JPS6221251B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an inductor.

There are two types of inductors: an air-core type in which a wire is wound around a non-magnetic support, and a cored type in which a wire is wound around a magnetic support. In either case, conductive wires such as polyurethane copper wires and silk wires are conventionally used as the windings. In recent years, with the miniaturization of electronic circuits, there has been a demand for smaller electronic components, and resistors, capacitors, and transistors are rapidly being made into chips, but the progress of making inductors into smaller chips has lagged behind. be. The reason for this is that the conventional wire-wound type has problems with the heat resistance of the conductor and the connection between the conductor and external terminals in the solder depth when it is mounted on a board as a chip component. It will be done.

A conventional example of this type is shown in cross section in FIG. It consists of winding a polyurethane wire 2 around a magnetic support 1,
The terminal 4 of the winding is inserted into the magnetic body 3 and connected to the external electrode 5.
The external electrode is conductive Ag paint. When such an inductor is soldered, the heat resistance of the polyurethane wire 2 is insufficient, and the connection between the external electrode and the winding wire is easily broken, resulting in defects. Therefore, it has been considered to provide a thin laminated inductor by forming a coil-shaped conductive pattern on a magnetic sheet and continuously laminating the conductive pattern. This method is very effective for downsizing inductors, but when multilayering is used to increase inductance, the number of layers becomes extremely large, making the process complicated, and the finished external shape becomes uneven. The disadvantage is that it is easy to do so. Another problem is that it becomes complicated to change the lamination method in order to obtain products with the same shape but different inductance.

The present invention eliminates such conventional drawbacks, and provides a method for manufacturing an inductor that is simple in process, easy to adjust inductance, and less likely to cause trouble in the solder depth.

The present invention manufactures an inductor in which a conductive wire having a film containing a magnetic material is wound around a magnetic material support, the surrounding area is coated with a magnetic material, and then fired, and the winding wire is embedded in the fired magnetic material. This is the way to do it.

Examples of the present invention will be specifically described below.

Mix magnetic powder mainly composed of Fe ₂ O ₃ with terepinol containing 4 wt % of 100 cps ethyl cellulose at a ratio of 40 wt % to make a paste. Laminate this on a polyester sheet using a printing method to form a paste with a length of 5 as shown in Figure 2.
A magnetic support 6 having a width of 4 mm, a width of 4 mm, and a thickness of 1.5 mm was produced by repeating printing and drying at 120°C. Then the third
As shown in the figure, a through hole 7 for an end stop was drilled with a drill having a diameter of 100 μm. On the other hand, the conductor has a diameter of 75 μm.
Using a 90wt%Ag-10wt%PD alloy wire, first coat it with a thin layer of the above-mentioned magnetic paste and dry it, then coat it with terepinol containing only the vehicle portion, that is, 4wt% of 100cps ethyl cellulose, without magnetic powder. A magnetic material-coated conducting wire 8 having a cross section shown in FIG. 4 was obtained. That is, the conductor 8 is
It consists of an Agpd alloy wire 81, a magnetic substance-containing layer 82, and a resinous dry film 83. The reason why the conducting wire has two layers of coating is that the coating strength is weak if only the magnetic material-containing layer 82 is used, and there is a risk that peeling will occur during subsequent winding.

Next, as shown in FIG. 5, the above-mentioned conducting wire 8 was wound around the magnetic support 6 to form a coil. after that,
Exposing the Agpd alloy wire only at the wire end of conductor 8,
Using commercially available Agpd paste as shown in Figure 6,
The external terminal 9 was formed by covering the end face of the magnetic support 6. Further, the magnetic paste was repeatedly applied and dried over the entire outer periphery of the coil except for the external terminal 9, so that the surface was made substantially smooth, thereby forming a closed magnetic circuit. This is fired at 900℃,
A closed magnetic circuit type inductor shown in FIG. 7 was obtained. In the case of the thus obtained inductor having 18 turns, the inductance was 7 μH, and the frequency characteristic of Q was as shown in FIG. Further, as shown in FIG. 9, the cross section of the inductor has a conductor 81 buried in the fired magnetic material 10, and the spaces between the conductors were also made of the fired magnetic material. Here, 11 is
The external terminal 9 is coated with Ag paint.

In the manufacturing method of the present invention, since a conductive wire having a layer containing a magnetic substance is used, there is little formation of voids between the conductors even after firing, and as shown in a part of the cross section in FIG. It was found that even when the conductor was wound, the space between the conductors was made of fired magnetic material.

In the above embodiment, the magnetic material 6 used was one in which ferrite powder mainly composed of Fe ₂ O ₃ was kneaded with a vehicle, the resulting magnetic paste was printed and dried, and the process was repeated to make it thicker. In addition, a magnetic paste with a reduced amount of vehicle may be extruded. Furthermore, it may be a product obtained by firing these materials, or a product obtained by press-molding and firing a magnetic powder. Although the shape is square in the embodiment, it may be round. Furthermore, since the firing temperature and magnetic properties of magnetic powder differ depending on the composition, it is determined based on the required values of inductance and Q. Furthermore, various known vehicles can be used.

In addition, in the example, it is used as a conductor of the conducting wire.
Although a 90wt%Ag-10wt%PD alloy wire was used, the conducting wire may be any metal alloy wire that does not melt at the firing temperature of the magnetic material. Agpd alloy, Agpdpt alloy,
CuZnAl alloy etc. can be applied.

Next, the magnetic substance-containing layer of the conducting wire 8 can be formed by applying various known magnetic substance-containing pastes in addition to the above embodiments. If butyral resin powder and di-n-butyl phthalate dissolved in terepinol were used as the vehicle, the film would be slightly stronger than the above example, but if only the magnetic material-containing layer was used, peeling would occur during winding. Furthermore, it is necessary to form a film only on the vehicle. In order to maintain a high magnetic density near the conductor after firing, it is necessary to increase the magnetic content of the magnetic paste, which makes the magnetic material-containing layer brittle and easily peeled off after drying. By further coating only the vehicle that does not contain magnetic powder, an extremely thin resinous layer is formed, which prevents the magnetic material-containing layer from peeling off.

As is clear from the above description, since the inductor manufacturing method of the present invention basically uses a winding method, it is possible to obtain high inductance by using multilayer winding. In addition, since coated conductors containing magnetic materials are used in the manufacture of inductors, even if they are tightly wound with multilayer windings, there is a magnetic material between the conductors, so the conductors may short-circuit during firing. In addition, the inductance is high. In addition, since the conductor wire is covered with a vehicle, there is no peeling of the magnetic layer during winding, making multilayer winding easy, and the process is much simpler than the conventional method of forming conductor coils by printing. It has many advantages such as:

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional inductor, Figure 2 is a sectional view showing a conventional inductor.
3, 5, 6, and 7 are perspective views showing each step of the inductor manufacturing method according to the present invention, and FIG. 4 is a cross-sectional view of an example of a conductive wire used in the present invention. FIG. 8 is a diagram showing an example of the characteristics of an inductor manufactured according to the present invention, and FIGS. 9 and 10 are cross-sectional views of an example of the inductor manufactured according to the present invention. 6...Magnetic material support, 8...Conducting wire, 81...Conductor, 8
2... Magnetic material-containing layer, 83... Resin-like layer, 9... External terminal, 10... Sintered magnetic material.

Claims (1)

[Claims] 1. A conductive wire having a magnetic material-containing film is wound around a magnetic material support to form a coil, and both ends of the conductive wire are positioned on both end surfaces of the magnetic material support to form an external coil. After forming the terminal, the outer periphery of the coil excluding the external terminal part is coated with magnetic paste, and then dried.
A method for manufacturing an inductor, which comprises then firing the inductor. 2. In the statement of claim 1, the magnetic support is a fired ferrite mainly composed of Fe ₂ O ₃ , and the conducting wire is an AgPd alloy wire with an Fe ₂ O ₃ -based magnetic layer and a resin coating thereon. A method for manufacturing an inductor, the inductor being a composite wire coated with , the external terminal being AgPd paste, and the magnetic paste being a paste obtained by kneading Fe ₂ O ₃ based magnetic powder and a vehicle.