Z-axis magnetic field sensor

Abstract

The invention provides a Z-axis magnetic field sensor. The Z-axis magnetic field sensor comprises a plastic packaging layer, a magnetic resistor Die, a plurality of pins and a first shielding layer. And the first shielding layer is arranged on the upper surface of the magnetoresistive Die and consists of a plurality of soft magnetic material blocks in an X-Y plane so as to shield a magnetic field in the X-Y direction on the upper surface of the magnetoresistive Die. The magnetic resistor Die is manufactured by adopting a wafer front-end process and comprises a magnetic resistor and a Z-axis magnetic field conversion part above the magnetic resistor. Each welding spot on the upper surface of the reluctance Die is directly covered by an independent soft magnetic material block in the first shielding layer to form a wiring end, and each pin is in one-to-one correspondence contact with the welding spot. The Z-axis magnetic field sensor provided by the invention is manufactured by combining a semiconductor front-end process and a special packaging process, so that the volume size is effectively reduced, an XY plane interference magnetic field is shielded more thoroughly, and the anti-interference capability is stronger.

Description

Technical Field

[0001] This application relates to the technical field of magnetic field measurement technology or magnetic field sensing technology, and particularly relates to a Z-axis magnetic field sensor structure package with good anti-interference performance, simple process and low cost. Background Art

[0002] A Z-axis magnetic field sensor refers to a magnetic sensor used for measuring the magnetic field in the direction perpendicular to the plane, which is commonly found in three-dimensional magnetic induction applications and is widely used in fields such as navigation, industrial control, and electronic devices. According to the type of sensor, Z-axis magnetic field sensors are mainly divided into Hall effect, magnetoresistive (such as AMR, GMR, TMR), fluxgate, and magneto-impedance sensors. A Z-axis magnetic field sensor usually uses a magnetic focusing structure (or magnetic field conversion structure) made of soft magnetic material (such as NiFe) to convert the magnetic field in the Z-axis direction into a magnetic field in the X-Y plane, and measures the magnetic field intensity in the X-axis or Y-axis direction by sensing the magnetoresistance in the X-axis or Y-axis direction, so as to indirectly obtain the magnetic field intensity information in the Z-axis direction.

[0003] Among the numerous performance indicators for measuring Z-axis magnetic field sensors, volume and anti-interference ability have always been two core indicators that are focused on. This is because when the soft magnetic material converts the magnetic field in the Z-axis direction into the X-Y plane direction, the original magnetic field in the X-Y plane will interfere with the measurement. For the constant interference magnetic field in the X-Y plane, a multi-magnetoresistance setting can be used to cancel it, but it is powerless for the gradient interference magnetic field in the X-Y plane. In addition, there are often strict limitations on the volume of the Z-axis magnetic field sensor in the electromagnetic measurement application environment (especially in equipment). For example, usually only a small chip installation position is reserved for the Z-axis magnetic field sensor on the PCB board. Therefore, how to enhance the anti-interference ability of the Z-axis magnetic field sensor and reduce its volume has become an important improvement direction in the industry. Summary of the Invention

[0004] In view of this, this application manufactures a Z-axis magnetic field sensor by combining semiconductor front-end processes and special packaging processes to improve the Z-axis magneto-impedance interference ability and reduce the volume size. The Z-axis magnetic field sensor provided by this application has a small volume, a simple structure, and can effectively shield the influence of all X-Y plane interference magnetic fields, improving the measurement accuracy of the Z-axis magnetic field.

[0005] The Z-axis magnetic field magnetic sensor provided by this application includes: a plastic package layer, a magnetoresistive Die, several pins, and a first shielding layer. The first shielding layer is disposed on the upper surface of the magnetoresistive Die and is composed of several soft magnetic material blocks in the X-Y plane to shield the XY-direction magnetic field on the upper surface of the magnetoresistive Die. The magnetoresistive Die includes a magnetoresistance and a Z-axis magnetic field conversion part fabricated above the magnetoresistance using a semiconductor front-end process, and several solder joints are provided on its upper surface. Each solder joint is directly covered by an independent soft magnetic material block in the first shielding layer to form a connection terminal, and each of the pins is in contact with the connection terminal in a one-to-one correspondence. The magnetoresistive Die, several pins, and the first shielding layer are all disposed within the plastic package layer, and the external signal terminals of the several pins are all exposed on one surface of the plastic package layer. The magnetoresistance type in the magnetoresistive Die is an XMR magnetoresistance, and the XMR includes at least TMR, AMR, and GMR.

[0006] The magnetoresistive Die includes several electrically connected magnetoresistances. Preferably, the magnetoresistive Die includes several magnetoresistances electrically connected into a half-bridge or a full-bridge. In the X-Y plane, the first shielding layer covers all the magnetoresistances of the magnetoresistive Die and the Z-axis magnetic field conversion part.

[0007] The above Z-axis magnetic field sensor fabricates a magnetoresistive Die with a Z-axis magnetic field conversion part through a semiconductor front-end process, and at the same time fabricates a specific first shielding layer at the upper end of the magnetoresistive Die during the packaging process, improving the anti-interference ability of the Z-axis magnetic field sensor and effectively controlling its volume size.

[0008] In one embodiment, in the X-Y plane, the overall outer contour of the first shielding layer is larger than and covers the upper surface of the magnetoresistive Die.

[0009] Preferably, the first shielding layer is composed of several rows of soft magnetic material strip blocks parallel to each other in the X-Y plane; two groups of solder joints are provided on the upper surface of the magnetoresistive Die, and each group of solder joints includes two solder joints. The connection line of the two solder joints is parallel to the several rows of soft magnetic material strip blocks in the X-Y plane. The pin is integrally L-shaped, and the lower surface of its long side is completely covered by some of the soft magnetic material strip blocks and is parallel to the several soft magnetic material strip blocks. A separate soft magnetic material strip segment is also provided on the upper surface of the magnetoresistive Die between the same group of pads.

[0010] To further improve the anti-interference ability of the Z-axis magnetic field sensor, the Z-axis magnetic field sensor further includes a second shielding layer disposed on the lower surface of the magnetoresistive Die and completely shielding the lower surface of the magnetoresistive Die in the XY plane. Preferably, the lower surface of the plastic package layer is flush with the lower surface of the magnetoresistive Die, and the second shielding layer is fabricated using an electroplating process on the plane where the lower surface of the plastic package layer is located. With such a setting, the volume size of the Z-axis magnetic field sensor can be further reduced.

[0011] In some embodiments, the second shielding layer is a whole strip of soft magnetic material, and a side blocking soft magnetic material strip is further arranged on the upper surface of the second shielding layer around the magnetoresistive Die.

[0012] The Z-axis magnetic field sensor provided by the present invention is fabricated by combining semiconductor front-end processes and special packaging processes, which not only effectively reduces the size and volume, but more importantly, enables the shielding layer to cover the relevant solder joints and the upper surface of the magnetoresistive Die during the packaging process, effectively improving the anti-interference ability against the X-Y plane magnetic field and the measurement accuracy of the Z-axis magnetic field. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0014] Figure 1a It is a top view structural diagram of the Z-axis magnetic field sensor provided by the present invention in the first embodiment.

[0015] Figure 1b It is a cross-sectional structural schematic diagram of the Z-axis magnetic field sensor provided by the present invention in the first embodiment.

[0016] Figure 1c It is a cross-sectional schematic diagram of the Z-axis magnetic field sensor provided by the present invention in some other embodiments. Figure 2a It is a top view structural diagram of the Z-axis magnetic field sensor provided by the present invention in the second embodiment.

[0017] Figure 2b It is a cross-sectional structural schematic diagram of the Z-axis magnetic field sensor provided by the present invention in the second embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the scope of protection of the present invention.

[0019] In this application, the terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising an..." does not exclude the presence of additional identical elements in the process, method, article or device comprising said element.

[0020] It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments may be combined with each other.

[0021] The technical solution provided by the present invention will be further described in detail below with reference to the accompanying drawings.

[0022] In one embodiment, the top view of the structure of the Z-axis magnetic field sensor provided by the present invention is shown in Figure 1, and the transverse cross-sectional view is as Figure 1b shown. In this embodiment, the Z-axis magnetic field sensor includes: a plastic package layer S, a magnetoresistive Die 1, a plurality of pins 2, and a first shielding layer 3. Among them, the first shielding layer 3 is disposed on the upper surface of the magnetoresistive Die 1 and is composed of a plurality of soft magnetic material blocks in the X-Y plane to shield the magnetic field in the XY plane direction on the upper surface of the magnetoresistive Die 1. The shape of the soft magnetic material block can be strip-shaped, block-shaped or other irregular shapes, which are not limited herein.

[0023] The magnetoresistive Die 1 includes a magnetoresistance and a Z-axis magnetic field conversion part (for example, nickel iron) fabricated on the magnetoresistance by using a semiconductor front-end process, and a plurality of solder joints are disposed on its upper surface. That is, the magnetoresistive Die 1 itself is a magnetoresistive unit fabricated on a substrate and having the ability of Z-axis magnetic field conversion and detection. Each solder joint is directly covered by an independent soft magnetic material block 31 in the first shielding layer to form a connection terminal, and each of the pins 2 is in contact with the connection terminal in one-to-one correspondence to connect the electrical input and output of the magnetoresistive Die 1 to one surface (which can be the upper surface or the lower surface, depending on the packaging method) of the plastic package layer S.

[0024] Furthermore, the number and connection relationship of the magnetoresistances in the magnetoresistive Die 1 are not specifically limited. The type of the magnetoresistance is an XMR magnetoresistance, and the XMR includes at least TMR, AMR, and GMR. Preferably, the magnetoresistive Die 1 includes a plurality of electrically connected magnetoresistances. For example, the magnetoresistive Die 1 includes a plurality of magnetoresistances electrically connected into a half-bridge or a full-bridge. In the X-Y plane, the overall outer contour of the first shielding layer 3 covers all the magnetoresistances and the Z-axis magnetic field conversion part of the magnetoresistive Die 1.

[0025] As can be seen from the above embodiments, in the Z-axis magnetic field sensor provided by the present invention, the magnetoresistive Die 1 fabricated using semiconductor front-end processes not only has a greatly reduced volume size but also already has the ability to sense the Z-axis magnetic field. Subsequently, during the packaging process, a specially designed shielding layer structure is added to the magnetoresistive Die 1 to shield the influence of the interfering magnetic field in the XY plane direction. In particular, the shielding layer covers the relevant solder joints of the magnetoresistive Die 1, which more effectively improves the shielding ability against the X-Y plane magnetic field and enhances the measurement accuracy of the Z-axis magnetic field sensor.

[0026] Specifically, in Figure 1a the first shielding layer 3 is composed of a plurality of soft magnetic material strips parallel to each other in the X-Y plane. Two groups of solder joints are provided on the upper surface of the magnetoresistive Die 1, and each group of solder joints includes two solder joints. The connection line of the two solder joints is parallel to the plurality of soft magnetic material strips in the X-Y plane.

[0027] Furthermore, as Figure 1b shown, in order to further improve the shielding effect of the Z-axis magnetic field sensor against the magnetic field in the XY plane direction, the Z-axis magnetic field sensor further includes a second shielding layer 4 provided on the lower surface of the magnetoresistive Die 1 and completely covering the lower surface of the magnetoresistive Die 1 in the XY plane. Preferably, the lower surface of the plastic encapsulation layer S is flush with the lower surface of the magnetoresistive Die 1; the second shielding layer is fabricated using an electroplating process on the plane where the lower surface of the plastic encapsulation layer S is located. With such a setting, the volume size of the Z-axis magnetic field sensor can be further reduced. The second shielding layer can be a single piece or composed of a plurality of soft magnetic material blocks.

[0028] As Figure 1c shown, in some embodiments, the second shielding layer 4 is a single-piece soft magnetic material strip segment, and a side blocking soft magnetic material strip 41 is further provided on the upper surface of the second shielding layer 4 around the magnetoresistive Die 1.

[0029] As Figure 2a 、 Figure 2b shown in another embodiment, the first shielding layer 3 is provided on the upper surface of the magnetoresistive Die 1 and is composed of a plurality of soft magnetic material blocks in the X-Y plane to shield the magnetic field in the XY plane direction on the upper surface of the magnetoresistive Die 1. Except for being covered with soft magnetic materials on the top, there are corresponding soft magnetic material blocks surrounding each solder joint, and each of the pins is in contact with a solder joint in a one-to-one correspondence. The pins are integrally L-shaped, and the lower surface of its long side is completely covered by some of the soft magnetic material strips and is parallel to the plurality of soft magnetic material strips. In this way, the interfering magnetic field generated by the current flowing through the pins will also be shielded by the soft magnetic material strips of the first shielding layer, further improving the measurement accuracy of the Z-axis magnetic field sensor.

[0030] Furthermore, in this embodiment, in order to prevent the upper surface of the magnetoresistive Die from being exposed too much, the first shielding layer 3 further includes a separate soft magnetic material strip 33 disposed on the upper surface of the magnetoresistive Die between the same group of pads. In this way, the magnetoresistive Die may be affected by a slight amount of XY plane interference magnetic field only at the solder joint, which can be reduced to meet the design requirements by designing the size of the solder joint.

[0031] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any technician familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present application, which should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A Z-axis magnetic field sensor, the Z-axis magnetic field sensor comprising: A plastic encapsulation layer, a magnetoresistor Die, a plurality of pins and a first shielding layer; characterized in that the first shielding layer is arranged on the upper surface of the magnetoresistor Die, and is composed of a plurality of soft magnetic material blocks in the XY plane to shield the XY direction magnetic field on the upper surface of the magnetoresistor Die; the magnetoresistor Die includes a magnetoresistor and a Z-axis magnetic field conversion part above the magnetoresistor using a semiconductor front-end process, and a plurality of solder joints are arranged on its upper surface; each solder joint is directly covered by an independent soft magnetic material block in the first shielding layer to form a wiring terminal, and each of the pins is in one-to-one contact with the wiring terminal; the magnetoresistor Die, the plurality of pins and the first shielding layer are all arranged in the plastic encapsulation layer, and the external signal terminals of the plurality of pins are all exposed on a surface of the plastic encapsulation layer.

2. The Z-axis magnetic field sensor according to claim 1, characterized in that: In the XY plane, the first shielding layer covers all magnetic resistors of the magnetic resistor Die and the Z-axis magnetic field conversion part.

3. The Z-axis magnetic field sensor according to claim 2, characterized in that: The first shielding layer is composed of a number of soft magnetic material strips and blocks that are parallel to each other in the XY plane; two groups of welding points are provided on the upper surface of the magnetic resistance Die, each group of welding points includes two welding points, and the connecting line of the two welding points is parallel to the number of soft magnetic material strips and blocks in the XY plane.

4. The Z-axis magnetic field sensor according to claim 3, characterized in that: The pin is L-shaped as a whole, with its long side parallel to the several soft magnetic material blocks and its lower surface completely covered by part of the soft magnetic material blocks. The first shielding layer also includes a separate soft magnetic material strip segment on the upper surface of the magnetic resistance Die arranged between the same group of pads.

5. The Z-axis magnetic field sensor according to any one of claims 1 to 4, characterized in that: The Z-axis magnetic sensor further includes a second shielding layer which is disposed on the lower surface of the magnetoresistive Die and completely blocks the lower surface of the magnetoresistive Die on the XY plane.

6. The Z-axis magnetic field sensor according to claim 5, characterized in that: The lower surface of the plastic sealing layer is flush with the lower surface of the magnetoresistive Die; and the second shielding layer is manufactured by electroplating process on the plane where the lower surface of the plastic sealing layer is located.

7. The Z-axis magnetoresistive sensor according to claim 5, characterized in that: The second shielding layer is a whole piece of soft magnetic material strip, and the upper surface of the second shielding layer is also provided with side blocking soft magnetic material strips surrounding the magnetic resistance Die.

8. The Z-axis magnetic field sensor according to claim 1, characterized in that: The magnetoresistance type in the magnetoresistance Die is XMR magnetoresistance, and the XMR at least includes TMR, AMR, and GMR.

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