JPH07201580A - Chip type inductor array - Google Patents

Abstract

PURPOSE:To make the impedance larger without increasing the length of a magnetic path, by performing molding so as to cover ferrite sintered bodies having a plurality of grooves and a plurality of leads put in the grooves with resin containing ferrite. CONSTITUTION:Copper-family leads 1 having large moduli of elasticity are formed into the shape of U. Ferrite sintered bodies 2 belong to an Ni-Zn family, and each three surfaces other than the bottoms have grooves 4. Leads 1 are fitted to the ferrite sintered bodies 2 by insertion like clips. Then the leads 1 are molded so as to cover the peripheries of the ferrite sintered bodies 2 with resin 3 containing ferrite excluding parts of the leads 1 not touching the ferrite sintered bodies. Incidentally, the resin containing ferrite is composed of thermosetting resin and 85-90-wt.% of the powder of a ferrite sintered body 2 having particle diameters 11-54mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip type inductor array used in a signal circuit and a power supply circuit of digital equipment.

[0002]

2. Description of the Related Art Generally, in order to reduce high frequency (100 MHz or more) noise in a signal circuit or power supply circuit of a digital device, an inductor is inserted in series in the circuit. As such an inductor, ferrite beads or a ferrite-containing resin is used. A coated inductor (molded inductor) is used.

A conventional mold type ferrite inductor for noise suppression will be described below.

FIG. 5 is a perspective view of a conventional chip-type inductor array, in which a ferrite-containing resin 6 is molded on a flat lead 7. The leads on the side surface of the mold are processed so as to become the terminal electrodes 8.

As a method of molding the lead with a resin containing ferrite, an injection molding method or a transfer molding method, which is easy to mass-produce, is used. The resistance value (impedance) at high frequency is proportional to the magnetic path length, and in order to increase the impedance, it is necessary to increase the magnetic path length, that is, the length of the lead.

However, in this case, the overall shape becomes large, which is against the miniaturization of parts.

[0007]

As described above, in order to increase the impedance by the conventional method, it is necessary to increase the magnetic path length, but it is against the trend of making the parts lighter, thinner and shorter.

In recent years, when used for a bus line of a digital circuit, a composite product (inductor array) having a plurality of inductors as many as the number of bus lines is desired.

The present invention solves the above-mentioned conventional problems, and provides a chip-type inductor array which is a composite component of inductor elements and a small surface-mount component for which demand is rapidly increasing as a noise countermeasure component. To aim.

[0010]

In order to solve such a conventional problem, a chip-type inductor array of the present invention comprises a ferrite sintered body having a plurality of grooves on three surfaces in the longitudinal direction of a rectangular parallelepiped. It comprises a plurality of elastic conductive leads fitted in the grooves, and a ferrite-containing resin molded so as to cover the ferrite sintered body and the leads.

[0011]

With this configuration, the ferrite sintered body having a groove formed in a shape covering the lead is fitted to the lead, and the lead portion not in contact with the ferrite sintered body is mixed with the powder of the ferrite sintered body. By covering with the ferrite-containing resin, the magnetic field around the leads can be maintained and the impedance at high frequency can be secured. This is because there is a ferrite sintered body whose magnetic permeability is about 10 times larger than that of the ferrite-containing resin in the magnetic flux portion formed around the lead, so that the impedance at high frequencies can be increased. Such a molded inductor is light, thin, short, and small, and can cope with high impedance at high frequencies.

Further, in order to secure a larger impedance at high frequencies, it is effective to form the groove of the ferrite sintered body deeper. This is because it is better to cover the lead with the ferrite sintered body part whose magnetic permeability is larger than that of the ferrite-containing resin.
This is because it has the effect of increasing the impedance.

Further, by providing a groove in the ferrite sintered body, it is possible to prevent the ferrite sintered body and the lead from being deviated from each other due to the resin pressure during molding (injection molding or transfer molding) of the ferrite-containing resin.

Further, the impedance can be changed by changing the particle size and the mixing amount of the ferrite powder of the ferrite-containing resin.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the chip type inductor array of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a chip type inductor array according to an embodiment of the present invention. FIG. 2 shows only the lead portion of this chip-type inductor array. FIG. 3 shows a ferrite sintered body having grooves on three surfaces other than the bottom surface.

In the figure, 1 is a lead, 2 is a ferrite sintered body, 3 is a ferrite-containing resin, 4 is a groove, and 5 is a terminal electrode.

A method of manufacturing the chip-type inductor array configured as described above will be described below.

First, a copper-based lead 1 having a large elastic modulus obtained by stamping a plate-shaped metal plate made of a conductive material is processed into a U-shape. The ferrite sintered body 2 is a Ni—Zn system and has grooves 4 on three surfaces other than the bottom surface. The lead 1 is fitted to the ferrite sintered body 2 so as to form a clip shape, and the lead 1 is covered with the ferrite-containing resin 3 except for the portion of the lead 1 not in contact with the ferrite sintered body 2. Mold to cover the surroundings.

After that, both ends of the lead 1 are subjected to forming processing so as to become the terminal electrodes 5. The lead material used for the lead 1 is a spring material having high conductivity. Especially, the conductivity is 10% 1ACS or more, and the spring limit value is 200 N / m.
A copper alloy material of m ² or more is desirable.

The composition of the ferrite powder used in the ferrite sintered body 2 and the ferrite-containing resin 3 is NiO-.
In _{ZnO-CuO-Fe 2 O 3} , so-called NiO-ZnO
Use soft ferrite of the system.

In this embodiment, since the lead 1 is formed by punching a plate-shaped metal plate into a lead shape, a composite product can be easily produced. In the first step, forming of the hoop-shaped lead 1 is performed, in the second step, the ferrite sintered body 2 is fitted into the groove 4 and the lead 1, and in the third step, the ferrite-containing resin 3 is molded. It can be carried out in continuous steps such as forming the terminal electrode 5 by forming the leads in four steps, and is excellent in mass productivity.

The impedance can be changed by controlling the particle size and content of the powder of the ferrite sintered body 2.

In order to increase the impedance at high frequencies, it is necessary to use 85 to 90 wt% of powder of a ferrite sintered body having a particle diameter of 11 to 54 μm, and the rest a thermosetting resin.

The ferrite powder of the conventional ferrite-containing resin is also mixed in an amount of about 70 to 86 wt%, but the particle size is 2 to 10 μm, and the balance resin is a thermoplastic resin such as nylon or PPS. The reason why such a thermoplastic resin is used is that when the particle diameter is large, the coil or the lead is deformed by the resin pressure during molding.

However, as shown in FIG. 4 (a), it can be seen that higher impedance can be obtained by increasing the particle size of the ferrite powder. In particular, by setting the particle size of the ferrite powder to 11 μm or more, L = 10
The impedance per mm can be increased to Z = 10Ω or more.

As described above, in order to mix the ferrite powder having a larger particle diameter than the conventional one, a thermosetting resin such as epoxy or unsaturated polyester having good fluidity is used as the balance. As a result, the fluidity of the resin in the mold can be improved, and molding such as injection or transfer can be performed without deforming the coil or the leads.

However, when the particle size exceeds 54 μm, the impedance increases, but the injection of the ferrite-containing resin into the mold is not stable, and it is not suitable for mass production by injection molding.

As described above, the ferrite-containing resin of this embodiment is composed of 85 to 90 wt% of the powder of the ferrite sintered body having a particle diameter of 11 to 54 μm, and the rest being a thermosetting resin.

As shown in FIG. 4A, when the average particle diameter of the ferrite powder is changed, the same magnetic path length (L =
Even at 10 mm), the impedance at high frequency can be controlled. Further, as shown in FIG. 4B, the impedance can be controlled by changing the mixing amount of the ferrite powder even in the same magnetic path length (L = 10 mm).

[0031]

As described above, the chip-type inductor array according to the present invention has a ferrite sintered body having a plurality of grooves on the three surfaces of the rectangular parallelepiped in the longitudinal direction, and a U-shaped shape fitted in the grooves. Since it is composed of a plurality of elastic leads such as clips and a ferrite-containing resin molded so as to cover the ferrite sintered body, impedance characteristics can be increased without increasing the magnetic path length. it can.

Further, it is possible to support small-sized and high-density surface mounting,
Supports light and thin surface mounting. Moreover, since the ferrite sintered body is sandwiched by the elastic leads, it is possible to manufacture in a hoop shape with the lead frame continuously arranged, which is excellent in mass productivity. Since the outer shape is resin molding, it can be freely shaped for surface mounting, and can be used for high-speed automatic surface mounting. Further, since it is a closed magnetic circuit, noise is not adversely affected to other parts mounted in the vicinity of the chip inductor array.

[Brief description of drawings]

FIG. 1 is a perspective view of a chip inductor array according to an embodiment of the present invention.

FIG. 2 is a perspective view of a lead processed into a clip shape according to the embodiment.

FIG. 3 is a perspective view of a ferrite sintered body having a plurality of grooves on three surfaces other than the bottom surface of the rectangular parallelepiped of the embodiment.

FIG. 4 (a) Correlation diagram of particle diameter of ferrite powder of ferrite-containing resin and impedance (b) Correlation diagram of mixing amount of ferrite powder of ferrite-containing resin and impedance

FIG. 5 is a perspective view of a conventional chip-type inductor array.

[Explanation of symbols]

 1 Lead 2 Ferrite Sintered Body 3 Ferrite-Containing Resin 4 Groove

Claims (2)

[Claims] 1. A ferrite sintered body having a plurality of grooves on three surfaces in the longitudinal direction of a rectangular parallelepiped, a plurality of elastic conductive leads fitted in the grooves, and the ferrite sintered body and the leads. A chip-type inductor array having a ferrite-containing resin molded so as to cover it. 2. The ferrite-containing resin has a thickness of 11 to 54 μm.
85 ~ 90wt% of the powder of ferrite sintered body with the particle size of
The chip-type inductor array according to claim 1, wherein the chip-type inductor array comprises: