阅读说明：本技术 具有集成的磁通门传感器的部件承载件 (Component carrier with integrated fluxgate sensor ) 是由 赫尔诺特·舒尔茨 亚历山大·卡斯珀 马尔科·加瓦宁 马丁·伦兹霍夫 迈克尔·奥特纳 于 2018-03-29 设计创作，主要内容包括：提供了一种具有集成的磁场传感器的部件承载件(100-1100、1400),其中,该部件承载件包括：多个导电层结构和/或多个电绝缘层结构(101)；设置在该层结构上和/或该层结构中的励磁线圈(103)和传感器线圈(105、107)；位于励磁线圈和传感器线圈上方的第一磁性结构(109)；位于励磁线圈和传感器线圈下方的第二磁性结构(345)。(A component carrier (100) with an integrated magnetic field sensor is provided (1100, 1400), wherein the component carrier comprises: a plurality of electrically conductive layer structures and/or a plurality of electrically insulating layer structures (101); an excitation coil (103) and a sensor coil (105, 107) arranged on and/or in the layer structure; a first magnetic structure (109) located above the excitation coil and the sensor coil; a second magnetic structure (345) located below the excitation coil and the sensor coil.)

1. A component carrier (100) 1100, 1400) with an integrated magnetic field sensor, wherein the component carrier comprises:

a plurality of electrically conductive layer structures and/or a plurality of electrically insulating layer structures (101);

an excitation coil (103) and a sensor coil (105, 107) which are arranged on and/or in the layer structure;

a first magnetic structure (109) located above the excitation coil and the sensor coil;

a second magnetic structure (345) located below the excitation coil and the sensor coil.

2. The component carrier according to claim 1, wherein the excitation coil (103) and the sensor coil (105, 107) are arranged at least partially coplanar on and/or in the layer structure, in particular adjacent to each other.

3. The component carrier according to claim 1 or 2, wherein the first magnetic structure (103) and/or the second magnetic structure (105, 107) is made of a soft magnetic material having in particular between 10³And 10⁶Or between 10⁵And 10⁷In particular comprising a crystalline, polycrystalline and/or amorphous, in particular cobalt-based, metal alloy, in particular comprising at least one of Co, Ni, Si, Fe, Mo, nickel-iron soft magnetic alloy, a MetGlas material, a Vitrovac material.

4. The component carrier according to any of claims 1 to 3, wherein the first and/or second magnetic structures are composed of different materials and/or are configured as foils or sheets.

5. The component carrier according to any of claims 1 to 4,

wherein the material of the first magnetic structure (103) is characterized by a steeper hysteresis curve, and/or than the material of the second magnetic structure

Wherein the magnetization field with the highest magnetic permeability for the material of the first magnetic structure is smaller than the material of the second magnetic structure, and/or

Wherein the material of the first magnetic structure has a smaller magnetic reverse loss than the material of the second magnetic structure, and/or

Wherein the material of the second magnetic structure requires a higher external field strength to achieve magnetic saturation than the material of the first magnetic structure.

6. The component carrier according to any of the preceding claims, wherein the excitation coil (103), the first magnetic structure (109) and the second magnetic structure (345), in particular together with a driver circuit for the excitation coil, are configured such that the excitation coil generates an alternating magnetic field, in particular having a frequency between 1kHz and 200kHz, more in particular between 10kHz and 100kHz, which saturates the magnetization in the first magnetic structure (109) but not in the second magnetic structure (345).

7. The component carrier according to any of the preceding claims, wherein at least one of the excitation coil (103) and the sensor coil (105, 107) comprises electrically conductive windings, in particular wound in the same way, which are formed on one or more dielectric layers of the electrically insulating layer (101), in particular between 2 and 6 dielectric layers of the electrically insulating layer (101).

8. The component carrier according to claim 7,

wherein the dielectric layers (111, 113, 115, 117) in which the windings of the excitation coil (103) and the windings of the sensor coil (105, 107) are formed are the same dielectric layer, in particular the dielectric layers in which the windings of the excitation coil (103) and the windings of the sensor coil (105, 107) are formed are four dielectric layers, or

Wherein some of the dielectric layers (211, 213) are formed with windings of the excitation coil and windings of the sensor coil, in particular two dielectric layers are formed with windings of the excitation coil and windings of the sensor coil, while other dielectric layers (215, 217) are formed with windings of the sensor coil (205, 207) without windings of the excitation coil.

9. The component carrier according to any of the preceding claims, wherein an area of a lateral extension of the first magnetic structure (109) and/or an area of a lateral extension of the second magnetic structure (345) is equal to or smaller than a sum of an area of a lateral extension of the excitation coil (103) and an area of a lateral extension of the sensor coil (105, 107), in particular the area of a lateral extension of the first magnetic structure (109) and/or the area of a lateral extension of the second magnetic structure (345) is between 10% and 60%, more particularly between 20% and 40%, of a sum of an area of a lateral extension of the excitation coil (103) and an area of a lateral extension of the sensor coil (105, 107).

10. The component carrier according to any of the preceding claims, wherein a lateral shape of the first magnetic structure (109) and/or a lateral shape of the second magnetic structure (345) is substantially equal to a shape of a lateral area or a reduced lateral area covered by the excitation coil and the sensor coil.

11. The component carrier according to any of the preceding claims, wherein at least one of the excitation coil (103) and the sensor coils (105, 107) has a winding formed as one or more helically square or rectangular windings, two of the sensor coils being arranged adjacent to the excitation coil such that lateral midpoints (647) of the two sensor coils (605, 607) can be connected by a straight line extending through a lateral midpoint (653) of the excitation coil (603), the straight line (651, 751) in particular extending through a corner of the winding of the excitation coil or through and perpendicular to a side edge of the winding of the excitation coil (603, 703).

12. The component carrier according to any one of the preceding claims,

wherein the first magnetic structure (409) and/or the second magnetic structure (445) extend along the straight line (451) by an amount (e1, e2) between a distance (dm) of the lateral mid-points (447) of the two sensor coils (405, 407) and a distance (do) between ends of the two sensor coils (405, 407) along the straight line.

13. The component carrier according to any of the preceding claims, wherein the number of excitation coils is at least two, the number of sensor coils is at least two or at least six,

wherein four of the sensor coils and one excitation coil are arranged substantially in a coplanar arrangement, and the other two sensor coils and the other excitation coil are oriented perpendicular to the coplanar arrangement in a region laterally beside the four sensor coils and on the same electrically insulating layer structure, the region being bent by more than 0 °, in particular by substantially 90 °.

14. The component carrier according to any of the preceding claims, the component carrier being operable in a first and a second operation mode,

wherein during the first mode of operation saturation of magnetization occurs in the first magnetic material but not in the second magnetic material, in particular resulting in an increase of energy efficiency;

wherein during the second mode of operation saturation of magnetization occurs in both the first magnetic material and the second magnetic material, in particular resulting in an increase of sensitivity.

15. A method of manufacturing a component carrier with an integrated magnetic field sensor, wherein the method comprises:

connecting a plurality of electrically conductive layer structures and/or a plurality of electrically insulating layer structures (101);

forming an excitation coil (103) and a sensor coil (105, 107) on and/or in the layer structure;

forming a first magnetic structure (109) over the excitation coil and the sensor coil;

a second magnetic structure (345) is formed below the excitation coil and the sensor coil.

Technical Field

The invention relates to a component carrier with an integrated fluxgate sensor and also to a manufacturing method for manufacturing a component carrier with an integrated fluxgate sensor.

Background

A conventional planar fluxgate sensor comprises a magnetic core of substantially elongated shape overlying a field coil. By providing the excitation coil with an appropriate AC excitation current, the magnetic core may be brought into a series of cycles of magnetic saturation. Sensing of the external field is obtained by a pair of sense coils, which are typically disposed below the ends of the magnetic core.

EP 2194391 a1 discloses a wide range of magnetic sensors and methods of manufacturing the same, wherein the magnetic sensor is formed by a fluxgate sensor and at least one hall sensor. Wherein the magnetic core of the fluxgate sensor is formed of a magnetic region which also serves as a concentrator for the hall sensor. The magnetic regions are manufactured in a post-processing stage on a metallization layer, in which an excitation coil and a sensing coil of the fluxgate sensor are formed. The excitation coil and the sensing coil are formed on a semiconductor substrate that houses the conductive regions of the hall sensor. The fluxgate sensor described in EP 2194391 a1 comprises an excitation coil covering four sensing coils and located below a magnetic core. The excitation coil is generally square, while the magnetic core is in the shape of a cross (cross), and the magnetic core includes a first arm and a second arm perpendicular to each other. The sensing coils are arranged in pairs with the vertical axis passing near the ends of the arms of the magnetic core. If the excitation coil is supplied with a suitable excitation current, which is capable of saturating the magnetic material at a suitable frequency, the two halves of the first arm are magnetized in opposite directions. In the absence of an external field, two sensing coils would experience two equal and zero induced voltages if they were connected in different configurations. Conversely, if an external field is present, the first half of the first arm will be magnetized in the same direction as the external field, thereby amplifying its own total magnetization, while the second half of the first arm will be magnetized in the opposite direction and its total magnetization will decrease. Thus, the differential voltage of the sensing coil is non-zero and is amplitude modulated by the strength of the external field. Thus, the external field can be measured with high sensitivity and high reliability. The presence of the second arm enables the measurement of the components of the external field in two directions, and the presence of the further arm perpendicular to the two arms also enables the measurement of the components of the external field in three directions (e.g. three perpendicular directions), thereby enabling the implementation of a 3D fluxgate sensor.

DE 102004052909 a1 discloses a printed circuit board with a sensor for weak magnetic fields, which comprises a base board on which a first circuit for excitation and a first circuit for detection are formed; a body having soft magnetic cores, the body being laminated above and below the base plate, and the body being formed of a plurality of soft magnetic cores; and further comprising outer layers which are respectively laminated onto the body with the soft magnetic core and on which a second circuit for excitation and a second circuit for detection are formed.

US 6,270,686B 1 discloses a low-field magnetic field sensor with etched circuit coils comprising an amorphous core with epoxy bases superimposed with respect to each other on its top and bottom surfaces. One epoxy base has a coil Y etched thereon, a second epoxy base has a coil X etched thereon, and the remaining epoxy bases have a circular pattern etched thereon. The amorphous core is formed from at least two amorphous sheets stacked on opposite sides of an epoxy base sheet.

Conventional fluxgate sensors or sensors typically used to detect magnetic fields may require a large amount of space, may not be reliable under all conditions, and may not have sufficient accuracy or may not have ideal sensitivity.

There is therefore a need for a magnetic field sensor, in particular a fluxgate sensor, or a magnetic field sensor that generally requires less space, has better reliability, improved accuracy and/or improved sensitivity. Furthermore, there is a need for a fluxgate sensor having an improved energy efficiency, in particular requiring less energy or having less energy consumption for operation.

Disclosure of Invention

This need may be solved by the subject matter of the independent claims. The dependent claims specify particular embodiments of the invention.

According to an embodiment of the invention, a component carrier with an integrated magnetic field sensor (e.g. magnetometer), in particular a (planar) fluxgate sensor, is provided, wherein the component carrier comprises a plurality of electrically conductive layer structures and/or a plurality of electrically insulating layer structures; an excitation coil and a sensor coil arranged on and/or in the layer structure; a first magnetic structure located over the excitation coil and the sensor coil; and a second magnetic structure located below the excitation coil and the sensor coil.

The magnetic field sensor may be configured to measure a magnetic field or a magnetic flux in at least one direction, in particular to measure the strength and direction of the magnetic field, and the magnetic field sensor may be configured as a (planar) fluxgate sensor.

In the context of the present application, the term "component carrier" may particularly denote any support structure capable of accommodating one or more components thereon and/or therein to provide mechanical support and/or electrical connection. In other words, the component carrier may be configured as a mechanical and/or electronic carrier for the components. In particular, the component carrier may be one of a printed circuit board, an organic interposer, and an IC (integrated circuit) substrate. The component carrier may also be a hybrid board combining different ones of the above-mentioned types of component carriers.

In one embodiment, the component carrier comprises a stack of at least one electrically insulating layer structure and at least one electrically conductive layer structure. For example, the component carrier may be a laminate of the mentioned electrically insulating layer structure(s) and electrically conductive layer structure(s), in particular a laminate formed by applying mechanical pressure, if necessary supported with thermal energy. The mentioned stack may be provided as a plate-shaped component carrier which is able to provide a large mounting surface for other components and which is still very thin and compact. The term "layer structure" may particularly denote a continuous layer, a patterned layer or a plurality of non-continuous islands in a common plane.

In one embodiment, the component carrier is shaped as a plate. This contributes to a compact design, wherein the component carrier still provides a large base for mounting components on the component carrier. Furthermore, particularly a bare die, which is an example of an embedded electronic component, can be easily embedded in a thin board such as a printed circuit board thanks to its small thickness.

In one embodiment, the component carrier is configured as one of a printed circuit board and a substrate (in particular an IC substrate).

In the context of the present application, the term "printed circuit board" (PCB) may particularly denote a component carrier (which may be plate-shaped (i.e. planar), three-dimensionally curved (e.g. when manufactured using 3D printing) or which may have any other shape) which is formed, for example, by applying pressure, if necessary with the supply of thermal energy, laminating a number of electrically conductive layer structures with a number of electrically insulating layer structures. As a preferred material for PCB technology, the electrically conductive layer structure is made of copper, while the electrically insulating layer structure may comprise resin and/or glass fibres, so-called prepreg or FR4 material. The various conductive layer structures can be connected to each other in a desired manner by the following process: a through hole is formed through the laminate, for example by laser drilling or mechanical drilling, and the via hole is formed as a through hole connection by filling the through hole with a conductive material, in particular copper. In addition to one or more components that may be embedded in a printed circuit board, printed circuit boards are typically configured to receive one or more components on one or both opposing surfaces of a plate-like printed circuit board. They may be attached to the respective major surfaces by welding. The dielectric portion of the PCB may be composed of a resin with reinforcing fibers, such as glass fibers.

In the context of the present application, the term "substrate" may particularly denote a small component carrier having substantially the same dimensions as the components (particularly electronic components) to be mounted on the component carrier. More specifically, a baseplate can be understood as a carrier for electrical connections or electrical networks and a component carrier comparable to a Printed Circuit Board (PCB), but with a comparable higher density of laterally and/or vertically arranged connections. The lateral connections are, for example, conductive paths, while the vertical connections may be, for example, drilled holes. These lateral and/or vertical connections are provided within the substrate and may be used to provide electrical and/or mechanical connection of a housed or non-housed component (e.g. bare die), in particular of an IC chip, to a printed circuit board or an intermediate printed circuit board. Thus, the term "substrate" may also include "IC substrates". The dielectric portion of the substrate may be composed of a resin with reinforcing balls, such as glass balls.

In an embodiment, the at least one electrically insulating layer structure comprises at least one of: resins (such as reinforced or non-reinforced resins, for example epoxy or bismaleimide-triazine resins, more particularly FR-4 or FR-5), cyanate esters, polyphenylene derivatives, glass (in particular glass fibers, multiple layers of glass, glassy materials), prepregs, polyimides, polyamides, Liquid Crystal Polymers (LCP), epoxy-based reinforced (laminate) films, polytetrafluoroethylene (teflon), ceramics and metal oxides. Reinforcing materials made of glass (multiple layer glass), such as meshes, fibers or spheres, for example, may also be used. While prepreg or FR4 is generally preferred, other materials may be used. For high frequency applications, high frequency materials such as polytetrafluoroethylene, liquid crystal polymers and/or cyanate ester resins can be applied in the component carrier as an electrically insulating layer structure.

In an embodiment, the at least one conductive layer structure may include at least one of copper, aluminum, nickel, silver, gold, palladium, and tungsten. Although copper is generally preferred, other materials or coatings thereof are possible, particularly coated with superconducting materials such as graphene.

The at least one component may be selected from a non-conductive inlay, a conductive inlay (such as a metal inlay, preferably comprising copper or aluminum), a heat transfer unit (e.g. a heat pipe), a light guiding element (e.g. a light guide or light conductor connection), an electronic component, or a combination thereof. For example, the components may be active electronic components, passive electronic components, electronic chips, storage devices (e.g., DRAM or other data storage), filters, integrated circuits, signal processing components, power management components, optoelectronic interface elements, voltage converters (e.g., DC/DC converters or AC/DC converters), cryptographic components, transmitters and/or receivers, electromechanical transducers, sensors, actuators, micro-electromechanical systems (MEMS), microprocessors, capacitors, resistors, inductors, batteries, switches, cameras, antennas, logic chips, and energy harvesting units. However, other components may be embedded in the component carrier. For example, a magnetic element may be used as the component. Such magnetic elements may be soft magnetic elements, in particular ferromagnetic elements, antiferromagnetic elements or ferrimagnetic elements, for example ferrite cores, or paramagnetic elements. However, the component may also be a further component carrier, for example in the form of a plate in a plate. The component may be surface mounted on the component carrier and/or may be embedded inside the component carrier. Furthermore, other components may also be used as the component, which in particular generate and emit electromagnetic radiation and/or are sensitive to electromagnetic radiation propagating from the environment.

In an embodiment, the component carrier is a laminate type component carrier. In such an embodiment, the component carrier may be constructed of a multilayer structure which is stacked and joined together by applying pressure, if necessary supported by thermal energy.

The component carrier may be configured to carry further electrical and/or electronic components, such as resistors, capacitors, diodes, transistors or integrated circuits. The fluxgate sensor is capable of measuring at least one component of the external magnetic field, for example a 1D fluxgate sensor can be provided. To realize a 1D fluxgate sensor, there may be at least one excitation coil and two sensor coils or two windings of one sensor coil. To implement a 2D fluxgate sensor, there is at least one excitation coil and four sensor coils (e.g. arranged in a plane). To realize a 3D fluxgate sensor, there may be at least two excitation coils and six sensor coils or integrated field shaping elements.

The excitation coil and the sensor coil may be realized, for example, by etching appropriately etched copper traces on the electrically insulating layer structure. The excitation coil and/or the sensor coil may be present on one or more electrically insulating layer structures. The parts of the excitation coil and/or the sensor coil on the different layers may be electrically connected via through holes or vias.

For a 1D fluxgate sensor or a 2D fluxgate sensor, the excitation coil and the sensor coil may be arranged substantially alongside each other at the same vertical height or position. For example, the excitation coil and the sensor coil, or at least a portion thereof, may be formed on the same layer of the electrically insulating layer or layer structure. Thus, manufacturing can be simplified. In one layer, the excitation coil and/or the sensor coil may for example comprise N windings, wherein N is larger than 1, for example between 5 and 100 windings, for example 15 windings. The excitation coil and the sensor coil may for example be arranged between M coils, wherein M is larger than 1, for example between 2 and 6, or even more, in particular four superimposed layers. For example, in the n-layer component carrier or the PCB, the m-layer fluxgate may be integrated (integrally provided). The excitation coil and the sensor coil may be configured in substantially the same shape, for example in the form of a rectangle, a circle or a quadratic spiral. The windings may for example be formed as copper tracks. The excitation coil and the sensor coil may be manufactured, for example, by etching a copper layer covering the insulating layer structure.

The magnetic structure may be magnetizable and may for example comprise a ferromagnetic material or a ferrimagnetic material. Magnetic structures generally do not have a permanent magnetic field or generally do not generate their own magnetic field, but are magnetizable and have a high permeability to magnetic fields. The excitation coil may generate a magnetic field in the first magnetic configuration and also in the second magnetic configuration during operation as a fluxgate sensor when the excitation coil is supplied with a suitable AC current. Herein, in the first magnetic structure and the second magnetic structure, due to the opposite arrangement of the excitation coil and the first magnetic structure and the second magnetic structure, magnetic fields (within the first magnetic structure and/or the second magnetic structure) pointing in opposite directions may be generated, as is known from a conventional planar fluxgate sensor. The first magnetic structure and the second magnetic structure may both be continuous structures, e.g. each integrally formed. The first and/or second magnetic structure may be formed directly on one of the electrically insulating layer structures, or may be prefabricated and may be attached to one of the electrically insulating layer structures. The first magnetic structure and/or the second magnetic structure may have similar or identical thicknesses, for example between 1 μm and 500 μm, in particular between 10 μm and 100 μm, or different thicknesses, depending on the respective material and/or the desired target. The first and second magnetic structures may be made of different materials and may have the same or different shapes. The vertical distance between the excitation coil and the sensor coil on one side and the first magnetic structure may be substantially equal to or at least close to the vertical distance between the excitation coil and the sensor coil on one side and the second magnetic structure on the other side. The first and second magnetic structures may sandwich the excitation coil and the sensor coil between the first and second magnetic structures.

The first magnetic structure (also referred to as a core plate) and the second magnetic structure may focus the lines of magnetic flux among them, and in particular, the second magnetic structure may help to enclose the lines of magnetic flux to concentrate them into the magnetic structure. By concentrating the lines of magnetic flux within the first magnetic structure and/or the second magnetic structure, the energy required to drive the excitation coil to generate the alternating magnetic field may be reduced. Therefore, less energy may be required to drive the excitation coil in order to obtain sensitivity similar to that of the conventional fluxgate sensor.

The first magnetic structure as well as the second magnetic structure may be configured as a foil or a sheet or a plate extending mainly in a plane parallel to the electrically insulating layer structure of the component carrier. The first magnetic structure and/or the second magnetic structure may for example be made by cutting out a suitable shape from a prefabricated foil, which may be obtained in a conventional manner, or may be obtained from a metal sheet obtained in a conventional manner, such as a metal sheet for a conventional transformer. Both the first and second magnetic structures may be highly magnetic permeable, but may be characterized by different hysteresis curves.

According to an embodiment of the invention, the excitation coil and the sensor coil are arranged at least partially coplanar on and/or in the layer structure, in particular adjacent to each other.

In the layer structure, the excitation coil and the sensor coil may extend substantially at the same vertical level. For example, the excitation coil may not be above or below the sensor coil, but may be located substantially within the same vertical extent. When the excitation coil and/or the sensor coil are configured to extend over multiple layers of the electrically insulating layer structure, at least a portion of the excitation coil and a portion of the sensor coil may be arranged coplanar with each other, in particular in the same layer of the electrically insulating layer structure, or on the electrically insulating layer structure. The excitation coil and the sensor coil can be manufactured on the same layer when they are at least partially coplanar with each other, thereby simplifying manufacturing.

According to an embodiment of the invention, the first and/or the second magnetic structure is made of a soft magnetic material having in particular between 10³And 10⁶Or between 10⁵And 10⁷In between, the material comprising in particular a crystalline, polycrystalline and/or amorphous, in particular cobalt-based, metal alloy, the material being characterized by a high maximum direct magnetic permeabilityThe material comprises in particular at least one of Co, Ni, Si, Fe, Mo, nickel-iron soft magnetic alloy, a MetGlas material, a Vitrovac material.

When the first magnetic structure and/or the second magnetic structure have high permeability, they can effectively focus the magnetic field lines within the magnetic structure, thereby increasing sensitivity or reducing energy consumption.

According to an embodiment of the invention, the first magnetic structure and/or the second magnetic structure are composed of different materials and/or are configured as a foil or sheet. The inventors have found by performing measurements of sensitivity and energy consumption that different materials for the first and second magnetic structures may increase the sensitivity and/or decrease the energy consumption of the fluxgate sensor.

According to an embodiment of the present invention, the material of the first magnetic structure is characterized by a steeper hysteresis curve than the material of the second magnetic structure; a field for magnetization having a maximum magnetic permeability for the material of the first magnetic structure is smaller than that for the material of the second magnetic structure; and/or wherein the material of the first magnetic structure has a smaller magnetic reverse loss than the material of the second magnetic structure; and/or wherein the material of the second magnetic structure requires a higher external field strength to achieve magnetic saturation than the material of the first magnetic structure. The first magnetic material and the second magnetic material may have different saturation magnetizations.

The first magnetic structure is for example characterized in that its hysteresis curve after a steep increase substantially has a kink, wherein the kink is substantially situated at a magnetization substantially equal to the saturation magnetization. Thus, the material of the first magnetic structure may substantially reach saturation with a lower field for magnetization than the material of the second magnetic structure. Less energy is required to reverse magnetize the material of the first magnetic structure than is required to reverse magnetize the material of the second magnetic structure. The permeability may generally vary with a varying field for magnetization. The permeability of the material of the first magnetic structure and the material of the second magnetic structure may increase starting from a vanishing field for magnetization to assume a maximum at a particular field for magnetization and then may decrease as saturation of the magnetization is reached. The magnetic reverse loss may correspond to an area enclosed by a hysteresis curve of the respective material. The magnetic reversal loss may be related to the energy required to magnetize or reverse the (saturation) magnetization of the respective material.

The inventors found that when one of these characteristics of the materials of the first magnetic structure and the second magnetic structure is satisfied, and if the shapes of the first magnetic structure and the second magnetic structure are further appropriately selected or designed, the sensitivity can be increased or the power consumption can be reduced. The selection of materials and shapes may result in improved energy efficiency and/or sensitivity.

According to an embodiment of the invention, the excitation coil, the first magnetic structure and the second magnetic structure are configured, in particular together with a driver circuit for the excitation coil, such that the excitation coil generates an alternating magnetic field, in particular having a frequency between 1kHz and 200kHz, more in particular between 10kHz and 100kHz, which saturates the magnetization in the first magnetic structure, but not the magnetization in the second magnetic structure. When the material of the second magnetic structure is not saturated during operation of the fluxgate sensor, the sensitivity may be increased, and/or the energy consumption may be reduced.

According to an embodiment of the invention, at least one of the excitation coil and the sensor coil comprises an electrically conductive winding, in particular wound in the same way, formed on one or more dielectric layers of the electrically insulating layer, in particular on between 2 and 6 dielectric layers of the electrically insulating layer. In the n dielectric layers, m fluxgate layers may be integrated (e.g., m < n, where n is a natural number). The conductive winding may be configured as a copper trace, e.g. comprising straight portions extending perpendicular to each other to form e.g. a spiral. When the excitation coil and/or the sensor coil is provided on more than one dielectric layer of the electrically insulating layer, a higher inductivity may be achieved, thereby increasing the sensitivity and/or accuracy, and/or reducing the energy consumption.

According to an embodiment of the present invention, the dielectric layers forming the windings of the excitation coil and the windings of the sensor coil are the same dielectric layer, in particular, the dielectric layers forming the windings of the excitation coil and the windings of the sensor coil are four dielectric layers, or the windings of the excitation coil and the windings of the sensor coil are formed on some of the dielectric layers, in particular, the windings of the excitation coil and the windings of the sensor coil are formed on two of the dielectric layers, while the windings of the sensor coil are formed on the other dielectric layers without the windings of the excitation coil.

When the windings of the excitation coil and the windings of the sensor coil are formed on one or more of the same dielectric layers, manufacturing may be simplified. For example, if the magnetic field generated by the excitation coil drives a magnetization in the first magnetic structure that is at saturation, the excitation coil may include conductive windings on fewer layers than the conductive windings of the sense coil. In this case, on some dielectric layers, parts of the excitation coil and parts of the sensing coil may be arranged jointly, in particular side by side. In other dielectric layers, only portions of the sense coil may be provided, and may be laterally larger than portions of the sense coil in the dielectric layer that are typically used to house portions of the excitation coil and portions of the sense coil. Thus, in this case, the sensing coil may be formed of winding portions in different dielectric layers having different dimensions. This can improve sensitivity.

According to an embodiment of the invention, the area of the lateral extension of the first magnetic structure and/or the area of the lateral extension of the second magnetic structure is equal to or smaller than the sum of the area of the lateral extension of the excitation coil and the area of the lateral extension of the sensor coil, in particular the area of the lateral extension of the first magnetic structure and/or the area of the lateral extension of the second magnetic structure is between 20% and 40% of the sum of the area of the lateral extension of the excitation coil and the area of the lateral extension of the sensor coil.

The area of the lateral extension may be selected, for example, such that saturation of the magnetization in the first magnetic structure is achieved during operation, while saturation of the magnetization in the second magnetic structure is not achieved. The lateral extension of the first magnetic structure and/or the second magnetic structure may be largest in the direction of the to be detected component of the external magnetic field. In directions perpendicular to these directions, the extension may be smaller (e.g. smaller than the extension of the coil), thereby saving material.

According to an embodiment of the invention, the lateral shape of the first magnetic structure and/or the lateral shape of the second magnetic structure is substantially equal to the shape of the lateral area or the reduced lateral area covered by the excitation coil and the sensor coil. The first magnetic structure and/or the second magnetic structure may completely overlap the excitation coil and the sensor coil in a projection perpendicular to the layer structure. Thereby, the lines of magnetic flux may be focused and concentrated within the first and second magnetic structures. The lateral regions covered by the excitation coil and the sensor coil may for example have a cross shape (cross shape), wherein for example corners or side edges of the excitation coil and the sensing coil are closest to each other.

According to an embodiment of the invention, at least one of the excitation coil and the sensor coil has a winding formed as one or more squares or rectangles with a spiral, two of the sensor coils being arranged adjacent to the excitation coil such that lateral midpoints of the two sensor coils can be connected by a straight line extending through the lateral midpoints of the excitation coil, the straight line extending in particular through a corner of the winding of the excitation coil or through and perpendicular to a side edge of the winding of the excitation coil. Thereby, a compact arrangement or an arrangement wherein the magnetic structure covers a larger area of the coil may be achieved.

According to an embodiment of the invention, the first magnetic structure and/or the second magnetic structure extends along the straight line by an amount between a distance of lateral midpoints of the two sensor coils and a distance between ends of the two sensor coils along the straight line. It has been found in experiments that the extensions of the first and/or second magnetic structure do not have to be identical to the extensions of the combination of the excitation coil and the (adjacent) sensing coil, but may be somewhat smaller to reach only the middle point of the sensing coils arranged adjacent to the (central) excitation coil, respectively. Thereby, material may be saved while maintaining the desired sensitivity and energy consumption.

According to an embodiment of the invention, the number of excitation coils is at least two, the number of sensor coils is at least six, wherein four of the sensor coils and one excitation coil are arranged in a substantially coplanar arrangement, and the other two sensor coils and the other excitation coil are oriented perpendicular to the coplanar arrangement in a region laterally beside the four sensor coils and on the same electrically insulating layer structure, the region being bent over substantially 90 °.

Advantageously, the 3D fluxgate sensor may be manufactured starting from a layer structure having therein a first region in which a first central excitation coil is provided surrounded by a first set of four sensing coils and a second region comprising a second central excitation coil flanked by a second set of two sensing coils. The first magnetic structure may be present over the coil in the first region and may also be present over the coil in the second region. Likewise, the second magnetic structure may be present under the coil in the first region, and under the coil in the second region. Finally, the first and second regions may be oriented perpendicular to each other by bending the layer structure around a bending line between the first and second regions. Accordingly, the 3D fluxgate sensor may be efficiently manufactured. In another configuration, two panels may be separately manufactured and then reconnected in a perpendicular configuration. For example, the reconnection may be performed by a welding method, a bonding method, or the like.

It should be understood that the features disclosed, described or explained for the component carrier, either individually or in any combination, can also be applied individually or in any combination to the method of manufacturing a component carrier according to an embodiment of the invention and vice versa.

According to an embodiment of the invention, a method of manufacturing a component carrier with an integrated fluxgate sensor is provided, wherein the method comprises connecting a plurality of electrically conductive layer structures and/or a plurality of electrically insulating layer structures; forming an excitation coil and a sensor coil on and/or in the layer structure; forming a first magnetic structure over the excitation coil and the sensor coil; a second magnetic structure is formed below the excitation coil and the sensor coil.

The component may further comprise a component, in particular an electronic component, mounted and/or embedded in the at least one electrically insulating layer structure and/or the at least one electrically conductive layer structure.

The component carrier may be selected from the group consisting of electronic components, non-conductive and/or conductive inlays, heat transfer units, light guide elements, energy harvesting units, active electronic components, passive electronic components, electronic chips, memory devices, filters, integrated circuits, signal processing components, power management components, optoelectronic interface elements, voltage converters, cryptographic components, transmitters and/or receivers, electromechanical transducers, actuators, microelectromechanical systems, microprocessors, capacitors, resistors, inductors, batteries, switches, cameras, antennas, magnetic elements, other component carriers, and logic chips.

The at least one electrically conductive layer structure comprises at least one of copper, aluminum, nickel, silver, gold, palladium and tungsten, any of the mentioned materials optionally being coated with a superconducting material, such as graphene.

The at least one electrically insulating layer structure comprises a resin, in particular a reinforced or non-reinforced resin, such as an epoxy resin or a bismaleimide-triazine resin; FR-4; FR-5; a cyanate ester; a polyphenylene derivative; glass; prepreg preparation; a polyimide; a polyamide; a liquid crystalline polymer; an epoxy-based reinforcing film; polytetrafluoroethylene; at least one of a ceramic and a metal oxide.

The component carrier is shaped as a plate.

The component carrier is configured as one of a printed circuit board and a substrate.

The component carrier is configured as a laminate-type component carrier.

Embodiments of the present invention will now be described with reference to the accompanying drawings. The invention is not limited to the embodiments illustrated or described.

Drawings

Fig. 1 schematically shows a component carrier according to an embodiment of the invention in a side view;

fig. 2 schematically shows a component carrier according to an embodiment of the invention in a side view;

fig. 3 schematically shows a component carrier according to an embodiment of the invention in a side view;

fig. 4 schematically shows a component carrier according to an embodiment of the invention in a side view;

fig. 5 schematically shows a component carrier according to an embodiment of the invention in a side view;

fig. 6 and 7 schematically show a component carrier configured as a 2D fluxgate sensor according to an embodiment of the present invention in a front view;

fig. 8 and 9 schematically show a component carrier with a 1D fluxgate sensor according to an embodiment of the present invention in a front view;

fig. 10 schematically shows in a perspective view a component carrier with an integrated fluxgate sensor according to an embodiment of the present invention;

fig. 11 schematically shows an intermediate step in front view for manufacturing a component carrier configured as a 3D fluxgate sensor according to an embodiment of the present invention;

fig. 12 and 13 schematically show method steps for manufacturing a component carrier with an integrated 3D fluxgate sensor according to an embodiment of the present invention;

fig. 14 shows a component carrier according to a further embodiment of the invention in a schematic side view;

figure 15 shows a hysteresis curve of a material used in the component carrier according to an embodiment of the invention; and

fig. 16 and 17 show the experimental results.

Detailed Description

The component carrier 100, which is shown in a schematic side view in fig. 1, comprises a plurality of electrically conductive layer structures and/or a plurality of electrically insulating layer structures 101, which are placed on top of each other and connected to each other after pressing them together and applying a suitable temperature. The layer structure may include prepreg material including resin and fibers, and may have structures such as conductive copper traces thereon. The component carrier 100 further comprises sensor coils 105 and 107 and an excitation coil 103 arranged in a stack of layer structures 101. The component carrier further comprises a first magnetic structure 109 located above the excitation coil 103 and the sensor coils 105, 107.

In the example shown in fig. 1, the stack of layers 101 comprises a first layer 111, a second layer 113, a third layer 115 and a fourth layer 117, which are placed on top of each other and connected to each other. Portions of each of the excitation coil 103, the sensing coil (sensor coil) 105, and the sensing coil 107 are formed on each of the layers 111, 113, 115, 117. In the first layer 111, the exciter coil 103 comprises windings 119, in the second layer 113 the exciter coil 103 comprises windings 121, in the third layer 115 the exciter coil 103 comprises windings 123, and in the fourth layer 117 the exciter coil comprises windings 125, wherein the windings 119, 121, 123, 125 of the exciter coil 103 are electrically connected to each other using electrically conductive vias or vias 127. In each layer 111, 113, 115, 117, for example, 10 to 20 windings may be provided. Also, sensing coil 105 includes winding 129 in first layer 111, winding 131 in second layer 113, winding 133 in third layer 115, and winding 135 in fourth layer 117. Sensing coil 107 includes windings 137 in a first layer, windings 139 in a second layer, and windings 141 in a third layer, and windings 143 in a fourth layer, which windings of sensing coil 107 may be configured as windings 129, 131, 133, 135 of sensing coil 105, which windings of sensing coil 105 may also be configured as windings 119, 121, 123, and 125 of excitation coil 103, particularly also including conductive vias 127 for electrically connecting winding portions in different layers to each other.

As can be seen from fig. 1, the windings 129 of the sensing coil 105, the windings 119 of the excitation coil 103 and the windings 137 of the sensing coil 107 are arranged coplanar with each other in the same layer 111 of the layer structure 101. The other windings of the excitation coil 103 and the sensing coils 105, 107 are also arranged on or in the same layer and are arranged coplanar and adjacent to each other.

The component carrier 200, which is schematically shown in a side view in fig. 2, further comprises a first layer 211, a second layer 213, a third layer 215 and a fourth layer 217 in a stack of layers 201. However, the exciting coil 203 includes the windings 219 and 221 only in the first layer 211 and the second layer 213, and does not include the windings in the third layer 215 and the fourth layer 217. In the first layer 211 and the second layer 213, the windings 229 and 231 of the sense coil 205 and the windings 237 and 239 of the sense coil 207 are coplanar with the windings 219 and 221 of the excitation coil 203. In the first layer 211 and the second layer 213, the sensing coils 205, 207 have a lateral extension s1, whereas in the third layer 215 and the fourth layer 217, the sensing coils 205, 207 have a lateral extension s2 larger than s1, the extension s2 being in particular between 1.5 and 1.9 times the extension s 1.

In the embodiments shown in fig. 1 to 15, the respective excitation coil is configured to generate an alternating magnetic field, which magnetizes the first magnetic structure (above the excitation coil and the sensor coil) to saturation.

Fig. 3, 4 and 5 schematically show other embodiments of a component carrier similar to the embodiment shown in fig. 1 and 2 in side view, but comprising a second magnetic structure 345 below the excitation coil 303 and the sensing coils 305, 307, for example with reference to fig. 3. The second magnetic structures 345, 445, 545 of the component carriers 300, 400, 500 shown in fig. 3, 4 and 5, respectively, may be made of a material different from the material of the first magnetic structures 309, 409, 509, respectively. Furthermore, the thickness d1 of the first magnetic structure 309 may be smaller than the thickness d2 of the second magnetic structure 345. This may be the case when the second magnetic structure 345 is comprised of a transformer soft magnetic material or sheet metal. Both the material of the first magnetic structure and the material of the second magnetic structure may be made of a material of high magnetic permeability. The saturation induction of the material of the first magnetic structure may be different from the saturation induction of the material of the second magnetic structure. The material of the first magnetic structure 309 may for example be MetGlas 2714A (with a saturation induction of 0.57T) and the second magnetic structure may for example comprise Vitrovac 6155U55F (with a saturation polarization of 0.99T, with an atomic percentage composition of 73% Co, 5% Fe, 5% Si, 17% B). MetGlas 2714A may have a steep hysteresis curve, while Vitrovac 6155U55F may have a more gradual hysteresis curve. The lateral extension e1 of the first magnetic structure 309 may be substantially equal to the lateral extension c of the combination of the sensing coil 305, the excitation coil 303 and the sensing coil 307. The lateral extension e2 of the second magnetic structure 345 may be substantially equal to the lateral extension e1 of the first magnetic structure and may also be substantially equal to the lateral extension c of the coils 305, 303, 307.

In the embodiment of the component carrier 400 shown in fig. 4, the extension e1 of the first magnetic structure 409 and the extension e2 of the second magnetic structure 445 are smaller than the combined lateral extension c of the coils 405, 403 and 407. In particular, extension e1 and extension e2 may be in a range between a distance dm between midpoints 447 of sense coils 405, 407 and a distance do between laterally outer ends 449 of sense coils 405 and 407. The lateral extension e1 of the first magnetic structure 409 and the lateral extension e2 of the second magnetic structure 445 are preferably not smaller than the distance dm between the midpoints 447 of the sense coils 405, 407.

In the component carrier 500 shown in fig. 5, the lateral extension e1 of the first magnetic material is smaller than the lateral extension c of the coil, but the lateral extension e2 of the second magnetic material 545 is substantially equal to the lateral extension of the coils 505, 503, 507.

In the embodiment shown in fig. 4, saturation of the first magnetic structure 409 may also be achieved when the lateral extension e1 is smaller than the extension of the coil, due to the configuration depending on the excitation coil 403.

In general, the first magnetic structure and the second magnetic structure may be formed in an integrated manner and may be continuous without being separated.

By designing and constructing the first magnetic structure 509 in fig. 5 such that the lateral extension el is smaller than the lateral extension c of the sensing coil 505, the excitation coil 503 and the sensing coil 507, a linearization of the voltage induced in the sensing coils 505, 507 depending on the magnitude of the external field may be achieved.

Embodiments 600 and 700 of the component carrier schematically show in front view embodiments providing a 2D (two dimensional) fluxgate sensor in different configurations. In the embodiment shown in fig. 6 and 7, one excitation coil and four sensing coils are disposed on a common dielectric layer such that all coils are coplanar with one another.

In the embodiment of the component carrier 600 shown in fig. 6, the sensing coils 605 and 607 are adjacent to the central excitation coil 603, wherein the outer corners of the excitation coil 603 are closest to the outer corners of the sensing coils 605, 607. A straight line 651 connecting the lateral midpoints 647 of the sensing coils 605, 607 extends through the midpoint 653 of the excitation coil 603. The sensing coils 605, 607 are able to measure the component of the external field parallel to the straight line 651. Further sensing coils 604 and 606 are arranged such that a straight line 655 connecting the mid-points 657 of said coils 604, 606 is oriented perpendicular to the straight line 651. The first magnetic structure 609 is shaped as a cross (cross), one arm extending along a line 651 and the other arm extending along a line 655.

An embodiment 700 of the component carrier according to an embodiment of the invention, shown in a front view in fig. 7, has an excitation coil 603 and sensing coils 604, 605, 606, 607 which are arranged such that the side edges of the central excitation coil 603 and the respective side edges of the four sensing coils are arranged next to one another. The first magnetic structure 709 further comprises two arms, one extending along a straight line connecting the coils 605, 607 and the other extending along a line connecting the middle points of the sensing coils 604, 606. Thereby, a compact configuration is achieved.

The embodiment shown in fig. 6 and 7 also includes a second magnetic structure located below the excitation and sensing coils.

Fig. 8 and 9 schematically show embodiments 800 and 900 of a component carrier providing a 1D (one-dimensional) fluxgate sensor. In the illustrated embodiment, four layers are provided, each layer of the respective sensing 805, 807 and excitation 803 coils having 15 windings. A 75 μm line space technique was applied. The horizontal extension of the coil may be, for example, 18mm and the vertical extension of the coil may be 6 mm. The embodiment shown in fig. 9 provides a 15mm x 6mm extension of the coil, whereas the embodiment shown in fig. 8 has an extension of the coil of 18mm x 6 mm. Other extensions are also possible.

Fig. 10 shows a component carrier 1000 according to an embodiment of the invention in a perspective view. Four layers 1011, 1013, 1015 and 1017, respectively having sensing coil and exciting coil winding portions formed thereon, are stacked on top of each other. Electrical connection traces 1059 lead from the coils to terminals 1061 for connecting the sensing coils 1005, 1007 to the detection circuitry and the excitation coil 1003 to the driver circuitry. The component carrier 1000 may further comprise a first magnetic structure located above the coil and a second magnetic structure located below the coil, which may be configured as the magnetic structure shown, for example, in fig. 1-5, 6, 7, or 9.

Fig. 12, 13 show in front view and side view steps for manufacturing a component carrier with an integrated (integrated) 3D fluxgate sensor according to an embodiment of the invention. Thus, the component carrier 1100 is manufactured starting from a layer structure shown in front view in fig. 11, which has a first region 1162 and a second region 1164 which are coplanar with one another. In a first region 1162, a 2D fluxgate sensor is implemented, which may be a component carrier similar to the one with the integrated 2D fluxgate sensor 700, as shown in fig. 7. On the upper side, the first and second regions 1162, 1164 may comprise first magnetic structures, and on the lower side, the first and second regions 1162, 1164 may comprise second magnetic structures, which may for example be configured as shown in side views as shown in fig. 3, 4, 5, or as shown in front views as in fig. 6 and 7.

In the second region 1164, the component carrier 1100 includes a 1D fluxgate sensor, which 1D fluxgate sensor may be configured similar to the fluxgate sensor 800 or 900 as shown in fig. 8 and 9. Thus, the 2D fluxgate sensors in the first region 1162 and the 1D fluxgate sensors in the second region 1164 are initially arranged in a substantially coplanar arrangement in a plane or in a plurality of common planes with windings, which may depend on the specific application. Furthermore, terminals 1161 connected to different coils via connection wires 1159 are provided for making electrical contact of the coils with driver or detection circuitry. A side view of the component carrier 1100 at this intermediate method step is shown in fig. 12.

In a next method step, the component carrier 1100 is modified such that the second region 1164 is bent 90 ° with respect to the first region 1162 about a bending axis 1167, which bending axis 1167 is located in a front surface 1169 of the stack 1101 of layers in which the excitation and sensing coils are integrated. In the side views shown in fig. 12 and 13, a first magnetic structure 1109 on the upper side, and a second magnetic structure 1145 can also be seen, which can be constructed similarly to those shown in the embodiments 300, 400, 500, 600, 700 in fig. 3, 4, 5, 6 and 7, respectively.

Therefore, to manufacture a 3D fluxgate sensor, one starts with a 2D design and a 1D design arranged coplanar and side by side. To enable the two regions to bend relative to each other, a cavity 1171 is provided between the first region 1162 and the second region 1164. Cavity 1171 has been created by 2.5D techniques, substantially removing portions of the layer structure. The final component carrier 1100 as shown in fig. 13 may then be supported with auxiliary support devices to enhance mechanical strength. For example, the component carrier may be encapsulated using resin or injection molding.

Fig. 14 schematically shows a component carrier 1400 according to a further embodiment of the invention in a schematic side view. The upper portion of the component carrier 1400, which is labeled with reference numeral 1473, may be configured similarly to the component carriers 100 or 200 shown in fig. 1 and 2, respectively. Using 2.5D technology, cavities 1475 have been created in a multilayer structure 1477 that includes multiple dielectric and/or conductive layers, which multilayer structure 1477 may contain other electrical and/or electronic components and/or copper traces. In the cavity 1475, a thick second magnetic structure 1445 is inserted, which may function similar to the second magnetic structure shown, for example, in fig. 3, 4, 5, 6, 7. Thus, it is possible to integrate together a second magnetic structure 1445 having a relatively large thickness d2, which thickness d2 is much larger than the thickness d1 of the first magnetic structure 1409 above the sense and excitation coils. Furthermore, electrical and/or electronic components or integrated circuits 1479 may be integrated in the multilayer structure 1477.

Fig. 15 shows a graph of the hysteresis curve 1681 of the material of the first magnetic structure and the hysteresis curve 1683 of the material of the second magnetic structure. Both are narrow hysteresis curves for soft magnetic materials. Therein, the field for magnetization is indicated on the abscissa 1685, and the resulting magnetization is indicated on the ordinate 1687. As can be seen from fig. 16, the hysteresis curve 1681 has a greater steepness than the hysteresis curve 1687. Furthermore, the external field 1689 by which the material of the first magnetic structure reaches its saturation magnetization 1691 is smaller than the field 1693 for magnetization by which the material of the second magnetic structure reaches its saturation magnetization 1695. Furthermore, the area within the hysteresis loop (area 1697) of the material of the first magnetic structure is much smaller than the area 1699 within the hysteresis loop of the hysteresis curve 1683 of the material of the second magnetic structure. The saturation induction 1695 of the second magnetic structure can be lower or higher than the saturation induction 1691 of the material of the first magnetic structure.

The second magnetic structure may be configured as a relatively thick strip having a high permeability and hysteresis curve, which may facilitate the formation and amplification of the magnetic circuit. This may be a boundary condition for designing the second magnetic structure. It may not be necessary to close the magnetic circuit across the edges because, due to the aspect ratio, the field may not be directed as in conventional sensing of 3D coil assemblies. Different materials may contribute to improving the performance of the fluxgate sensor. The fluxgate sensor may have a higher sensitivity than a conventional fluxgate sensor. Furthermore, the energy consumption or required current may be lower than conventionally known. By suitably combining differently selected materials of the first and second magnetic structures several advantages can be obtained. The first magnetic structure may achieve magnetic saturation during operation, while the second magnetic structure may not reach saturation. The magnetic structure of the lower part may for example be formed by an iron foil.

Fig. 16 shows curves 1786, 1788, 1790, 1792 of the induced voltage in the sensing coil (on ordinate 1785) as a function of the external field (on abscissa 1784) for a wound magnetic core, a fluxgate sensor with transformer plates as second magnetic structure, a fluxgate sensor with closed iron as second magnetic structure and a conventional fluxgate sensor without second magnetic structure, respectively. As can be understood from fig. 16, the curves 1788, 1790 corresponding to the measurement results of the fluxgate sensor according to the embodiment of the present invention are superior compared to the conventional fluxgate sensor characterized by the curve 1792.

Thus, the voltage at the exciting coil is about 17V. The external field increases from 0 to 150 μ T and the voltage at the sensing coil is measured.

In the final fluxgate sensor, the external field to be measured can be deduced to be proportional to the amplitude of the second harmonic of the frequency of the excitation voltage. Such a curve 1703 is shown in fig. 17, which is measured using a fluxgate sensor according to an embodiment of the present invention. The excitation current was about 100mA (coil resistance 10 ohms). The external field (on abscissa 1701) varies from-110 to 110 μ T and the magnitude of the second harmonic of the voltage at the sense coil is measured (on ordinate 1702). Curve 1703 shows good linearity and high sensitivity of about 4.5 mv/. mu.T. The excitation frequency was 100 kHz.

The main idea of an embodiment according to the invention is that a soft magnetic core (e.g. a nickel-iron soft magnetic alloy) guiding and "collecting" the magnetic field is placed on top of the coils separated by a thin dielectric layer (the thin dielectric layer is required to avoid electrical short-circuiting of the coils, i.e. the excitation and sensing coils) and can be used as glue holding the foil. The key characteristics of the nickel-iron soft magnetic alloy used are its remarkable bending of the hysteresis curve and its high permeability to reach saturation during operation. In addition, on the bottom side of the device, a second metal foil may be placed. The line/space ratio of the coil can have a significant effect on the input/output signal ratio. The smaller the line/space ratio (which equates to a higher amount of roll), the higher the induced voltage required because the resistance of the trace increases, and vice versa. Typical L/S ratios may be 75 μm (3mil) to 50 μm (2mil) and copper thicknesses may vary from typical 12 μm to 35 μm to keep the voltage at a lower level. The thickness of the copper may also range from 6 μm to 150 μm. The insulation on the coil can be printed (ink-jet, screen printed) or laminated with a thin FR4 material.

Other possible options for placing the metal sheet (in particular the second magnetic structure) are: embedding (ECP, central core), deposition of metal by PVD (sputtering or wet chemical process) (electroplating), full-surface re-lamination and photosensitive structuring.

Since the metal sheet (in particular the second magnetic structure) may establish the function of increasing/guiding the magnetic field, it is also possible to apply only one layer of glue and cover this layer with a protective foil. Thereafter, the foil may be removed, and the fluxgate may be disposed at any position on the metal plate (e.g., a certain position on a vehicle, a ship). This may have a similar or the same effect as a metal plate.

The length or lateral extension of the soft magnetic material of high permeability (e.g., the first magnetic structure and/or the second magnetic structure) may have a large impact on the performance of the fluxgate sensor.

An embodiment of the present invention may provide the following advantages:

lower power requirements than a simple core;

miniaturization by HDI technology;

combined with 2.5D technology;

reduction of components on/in the PCB;

higher reliability;

cost-effective;

simple processing/manufacturing;

no coil overlap;

current/EMV measurement.

The second magnetic structure may be glued to the bottom.

The disclosed layer assembly may enable fluxgate sensors to be implemented in different laminates. Further, miniaturization can be achieved by applying a different manufacturing method such as an MSAP process, or by using a semiconductor technology applying a CMOS process on a silicon substrate.