JPS62113492A - Thermoplastic resin molded unit serving as circuit board as well - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a thermoplastic resin molded product that can also be used as a circuit board.
Specifically, we provide a thermoplastic resin molded product that can be used as a circuit board, in which a thermoplastic resin molded product is directly used as an electric circuit board, and an electric circuit is formed thereon to connect and hold electrical and electronic components. Electronic/electrical products, automobiles, OA
It is preferably used for components, housings, etc. of equipment, daily miscellaneous goods, etc.

(Prior art) When incorporating circuits into electronic and electrical products, so-called printed wiring boards, in which circuits are printed on a board, are commonly used. However, such printed boards are generally made of thermosetting resin such as phenol resin or epoxy resin. A flat board dedicated to a specific printed circuit is made from a synthetic resin, coated with copper, and then coated with resist, etched, plated, etc.Then, transistors and resistors are attached to the printed board carrying the desired circuit. Elements, capacitors, and other electrical and electronic components are soldered together to create the circuit part of an electrical product.This circuit part is then assembled, for example, with other parts into the product's housing, and performs its intended function. become.

[Problem to be solved by the invention]

However, when assembling electronic and electrical products using conventional printed circuit boards, there are the following problems. First, since the circuit is fixedly arranged on a dedicated flat plate, a minimum amount of space must be secured within the product to accommodate this flat plate, making it difficult to miniaturize the product. This problem must be given particular importance, especially now that the size of electrical products is becoming smaller. In order to perform circuit layout within a limited space,
It is possible to divide the printed circuit board into several pieces and arrange them, but in that case extra effort is required to create the printed circuit boards, and wiring between the printed circuit boards must be considered. Other problems arise.

Next, since the printed circuit board has a planar structure, there is little freedom in the design of the resulting product. It is particularly difficult to solve this freedom of design along with the above-mentioned space problem. Furthermore, printed circuit boards are manufactured through complicated processes and are expensive.

[Means for solving problems]

The present invention has been made in view of the above-mentioned problems, and instead of the conventional printed circuit board, a circuit is formed directly on a molded product, and in addition to its original role, the circuit is also formed on the molded product. The idea was to make it also function as a substrate, thereby solving the various problems mentioned above all at once.

That is, the present invention is characterized in that a circuit is formed directly on a molded article made of thermoplastic resin by applying conductive paint, adhering metal foil, metal plating, etc., and furthermore, electrical/electronic parts are connected and held to this. The present invention provides a thermoplastic resin molded product that can also be used as a circuit board. Molded articles made of thermoplastic resin obtained by the present invention and structures made of circuits and functional parts directly formed thereon are mainly components of electronic/electrical products, automobiles, OA equipment, daily miscellaneous goods, etc., to name a few. For example, it is used for terminal boards in telephone handsets, micromotor brackets, other components, housings, etc.

According to the present invention, a molded article made of a thermoplastic resin can have a three-dimensional structure. This is because, as will be described later, a circuit is formed by directly printing a conductive paint on the molded product, or by adhering a metal foil or, in some cases, plating it. Therefore, even if the molded product is also used as a circuit board, it can maintain the same shape as before, and is not required to be flat like a conventional printed circuit board. Rather,
By removing the dedicated printed circuit board and installing the circuit directly on the molded product, the three-dimensional structure and design of the product becomes more flexible.

In such cases, the molded product can have three combined roles: the original role of a molded product as a component, the role of a circuit board, and the role of a board with functional parts. becomes.

Depending on the case, the molded product that also serves as a circuit formed in this way may be attached to a separate substrate, or it may be a molded product that is integrally attached to the substrate using the outsert molding method. Electric circuits and wiring can also be formed thereon.

In the present invention, the molded article is made of thermoplastic resin. Thermoplastic resins are not particularly limited, but examples include polyolefins such as polyethylene and polypropylene, aromatic polyesters made of aromatic dicarboxylic acids and diols or oxycarboxylic acids such as polyethylene terephthalate and polybutylene terephthalate, and polyacetyls (homo or oxycarboxylic acids). copolymer), polystyrene, polyvinyl chloride, polyamide, polycarbonate, ABS, polyoxyphenylene oxide, polyoxyphenylene sulfide, fluororesin, and the like. Further, two or more of these thermoplastic resins can be used in combination.

Furthermore, various additives and reinforcing materials can be added to these resins as necessary in order to improve various properties such as mechanical, electrical, chemical properties and flame retardancy.

Application of a conductive paint can be cited as a means for forming the electric circuit of the present invention. Examples of the conductive paint include root thread, gold thread, palladium-based, platinum-based, or a mixture thereof, and carbon-based paste. More specifically,
There are silver thread paste, gold thread paste, silver-palladium paste, silver-platinum paste, silver-epoxy resin, and carbon paste.

The paint may contain a known filler having a conductive function, an inorganic filler whose surface is treated with metal, and the like.

Particularly suitable is a paint containing silver-coated glass beads. A screen is usually used to print such conductive paint.

This screen is provided with a circuit pattern that allows the conductive paint to pass through, and the circuit is easily formed by placing the screen on the molded product and applying the conductive paint. After that, the applied conductive paint is 80~2
Sintered at a temperature of 00°C. As a result of printing the conductive paint in this manner, a circuit can be constructed even if the molded product is not flat, has a three-dimensional structure, or has a curved surface. Note that instead of using the screen, the conductive paint may be applied by other means.

If the adhesion of the conductive paint to the molded product is poor, pre-treat the surface of the molded product before applying the conductive paint. Examples of surface pretreatment methods include corona discharge method and primer coating method. Further, this conductive primer paint and the conductive paint used in the present invention can be mixed and used. This surface pretreatment method may be any method suitable for the thermoplastic resin used.
Not particularly limited. In addition, a resin composition in which a modifier such as a surfactant is added to a thermoplastic resin may be used to improve paintability and adhesion as described below.

Another method for configuring a circuit on a molded article is to adhere metal foil to the molded article.

Any metal foil may be used as long as it has good conductivity and malleability, and examples include silver foil and gold foil. As the bonding method, a hot stamping method can be mentioned, but it is not particularly limited.

In addition to the above, it is also possible to configure a circuit on a molded product by, for example, transfer printing, batt printing, electroless plating, or the like.

According to the present invention, electric/electronic components are held in a molded article made of thermoplastic resin before or after an electric circuit is applied thereto. For example, in a thermoplastic resin molded product that also serves as a circuit board, a hole is formed to match the size of the desired electronic component, and preferably this hole is smaller in diameter than the electronic component. is press-fitted and held securely by the elasticity of the resin. Then, a circuit is formed by applying, for example, a conductive paste to the molded product that holds the electronic component so that it comes into contact with the leads of the electronic component, and the molded product that also serves as a circuit board is a component that is equipped with electrical and electronic components. get. Of course, it is also possible to press-fit the leads of the electronic components so that they are connected to the circuit after the circuit is configured. In addition, in order to hold large electric/electronic components in a circuit, it is possible to attach them to mounting parts that have been formed into a molded product in advance, and by performing injection molding with the necessary electronic components, the process can be simplified. It is further simplified.

〔Effect of the invention〕

According to the present invention as described above, first, since a board dedicated to printed wiring can be omitted, all conventional problems caused by the use of this board can be eliminated. That is, not only can the time, labor, and expense required for producing a printed circuit board be eliminated, but also the space occupied by the printed circuit board can be eliminated from within the product. This means that the product can be made smaller and lighter, and the cost of the product itself is also reduced. In addition, in the thermoplastic resin molded product that can also be used as a circuit board of the present invention, the shape of the thermoplastic resin molded product does not matter when configuring the circuit. Therefore, the circuit can be configured three-dimensionally, and there is a high degree of freedom in the design of the molded product. can be increased. Furthermore, by equipping the molded product with functional parts and allowing the molded product to hold electronic components, one part can serve multiple roles, and further simplify manufacturing and reduce weight. become achievable.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

1 and FIG. 2, which is a section taken along the line nn of FIG. 1, shows a component 1 of an electrical appliance suitably constructed for the purpose of explaining the invention. This component 1 is made of thermoplastic resin,
It is made, for example, from polybutylene terephthalate and is here constructed as a housing. Its bottom part 2 is curved and has holes 3 for receiving other parts.
is provided. Further, the bottom portion 2 is provided with a hole 5 for holding an element 4 of an electric/electronic component such as a transistor or a resistor, and the element 4 is press-fitted into the hole 5. A circuit 7 formed by screen printing is formed on a portion 6 of the surface of the bottom portion 2 so that the component 1 also serves as a circuit board. FIG. 3 also shows a method of contacting the circuit 7 made of conductive paint with the lead 8 of the element 4 held in the hole 5. As is clear from this example, according to the present invention, a circuit can be easily constructed even when the molded product is three-dimensional! Wear. If a conventional printed circuit board were used in this embodiment, it would be necessary to further accommodate a printed wiring board on the bottom part 2.
In that case, installation would be difficult because the bottom portion 2 is not flat and the boss 9 is present. Therefore, the thermoplastic resin molded product for use as a circuit board of the present invention not only saves space but also increases the degree of freedom in design. Further, although the circuit 7 is formed where the element 4 is press-fitted into the hole 5, such a configuration further simplifies the structure and facilitates manufacturing.

Another embodiment of the invention is shown in FIG. What is shown in this embodiment is a sectional view of a thermoplastic resin molded product used as an end bracket 10 of a micromotor, for example.

The thermoplastic resin used here is, for example, polyacecool. Circuits 11 and 12 are provided on the upper and lower surfaces of the end bracket 10 by bonding metal foil using a stamping method. In this example,
A feature is that the end bracket 10 is provided with functional parts. The end bracket 10 has electrical components 13
A holding part 14 that holds the electrical part 13, a motor bearing 15, and other functional parts 16 are integrally formed.
7 is pressed into contact with the circuit 1 by a holding component 14.

In this way, by giving the end bracket 10 a role as a circuit board in addition to holding functional components,
Miniaturization and ease of assembly can be achieved. The end bracket may have a curved shape, and can have various configurations depending on the desired use.

[Brief explanation of drawings]

Fig. 1 is a plan view showing one embodiment of the present invention, and Fig. 2 is a plan view showing an embodiment of the present invention.
3 is a partially enlarged sectional view of FIG. 1, and FIG. 4 is a sectional view showing another embodiment of the present invention. 1... Component 21. , bottom 3...hole 4...element 5...hole
6... Top surface 7... Circuit 8... Lead 9... Boss 10... End bracket/nod 11... Circuit 12... Circuit 13... Electrical parts 14... Holding parts 15
...Motor bearing 16...Functional parts 17...
・Lead

Claims (1)

[Scope of Claims] 1. A thermoplastic resin molded product that doubles as a circuit board, characterized in that electrical and electronic components are connected and held to an electric circuit formed directly on the thermoplastic resin molded product. 2. The thermoplastic resin molded product that also serves as a circuit board according to claim 1, wherein the electric circuit is formed by applying a conductive paint. 3. The thermoplastic resin molded product that can also be used as a circuit board according to claim 2, wherein the conductive paint is a paste of silver thread, gold thread, palladium, platinum, a mixture thereof, or carbon. 4 Silver-based paste is silver-palladium-based paste, silver-
4. The thermoplastic resin molded article for use as a circuit board according to claim 3, which is selected from platinum paste or silver-epoxy resin. 5. The thermoplastic resin molded product that also serves as a circuit board according to claim 1, wherein the electric circuit is provided by adhering metal foil. 6. The thermoplastic resin molded product that also serves as a circuit board according to claim 1, wherein the electric circuit is provided by electroless plating. 7. The thermoplastic resin molded product for use as a circuit board according to any one of claims 1 to 6, wherein the molded product has a three-dimensional structure.