# US 2018/0323002 A1 · Smd inductor with high peak current capacity and low losses, and method for the production thereof

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- Number: US 2018/0323002 A1
- Document ID: US20180323002A1
- Status: Published application
- Kind: A1
- Application number: 15/771,576
- Filed: 2016-11-10
- Published: 2018-11-08
- Earliest claimed: 2015-11-20
- Assignees: Epcos AG
- Applicants: Epcos AG
- Inventors: Dirk Beckmann; Anneliese Drespling; Felipe Jerez
- Web page: https://patentgrep.com/patent/US20180323002A1

## CPC

- H01F 27/292: {Surface mounted devices}
- H01F 17/045: {with core of cylindric geometry and coil wound along its longitudinal axis, i.e. rod or drum core}
- H01F 27/2823: {Wires (H01F27/2866 takes precedence)}
- H01F 2003/106: {Magnetic circuits using combinations of different magnetic materials}
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

An SMD inductor as a component and a method for producing an SMD inductor. The inductor simultaneously has low losses and a high peak current-carrying capacity and also a high mechanical stability. To that end, it includes an inner core piece, an outer core piece and a coil having a wire. The inner core piece includes an alloy. The outer core piece includes ferrite. The wire is wound around the inner core piece, and the inner core piece with the wire is arranged in the outer core piece.

## Claims

### Claim 1

An SMD inductor having a high peak current-carrying capacity and low losses, comprising
an inner core piece, an outer core piece and a coil having a wire, wherein
the inner core piece comprises an alloy,
the outer core piece comprises ferrite,
the wire is wound around the inner core piece,
the inner core piece with the wire is arranged in the outer core piece.

### Claim 2 (depends on 1)

The SMD inductor according to claim 1, wherein
the inner core piece comprises a central section having a round, oval or polygonal cross section, and
the wire is wound around the central section.

### Claim 3 (depends on 1)

The SMD inductor according to claim 1,
wherein the alloy comprises iron.

### Claim 4 (depends on 1)

The SMD inductor according to claim 1,
wherein the alloy of the inner core piece is sintered.

### Claim 5 (depends on 4)

The SMD inductor according to claim 4, wherein the inner core piece comprises individual, isolated grains.

### Claim 6 (depends on 1)

The SMD inductor according to claim 1,
wherein the wire of the coil comprises 1.5≤Z≤100 turns.

### Claim 7 (depends on 1)

The SMD inductor according to claim 1
furthermore comprising one or a plurality of wires, wherein the wires are connected in parallel or in series.

### Claim 8 (depends on 1)

The SMD inductor according to claim 1,
wherein the inner core piece comprises a central section and all wires are wound around the central section.

### Claim 9 (depends on 1)

The SMD inductor according to claim 1,
wherein
the outer core piece comprises an outer wall having a cutout,
the cutout comprises a first area and a second area, which is not parallel to the first area,
the transition from the first area to the second area for the purpose of avoiding stress cracks is shaped asymmetrically in relation to an angle bisector with respect to both areas.

### Claim 10 (depends on 9)

The SMD inductor according to claim 9, wherein the transition comprises different transition dimensions a≠b.

### Claim 11 (depends on 1)

The SMD inductor according to claim 1,
wherein
the peak current-carrying capacity is determined by the energy content L*I2,
L=0.9*L0,
L0 is the inductance without current,
I is the current at which L=0.9*L0, and
L*I2 is greater than or equal to 1.2 mWs in the case of a structural size having a basic area of 12 mm×12 mm,
L*I2 is greater than or equal to 0.45 mWs in the case of a structural size having a basic area of 10 mm×10 mm,
L*I2 is greater than or equal to 0.36 mWs in the case of a structural size having a basic area of 7 mm×7 mm, or
L*I2 is greater than or equal to 0.25 mWs in the case of a structural size having a basic area of 6 mm×6 mm.

### Claim 12 (depends on 1)

The SMD inductor according to claim 1,
wherein the losses at a frequency of 300 kHz, at 30 mT and at 20° C. are less than or equal to 600 kW/m3 in the core material.

### Claim 13

A method for producing an SMD inductor, comprising the following steps of:
providing an inner core piece composed of an alloy, an outer core piece composed of ferrite, and a wire,
winding the wire onto the inner core piece to form a coil,
arranging the inner core piece with the coil in the outer core piece,
interconnecting the coil with external terminals.