JP2002057050A - Large current choke coil and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a large current choke coil which has a d.c. superimposing characteristic and inductance temperature characteristic featuring an Fe-Si-Al alloy and is inexpensive because of elimination of insulation processing step during mounting. SOLUTION: This coke coil is provided with a winding coil 6a which is electrically insulated and formed in an intermediate foot part, and it is formed of a pot-type core 7a made of Fe-Si-Al alloy, and a plate core 5a-1 which is provided with a plurality of electrode terminals 5a-2 and is made of Ni-Zn ferrite. Both ends of the winding coil 6a is electrically connected with the electrode terminals 5a-2 respectively, and the cores 7a and 5a-1 comprises a closed magnetic circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a notebook computer,
The present invention relates to a large-current choke coil suitable as a secondary-side inductor of various DC-DC converters used for game machines and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, various electronic devices have been greatly multi-functionalized and reduced in size and weight due to miniaturization, high integration and high frequency of LSI. For example, taking a notebook computer as an example, a multi-functional, high-quality
High-speed (improve processing capacity), large-capacity and high-speed storage devices, each block of DC-DC converter that supplies power (for example, for CPU, 5 volt line, 3.3 volt line, charging The current of each line is increasing.

As the degree of integration of such components increases, the heat generated from the CPU, DC-DC converter, and the like increases, and control of heat around the circuit is an important issue. In other words, it is important for a DC-DC converter of a notebook personal computer using a high-performance CPU not only to have a high efficiency at a large current but also to maintain a predetermined performance even at a high temperature. Furthermore, each component as a notebook computer is required to be thin and capable of high-density mounting.

Conventionally, as a choke coil used in a notebook personal computer or the like, an Fe--Si--Al alloy powder magnetic core or Mn
-A type using Zn-based ferrite, Ni-Zn-based ferrite, or the like has been commercialized.

[0005]

These choke coils are individually characterized by each core material. For example, a choke coil using an Fe-Si-Al-based alloy dust core has a feature that a decrease in inductance under a large current is smaller than that of a ferrite core due to a large saturation magnetic flux density.

[0006] In the worst case, such a characteristic can be obtained even when an inrush current or an overcurrent exceeding the design value flows through the circuit.
This means that rapid deterioration of the inductance (thermal runaway) does not occur, which is an important point for improving circuit reliability.
In addition, since the Curie temperature is high, there is an advantage that the change in inductance with respect to temperature is small.

On the other hand, since the insulation resistance is low, it is necessary to perform insulation treatment such as resin molding when forming a choke coil. In particular, since the bottom surface of the product comes into contact with the substrate, it is important to ensure insulation. This leads to disadvantages such as an increase in cost due to an increase in the number of manufacturing steps and an increase in product size due to securing the area of the insulating portion.

On the other hand, a choke coil using a Mn—Zn-based ferrite core has a characteristic that the core loss of the material is small and the circuit is highly efficient, but the inductance changes with temperature. Since it is large or has a low insulation resistance and requires insulation treatment like the Fe-Si-Al alloy core, there are disadvantages such as an increase in product size.

Further, a choke coil using a Ni—Zn ferrite core does not require an insulation treatment because of its high specific resistance, so that the product size can be reduced and the product can be provided at low cost. However, the temperature characteristic of the inductance is inferior to that of the Fe-Si-Al alloy like the Mn-Zn ferrite. Table 1 shows a comparison of various characteristics of the conventional product.

[0010]

[Table 1]

Accordingly, an object of the present invention is to provide Fe-Si-A
An object of the present invention is to provide a large current choke coil which has DC superimposition characteristics and temperature characteristics of inductance, which are features of an l-based alloy dust core, and does not require insulation treatment, and a method of manufacturing the same.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a Fe-Si-Al-based alloy and a plate-like magnetic material having good DC superposition characteristics and temperature characteristics on a pot-shaped magnetic core of the component. It is not necessary to insulate the core, which is effective for miniaturizing products.
It is configured using i-Zn ferrite.

That is, the present invention relates to a Ni-Zn based magnet having a coiled core formed of a metal magnetic material and having a winding coil formed in the middle foot portion and electrically insulated, and a plurality of electrode terminals. A large current comprising a plate-shaped core made of ferrite, both ends of the coil are electrically connected to the electrode terminals, and a closed magnetic path is formed by the pot-shaped core and the plate-shaped core. It is a choke coil.

The present invention also relates to the present invention, wherein the pot-shaped magnetic core is made of Fe
This is a large current choke coil made of a -Si-Al alloy.

Also, the present invention provides a semiconductor device having a plurality of electrode terminals.
A winding coil is arranged on a plate-shaped magnetic core made of i-Zn-based ferrite, and both ends of the winding coil are electrically connected to the electrode terminals, respectively, and a hollow portion of the winding coil is made of a metal magnetic material. This is a method for manufacturing a large current choke coil in which a closed magnetic circuit is formed by electrically insulating and fitting the middle legs of the pot-shaped magnetic core.

Further, according to the present invention, the pot-shaped magnetic core may be made of Fe
This is a method for producing a large current choke coil using a Si-Al alloy.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A high current choke coil according to an embodiment of the present invention and a method for manufacturing the same will be described below.

FIGS. 1, 2, 3 and 4 show the components of a large-current small choke coil according to the present invention. FIG. 1 shows a pot-shaped magnetic core 7a, and FIG. Magnetic core 5
a-1; FIG. 3 is a diagram showing the winding coil 6a;
FIG. 3 is a view showing an external electrode terminal 5a-2.

FIG. 1A is a top view of the pot-shaped magnetic core 7a.
FIG. 1B is a side view, and FIG. 1C is a front view. As for the external dimensions, the major axis is 16 mm, the minor axis is 9 mm, and the midfoot in the core is φ5 mm. Here, the pot-shaped magnetic core 7a
Is made of a metal magnetic material, and in this embodiment, in particular, Fe-S
Sendust (registered trademark, manufactured by Tokin Co., Ltd.), which is an i-Al alloy, was used.

FIG. 2A is a top view of the plate-shaped magnetic core 5a-1, FIG. 2B is a side view, and FIG. 2C is a front view.
The external dimensions are 13 × 13 × 2 mm. Here, the material of the plate-shaped magnetic core 5a-1 was Ni-Zn ferrite.

FIG. 3A is a top view of the winding coil 6a, FIG. 3B is a side view, and FIG. 3C is a front view.
The winding coil is made of a copper-based material, is a rectangular wire with an insulating film coating, and is wound by edgewise winding. The solder connection portions at both ends are peeled off by solder. The outer dimensions of the rectangular wire are 0.3 mm in the thickness direction and 2 mm in the width direction, and the number of turns is 3.5 T (turn). The angle at which the end of the coil is pulled out is 90 degrees.

FIG. 4A is a top view of the external electrode terminal 5a-2, FIG. 4B is a side view, and FIG. 4C is a front view. As shown in FIG. 4, the external electrode terminal has a U-shape and is made of phosphor bronze having a spring property, but copper or a plated steel plate can also be used.

FIGS. 5 to 7 are external perspective views showing a state in which these parts are assembled. FIG. 5 shows a plate-shaped magnetic core 5.
It is an external appearance perspective view which shows the state which combined external electrode terminal 5a-2 with a-1.

As shown in FIG. 5A, an adhesive which cures at a high temperature is applied to the plate-shaped magnetic core 5a-1, and the external electrode terminal 5a-2 is fitted in the direction of the arrow so as to be bonded.
After the combination as shown in FIG. 5 (b), the mixture is heated for 2 hours using a thermostat at a temperature of 150 ° C., the adhesive is cured, and the external electrode terminals 5a-2 are fixed to the plate-shaped magnetic core 5a-1. Was.

FIG. 6 is an external perspective view showing a state where the winding coil 6a is combined with the plate-shaped magnetic core with external electrode terminals shown in FIG. 5B. As shown in FIG.
a was attached in the direction of the arrow, and the solder connection portions at both ends of the winding coil 6a and the solder connection portions 8 of the external electrode terminals 5a-2 were connected by high-temperature solder to form a shape as shown in FIG.

FIG. 7 shows that the assembled parts of FIG.
FIG. 4 is an explanatory diagram showing a state in which a crucible-shaped magnetic core made of a -Si-Al-based alloy is attached to produce a large current choke coil. As shown in FIG. 7A, the pot-shaped core 7a and the plate-shaped core 5
a-1 by applying an adhesive to both contact portions thereof;
The middle leg of a is fitted into the hollow portion of the coil and bonded in the direction of the arrow to form a closed magnetic circuit with the pot-shaped magnetic core 7a and the plate-shaped magnetic core 5a-1, as shown in FIG. 7 (b). Use a large current choke coil. Here, the adhesive used in the step of FIG. 5 is heated in a thermostat at a temperature of 150 ° C. for 2 hours to cure the adhesive. The final shape of the large current choke coil according to the present invention is as shown in FIG. The reason why the high-temperature solder is used in the process of FIG. 6 is that the heating in the constant temperature bath and the subsequent heating by the user for soldering to the external electrode terminals 5a-2 are performed at both ends of the winding coil 6a. This is for protecting the connection of the external electrode terminal 5a-2.

Next, the DC superposition characteristics of the large current choke coil obtained by the above-described method were measured. Here, for comparison, a comparative product was manufactured using a core material different from that of the present invention and using the same manufacturing method as described above, and the characteristics were evaluated. Table 2 shows details of the core material of the comparative product.

[0028]

[Table 2]

Here, the material used for these high-current choke coil components is an Fe-Si-Al alloy,
The Curie temperature is 500 ° C., the saturation magnetic flux density is 0.75 T, the magnetic permeability is 80, and the specific resistance is 10 ⁴ Ω · cm. The Ni—Zn ferrite core has a Curie temperature of 180 ° C., a saturation magnetic flux density of 0.45 T, a magnetic permeability of 800, and a specific resistance of 10 ⁴ Ω · m. The Mn-Zn ferrite core has a Curie temperature of 22.
The temperature was 0 ° C., the saturation magnetic flux density was 0.5 T, the magnetic permeability was 2,000, and the specific resistance was 1.0 Ω · m.

FIGS. 8 to 11 show the results of the DC superposition characteristics of the large current choke coil. Solid line is ambient temperature 20
° C, and the broken line shows the case where the environmental temperature is 100 ° C. The product of the present invention shown in FIG. 8 has a good change in inductance (between 20 and 100 ° C.) with respect to the temperature of the DC bias characteristic under a large current (10 A or more), similarly to the comparative product shown in FIG. Conversely, Ni shown in FIGS.
-Zn ferrite cores, comparative products composed of Mn-Zn ferrite cores,
(20-1) with respect to the temperature of the DC
The change of inductance is large.

Further, since the present invention uses a Ni—Zn ferrite material having a large material specific resistance on the bottom surface which is in direct contact with the mounting substrate, unlike the comparative product, no insulation measure is required. The working process is also greatly reduced. Further, since no insulating component is required, it can greatly contribute to miniaturization of the product.

[0032]

As described above, according to the present invention, Fe-Si-A
An inexpensive large-current choke coil that has the characteristics of the DC superposed core and the temperature characteristic of inductance, which are the characteristics of an l-based alloy dust core, eliminates the need for an insulating process, reduces the number of manufacturing steps, and is inexpensive. Can be provided.

[Brief description of the drawings]

FIG. 1 shows an F used in a large current choke coil according to the present invention.
FIG. 1 (a) is a top view, FIG. 1 (b) is a side view, and FIG.
(C) is a front view.

FIG. 2 shows N used in a large current choke coil according to the present invention.
FIG. 2A is a top view of a plate-shaped magnetic core using an i-Zn-based ferrite material, FIG. 2B is a side view, and FIG. FIG.

FIG. 3 is a view showing a winding coil shape using a rectangular wire made of a copper-based material used for a large current choke coil of the present invention, FIG. 3 (a) is a top view of the winding coil, and FIG. FIG. 3B is a side view, and FIG. 3C is a front view.

FIG. 4 is a view showing an external electrode terminal using phosphor bronze used for a large current choke coil of the present invention, and FIG.
4B is a top view of the external electrode terminal, FIG.
(C) is a front view.

FIG. 5 is an external perspective view showing a state in which a plate-shaped magnetic core used for a large current choke coil of the present invention and external electrode terminals are combined. FIG. 5A is a diagram illustrating a state where external electrode terminals are fitted to a plate-shaped magnetic core, and FIG. 5B is a diagram illustrating a state where external electrode terminals are fixed to the plate-shaped magnetic core.

FIG. 6 is an external perspective view showing a state in which a winding coil used in the high current choke coil of the present invention and a plate-shaped magnetic core are combined.
FIG. 6A is a diagram illustrating a state in which a winding coil and a plate-shaped magnetic core are combined, and FIG. 6B is a diagram illustrating a state in which the winding coil and the plate-shaped magnetic core are fixed.

FIG. 7 is an explanatory view showing a state in which the large current choke coil of the present invention is assembled. FIG. 7A shows a state in which a pot-shaped magnetic core and a plate-shaped magnetic core to which a winding coil is connected are combined, and FIG. 7B shows a final shape of a large current choke coil after assembly. FIG.

FIG. 8 is a diagram showing the temperature characteristics of direct current superposition in the large current choke coil of the present invention, in which the solid line shows the characteristics at a temperature of 20 ° C. and the broken line shows the characteristics at a temperature of 100 ° C.

FIG. 9 is a diagram showing a temperature characteristic of direct current superposition of a choke coil of a comparative product using an Fe—Si—Al alloy dust core;
The solid line in the figure shows the characteristic at a temperature of 20 ° C., and the broken line in the figure shows the characteristic at a temperature of 100 ° C.

FIG. 10 shows the temperature characteristics of DC superposition of a comparative choke coil using a Ni—Zn-based ferrite material, the solid line in the figure shows the characteristic at a temperature of 20 ° C., and the broken line in the figure shows the temperature of 1
The characteristics at 00 ° C are shown.

FIG. 11 is a diagram showing a temperature characteristic of DC superposition of a choke coil of a comparative product using a Mn—Zn-based ferrite material. A solid line in the diagram shows a characteristic at a temperature of 20 ° C. The characteristics below are shown.

[Explanation of symbols]

 5a-1 Plate-shaped magnetic core 5a-2 External electrode terminal 6a Winding coil 7a Pot-shaped magnetic core 8 Solder connection part

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01F 41/04 H01F 15/10 D

Claims (4)

[Claims] 1. A crucible-shaped magnetic core made of a metallic magnetic material having a winding coil formed electrically insulated on a middle foot portion, and a plate made of a Ni—Zn ferrite having a plurality of electrode terminals Characterized in that both ends of the winding coil are electrically connected to the electrode terminals, respectively, and a closed magnetic circuit is formed by the pot-shaped core and the plate-shaped core. Current choke coil. 2. The large current choke coil according to claim 1, wherein said pot-shaped magnetic core is made of an Fe—Si—Al alloy. 3. A winding coil is disposed on a plate-shaped magnetic core having a plurality of electrode terminals and made of Ni—Zn-based ferrite, and both ends of the winding coil are electrically connected to the electrode terminals, respectively. A method for manufacturing a large-current choke coil, comprising forming a closed magnetic circuit by electrically insulating and fitting a midfoot portion of a pot-shaped magnetic core made of a metal magnetic material into a hollow portion of a wound coil. 4. The method for manufacturing a large current choke coil according to claim 3, wherein said pot-shaped magnetic core is made of an Fe—Si—Al alloy.