EP2917966A1

EP2917966A1 - Three-dimensional antenna

Info

Publication number: EP2917966A1
Application number: EP13798246.8A
Authority: EP
Inventors: Antonio Rojas Cuevas; Juan FERNÁNDEZ REINA; Francisco Ezequiel NAVARRO PERÉZ; Maria Mar VILLARRRUBIA GARCIA
Original assignee: Premo SA
Current assignee: Premo SA
Priority date: 2012-11-12
Filing date: 2013-11-11
Publication date: 2015-09-16
Also published as: WO2014072075A4; ES2460368B1; ES2459892A1; WO2014072075A1; ES2459892B1; ES2460368A1

Abstract

Three-dimensional antenna comprising: at least one core (10), three windings (21, 22, 23) arranged around three orthogonal axes of said core which is at least one, and a base, having the core a second platings (50) formed onto Its lower faces and connected to said windings, being said core arranged on top of the base, wherein said base is a printed circuit board (30) comprising a series of first platings an upper portions (41) disposed on the upper face of the PCB (30), and a side portions (42) which extends through the side faces of the PCB, and being connected to the upper portions through a printed circuit (43). The present invention provides a three-dimensional antenna that operates over a wide frequency range. The antenna has a higher connections strength and is compatible with automated optical inspection systems.

Description

DESCRIPTION

THREE-DIMENSIONAL ANTENNA

Background of the invention

The present invention refers to a three-dimensional antenna, capable of receiving and/or transmitting signals on any of the three dimensions, in addition, the antenna has an operating capacity at both low and high frequency (Hybrid). In particular, the present invention can be used in applications such as automotive because of its compatibility with Automated Optical Inspection systems, also known as AOI, and its wide range of operating frequencies.

Description of the related art

Some examples of a three-dimensional hybrid antenna can be found for example in Spanish Patent ES-B1 -2200652 that discloses a three dimensional antenna comprising a rectangular shaped monolithic magnetic core, with a three mutually orthogonal windings arranged so that the antenna receives a signal in each of the windings when is subjected to a low frequency electromagnetic field. Furthermore, the embodiment disclosed in the aforementioned document ES2200652 has a core adhesively bonded to a plastic base, being said plastic base provided with terminals on its bottom side for interconnection between the windings disposed surrounding the core and external systems.

The devices of the prior art have problems with the robustness of their connections, in that the terminals arranged in the plastic base usually are filaments with a reduced dimension. Moreover, the junction between the base and the core must necessarily be made by adhesives that must support a wide range of temperatures. Furthermore, these connections are usually in non-visible areas, so an optical inspection can not determine whether the connections are correct. In current devices, such inspections require more sophisticated measurements than visual inspection, consequently, this operation slow down the production process.

The EP1489683 document discloses a three-dimensional antenna which, according to one of the embodiments described, has a monolithic core around which windings are wound, said core being provided with metal terminal plates attached, which are used as connectors with the base, the ends of the windings are welded on this metal terminal plates to assure a secure electrical connection. In this embodiment the connectors should be first produced from a metal plate and then attached to the core in a not specified manner. This construction is expensive and requires accurate assembly processes due to the small size of the antenna; there is also the possibility that these connectors are accidentally detached from the core, producing an antenna failure.

Moreover, the proposed arrangements in the prior art lack the flexibility to add new antennas (or derivatives of existing antennas) in that they require the manufacture of a new base, or in the best case, the required peel adhesive that bonds the core to the base to access the terminal connections.

Furthermore, the antennas disclosed in the prior art operate only at low frequency and current industrial applications require that such antennas may also operate at higher frequencies while maintaining or reducing its current volume.

Accordingly, the present invention provides a three-dimensional antenna that operates over a wide frequency range (between 5 KHz and 30 MHz), which has a higher connections strength and that is compatible with automated optical inspection systems (AOI).

Summary of the invention

Specifically, the present invention relates to a three-dimensional antenna comprising:

- at least one core;

- three winding wound around three mutually orthogonal axes, each of said windings surrounding said core which is at least one.

- a base;

in which said at least one core is arranged on top of the base. In particular, the base is a printed circuit board comprising a plurality of first platings or metallizations connected to the windings, said first platings extended through the top of the printed circuit board, and said at least one core comprises a second platings which are connected to the windings and to said base first platings.

Additionally said first platings also cover side sections of the base.

The aforementioned at least one core is concerned, according to a first embodiment, to a single monolithic core, around which the three windings are wound about three core orthogonal axes. A second alternative embodiment includes three independent cores, each with an axis around which a winding is wound, said three cores are fixed on the base so that said axes of said three cores remain mutually orthogonal. Thereafter the term core as used in this description refers to this monolithic core or to this set of three cores indistinctly.

Throughout this document the term plating or metallization refers to additions or extensions of electrically conductive metal layer on the core or base. The bond between the core and the second platings is performed by the core manufacturing process itself, by chemical bath and subsequent processes of sintering, the remaining connections between the windings and the platings are made by welding, achieving overall a greater strength of the connections.

Contact between said second platings of said core and first platings of said base provide an electrical connection between the base and the windings.

In particular, the base is a printed circuit board comprising a plurality of platings connected to the windings through the second platings, said first platings may extend to partially cover the sides of the printed circuit board, to provide electrical connections through lateral contact. In a preferred embodiment, the core is a ferrite core, more specifically the core may be a ferrite core comprising a Nickel-Zinc alloy, a Manganese-Zinc alloy, or amorphous Cobalt.

This core composition provide ferromagnetic qualities necessary for its operation, while high

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electrical resistivity, preferably equal to or greater than 10 Dm, which allows its surface second platings to be electrically isolated with respect to each other .

In order to operate in a broader frequency range, the aforesaid orthogonal windings are configured for operation at low frequencies (approximately between 300KHz and 5KHz) and further provides at least one winding with a smaller number of turns in such a way which provides a high frequency operation (approximately between 3MHz and 30MHz). Since the directivity at high frequencies is not so critical to the operation of the antennas, it can be used a single high frequencies winding, which can be added to the aforementioned windings to provide an antenna operation in two or three dimensions.

In another preferred embodiment, the high frequency winding may be a branch from an intermediate point of one low frequency winding. Additionally, branches can be provided in the three low frequency windings to obtain a three-dimensional antenna also at high frequencies without increasing the volume of the device.

Moreover, the high frequency winding can be printed and/or embedded in the printed circuit board. To improve the ability of the antenna to withstand external physical forces, there is an over- mold, at least in the windings and the core.

If it is required to increase the electric insulation the over-mold can be vacuum molded. A preferred material for said over-mold is a polymer material comprising a high thermal performance plastic, capable of withstanding the high temperatures reached during operation and assembly without burning.

Brief description of the drawings

The foregoing and other advantages and features will be more fully understood from the following detailed description of an embodiment with reference to the accompanying drawings, which should be taken as illustrative and not limiting, in which:

Figure 1 shows a perspective view of an antenna according to a first embodiment of the present invention;

Figure 2 shows a perspective view an exploded view according to a first embodiment of the antenna of Figure 1 ;

Figure 3 shows a perspective view of an exploded view of a core, a first and second windings and a base for an antenna according to a first embodiment of the present invention;

Figure 4 shows a perspective view of a monolithic core according to a first embodiment of the present invention;

Figure 5 shows a perspective view of a core, a first and second windings and a base for an antenna according to a first embodiment of the present invention;

Figure 6 shows a perspective view of a core, a first and second windings and a base for an antenna, and a third winding, corresponding with the Z axis, in an exploded position, according to a first embodiment of the present invention;

Figure 7 shows a perspective view of an antenna according to a second embodiment of the present invention;

Figure 8 shows a perspective view an exploded view according to a second embodiment of the present invention;

Figure 9 shows a perspective view of a core with a horizontal axis around which a winding is wound, according to a second embodiment of the present invention;

Figure 10 shows a perspective view from the bottom side of a circular core with a vertical axis around which a winding is wound, according to a second embodiment of the present invention.

Detailed description of preferred embodiments

Figure 1 shows an antenna 1 comprising a covering 60 and a printed circuit board 30 (also known as PCB) being the internal components of the antenna embedded in that covering 60. In particular embodiments of the present invention, the covering 60 may be a pre-molded cover, or an over-molded or vacuum molded cover, directly molded on the components arranged on the printed circuit board 30.

Figures 2 and 3 show an exploded view of the antenna 1. In this embodiment, the antenna 1 comprising a base, a monolithic core 10, and three windings 21 , 22 and 23 wound around three orthogonal axes of said monolithic core 10. A first winding 21 wounded around a first axis in the "X" abscissa axis orientation, a second winding 22 wounded around a second axis in the "Y" ordinate axis orientation and a third winding 23 wounded around a third axis in the "Z" orientation surrounding said two windings 21 and 22.

The cited covering 60 encapsulates said core 10 and said windings 21 , 22 and 23, being this encapsulating material preferably a plastic polymer with high thermal stability and low contraction coefficient, able to resist the high temperatures achieved during the antenna 1 operation.

As can be seen in detail by reference to Figure 4, the core of this embodiment is a monolithic core and its shape has four corner blocks .13, two side arms 12 and a flat body 11. The flat body 11 , around which the first winding 21 is wound, has a lower thickness than the side arms 12, allowing the second winding 22 to be wound around said two lateral arms 12 perpendicular to the said first winding 21 without contacting with said first winding 21. The four corner blocks 13 act as retaining elements for the first and second windings 21 and 22, and allow wounding the third winding 23 without contact with the other two windings 21 and 22.

The core 10 has integrally four electrically conductive second platings 50 at its corner lower surface, these four second platings 50 are each connected by welding to one initial section or end of the first and second windings 21 and 22, providing a single piece including core 10, first and second windings 21 and 22 and electric connectors without loose wires.

In this embodiment, the base is a printed circuit board or PCB 30, and includes between six to twelve electrically conductive first platings 40. In this particular embodiment, the PCB 3 comprises six electrically conductive first platings 40 in the PCB 3 upper surface, four of them configured and arranged to be electrically connected with the second platings 50 of the core 10 by contact and welding, and the others configured to be electrically connected with the third winding 23 welding their ends on it. This third winding 23 is overlapped to the core 10 after welding the core 10 to the PCB 30 (Fig. 6).

In this embodiment, some of the first platings 40 has a upper portions 41 disposed on the upper face of the PCB 30 in a position coincident with the mounting position of second platings 50 of the core 10, and a side portions 42 which extends through the side faces the PCB 30, and being connected to the upper portions 41 through a printed circuit 43.

This configuration allows easy and strong electrical connection between the three windings 21 , 22 and 23 and side portions 42 of the first platings 40, disposed on the side surfaces of the PCB 30, through the second platings 50, allowing an easy connection to other systems, which eliminates the need for terminals connection which usually is a no automatized process.

So that when this antenna 1 is incorporated into another system the electric connections with this system are not hidden under the bottom of the PSB 30, as in the known state of the art, thanks to this side portions 42 of the first platings 40 these electrical connections may be lateral, and may be visible and checked by an automatic optical inspection (AOI) to determine a proper welding.

In the cited prior art known, this electrical connections will be made only on the bottom of the PCB 30, and require more complex inspection involving performing electrical measurements to determine the electrical continuity, being this inspection process slower and more expensive.

In order to operate in a broader frequency range, the aforesaid windings 21 , 22 and 23 are configured for operation at low frequencies (approximately between 300KHz and 5KHz) and further provides at least one winding with a smaller number of turns in such a way which provides a high frequency operation (approximatel between 3MHz and 30MHz). Since the directivity at high frequencies is not so critical to the operation of the antennas, it can be used a single high frequencies winding, which can be added to the aforementioned windings 21 , 22 and 23 to provide a antenna 1 operation in two or three dimensions.

In another preferred embodiment, the high frequency winding may be a branch from an intermediate point of one low frequency winding 21 , 22 and/or 23. Additionally, branches can be provided in the three low frequency windings 21 , 22 and 23 to obtain a three-dimensional antenna 1 also at high frequencies without increasing the volume of the device.

Moreover, the high frequency winding can be printed and/or embedded in the printed circuit board 30.

In particular embodiments of the present invention, the PCB 30 may have additional side portions 42 of the first platings 40 along its lateral sides, connected with the aforesaid high frequency winding or windings, allowing his connection with a system in the same way as the first, second and third winding 21 , 22 and 23.

Referring to the manufacturing materials, the core 10 is usually a ferrite core, ferrite core having an electrical resistivity equal to or greater than 10 Qm. In particular a core made of Ni-Zn alloy, or Mn-Zn, other embodiments may incorporate a core made of amorphous cobalt, or a combination of this elements.

The windings 21 , 22 and 23 are preferably of a diameter between 0.01 mm and 1 mm and can be preferably enameled copper wire with polyurethane and/or polyamide with a heat index exceeding 150°C.

Second platings 50 are formed onto the core 10, preferably by chemical baths and are preferably made of Sn100 tin to facilitate its soldering to the PCB 30.

In this embodiment the third winding 23 is superposed to the core 10, as shown in Figure 6, and is fixed on the PCB 30 by four bonding adhesives points 70, and said third winding 23 is electrically connected to the first platings 40 by welding.

Figure 5 shows the assembly of the core 10 with the first and second windings 21 and 22 disposed on the PCB 30.

Figure 7 and thereafter shown a second preferred embodiment of the present invention, wherein Figure 7 shows a full view of the assembled antenna 1 , and Figure 8 an exploded view of the antenna 1 , showing the base integrating the core 10 and the windings 21 , 22 and 23, the covering 60, and an optional cushioning material 61.

As seen in this figure, this alternative embodiment includes three independent cores 10a, 10b and 10c, each with an axis around which a winding 21 , 22 or 23 is wound, said three cores 10a, 10b and 10c are fixed on the PCB 30 so that said axes of said three cores 10a, 10b and 10c remain mutually orthogonal working together as a single monolithic core 10. This is the only substantial difference with respect to the first embodiment; all the other aspects are equivalents. Figure 9 shows a core 10a or 10b with a horizontal axis corresponding to the axis "X" or "Y", and Figure 10 shows a lower view of a core 10c with a vertical axis "Z". These figures show the second platings 50 formed onto the lower faces of said core 10a, 10b and 10c.

In the same way as in the first described embodiment, the winding 21 , 22 and 23 initial section and ends are electrically connected by welding with these second platings 50, securing its correct electrical connection.

The base of this embodiment is equivalent to that of the previous embodiment, and also has the first platings 40, which has a upper portions 41 disposed on the upper face of the PCB 30 in a position coincident with the mounting position of second platings 50 of the cores 10a, 10b and 10b, and a side portions 42 which extends through the side faces of the PCB 30, and being connected to the upper portions 41 through a printed circuit 43, as shown in Figure 8. These first platings 40 can also be printed.

The mounting and connecting way of this second embodiment is the same as explained for the first embodiment.

An alternative applicable to any of the embodiments is the inclusion of the said cushioning material 61 , shown in Figures 7 and 8, which is situated above the covering 60, and serves as antenna's protection against impacts or other physical forces.

Claims

1. -Three-dimensional antenna comprising:

- at least one core ( 10);

- three windings (21 , 22 and 23) wound around three mutually orthogonal axes, each of said windings surrounding said core (10) which is at least one.

- a base;

in which said at least one core is arranged on the base,

characterized in that:

said base is a printed circuit board (30) comprising a plurality of electrically conductive first platings (40) located at least at the top of the printed circuit board

(30), and

- said at least one core (10) comprises electrically conductive second platings (50) which are electrically connected to the windings and to said base electrically onductive first platings (40).

2. - Antenna according to claim 1 characterized in that said electrically conductive first platings (40) extend also covering side surfaces (41 ) of said base.

3. - Antenna according to claim 1 or 2 characterized in that the connection between the windings (21 , 22 and/or 23) and said electrically conductive second platings (50) is performed by welding.

4. -Antenna according to claims 1 , 2 or 3 characterized in that said electrically conductive second platings (50) are formed onto said at least one core (10), by chemical baths and/or sintering processes.

5. - Antenna according to any preceding claim characterized in that the core (10) is a ferrite

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core having an electrical resistivity equal to or greater than 10. Dm.

6.- Antenna according to claim 5 characterized in that the ferrite core comprises a nickel-zinc alloy, a manganese-zinc alloy, amorphous cobalt or any combination of them.

7. -Antenna according to any preceding claim characterized, in that at least the windings (21 , 22 and 23) and the at least one core (10) are over-moulded providing a covering (60).

8. - Antenna according to claim 7 characterized in that said covering (60) is vacuum moulded.

9. -Antenna according to claims 7 or 8 characterized in that the moulded material is a plastic polymer with high thermal performance.

10. -Antenna according to any of the preceding claims characterized in that comprises three cores (10a, 10b and 10c) each of them including one of said three windings (21 , 22 and 23) wound around ,

11. -Antenna according to claim 7 characterized in that a cushioning material (61 ) is provided in the upper side of the over-moulded covering (60).

12. - Antenna according to claim 11 characterized in that the cushioning material (61 ) comprises an acrylic material capable of withstanding the temperatures present in. a reflow thermal profile without burning.

13. -Antenna according to any of claims 1 to 9 characterized in that it has a single monolithic core (10), and in that all three windings (21 , 22 and 23) are wounded there around.

14. -Antenna according to claim 13 characterized in that comprise at least one further high- frequency winding.

15. -An antenna according to claim 14, characterized in that the high-frequency winding has fewer turns than the three windings (21 , 22 and 23).

16. -Antenna according to claim 14 or 15 characterized in that said high-frequency winding is connected to an intermediate point of at least one of the three windings (21 , 22 or 23).

17. - Antenna according to claim 14, 15 or 16 characterized in that said high-frequency winding is a planar winding printed on the printed circuit board (30).