JP2696403B2 - Method of manufacturing injection-molded printed wiring body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for manufacturing an injection-molded printed wiring body in which a substrate on which a conductor pattern is printed is integrated on a synthetic resin molded body.

[Conventional technology]

In recent years, the so-called injection-molded wiring board (MCB), in which a printed circuit is formed by an additive method such as chemical plating on a molded product in which a sur hole, a support, a protrusion, a snap, and the like are integrally formed by injection molding, has been receiving attention. Usage is expanding.

Conventionally, in order to form a conductor pattern in this MCB, a chemical plating method has been mainly used.However, in order to make the formation of the conductor pattern simpler and more economical, a transfer method, that is, a film or sheet of polyester or the like is used. A desired circuit pattern is formed by printing or vacuum evaporation using a conductive substance, and after injection molding using an injection mold installed in a mold, the film or sheet is peeled from the molded body. A method of transferring a circuit pattern or the like has been developed.

[Problems to be solved by the invention]

However, also in the above transfer method, the inserted synthetic resin film or sheet is deformed by the injection pressure, so that the pattern is likely to be inaccurate and wrinkles are also likely to occur.

Therefore, the injection pressure cannot be increased, and it is difficult to obtain a thin molded body. On the other hand, if the injection pressure is low, the adhesion of the pattern is reduced, and the conductivity is also impaired.

In the case of a resin having a high injection molding temperature, for example, engineering plastics, the inserted synthetic resin film or sheet is greatly deformed by heat and melts depending on the type.

 There is a problem that it is difficult to manufacture a printed wiring board having a multilayer structure.

An object of the present invention is to provide a simpler and more economical method for producing an injection-molded printed wiring body without such problems.

[Means for solving the problem]

Therefore, the present inventor repeatedly examined a simple and economical drying process of a conductor pattern, and as a result, one of the inventors previously developed a conductive ink printing method using a hot press or a hot roll and a picture forming method. The present inventors have found that the problem can be solved by combining the techniques described above and arrived at the present invention.

That is, the present invention provides a step of printing a conductor pattern on an impregnating substrate, a step of heating it or a heating roll, and a step of printing an insulating pattern thereon.
A step of printing a resistor pattern from above;
An object of the present invention is to provide a method of manufacturing an injection-molded printed wiring body, which mainly comprises a step of placing the laminate obtained in the above step in a predetermined mold and a step of injection molding using the mold.

 Hereinafter, the present invention will be described in detail.

In the present invention, first, a step of printing a conductor pattern on the impregnable substrate is performed.

The impregnating base material referred to here is a sheet-like base material capable of impregnating the vehicle (binder) contained therein when the conductor pattern printed thereon is heated and pressed. Say. Specific examples thereof include paper, nonwoven fabric, and fabric such as woven or knitted fabric, and particularly preferably paper. In addition, their properties can be more suitably improved by resin coating.

The fiber used as a raw material for paper may be any of natural fiber, regenerated fiber, and synthetic fiber.
Those having a heat resistance of 0 ° C. or more are preferred.

For general use, natural fiber paper such as Japanese paper is sufficient, but when heat resistance is particularly required, high heat resistant aramid paper or the like is suitable.

This aramid paper is obtained by making aramid fiber.

 Kevlar commercially available as aramid fiber (De
Tupont) (Made by Enka), Technora
(Manufactured by Teijin Limited) or the like, and aramid paper itself
Use a commercial product made from paper made from these fibers
Can be.

Aramid paper is a conductive pattern supporting substrate having excellent heat resistance, dimensional stability, and air permeability derived from the properties of aramid fiber such as high heat resistance and high strength.

When this aramid paper is used, it is possible to directly solder the conductor pattern formed thereon, and a resin having no heat resistance such as a heat-resistant engineering plastic, for example, a molded article of a general-purpose resin Even so, soldering and the like can be made possible by the heat resistance of the aramid paper.

In addition, if a thermosetting resin such as an unsaturated polyester or epoxy resin is applied to the impregnating substrate or solid-printed before forming the pattern, the impregnating substrate absorbs moisture and absorbs water like aramid paper. It is particularly effective when there is a problem in terms of the properties. In addition, it is possible to prevent wasteful infiltration of expensive conductive ink, to form a uniform pattern layer by smoothing the surface, and to mold the base material. The effect of improving the adhesion to the body is obtained.

In the present invention, a conductive pattern is formed on the base material, and a conductive paste or conductive ink used at that time is a paste of a conventionally used metal conductor such as copper, silver, and silver palladium. Alternatively, ink can be used. As a vehicle agent or a binder contained therein, a thermoplastic resin, for example, a resin of a polyacryl type, a polyvinyl chloride type or a polyvinyl acetal type is used. In addition, a thermosetting resin which is fluidized when heated and pressurized and thermosets can be used.

A pattern printing method, for example, a screen printing method, a pad printing method, a gravure printing method, a flexographic printing method, or the like is used to form the conductor pattern. Among these, the screen printing method is particularly preferred. After printing, 100 ~ 2
It is preferable to dry at 00 ° C, preferably at 130 to 160 ° C for about 1 to 5 minutes.

Next, a step of hot-pressing or hot-rolling the impregnated substrate on which the conductor pattern obtained in the above step is printed is performed.

This step is important in the present invention. That is, at the stage of screen printing using a conductive paste, for example, a silver paste, the conductivity of the pattern circuit is still insufficient. However, when this is heated and rolled, the electrical conductivity is dramatically improved (substantially lower by one digit), which is surprising.

The heating condition is preferably 160 ° C. or higher, for example, about 170 ° C. for about 10 minutes. However, in practice, it is desirable that the optimum heating temperature is determined in advance by a preliminary test in consideration of the vehicle starting temperature of the conductive paste, the heat resistance of the base material, and the like.

The pressurizing condition is preferably 5 to 100 kg / cm ^2, but as with the heating condition, it is desirable to set the optimum condition in a preliminary test before carrying out the test.

As a machine used for the hot press or the hot roll, a heating press machine conventionally used for these machines and a heating roll machine used for calendering can be used.
In addition, favorable results can be obtained by appropriately using a protective plate, a glossy plate, a cushion material, a sheet for preventing fusion, etc., which are conventionally used in the hot pressing method. The use of these prior arts is the same in the case of hot rolls.

Subsequently, a desired insulating pattern is formed on the printed wiring intermediate that has been heated or rolled. A printing method, particularly a screen printing method, is suitable for the forming method.

As the insulating material, a known polyester-based, epoxy-based, urethane-based insulating paint or resist ink used for a so-called cover coat can be used.
It is preferable that the insulating pattern is formed by laminating two or more times according to the purpose.

After the step is completed, a step of printing a resistor pattern is performed according to the purpose. In the case of a wiring body that does not require a resistor, this step can be omitted.

As the resistor, a known alloy such as nichrome or a resistor such as carbon can be used, but using carbon is advantageous in terms of cost.

The printing in this step is preferably performed by an ordinary screen printing method using, for example, an ink in which carbon is uniformly dispersed in a polyester vehicle.

Next, in order to perform the injection molding method, the printed wiring intermediate is set in a predetermined mold. As the installation method, any of the methods used in the conventional painting process can be used. in this case,
It is a simple method to attach the printed wiring intermediate to the mold using a double-sided tape or the like.However, the carrier fabric is continuously supplied into the mold by an appropriate mechanical method, and the A method in which the intermediate is detachably attached and inserted is preferable because continuous molding is possible and the stretching and strength of the base material with the conductive pattern can be reinforced by the backing fabric.

 Alternatively, a commercially available in-mold apparatus may be used.

Normally, the conductor pattern of the intermediate is integrated with the mold as a set so that the conductor pattern comes to the front. Alternatively, the conductor pattern may be integrated as a set so that the conductor pattern is in contact with the surface of the molded body. In the latter case, there is an effect that the insulating coating on the conductor pattern to be finally performed can be omitted.

Finally, a step of injecting a resin into the mold and performing injection molding is performed.

The synthetic resin used in this step can be injection-molded and can be used as long as it has heat resistance according to the application.Especially heat-resistant engineering plastics such as polyethersulfone, polyetherimide, polysulfone , Polyacrylate, polyphenylene sulfide, etc. are preferred. Since aramid paper has heat resistance, if this is used, general-purpose plastics such as polyester, ABS, polyphenylene oxide, polycarbonate, and modified polystyrene are used even when heat resistance is required by soldering or the like. Can be used.

[Action]

Circuits printed with conductive patterns using a conductive paste on a plastic film etc.
Insufficient conductivity and can be used only for special applications such as circuits with extremely weak currents such as signal circuits. Similarly, the conductor pattern formed on the impregnating base material of the present invention before hot pressing also lacks electrical conductivity and can be used only for special applications. It is presumed that the following action mechanism causes the conductivity to improve by one digit or more after passing through the heating press process, and to be transformed into a printed wiring body which is effective for various uses at once.

That is, metal particles such as copper and silver in the conductive paste are good conductors as is well known, but the synthetic resin vehicle surrounding the metal acts as a poor conductor, and as a whole, the conductivity is insufficient. Seems to be. Therefore, the conductivity of the pattern circuit formed by printing using the pattern must be poor. However, when it is heated and pressed by a hot press or a hot roll, the synthetic resin vehicle present in the paste is plasticized by heat and becomes fluid, and at the same time, the impregnable base material is applied by the applied pressure. It is soaked in. That is, it is as if the fluid permeated the filter paper. As a result, the pattern on the substrate mostly remains as bare metal particles,
Moreover, since they are rolled, they are connected to each other to form layers. It is not necessary to say that the metal particle layer is a good conductor. For this reason, it is speculated that the conductivity is improved by an order of magnitude and the metal particles exhibit conductivity closer to the conductivity inherent to the metal particles.

Conductive pattern base material (intermediate) whose conductivity has been improved in advance by a heating press or heating roll
Is one of the features of the present invention.

Next, in the present invention, a printed wiring intermediate having the above-described improved conductivity is installed in an injection mold, and a hot-melt resin is injected into the mold. The resin fills up with some biting into it.
As a result, a molded article having aramid paper or the like firmly adhered to the surface due to the heat and pressure is formed.

On the other hand, in the case of painting with a conventional plastic sheet, at the time of injection, the hot-melt resin travels through a long narrow path on its surface while compressing and eliminating existing air.
It is difficult to remove the airflow resistance, especially the air on the opposite side of the pattern of the sheet in contact with the mold, leaving air behind, which results in incomplete transfer and molding due to undulation or air pockets.

Further, in addition to the above-mentioned resistance of the rejected air, the sheet has a high thermal conductivity, so that the surface of the injection resin is easily cooled, and the resistance of the resin flow is further increased, and as a result, the sheet is deformed.
Further, the plastic sheet may be softened or deformed or melted by the heat of the injection resin.

In contrast, in the case of the present invention, the impregnating substrate, for example, aramid paper, entirely contains air between its fibers, and the existing air for the inflowing resin is easily compressed between the fibers by the injection resin pressure. As a result, it is possible to avoid the above-mentioned adverse effects due to the accumulation of air, the resistance of the airflow, and the like.

In addition, since the impregnating base material containing a large amount of air has low heat conduction, rapid cooling of the resin surface at the time of injection can be avoided, which is useful for reducing the resistance of the resin flow and obtaining a good surface condition. This makes it possible to use a resin such as a heat-resistant engineering plastic having a high plasticizing temperature.

Furthermore, in the present invention, the injection pressure can be increased, and the contact between the substrate and the resin can be performed under high pressure and high temperature by utilizing the fact that the thermal conductivity of the impregnated substrate to be used is low. It is presumed that the adhesion of the base material to the surface of the molded body is improved, the surface roughness of the conductor pattern is reduced, the metallic luster is obtained, and the conductivity is further improved. or,
It is considered that irregularities on the surface of the impregnating base material, for example, aramid paper, also exert an anchor effect and contribute to the improvement of adhesion to a molded article.

〔Example〕

 Hereinafter, the present invention will be described with reference to examples.

Example 1 (Touch panel) Aramid paper (manufactured by Daifuku Paper Co., Ltd.) KVP-A To the Epo
Kishi-based ink (PS ink, 2 manufactured by Teikoku Ink Manufacturing Co., Ltd.)
Liquid) is solid printed on one side and impregnated.
Let it cure and then put silver pour on it as conductive ink
Dah (conductive material AgC-A manufactured by Fukuda Metal Foil & Powder Co., Ltd.) )When
Acrylic paint (Selinol manufactured by Teikoku Ink Manufacturing Co., Ltd.)
VG medium ) And 7: 3 weight ratio
Screen printing the conductive touch panel pattern
Was. After drying this at 150 ° C for 2 minutes,
17 using a hot press machine (MHPC-385-750)
It was heated and pressed at 0 ° C. for 10 minutes. Guided by this hot press
Measurement of both ends of a circuit with a body pattern resistance of 150 mm x 0.5 mm
What was 6.2 Ω before the heating press decreased to 2.0 Ω,
The conductivity was improved.

Next, a predetermined insulating pattern is screen-printed to a thickness of about 8 μ using a polyester-based ink manufactured by Fujikura Kasei Co., Ltd. on the conductive pattern forming intermediate for a touch panel obtained in the above process.

This was dried at 150 ° C. for about 2 minutes, and then a predetermined insulating pattern was screen-printed with the above-mentioned polyester ink three more times to a thickness of 24 μm, and then dried at 150 ° C. for 2 minutes.

Next, a predetermined resistance pattern was formed thereon by screen printing using a carbon-containing polyester-based ink (trade name: Dodide, manufactured by Fujikura Kasei Co., Ltd.). This is 15
Dry and heat at 0 ° C. for about 2 minutes.

 The printed wiring board for touch panel obtained above
Installed in the injection mold, ABS resin (Asahi Kasei Kogyo Co., Ltd.)
Stylac 121) Mold temperature 40 ℃, resin temperature 2
Printed wiring board on ABS resin after painting and injection molding at 00 ° C
Was obtained, and the desired touch panel was obtained. this
Good solder when soldered to give terminals
I was able to attach.

Example 2 (Remote control switch) Change pattern to remote control switch pattern and inject
Polyetherimide resin (Ultem manufactured by EPL) )
Other than changing the metal temperature to 100 ℃ and the resin temperature to 390 ℃
Printed circuit board for remote control switch in the same manner as in Example 1.
Is a painted polyetherimide remote control switch
A molded article was obtained.

In addition, this was soldered to the circuit satisfactorily.

〔The invention's effect〕

According to the present invention, an injection-molded printed wiring body in which an impregnated base material (for example, aramid paper) having a conductor pattern is integrally formed on a molded body can be simply and economically produced by a dry process.

Further, when a heat-resistant base material such as aramid paper is used for the injection-molded printed wiring body of the present invention, there is an effect that heat resistance is imparted even to a general-purpose resin molded body. Further, the printed wiring base material used in the present invention has good followability to the unevenness of the molded body, is less likely to wrinkle, has good smoothness (flat), and has a pattern formed by a hot press or a hot roll in an intermediate step. Has the characteristics that the conductivity is greatly improved and the vicinity of the gate is not attacked. In addition, the surface state of the aramid paper has an anchoring effect when integrated with the molded product, and the adhesion is extremely excellent.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Isao Isoshi 2-5-1, Komagata, Taito-ku, Tokyo Inside Green Mark Manufacturing Co., Ltd. (72) Inventor Takeshi Kikuchi 2-1-1, Komagata, Taito-ku, Tokyo Green Mark Manufacturing Co., Ltd.

Claims (7)

(57) [Claims] A step of printing a conductive pattern on the impregnable substrate, a step of heating the roll or a heating roll thereof, a step of printing an insulating pattern thereon, and a step of printing a resistor pattern thereon. A method for producing an injection-molded printed wiring body, comprising, as main steps, a step of placing the laminate obtained in the step in a predetermined mold and a step of injection molding using the mold. 2. The method according to claim 1, wherein the conductive pattern is printed after a polyester resin or an epoxy resin is previously applied or solid printed on the impregnating base material. A method for manufacturing an injection-molded printed wiring body. 3. The method according to claim 1, wherein the printing in each of the steps (1) and (2) is performed by screen printing.
A method for producing an injection-molded printed wiring body according to the above. 4. An insulating pattern forming step (step),
3. The method for manufacturing an injection-molded printed wiring body according to claim 1, wherein said insulating pattern is formed in two or more layers. 5. The method of manufacturing an injection-molded printed wiring body according to claim 1, wherein the printing (step) of the resistor pattern is performed by carbon printing. 6. The method for producing an injection-molded printed wiring body according to claim 1, wherein the impregnable substrate is paper, nonwoven fabric, or fabric. 7. The impregnated base paper is aramid paper.
A method for producing an injection-molded printed wiring body according to the above.