book was disconnected. The effect of EMI shielding is the electric field, 1
At 0dB below 00MHz, the volume resistivity is 1015Ωc
It was m.

[0026]

[Effects of the Invention] In the plastic molded product obtained by the manufacturing method of the present invention, conductive wires whose surfaces are coated with an electrically insulating material are arranged in approximately a predetermined electric circuit pattern, and the conductive wires are arranged so as to roughly follow the shape of the molded product. After shaping, it is fixed with an electrically insulating material, or the conductive wire whose surface is electrically insulated is generally placed on the upper surface of an electrically insulating adhesive thin sheet (prepreg) or between electrically insulating adhesive thin sheets. One of the characteristics of this method is that it is arranged to form a predetermined electrical circuit pattern and then shaped to roughly follow the shape of the molded product to form a preform, which is then insert molded.
Unlike the subtractive method, additive method, printing method, etc. that have been conventionally employed in the production of plastic molded products with circuits, there is no need to strictly control the conductor width, conductor spacing, etc. of the electric circuit pattern.

Furthermore, as mentioned above, the insulated conductor alone or this insulated conductor can be made of an electrically insulating adhesive thin film material (such as prepreg).
It is characterized in that the wire fixed on the top is shaped roughly along the shape of the molded product, but these insulated conductors or those fixed with prepreg etc. are plastic and can be easily shaped. It does not require any particularly precise jigs or equipment, and has a high degree of freedom in design.

In addition, since the preform is used as the insert material as described above, various general-purpose molding methods such as injection molding, compression molding, reaction injection molding (RIM), and liquid resin injection molding (RTM) can be used. Molding methods can be applied.

Since the surfaces of the conductors that form the electric circuit pattern are electrically insulated, there is no problem in contacting or overlapping the conductors when forming a circuit, and conventional techniques do not allow multilayer electric circuits to be formed. The structure can be achieved by arranging the required number of insulated conductive wires, and can be used for copper-clad insulating plates, catalyst-containing insulating plates, resists for forming electrical circuits, screen printing equipment for resists, resist dry film laminators, and etching equipment. , electric and/or chemical plating equipment, prepreg for multilayering, presses, etc. are not required.

In addition, since the molding material using the preform as an insert material is electrically conductive, it can be coated with a conductive ink film, plating, sputtering, etc. like conventional electrically insulating molding materials. There is no need for a process for providing an EMI shielding layer such as a thermally sprayed metal film on the surface and/or inner surface of the molded product. Moreover, since the obtained molded product has electrical conductivity, it is possible to prevent various troubles caused by accumulation and discharge of static electricity.

[0031] Due to the above characteristics, the present invention
In addition to miniaturizing electronic devices, improving their performance, making them more compact, shortening development time, and reducing costs, they can greatly contribute to preventing problems caused by electromagnetic waves and static electricity.

[Brief explanation of the drawing]

[Fig. 1] A state in which an insulated conductor is fixed with a terminal fixing plate and an intermediate part fixing plate in the first step for obtaining a plastic molded product according to an embodiment of the present invention, and is not bent at right angles along a crease line. FIG.

FIG. 2 is a perspective view showing the preform state in the post-process of FIG. 1;

[Fig. 3] Another embodiment of the present invention, in which an insulated conductor wire, which is the first step for obtaining a plastic molded product, is fixed with a terminal fixing plate and placed on the top surface of an electrically insulating adhesive thin sheet. FIG. 3 is a front view showing the state before being bent along the crease line.

[Explanation of symbols]

1 Insulated conductor wire
2 Terminal fixing plate 3 Intermediate fixing plate
4 Fold line 5 Guide hole
6 Guide hole 7 Rib position
8 Opening position 9 Solidified polyimide
10 Electrically insulating adhesive thin film

Claims (1)

[Claims] Claim 1: Conductive wires whose surfaces are electrically insulated are arranged to roughly form a predetermined electrical circuit pattern, shaped to roughly follow the shape of the molded product, and then fixed with an electrically insulating material or electrically insulated. A molded product is formed by arranging conductive wires whose surfaces are electrically insulated on the upper surface of an insulating adhesive thin sheet or between electrically insulating adhesive thin sheets so as to form approximately a predetermined electrical circuit pattern. A method for producing a plastic molded product, which comprises shaping a preform so as to roughly follow its shape, and then integrally molding the preform as an insert material using a conductive molding material.