JPH0481321B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a closed magnetic circuit type chip inductor manufactured by firing. Conventional Structures and Their Problems In recent years, there has been a demand for miniaturization of various electronic components, and inductors as one of the electronic components have also been made into chips. Typical methods for making chips include a printing method and a wire winding method.
The first method is to form a coil-shaped conductive pattern on a magnetic sheet using a printing method, and to construct a thin laminated inductor by continuously laminating the coil-shaped conductive pattern. Further, as a second method, there is a method shown in FIG. This involves winding a winding 2 coated with resin or the like around a magnetic bar 1.
The terminal 3 of the coil body is connected to the internal electrode 4, and the coil body is coated with magnetic powder 5 by pressure molding, and then fired in air at a firing temperature of 800 to 1300°C.
Further, an external electrode 6 is provided on the internal electrode 4 to constitute a closed magnetic circuit type chip inductor. However, these methods have the following problems. First, in the first method, when multi-layering is used to increase inductance, the number of layers becomes extremely large, the process becomes complicated, and the finished shape tends to be uneven. In the second method, the Cu wire conventionally used as the wire for inductors oxidizes during firing, resulting in poor conductivity, or breaks due to the heat during firing. Purpose of the invention The present invention eliminates such conventional problems,
An object of the present invention is to provide a chip inductor that is easy to manufacture and has stable performance. Structure of the Invention The chip inductor of the present invention basically relates to an improvement of the second method, and involves winding a conductor around a magnetic material with a conductor coated with a heat-resistant insulator and a resin. A coil body is formed with internal terminals provided at both ends of the conductor, and this coil body is sheathed with a sintered magnetic material made by pressure-molding magnetic powder and then fired. A chip inductor in which the internal terminal is exposed and an external terminal is attached, the conductor having an Al content of 3 to 8
% by weight, and the balance is Cu. This allows the wire to have oxidation resistance and mechanical strength that can withstand tensile stress when it is wound around a magnetic material. In addition,
In the present invention, the reason why the Al content is set to 3 to 8% by weight is to reduce the resistance value of the inductor to obtain the desired Q value, and by adding Al, to provide the above mechanical strength and to improve the surface of the inductor. This is to provide oxidation resistance by using the formed Al ₂ O ₃ as a protective film. Al
If the content is less than 3% by weight, the addition of Al will result in less Al ₂ O ₃ being formed on the surface, resulting in easy oxidation, resulting in wire breakage and poor conductivity, making it difficult to obtain the desired Q value. do not have. If the Al content exceeds 8% by weight, the hardness of the alloy increases and it becomes difficult to process it into a wire rod. Description of Examples Hereinafter, the structure and operation of the present invention will be specifically explained based on Examples. FIG. 2 shows a cross-sectional view of a conductive wire used in a chip inductor in an embodiment of the present invention.
As shown in FIG. 2, the conducting wire 10 has a conductor 7 covered with a heat-resistant insulator 8, and further covered with a resin 9. In this example, a 70 μφ 8 wt% Al-92 wt% Cu alloy wire was used as the conductor, and a magnetic material mainly composed of Fe ₂ O ₃ , NiO, and ZnO was used as the heat-resistant insulator.
Polyester resin was used as the resin.
Here, the AlCu alloy wire was obtained by a wire drawing method.
In addition, the magnetic material, which is a heat-resistant insulator, is 6.7% butyral resin powder + 3.3% di-n-butyl phthalate + 90%
% terpinol vehicle and 60% magnetic powder and knead it, then add polyisocyanate to the paste.
A 20% 45% ethyl acetate solution was added and mixed well, then applied and dried. For polyester resin, add a 45% solution of polyisocyanate to a 20% solution of ethyl acetate.
A well-mixed solution was applied. The purpose of coating with polyester resin is to prevent the strength of the coating from being weak when using only a magnetic material, which is a heat-resistant insulator, and peeling occurs during winding. The following method was used to manufacture a chip inductor using the wire rod as described above. Third
As shown in the figure, the width is 3mm, length is 5mm, and thickness is 2mm.
A conductive wire 12 made of the wire according to the present invention is tightly wound around a ferrite fired body 11 mainly composed of Fe ₂ O ₃ , NiO, and ZnO, and wound with 40 turns, and both ends 13 of the conductive wire are wrapped with Ag-
Internal terminals 14 were formed by connecting with Pd paste.
Furthermore, this coil body 15 is coated with magnetic powder 16 mainly composed of Fe ₂ O ₃ , NiO, and ZnO as shown in FIG.
It is fired at 850°C, and both end faces are polished to expose the internal terminal 14 of the terminal part of the coil body.
External terminals 17 were formed by dipping Ag--Pd paste on both end faces. In this way, a chip inductor as shown in FIG. 5 was obtained. 1% Al-99% by weight of 70μφ as a conductor using the same manufacturing method
A chip inductor was obtained using a Cu alloy wire, a 3 weight Al-97 weight Cu alloy wire, and a 6 weight% Al-94 weight% Cu alloy wire. An attempt was made to make a 70μφ 15wt% Al-85wt%Cu alloy wire by wire drawing, but the hardness of the alloy could not be increased. When the cross section of such an inductor was observed, it was found that the fired magnetic material was continuously formed between the wire rods, and that a film layer of Al ₂ O ₃ was formed on the surface of the wire rod. The obtained inductance values of each chip inductor were as shown in Table 1.

[Table] Also, the frequency characteristics of Q were as shown in Figure 6. As can be seen from FIG. 6, when the Al content is set to 3 to 8% by weight as in the present invention, the desired Q frequency characteristics can be obtained, but beyond that, the desired Q frequency characteristics cannot be obtained. I can't. In the examples, the shape of the ferrite fired body was square, but the shape of the fired body in the present invention is not limited in any way, and even if it is round, for example, the same effect as above can be obtained. . Effects of the Invention As is clear from the above description, according to the present invention, if an alloy wire containing 3 to 8% by weight of Al and the remainder being Cu is used as a wire rod for a chip inductor,
It eliminates the problems of conventional methods, such as being able to be fired in air and having the mechanical strength to withstand winding around a magnetic material.Furthermore, chip inductors can be manufactured using a wire-wound method, which eliminates the need for conventional printing methods. This method has the advantage that the process is much simpler than the previously used manufacturing method for chip inductors.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional chip inductor, FIG. 2 is a sectional view of a conducting wire used in an embodiment of the present invention,
FIG. 3 is a perspective view of a coil element according to an embodiment of the present invention, FIG. 4 is a perspective view of a press-molded body thereof, and FIG.
The figure is a perspective view of an embodiment of a chip inductor manufactured using the wire according to the present invention, and FIG. 6 is a frequency characteristic diagram of the Q. 1... Magnetic rod, 2... Winding wire, 3... Winding terminal, 4... Internal electrode, 5... Magnetic powder, 6... External electrode, 7... Conductor, 8... Heat resistance Insulator, 9...
...Resin, 10...Conducting wire, 11...Sintered magnetic material, 1
2... Conductor wire, 13... Conductor wire terminal, 14... Internal terminal, 15... Coil element, 16... Magnetic powder,
17...External terminal.

Claims (1)

[Claims] 1. A conductor wire coated with a heat-resistant insulator and resin is wound around a magnetic material to form a coil element with internal terminals provided at both ends of the conductor, and this coil element is coated with magnetic powder. A chip inductor that is packaged with a sintered magnetic material that is pressure-molded and then fired, and has external terminals attached with the internal terminals exposed on both opposing end surfaces of the sintered magnetic material, the conductor being made of Al. A chip inductor characterized by being an alloy containing 3 to 8% by weight of Cu with the remainder being Cu.