EP0157927B1 - Electronic component, in particular a chip inductance - Google Patents

Description

The present invention relates to a chip inductor with a solid core part with a vertical prismatic three-dimensional shape, in particular cuboids or cubes, consisting of ferromagnetic or electrically non-conductive material, in particular ferrite, ceramic or plastic, with electrical contact surfaces arranged on preferably separate side surfaces of the core part and with one serving as a winding space hollow cylindrical recess in which a winding carrier including the winding is accommodated.

Chip inductors are smaller than conventional wired inductors, can be manufactured with less effort and are more suitable for use in automatic assembly machines for printed circuit boards. The known chip inductors are partly manufactured using layer technology or equipped with rectangular or cylindrical wire-wound magnetic cores.

To manufacture the chip inductance in layer technology, a carrier is coated with a magnetic layer and a conductor track formed into a coil is applied to this layer, the partial inductance produced in this way being combined with further partial inductances to form a stack, depending on the desired inductance. Numerous methods are known for through-contacting the ends of the coils.

These chip inductors are characterized by their space-saving design, can be soldered directly to printed circuit boards and do not require any additional wires as connection elements.

A disadvantage is their complicated manufacture due to the layering technique. Variations in the layer thickness of the magnetic layer that are unavoidable in production cause undesirable fluctuations in the L and Q values of the inductors. Silver or a silver-palladium alloy, for example, must be used as the material for the coil conductor tracks and a high ohmic resistance of the conductor tracks must be accepted. Since the conductor tracks are embedded in the magnetic layer, magnetic saturation occurs due to the closed magnetic circuit, even at low values; the DC bias properties of the chip inductance are consequently deteriorated. In addition, the number of coil turns cannot be selected to any desired height and therefore no inductance of any desired value can be set.

EP-A-25605 shows a chip inductance of the type mentioned at the outset, that is to say an inductance equipped with a solid core part. The core part of this inductance is provided with a blind hole and an opening arranged centrally in the bottom of the blind hole, into which an isolated, i.e. is not glued in one piece with the core part of the roll core by means of its pin. In this embodiment, the electrodes are brought up to the edge of the blind hole and contacted there with the winding ends.

In addition to the considerable amount of work involved, gluing in the roll core leads to considerable fluctuations with regard to the required central alignment of the roll core in the core part. This version also offers only a limited winding space and also requires a roll core that is not easy to manufacture in terms of press technology. Since the roll core has two flange ends molded onto its winding support, winding of the winding support is only possible in one position in which the roll core is arranged at a spatial distance from the core part. A one-piece connection of the roll core to the core part is therefore ruled out.

EP-A-79 659 shows a chip inductance with two core parts, one being designed as a balancing element and the other as a roller core, which is connected in one piece to a base designed with contact feet.

GB-A-567963 describes a well-known shell core consisting of a cover part and a core part with a slug connected in one piece to this core part.

DE-OS 3 225 782 AI also shows a chip inductor equipped with a ferrite roll core, in which the wound roll core is embedded in a rectangular potting, against the one end face of which the ends of strip-shaped connecting elements lie, the other ends of which are electrically connected conductive, solderable layers of the end faces of the roller core flanges are contacted.

It turns out to be disadvantageous in this embodiment that the outer connection elements require two additional processing steps interrupted by a casting process, namely first the contacting with the outer end faces of the ferrite roller core and finally, after casting, the final flanging in the direction parallel to the corresponding end faces of the Potting created cuboid.

The present invention is based on the object, e.g. to provide chip inductance of the type mentioned at the outset which can be used as an HF choke, which can be produced only with little effort and can be largely shielded, can be contacted without impairing the quality, and i. u. optionally both small and large inductors with high quality enabled.

To achieve this object, the invention provides for a chip inductor according to the preamble of claim 1 that the recess is a hollow cylindrical, which surrounds a slug connected in one piece to the core part and serving as a support for the winding, that the side surfaces of the electrical contact surfaces Core part are connected to the recess via open-edge channels and that the ends of the winding are guided through the channels to the electrical contact surfaces and are contacted with them.

If the solid core part consists of electrically non-conductive material such as ceramic or plastic, it is suitable, for example, for the production of so-called Air coils in chip design. When using ferromagnetic materials for the core part, this is preferably used to create RF choke chips, transformer chips, etc.

A magnetic closure of the chip inductance can be brought about by covers made of ferromagnetic material, which is applied to the side surface of the core part formed with the recess.

The required magnetic closure can also be achieved by a cover made of cast resin, which is mixed with carbonyl iron or ferrite powder, which fills the free space in the channels and the recess.

• Fig. 1 ein massives Kernteil nach der Erfindung in perspektivischer und teils geschnittener Ansicht,
• Fig. 2 in der Darstellung nach Fig. 1 ein Kernteil nach Fig. 1 mit eingesetzter elektrischer Wicklung,
• Fig. 3 in der Darstellung nach Fig. 1 eine HF-Drossel mit einem zweiten Ausführungsbeispiel eines Kernteils,
• Fig. 4 in der Darstellung nach Fig. 1 ein weiteres Ausführungsbeispiel einer HF-Drossel mit gegenüber Fig. 1 bis 3 abgewandeltem Kernteil,
• Fig. 5 gleichfalls in der Darstellung nach Fig. 1 ein weiteres Ausführungsbeispiel einer HF-Drossel mit gegenüber Fig. 1 bis 4 unterschiedlichem Kernteil.

The invention is explained in more detail below on the basis of exemplary embodiments. It shows:

• 1 is a solid core part according to the invention in perspective and partially sectioned view,
• 2 shows a core part according to FIG. 1 with an inserted electrical winding,
• 3 shows an RF choke with a second exemplary embodiment of a core part,
• 4 shows a further exemplary embodiment of an HF choke with a core part modified compared to FIGS. 1 to 3,
• Fig. 5 also in the illustration of FIG. 1, a further embodiment of an RF choke with different core parts compared to FIGS. 1 to 4.

In the figures, the same parts are designated with the same reference numerals.

The solid core part 1 shown in Fig. 1 for a chip inductance, e.g. HF choke or transformer, depending on the inductance to be created, consists of a ferromagnetic material, in particular ferrite, or, if e.g. an air coil in chip design is to be manufactured from electrically non-conductive material, in particular ceramic or plastic. The core part 1 itself has a vertical prismatic spatial shape, preferably a cube or cuboid shape. Vertical prismatic spatial shapes with pentagonal and polygonal floor plans are also conceivable.

As a changing room for e.g. A winding 16 shown in FIG. 2 serves a hollow cylindrical recess 2 which surrounds a slug 10. In particular for core parts made of ceramic or plastic, such as are preferably used for air coils, the hollow cylindrical recess 2 can be replaced by a slot-free, exclusively blind hole-like recess.

Side surfaces of the core part 1 lying opposite one another are covered with electrically conductive contact surfaces 3, which are deposited on these side surfaces, for example in the so-called Nikkel carbonyl process, and are coated with high-melting solder. To lead the winding ends 17, 18 of the winding 16 to the contact surfaces 3, channels 4, 5 leading from the contact surfaces 3 to the recess 2 are provided. The contact surfaces 3, which preferably cover the entire side surfaces, expediently overlap the end edges 6, 7 to the adjacent side surfaces and cover the edge surfaces 8, 9 of these side surfaces. This will e.g. with a mirror-image arrangement of a second core part, on the first the connection of the two core parts is facilitated and additionally the contact 19 of the winding ends 17, 18 with the contact layers 3 is facilitated by the solderable contact layers 3 extending into the channels 4, 5.

For automatic direction detection, d. H. To identify the chip position or direction, as used when using these chips for automatic placement machines e.g. is advantageous for printed circuit boards, - as shown in Fig. 3 - corresponding end edges 12, 13 of the core part 1 are chamfered. This enables reliable detection of the chip direction and positioning of the connections in relation to the printed circuit board.

The end face 11 of the slug 10 can, according to FIGS. 1 to 3, be level with the recessed side face of the core part 1 or, as shown in FIGS. 4 and 6, set back with respect to the end edge of the recess 2. In the latter two cases, the core part also has a e.g. Circular disk-shaped cover 14 (see FIG. 4) or the rectangular cover 15 shown in FIG. 5. The free end faces of the covers 14 and 15 are preferably flat to the recessed side surface of the core part 1. For this purpose, as shown in FIG 5 is shown - the side surface carrying the cover 15 together with the end surface 11 of the slug 10 can be set back by the amount of the cover thickness relative to the edge regions 21 of this side surface.

Which type of cover is ultimately chosen depends essentially on the requirements of the magnetic circuit for core parts and covers made of ferrite. It is also conceivable - as shown in Fig. 3 or in addition to the cover 15 Fig. 5 - embedding the winding 16 or pouring the recess 2 together with channels 4, 5 with potting compound, in particular epoxy resin, to produce or increase the magnetic shielding effect of the chip inductance is mixed with carbonyl iron or ferrite powder.

It is conceivable within the scope of the present invention that the cover is also designed as a solid core part, and that both core parts form what are known as shell core halves, which, depending on the desired air gap, have corresponding slug end faces 11. Arranged in pairs and mirror images on top of each other, this results in cores with excellent magnetic closure.

Claims (11)

1. Chip inductance having a solid core part (1) of upright prismatic configuration, in particular that of a right parallelepiped or cuboid, consisting of ferromagnetic or electrically non-conductive material, in particular ferrite, ceramic or plastic, having electrical contact surfaces (3) arranged on preferably separate side surfaces of the core part and having a hollow-cylindrical recess (2), which serves as coil space and in which a coil former together with winding is accommodated, characterized in that the recess (82) is a hollow-cylindrical recess which encloses a block (10) integrally joined to the core part (1) and serving as former of the winding, in that the side surfaces of the core part (1) bearing the electrical contact surfaces (3) are connected via channels (4, 5), open at the edges, to the recess (2) and in that the ends (17, 18) of the winding (16) are led through the channels (4, 5) to the electrical contact surfaces (3) and are contacted with the latter.

2. Chip inductance according to Claim 1, characterized in that the electrical contact surfaces (3) preferably cover the entire surfaces of mutually opposite side surfaces of the core part (1).

3. Chip inductance according to Claims 1 and 2, characterized in that the electrical contact surfaces (3) overlap the face edges (6, 7) with neighbouring side surfaces of the core part (1).

4. Chip inductance according to Claims 1 to 3 characterized in that the electrical contact surfaces (3) partially extend into the channels (4, 5).

5. Chip inductance according to Claims 1 to 4, characterized in that the electrical contact surfaces (3) are covered by a solderable layer.

6. Chip inductance according to Claim 1, characterized in that, for directional recognition, corresponding face edges of the solid core part (1) are bevelled.

7. Chip inductance according to Claims 1 to 6, characterized in that the face surface (11) of the block (10) is set back from the face edge of the recess (2), and in that the block face surface (11) and recess (2) are covered by a disc-shaped cover (14), which is preferably level with the recessed side surface of the core part (1).

8. Chip inductance according to Claims 1 to 7, characterized in that the side surface of the core part (1) provided with the recess (2) and the face surface (11) of the block (10) are set back from the edge surfaces (21) of this side surface, and in that this side surface is covered by a cover (15).

9. Chip inductance according to Claims 7 to 8, characterized in that the cover (14, 15) is composed of ferrite, ceramic or plastic.

10. Chip inductance according to Claim 1, characterized in that the winding (16) and, if appropriate, the winding ends (17, 18) are cast in casting compound (20) in particular epoxy resin.

11. Chip inductance according to Claim 10, characterized in that the casting compound (20) is mixed with carbonyl iron powder or ferrite powder.

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