JPH05121237A - Coil device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a highly reliable coil device in which solder thinning does not occur in a winding wire material at a solder connection portion. [Constitution] Copper or copper alloy conductor 11 is used as winding wire rod 5.
A coil device is formed by using an insulated electric wire 15 having solder corrosion resistance in which an iron or iron-nickel alloy plating layer 12, a metal plating layer 13 having good solder wettability, and a solderable insulating film 14 are sequentially provided on the outer periphery of Constitute.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil device, and more particularly to a micro coil or a micro inductor such as a chip coil or a precision coil.

[0002]

2. Description of the Related Art Conventionally, various coils have been incorporated and used as coil devices in electronic equipment. In recent years, as electronic devices have been downsized and improved in performance, coil devices have been similarly reduced in size and improved in performance. For this reason, the diameter of each component used for small coils, especially the winding wire material, has been further reduced,
Ultrafine copper wire with a conductor diameter of around 0.04 mm is also being used. Polyurethane enameled copper wire, which can be soldered without peeling off the insulating film, is widely used for the winding wire material.

As a small inductor, for example, FIG.
In the case of manufacturing the microinductor having the structure shown in FIG. 1, the polyurethane enamel copper wire is used as the winding wire rod 5, and the winding portion 2 of the core 1 provided with the flanges 3a and 3b is wound by a manual winding or an automatic winding. Winding, winding both ends of the winding wire material 5 at the beginning and end of winding to the lead parts 4a and 4b of the coil device several times, and these lead parts 4a and 4b are melted in a solder bath (not shown). The method of immersing in and soldering is generally performed.

[0004]

However, during the above-mentioned solder treatment step, the wire wound wire immersed in the molten solder bath is
Metallurgical diffusion occurs between the copper conductor of the winding wire and the tin component in the molten solder, copper atoms in the copper conductor diffuse and elute into the solder, and the conductor diameter becomes smaller. And the mechanical strength of the copper conductor in the portion to be soldered was deteriorated. The phenomenon of the solder thinning becomes more remarkable as the temperature of the molten solder bath is higher or as the immersion time in the solder bath is longer, and when it is not sufficient, the conductor may be broken. Therefore, there are problems that the yield of the coil product is reduced and the reliability of the solder-processed portion of the coil device is significantly impaired.

In order to solve these problems, an enameled wire provided with a polyurethane film that can be soldered at a lower temperature than before is used as a coil wire material to reduce the soldering temperature and suppress solder thinning as much as possible. However, this polyurethane film that can be soldered at low temperature has a drawback that the softening temperature is low and the heat resistance of the coil is lowered, and it has not been a sufficient solution.

Further, in order to improve the heat resistance of the coil, when an enameled wire provided with a solderable insulating film having a high softening temperature is used as a coil wire material, the soldering temperature must be raised. However, the contradictory result that the solder thinning of the conductor is further promoted was brought about.

The present invention has been made in order to solve the problems of the above-mentioned prior art, and provides a highly reliable coil device in which the strength of the winding wire material of the soldering portion of the coil device is maintained. The purpose is to

[0008]

In order to achieve the above object, the present invention provides an iron or iron-nickel alloy plating layer, a metal plating layer having good solder wettability, and soldering on the outer periphery of a conductor made of copper or a copper alloy. It is a coil device formed by winding an insulated electric wire having solder corrosion resistance, which is sequentially provided with a possible insulating film. The metal plating layer with good solder wettability of the insulated wire is formed of any one of copper, nickel, copper-nickel alloy, gold alloy, silver or silver alloy. The solderable insulating film of the insulated wire is made of a polyurethane paint, a solderable polyester paint, or a solderable polyesterimide paint.

[0009]

The insulated wire having solder corrosion resistance used for the winding wire material of the coil device of the present invention has an iron or iron-nickel alloy plating layer provided on the outer periphery of a conductor made of copper or a copper alloy, copper or copper. Since it acts as a barrier layer that prevents metallurgical diffusion between the copper alloy conductor and the tin component in the molten solder, the copper atoms in the conductor do not diffuse and elute into the molten solder and solder thinning can be suppressed. it can. The iron or iron-nickel alloy plating layer is effective as a barrier layer for preventing thermal diffusion of copper atoms, because the iron or iron-nickel alloy does not alloy with solder or copper at a temperature of 600 to 700 ° C. or less. , Therefore the copper atom of the conductor is iron or iron-
This is because it does not pass through the nickel alloy plating layer and elute into the solder. Further, by providing a metal plating layer having good solder wettability on the outer periphery of the iron or iron-nickel alloy plating layer, it is possible to provide solderability comparable to that of a commonly used copper conductor.

Therefore, in the coil device of the present invention, an ultrafine conductor can be used for the coil wire, and the soldering temperature in the soldering step of the solder connection portion of the coil wire can be increased, so that the soldering can be performed. It becomes possible to shorten the time. A solderable polyester film or a solderable polyesterimide film having a high softening temperature may be used as the solderable insulating film.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the coil device of the present invention will be described with reference to the drawings. The present invention is not limited to this embodiment. FIG. 1A is a front view showing the structure of the microinductor, and FIG. 1B is a sectional view of the insulated wire having solder corrosion resistance of the present invention.

Manufacture of Insulated Electric Wire Having Solder Corrosion Resistance The manufacturing of the insulated electric wire having solder corrosion resistance having the structure of FIG. 1B will be described. An iron plating layer 12 having a thickness of 0.5 μm is formed on the outer circumference of a copper conductor 11 having a diameter of 0.04 mm by an electroplating method, and further a copper plating layer 13 having a thickness of 0.1 μm is continuously formed on the outer circumference by an electroplating method. Was applied.
Next, this plated wire was coated with solderable polyester paint a plurality of times using a baking oven and baked to form a solderable polyester film 14 having a thickness of 6 μm, and a solder corrosion resistant polyester insulated wire 15 was manufactured. ..

Preparation of Evaluation Coil Sample A micro inductor having the structure shown in FIG. 1A was prepared as an evaluation coil sample. The core 1 is formed of a ferrite material, and includes a winding portion 2 and flanges 3a and 3b formed at both ends in the axial direction of the winding portion 2. The lead portion 4 made of a tin-plated copper material is formed on the outer surface of the one flange 3b of the core 1.
a and 4b are planted. For the coil winding, the solder corrosion resistant polyester insulated electric wire 15 manufactured as described above is used. The winding start end is twisted to the lead portion 4a of the coil, and then the solder corrosion resistant polyester insulated electric wire 15 is wound on the core 1. The wire portion 2 is spirally wound a required number of times, and the end of the winding is secured to the lead portion 4b several times. Next, the stripped lead portions 4a, 4b of the solder corrosion resistant polyester insulated electric wire 15 are immersed in a molten solder bath at 450 ° C. for 15 seconds to separate the solder corrosion resistant polyester insulated electric wire 15 and the lead portions 4a, 4b. I made a connection.

Comparative Example Production of Solderable Polyester Insulated Electric Wire and Production of Evaluation Coil Samples The same solderable polyester paint as in the example was applied a plurality of times on the outer periphery of a copper conductor having a diameter of 0.04 mm using a baking oven. , And a solderable polyester film having a thickness of 6 μm was provided by baking to manufacture a solderable polyester insulated wire. Next, using this insulated wire, a microinductor was manufactured as an evaluation coil sample by the same manufacturing method as in the above-described example.

Evaluation Test When the appearance of the insulated wire at each of the coil lead portions 4a and 4b was inspected using a magnifying glass for each of 10 pieces of the evaluation coil samples of the example and the comparative example produced as described above,
The samples of the examples are soldered lead portions 4a and 4b.
No solder thinning phenomenon was observed in any of the conductors at the soldering interface portion of the solder-corrosion-resistant polyester insulated electric wire 15 and no disconnection occurred. On the other hand, in the samples of the comparative examples, the phenomenon of solder thinning occurred in the conductors at the soldering interface portion of the solderable polyester insulated electric wire of the soldered lead portions 4a and 4b. Three of them were broken.

[0016]

The coil device of the present invention is an insulation in which an iron or iron-nickel alloy plating layer, a metal plating layer having good solder wettability, and a solderable insulating film are sequentially provided on the outer periphery of a copper or copper alloy conductor. Since the wire is used as a winding wire material, when the end of the coil winding wire material is soldered to the lead part of the coil device, the outer plating layer of this winding wire material has a metal plating layer with good solder wettability. It has the same solderability as the copper conductor of
Since the iron thinning or the iron-nickel alloy plating layer of the inner winding layer of the winding wire rod can prevent the solder thinning phenomenon of the winding wire rod, the winding wire rod is provided with the lead portions 4a, 4b of the coil device.
Does not reduce the mechanical strength of the wire even when soldered to the. Therefore, even when a wire having a very small conductor diameter such as a micro coil or a micro inductor is used, a disconnection accident due to the solder thinning of the wire at the solder joint is prevented, and the reliability and yield of coil products are improved. It is possible to improve the size of the coil device, and it is possible to design the coil device to be smaller and have higher performance. Further, in the solder connection process of the coil device, the solder processing temperature can be raised, so that the production efficiency can be improved by shortening the solder processing time.

[Brief description of drawings]

FIG. 1A is a front view showing the structure of a micro inductor. (B) It is sectional drawing of the insulated wire which has solder corrosion resistance of this invention.

[Explanation of symbols]

 1 core 2 winding part 3a, 3b flange 4a, 4b lead part 5 winding wire material 11 copper or copper alloy conductor 12 iron or iron-nickel alloy plating layer 13 metal plating layer with good solder wettability 14 solderable insulating film 15 Insulated wire with solder corrosion resistance

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01B 7/00 303 8936-5G

Claims (3)

[Claims] 1. A solder corrosion resistance comprising an iron or iron-nickel alloy plating layer, a metal plating layer having good solder wettability, and a solderable insulating film sequentially provided on the outer periphery of a conductor made of copper or a copper alloy. A coil device formed by winding an insulated wire. 2. A metal plating layer having good solder wettability of the insulated wire is formed of a plating layer of copper, nickel, copper-nickel alloy, gold, gold alloy, silver or silver alloy. The coil device according to claim 1. 3. The solderable insulating film of the insulated wire is formed by applying and baking a polyurethane paint, a solderable polyester paint or a solderable polyesterimide paint. Or the coil device according to 2.