JPS60163411A - Inductor element - Google Patents

Abstract

PURPOSE:To enable low cost and high performance by forming a terminal part which communicates with an internal coil winding on the end part of outer surface of the sintered ferrite core combined body by combining plural sintered ferrite cores unitarily with an adhesive including magnetic powder. CONSTITUTION:A magnetic adhesive is made by mixing the same sintered ferrite powder as one that is used for fabricating a ferrite core into an adhesive. The magnetic adhesive is applied onto the combined planes of a square-vessel- shaped ferrite core 1 and a flat-board-shaped ferrite core 2 respectively to combine the cores and the cores are cured by heating. The ends of coil windings led out to the respective part are cut so that the ends are in accordance with the end planes; of the sintered ferrited combined body. Then electroless plating is performed for them, the firm electrical connection of the terminal parts and the internal coil windings is attained. As the magnetic adhesive of such constitution has the extremely high permeability, the obtained inductance element has the closed magnetic circuit structure virtually. The low cost and the remarkable improvement in performance can be contrived.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a small inductor element, and more specifically, to
A coil winding made of an insulated conductor wire is housed in a sintered ferrite core, and a terminal part is formed at the outer end to be electrically connected to the coil winding, making it easily compatible with surface mounting. This invention relates to an inductor element.

In recent years, with the miniaturization of various electronic devices and the advancement of automatic mounting processes using robots, etc., passive elements such as chip capacitors with a leadless structure that can be directly soldered to hybrid IG boards and various printed wiring boards, etc. It is well known that many chip resistors are used.

Inductor elements are no exception, and there are already various chip inductor elements (small coil components without lead wires).
has been proposed and is commercially available.

Typical chip inductor elements include the following two types of quibs. One example is to print a part of an arc-shaped coil pattern on the surface of an unsintered ferrite tonto using thick film conductive paste, and then stack a large number of sheets one after another, and in the process, the edges of the coil pattern are printed. Conductive paste was poured into the through hole formed in the part and laminated.
It has a structure in which a coil is formed by sequentially connecting the patterns of sheets in series, which is sintered, and then terminal portions are formed at the ends. As another example of a chip inductor element, a conductive pattern is printed on the surface of a similarly unsintered Ferray 1 sheet using thick film conductive paste, and then this sheet is wound and formed into a cylindrical shape. The coil is then sintered in the same manner as before, and the terminal portion is formed at the outer end.

However, in any case, there is no difference in the structure in which an unsintered ferrite sheet is used, a pattern is printed on it using a thick film conductive paste, and then sintered. Since the firing temperature is usually 1000° C. or higher, a noble metal conductor must be used as the thick film conductive paste, which has the disadvantage that the material cost is very high, making it expensive. Additionally, during firing at such high temperatures, diffusion occurs from the conductor to the magnetic material, or from the magnetic material to the conductor.
As a result, the resistance of the coil increases, resulting in a decrease in Q.

Furthermore, in the former structure in which layers are stacked, it is necessary to sequentially connect the ends of the arcuate patterns formed on each sheet at the stage of stacking the unsintered ferrite sheets, making it necessary to make through holes one by one. The method of forming and pouring conductive paste to connect is extremely troublesome to manufacture and is not suitable for mass production, and if the pattern connection does not work well even with one seal among the many laminated sheets, The disadvantage is that the yield tends to inevitably drop because the parts become defective. Furthermore, the latter configuration in which the sheet is wound around has the disadvantage that the inductance is small since it becomes an open magnetic path configuration.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art as described above and to provide an inexpensive and high-performance compact inductor element.

The present invention, which can achieve such objects, uses a commonly used insulated conductor wire such as polyurekne coated copper wire as a coil material, and uses a plurality of sintered ferrite cores, The coil winding is housed in the space formed inside by the combination thereof, and the plurality of sintered ferrite cores are bonded and integrated with each other using an adhesive containing magnetic powder, and the outer surface of the sintered ferrite core assembly is It has a structure in which a terminal portion that is electrically connected to the internal coil winding is formed at the end portion.

Hereinafter, the present invention will be explained in more detail based on the drawings. FIG. 1 is an exploded perspective view of an embodiment of an inductor element according to the present invention, excluding the terminal portion. The inductor element shown in this embodiment is an ultra-small rectangular plate type chip inductor element, which is usually several cylinders in length and width. As is clear from the figure, this inductor element is composed of a plurality of sintered ferrite cores, in this embodiment, a rectangular pot-shaped ferrite core 1 and a flat plate-shaped ferrite core 2.

The square-shaped ferrite core 1 has a structure in which a rectangular loop groove 3 having a square cross section is formed on one side of a rectangular parallelepiped block. Therefore, as shown in FIG. 2, when the rectangular pot-shaped sintered ferrite core 1 and the flat plate-shaped sintered ferrite core 2 are combined and integrated with the adhesive 4 containing magnetic powder, the coil is inside the sintered ferrite core 1. A loop space is formed in which the winding 5 is accommodated. The coil winding 5 is accommodated in the loop space, and a terminal portion 6 electrically connected to the coil winding 5 is formed on the outer end surface of the obtained sintered ferrite composite as shown in FIG. It is something that does.

A deep inductor element having such a structure can be manufactured, for example, as follows.

Flowchart 1 of the manufacturing process is shown in FIG.

First, a rectangular pot-shaped ferrite core 1 and a flat plate-shaped ferrite core 2 are made. These two cores can be manufactured using the same process as for manufacturing a normal sintered ferrite core. In other words, the raw material powder is weighed, mixed and pulverized to a predetermined composition, then pre-calcined, pulverized and mixed with a solvent and an organic binder, made into granules by a spray dryer, sieved, and then granulated. It is only necessary to mold it into a predetermined shape and then fire it. Alternatively, the thermoplastic resin and the pulverized ferrite powder may be mixed and molded by injection molding. A square-shaped ferrite core 1 as shown in FIG. 1 is manufactured by such a well-known method. The flat ferrite core 2 may be formed by a similar method, or may be formed into a sheet shape using a doctor blade or the like and fired.

The coil winding 5 housed therein is preferably an air-core coil formed using so-called cement wire. That is, a wire material in which a resin coating such as polyvinyl butyral is further formed on the surface of a copper wire coated with a polyurethane insulation coating is used, and the wire material is bonded to each other while being wound in an atmosphere in which the resin coating is soluble, such as alcohol, to form a predetermined shape. The winding is formed into a shape that exactly fits into the rectangular loop groove 3 of the rectangular pot-shaped ferrite core 1. Then, this coil winding 5 is housed in the loop groove 3. The same sintered ferrite powder used to make the ferrite core is then mixed with an adhesive to form a magnetic adhesive. The magnetic adhesive is applied to the joint surfaces of the rectangular pot-shaped ferrite core 1 and the plate-shaped ferrite core 2, and the cores are bonded and cured by heating to be integrated. Then, after cutting the end of the coil winding 5 extending from the inside of the sintered ferrite body to the outside at the end position of the sintered ferrite body, the intermediate part is masked and the sintered ferrite body 1- Terminal portions 6 that are electrically connected to the coil winding 5 are formed at both outer ends of the combined body. This terminal portion 6 can be easily formed by electroless plating, for example. In other words, the end of the coil winding drawn out to the outside is cut to match the end surface of the sintered ferrite composite.
This is because only by applying electroless plating thereon, a reliable electrical connection between the formed terminal portion and the internal coil winding can be achieved. Another method for forming the terminal portion is to apply silver paste or the like to the end of the sintered ferrite composite and fit a metal cap such as tin-plated brass onto the end. You can create it, but
The electroless plating method described above is extremely simple, suitable for mass production, and reliable.

Now, the magnetic adhesive 4 is a mixture of ferrite powder, which has been pulverized and sintered through the usual process as described above, and an epoxy resin having high heat resistance. For example, a composition ratio of 10% by weight of the resin component to 90% by weight of the ferrite powder is suitable. One major feature of the present invention is that a plurality of sintered ferrite cores each containing a coil winding therein are bonded and integrated using such a magnetic adhesive. Since the magnetic adhesive having the above structure has a considerably high magnetic permeability (approximately several tens to hundreds of tens), the obtained inductance element has a substantially closed magnetic circuit structure.

The inductance element configured as in the present invention is extremely easy to use (and preferable) because the inductance L can be freely adjusted by the magnetic permeability of the sintered ferrite core serving as the base and the number of turns of the coil winding. Note that the shape of the chip inductor element according to the present invention is extremely small, for example, an outer diameter of 4.5×3, 2×2.2+n+a.

Therefore, it can be directly mounted on a hybrid IQ board or various printed wiring boards and soldered directly.

An example of the electromagnetic characteristics of the chip inductor element having the structure shown in the above embodiment is shown in FIGS. 6 and 7. FIG. 6 is a diagram of an inductance and one frequency characteristic curve, in which the number of turns of the coil winding is plotted as a parameter.

As can be seen from the figure, by appropriately adjusting the number of turns of the coil winding, the inductance L can be varied over a wide range, and an element with a desired inductance can be created and adjusted. Moreover, FIG. 7 is a Q-frequency characteristic diagram. It has been confirmed that by setting the number of turns of the coil winding to about 20 turns or more, Q becomes 100 or more, which provides sufficient performance for practical use.

Although one embodiment of the present invention has been described above, it goes without saying that the present invention is not limited to such a structure, and various changes can be made to the shape etc. of the sintered ferrite core used. Needless to say, it is. For example, both sintered ferrite cores may have the same rectangular pot-like structure and may be bonded to face each other, or various other structures are possible.

Since the present invention is an inductor element configured as described above, it uses a sintered ferrite core and an ordinary insulated conductor wire as the coil wire material, so it is possible to reduce the cost and coil winding. The resistance of the wire is low, and the number of turns can be adjusted freely, so the inductance L can be freely controlled, and the Q can also be varied by a large amount, making it possible to significantly improve performance. It is.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of an embodiment of an inductor element according to the present invention, excluding the terminal portion, FIG. 2 is a vertical sectional view thereof, FIG. 3 is a side view thereof, and FIG. 4 is an inductor element according to the present invention. FIG. 5 is a flowchart showing the manufacturing process, FIG. 6 is an inductance L-frequency characteristic diagram, and FIG. 7 is a Q-frequency hospitality diagram. 1. Square-shaped ferrite core, 2. Flat plate-shaped ferrite core, 3. Square loop groove, 4. Magnetic adhesive, 5. Coil winding, 6. Terminal part. Patent applicant: Fuji Electrochemical Co., Ltd. Agent: Minoru Shigemi Figure 1 Figure 5 Figure 6 fil Tonh (MHz) Figure 7 n Ton class (MHz) May 18, 1980 Commissioner of the Japan Patent Office Kazuo Wakasugi Beating, J%. 1. Indication of the case Patent Application No. 17903 filed in 1982 2. Name of the invention Inductor element 3. Person making the amendment Relationship to the case Patent applicant address 5-36-11 Shinbashi, Minato-ku, Tokyo Name Fuji Electrochemical Co., Ltd. Company 4, Agent address: 5-12-4 Shinbashi, Minato-ku, Tokyo 105 April 24, 1980 (Shipping date) 6. Subject to amendment

Claims (1)

[Claims] 1 It has a core shape that has a plurality of sintered ferrite cores, and a space for accommodating a coil winding is formed inside by the combination of these cores, and with the coil winding accommodated in the space, magnetic powder An inductor element having a structure in which the plurality of sintered ferrite cores are bonded and integrated by an adhesive containing the sintered ferrite cores, and terminal portions that are electrically connected to the coil winding are formed at both outer ends of the sintered ferrite combined body. .