KR910008627B1 - Thermoplastic resin molden unit serving as circuit board as well - Google Patents

Abstract

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Description

Thermoplastic molded article for dual use as a circuit board

1 is a plan view showing a specific example of the present invention.

2 is a cross-sectional view taken along the line II-II as shown in FIG.

3 is a partially enlarged cross-sectional view from FIG.

4 is a cross-sectional view showing another embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

1 component part 2 bottom part

3: opening 4: element

5: feet 6: upper surface

7: circuit 8: lead

9: boss 10: end bracket

11: circuit 12: circuit

13 electric parts 14 support parts

15: motor shaft bearing 16: functional part

17: lead

The present invention provides a component assembly for an electronic device comprising an article molded from a thermoplastic resin, a circuit board coated on the article, and an electronic component connected to the substrate. The circuit board is formed of an electrically conductive paint. In other words, the present invention relates to a thermoplastic resin article for dual use as a circuit board, and more particularly, to a circuit board having electrical and electronic components connected and held in an electric circuit formed directly on a thermoplastic resin molded article as an electric circuit board. Provided are thermoplastic molded articles for dual use. It finds a desirable use as component parts, housings, etc. for electronic and electrical appliances, automobiles, office automation equipment, sundries, and the like.

In incorporating circuits into electronic and electrical products, so-called printed wiring boards having circuits printed on substrates are commonly used. Such printed substrates are generally flat plates for exclusive use in certain printed circuits formed of thermosetting resins such as phenolic or epoxy resins, which are then coated with copper followed by resist coating, etching and plating. Thereafter, transistors, resistor elements, capacitors, and other electrical and electronic components are soldered onto the printed substrate with the desired circuit and in this way complete the circuit board of the electrical appliance. These circuit components, along with other components, are incorporated into the housing of the product to perform their specific functions.

Assembling electronic and electrical products using conventional printed substrates involves the following problems. First, since the circuit is fixedly arranged on a plate for exclusive use for the circuit, at least a space large enough to fit this plate must be securely provided in the product. For this reason, product miniaturization is not easy. This problem should be taken seriously, especially when the shrinking of electrical appliances is now making progress. It is possible to divide a printed circuit board into many parts and arrange them in place in order to provide a circuit arrangement in advance in a limited space. However, this method requires extra time and trouble in manufacturing the printed board and causes the problem of identifying the wiring between the printed board parts.

Then, the printed product has a low degree of freedom in terms of design since the substrate for exclusive use as printed is composed of flat surfaces. In particular, it is a very difficult task not only to solve the above-mentioned space problem but also to secure high design freedom. Furthermore, the printed substrate is produced through a compounding process and therefore this is expensive.

The present invention is summarized as follows.

The present invention has been made to address this problem.

Thus, instead of using a conventional substrate for exclusive use as a printed one, it forms a circuit directly on the molded article and thus the molded article has to play its dual role as a circuit board in addition to letting the molded article act on its own. An attempt was made to solve the difficulty.

As described above, the present invention is a dual-use circuit board which forms a circuit directly on a molded article of a thermoplastic resin by coating conductive paint, bonding metal foil, plating metal, and the like so that electrical and electronic components are connected and fixed thereon. It provides a thermoplastic resin molded article for. The structure obtained according to the invention, which consists of molded parts of thermoplastics and circuits and functional parts directly formed thereon, is obtained from component parts such as electronic and electrical appliances, automobiles, office automation equipment, daily necessities, such as telephones, telephones, Or it finds use mainly as terminal blocks in handsets, brackets for micromotors and similar component parts, and housings of others.

According to the present invention, the molded article formed of the thermoplastic resin may have a three-dimensional structure. This is realized by forming a circuit as described later on the molded article, as the case may be, by direct printing of conductive paint, bonding of metal foil or plating of metal. Thus, even if it is used as a double circuit board, the molded article keeps its previous shape, and thus does not need to be flat as in the case of a conventional printed board. Rather, the three-dimensional structure and design of the product will have much greater freedom because the circuit is provided directly on the molded article without requiring a substrate for exclusive use for the printed circuit.

In this way it is possible for the molded article to have a combined triple role as the component part itself, as a component part, as a circuit board and as a substrate on which the functional part is mounted.

Furthermore, in some cases, a molded article for dual use as a circuit formed in this way may be mounted on another substrate or an electric circuit, and the wiring is formed on a molded article integrally mounted on the substrate by an outserting molding method. Can be.

According to the present invention, the molded article may be formed of any of the thermoplastic resins described below. Thermoplastic resins are, for example, polyolefins such as polyethylene, polypropylene, aromatic dicarboxylic acids and aromatic polyesters, such as polyethylene terephthalate, polybutylene terephthalate, etc., made from diols or oxycarboxylic acids, and polyacetals. (Single- or co-polymer), polystyrene, polyvinylchloride, polyamide, polycarbonate, ABS, polyoxyphenylene oxide, polyoxyphenylene sulfide, fluoro resin and the like, but are not particularly limited thereto. These thermoplastic resins can be used in combination of two or more thereof. It is also possible to add various additives and reinforcing agents to these resins as needed to improve these various other properties such as mechanical, electrical and chemical properties and flame retardancy.

The coating of certain conductive paints can be cited as a means for forming the electrical circuit of the invention. Useful as conductive paints are silver, gold, palladium, platinum or mixtures thereof and carbon based pastes. More specifically they include silver, gold, silver-palladium, silver-platinum, on-epoxy resins and carbon based pastes.

Such paints are allowed to contain known fillers with conductive functions and known fillers with inorganic fillers which are surface treated with metals. In particular, paints comprising silver coated glass beads are preferred. In order to print such conductive paints, screens are usually used. In this screen, a pattern of a circuit is provided that allows the transmission of conductive paint. The circuit is easily formed by applying conductive paint on a molded article with the screens arranged thereon.

The applied conductive paint is then sintered at a temperature of 80-200 ° C. By printing with any conductive paint, the molded article is not flat, but a circuit can be constructed even if it has a three-dimensional structure or constitutes a curved surface. In addition, the conductive paint may be applied by other methods instead of using such screens.

If the conductive paint on the molded part is weakly bonded, the conductive paint should be applied after surface treatment before applying the conductive paint surface.

Examples of such surface pretreatment include corona discharge and primer coating. Such conductive primer coatings and conductive paints used according to the invention can be used in combination. Surface pretreatment is not particularly limited to any of those described above. It is only necessary to select a method suitable for the thermoplastic resin used. In addition, a resin composition of a thermoplastic resin to which a modifier including a surfactant is added may be used to improve the coating properties and tackiness described below.

As another means for constructing a circuit on a molded article, a method of bonding a metal foil on a molded article is useful. Any metal foil can be used as long as it has high conductivity and conductivity, but silver foil, gold foil and the like can be cited as an example. As a joining method, a hot stamping method can be mentioned without any limitation.

In addition, it is practical to construct a circuit on a molded article by, for example, decalcomania, pat printing, electroless plating, or the like.

According to the present invention, electrical and electronic components are fixed before or after an electric circuit is provided on a molded article formed of a thermoplastic resin. For example, as a circuit board molded from thermoplastic resin, a hole is formed in the electrical component that needs to be mounted on a molded article for dual use, which hole should be slightly smaller than the electronic component housed therein, This allows them to be kept safe due to the elasticity of the resin. Then, by forming a circuit by applying a conductive paste to contact with the lead of the electronic component on the molded article holding the electronic component thereon, thereby forming a component unit equipped with electrical and electronic components on the molded article for dual use as a circuit board. Get Of course, it is possible to crimp the circuit after being configured in such a way that the leads of the electronic component can be connected to these circuits. And in order to keep large electrical and electronic components on the circuit, they can be mounted on an accessory preconfigured on a molded article, and after the necessary electronic components are held in place, injection molding is further simplified.

The effects of the present invention are as follows.

As described above, according to the present invention, all of the conventional problems resulting from the use of the substrate will be eliminated since the substrate for the exclusive use of the printed wiring can be omitted first. Thus, not only the time, labor and cost required for the manufacture of the printed board can be saved, but the space occupied by such printed board does not need to be provided in the product. This means the possibility of reducing the size and weight of the product, as well as reducing the price of the product itself. In addition, the thermoplastic resin molded article for dual use as the circuit board of the present invention does not cause structural problems in the thermoplastic resin molded article in constructing the circuit.

This allows the circuit to be configured three-dimensionally with improved freedom of design of the molded part. In addition, if the molded article is provided as a functional part, or if the molded article is designed to have an electronic part, a single unit can play many roles as well as achieve the simplicity of manufacture and the reduction of weight.

EXAMPLE

The invention will become more apparent from the following description of the preferred embodiments in conjunction with the accompanying drawings.

1 and 2 show the cutting shown in FIG. 1, which shows a component 1 of an electrical appliance suitably made for the purposes of the present invention. This component member 1 is made of a thermoplastic resin, for example polybutylene terephthalate. This is configured as a housing in this embodiment. Its bottom part 2 is curved and is provided with an opening for receiving another part. In addition, on the bottom 2, a pit 5 is provided for the supporting elements 4 of electrical and electronic components such as transistors and resistors, and these elements 4 are press fit into these pits 5.

The circuit 7 formed by screen printing is then arranged on the part 6 of the surface of the bottom 2 so that the component member 1 can be provided as a double circuit board. 3 shows how the circuit 7 formed of conductive paint lies in contact with the lead 8 of the element 4 held in the pit 5.

This embodiment clearly shows that according to the invention the circuit can be easily configured even if the molded article is three-dimensional. If a conventional printed board is used in this embodiment, difficulties in mounting parts and elements are not at the bottom 2 because of the need to also house a board for wiring printed on the bottom 2. Or results from the fact that the boss 9 is present. Therefore, as a circuit board of the present invention, the thermoplastic resin molded article for dual use has achieved not only an increase in design freedom but also a space saving. An assembly with a circuit 7 formed where the element 4 is pressed into the pit 5 results in simplicity of structure and increased ease of manufacture.

4 shows another design example of the present invention. Shown in this figure is a cross-sectional view of a thermoplastic resin molded article used, for example, as an end bracket 10 of a micromotor. What is used as this thermoplastic resin is polyacetal, for example. Circuits 1 and 2 formed by bonding a metal foil thereon by a hot stamping method on the upper and lower surfaces of the end bracket 10.

This design example is characterized by the functional parts installed on the end brackets. Contact together by a holder member 14 and a holder member 14 for supporting the electrical component 13, the motor shaft bearing 15 and another functional component 16 on the end bracket 10. The lead 17 of the electric member 13, which is pressed on the circuit 11, is formed integrally. As described above, by providing the end bracket 10 having the role of the circuit board, it is possible to achieve miniaturization and ease of assembly in addition to the supporting functional parts. End brackets can have any curve and are allowed to be of various constructions to suit the desired application.

Claims (7)

A thermoplastic resin molded article for dual use as a circuit board, wherein the electrical and electronic parts are connected to and supported on an electric circuit formed directly on the molded article of the thermoplastic resin. 2. The thermoplastic resin molded article for dual use as a circuit board according to claim 1, wherein the electric circuit is formed by coating the molded article with a conductive paint. 3. The thermoplastic resin molded article for dual use as a circuit board according to claim 2, wherein the conductive paint is silver, gold, palladium, platinum or a mixture thereof or a carbon based paste. 4. The thermoplastic resin molded article for dual use as a circuit board according to claim 3, wherein the silver base paste is selected from silver-palladium base pastes, silver-platinum base pastes or silver-epoxy resins. 2. The thermoplastic resin molded article for dual use as a circuit board according to claim 1, wherein the electric circuit is provided by bonding a metal foil onto the molded article. The thermoplastic resin molded article for dual use as a circuit board according to claim 1, wherein the electric circuit is provided by an electroless plating method. The molded article of thermoplastic resin according to any one of claims 1 to 6, wherein the molded article has a three-dimensional structure.

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