Z-axis magnetic field sensor

Abstract

The utility model 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 manufactured 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 utility model is manufactured by combining a semiconductor preceding process and a special packaging process, so that the volume size is effectively reduced, the shielding of an XY plane interference magnetic field is more thorough, and the anti-interference capability is stronger.

Description

Technical Field

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

[0002] Z-axis magnetic field sensors are magnetic sensors used to measure magnetic fields perpendicular to a plane. They are commonly found in three-dimensional magnetic sensing applications and are widely used in navigation, industrial control, and electronic equipment. Z-axis magnetic field sensors are mainly classified into Hall effect, magnetoresistive (such as AMR, GMR, TMR), fluxgate, and magnetoresistive sensors according to their sensor type. Z-axis magnetic field sensors typically use a magnetically concentrated structure (or magnetic field conversion structure) made of soft magnetic materials (such as NiFe) to convert the magnetic field in the Z-axis direction into a magnetic field in the X-Y plane. By sensing the magnetoresistive field along the X or Y axis, the magnetic field strength in the X or Y axis direction is measured, thus indirectly obtaining the magnetic field strength information in the Z-axis direction.

[0003] Among the many performance indicators for Z-axis magnetic field sensors, size and anti-interference capability have always been two core focuses. This is because when soft magnetic materials convert the Z-axis magnetic field to the XY plane, the original XY plane magnetic field can interfere with the measurement. While constant interference magnetic fields in the XY plane can be canceled using multiple magnetoresistive devices, they are ineffective against gradient interference magnetic fields in the XY plane. Furthermore, the size of Z-axis magnetic field sensors is often strictly limited in electromagnetic measurement applications (especially within equipment). For example, a PCB board typically only reserves space for a small chip for the Z-axis magnetic field sensor. Therefore, enhancing the anti-interference capability of Z-axis magnetic field sensors and reducing their size has become a key area of ​​focus for improvement in the industry. Utility Model Content

[0004] In view of this, this invention combines semiconductor front-end processes with special packaging techniques to fabricate a Z-axis magnetic field sensor, thereby improving its Z-axis magnetoresistance interference capability and reducing its size. The Z-axis magnetic field sensor provided by this invention is small in size, simple in structure, and can effectively shield against the influence of all interfering magnetic fields in the XY plane, improving the measurement accuracy of the Z-axis magnetic field.

[0005] The Z-axis magnetic field sensor provided by this utility model includes: a molding compound, a magnetoresistive die, several pins, and a first shielding layer. The first shielding layer, disposed on the upper surface of the magnetoresistive die, is composed of several soft magnetic material blocks in the X-Y plane to shield the XY direction magnetic field of the upper surface of the magnetoresistive die. The magnetoresistive die includes a magnetoresistive component and a Z-axis magnetic field conversion section fabricated above the magnetoresistive component using semiconductor front-end technology. Several solder joints are disposed 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 terminal, and each pin corresponds to a terminal in contact. The magnetoresistive die, the several pins, and the first shielding layer are all disposed within the molding compound, and the external signal terminals of the several pins are exposed on one surface of the molding compound. The magnetoresistive type in the magnetoresistive die is XMR magnetoresistive, and XMR includes at least TMR, AMR, and GMR.

[0006] The magnetoresistive die comprises a plurality of electrically connected magnetoresistors. Preferably, the magnetoresistive die comprises a plurality of magnetoresistors electrically connected to form a half-bridge or a full-bridge. In the X-Y plane, the first shielding layer covers all the magnetoresistors of the magnetoresistive die and the Z-axis magnetic field conversion section.

[0007] The aforementioned Z-axis magnetic field sensor is fabricated using semiconductor front-end processes to create a magnetoresistive die with a Z-axis magnetic field conversion section. Simultaneously, a specific first shielding layer is fabricated on the top of the magnetoresistive die during the packaging process, which improves the anti-interference capability of the Z-axis magnetic field sensor and effectively controls its 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 strips parallel to each other in the X-Y plane; the upper surface of the magnetoresistive die has two sets of solder joints, each set including two solder joints, and the line connecting the two solder joints is parallel to the rows of soft magnetic material strips in the X-Y plane. The pin is generally L-shaped, and its long side lower surface is completely covered by part of the soft magnetic material strips and parallel to the rows of soft magnetic material strips. The upper surface of the magnetoresistive die between the same set of solder pads also has individual soft magnetic material segments. In this way, the interfering magnetic field generated by the current flowing through the pin 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.

[0010] To further improve the anti-interference capability of the Z-axis magnetic field sensor, the Z-axis magnetic sensor also 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 molding compound is flush with the lower surface of the magnetoresistive die, and the second shielding layer is fabricated using an electroplating process on the plane containing the lower surface of the molding compound. This configuration allows for a further reduction in the size of the Z-axis magnetic field sensor.

[0011] In some embodiments, the second shielding layer is a single piece of soft magnetic material, and the upper surface of the second shielding layer is also provided with side-blocking soft magnetic material strips around the magnetoresistive die.

[0012] The Z-axis magnetic field sensor provided by this utility model is manufactured using semiconductor front-end processes and special packaging processes. This not only effectively reduces the size and volume, but more importantly, the packaging process allows the shielding layer to cover the relevant solder joints and upper surface of the magnetoresistive die, effectively improving the anti-interference capability against X-Y plane magnetic fields and improving the measurement accuracy of Z-axis magnetic fields. Attached Figure Description

[0013] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0014] Figure 1a The top view of the Z-axis magnetic field sensor provided by this utility model in the first embodiment.

[0015] Figure 1b A schematic diagram of the cross-sectional structure of the Z-axis magnetic field sensor provided by this utility model in the first embodiment.

[0016] Figure 1c Cross-sectional schematic diagram of the Z-axis magnetic field sensor provided by this utility model in another embodiment.

[0017] Figure 2a The top view of the Z-axis magnetic field sensor provided by this utility model in the second embodiment.

[0018] Figure 2b A schematic diagram of the cross-sectional structure of the Z-axis magnetic field sensor provided by this utility model in the second embodiment. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0020] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0021] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0022] The present invention will now be described in further detail with reference to the accompanying drawings.

[0023] In one embodiment, the top view of the Z-axis magnetic field sensor provided by this utility model is shown in Figure 1, and the transverse cross-sectional view is shown in Figure 2. Figure 1b As shown. In this embodiment, the Z-axis magnetic field sensor includes: a molding layer S, a magnetoresistive die 1, several pins 2, and a first shielding layer 3. The first shielding layer 3 is disposed on the upper surface of the magnetoresistive die 1 and is composed of several soft magnetic material blocks in the X-Y plane to shield the magnetic field in the XY plane direction of the upper surface of the magnetoresistive die 1. The shape of the soft magnetic material blocks can be strip-shaped, block-shaped, or other irregular shapes, and is not limited here.

[0024] The magnetoresistive die 1 includes a magnetoresistive element and a Z-axis magnetic field conversion section (e.g., nickel-iron) fabricated above the magnetoresistive element using semiconductor front-end processes. Several solder joints are disposed on its upper surface. In other words, the magnetoresistive die 1 itself is a magnetoresistive unit fabricated on a substrate, possessing Z-axis magnetic field conversion and detection capabilities. Each solder joint is directly covered by an independent soft magnetic material block 31 in the first shielding layer, forming a terminal. Each pin 2 corresponds to and contacts a terminal to connect the electrical input and output of the magnetoresistive die 1 to a surface of the molding layer S (which can be the upper or lower surface, depending on the packaging method).

[0025] Furthermore, the number and connection relationship of the magnetoresistive dies 1 are not specifically limited. The type of magnetoresistive dies is XMR magnetoresistive, and XMR includes at least TMR, AMR, and GMR. Preferably, the magnetoresistive die 1 includes several electrically connected magnetoresistive dies. For example, the magnetoresistive die 1 includes several magnetoresistive dies electrically connected to form a half-bridge or full-bridge. In the X-Y plane, the overall outer contour of the first shielding layer 3 covers all the magnetoresistive dies 1 and the Z-axis magnetic field conversion section.

[0026] As can be seen from the above embodiments, the magnetoresistive die 1 fabricated using semiconductor front-end technology in the Z-axis magnetic field sensor provided by this invention not only has a significantly reduced size but also possesses the ability to sense Z-axis magnetic fields. Subsequent packaging adds a specially designed shielding layer structure to the magnetoresistive die 1 to shield it from the influence of interfering magnetic fields in the XY plane. In particular, the shielding layer covers the relevant solder joints of the magnetoresistive die 1, further improving the shielding capability against X-Y plane magnetic fields and enhancing the measurement accuracy of the Z-axis magnetic field sensor.

[0027] Specifically, in Figure 1a The first shielding layer 3 is composed of several rows of soft magnetic material strips that are parallel to each other in the X-Y plane. The upper surface of the magnetoresistive die 1 is provided with two sets of solder joints, each set of solder joints including two solder joints, and the line connecting the two solder joints is parallel to the rows of soft magnetic material strips in the X-Y plane.

[0028] Furthermore, such as Figure 1b As shown, to further improve the shielding effect of the Z-axis magnetic field sensor on the magnetic field in the XY plane, the Z-axis magnetic field sensor further includes a second shielding layer 4 disposed on the lower surface of the magnetoresistive die 1 and completely blocking the lower surface of the magnetoresistive die 1 in the XY plane. Preferably, the lower surface of the molding 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 molding layer S is located. This configuration allows for a further reduction in the size of the Z-axis magnetic field sensor. The second shielding layer can be a single piece or composed of several soft magnetic material blocks.

[0029] like Figure 1c As shown, in some embodiments, the second shielding layer 4 is a single piece of soft magnetic material, and the upper surface of the second shielding layer 4 is also provided with a side-blocking soft magnetic material strip 41 around the magnetoresistive die 1.

[0030] like Figure 2a , Figure 2bIn another embodiment shown, the first shielding layer 3 is disposed on the upper surface of the magnetoresistive die 1 and is composed of several soft magnetic material blocks in the X-Y plane to shield the magnetic field in the XY plane direction of the upper surface of the magnetoresistive die 1. Each solder joint is surrounded by corresponding soft magnetic material blocks in addition to being covered with soft magnetic material on top, and each pin is in contact with a solder joint in a one-to-one correspondence. The pin is generally L-shaped, with its long side lower surface completely covered by a portion of the soft magnetic material blocks and parallel to the several soft magnetic material blocks.

[0031] Furthermore, in this embodiment, to prevent excessive exposure of the upper surface of the magnetoresistive die, the first shielding layer 3 further includes individual soft magnetic material segments 33 disposed between the same set of pads on the upper surface of the magnetoresistive die. Thus, the magnetoresistive die may only be affected by a small amount of XY-plane interfering magnetic field at the solder joints, but this can be reduced to meet design requirements through solder joint size design.

[0032] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A Z-axis magnetic field sensor, the Z-axis magnetic field sensor comprising: A molding compound, a magnetoresistive die, a plurality of pins, and a first shielding layer; characterized in that the first shielding layer is disposed on the upper surface of the magnetoresistive die and is composed of a plurality of soft magnetic material blocks in the X-Y plane to shield the XY direction magnetic field of the upper surface of the magnetoresistive die; the magnetoresistive die includes a magnetoresistive component and a Z-axis magnetic field conversion section fabricated above the magnetoresistive component using semiconductor front-end technology, and a plurality of solder joints are disposed 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 terminal, and each pin is in one-to-one contact with the terminal; the magnetoresistive die, the plurality of pins, and the first shielding layer are all disposed within the molding compound, and the external signal terminals of the plurality of pins are all exposed on one surface of the molding compound.

2. The Z-axis magnetic field sensor as described in claim 1, characterized in that, In the X-Y plane, the first shielding layer covers all the magnetoresistance of the magnetoresistive die and the Z-axis magnetic field conversion section.

3. The Z-axis magnetic field sensor as described in claim 2, characterized in that, The first shielding layer is composed of several rows of soft magnetic material strips that are parallel to each other in the X-Y plane; the upper surface of the magnetoresistive die is provided with two sets of solder joints, each set of solder joints including two solder joints, and the line connecting the two solder joints is parallel to the rows of soft magnetic material strips in the X-Y plane.

4. The Z-axis magnetic field sensor as described in claim 3, characterized in that, The pin is L-shaped in general, and its long side lower surface is completely covered by a portion of the soft magnetic material strips and is parallel to the plurality of soft magnetic material strips. The first shielding layer also includes a separate soft magnetic material segment on the upper surface of the magnetoresistive die disposed between the same set of pads.

5. The Z-axis magnetic field sensor as described in any one of claims 1-4, characterized in that, The Z-axis magnetic field sensor also includes a second shielding layer disposed on the lower surface of the magnetoresistive die and completely obscuring the lower surface of the magnetoresistive die in the XY plane.

6. The Z-axis magnetic field sensor as described in claim 5, characterized in that, The lower surface of the molding layer is flush with the lower surface of the magnetoresistive die; the second shielding layer is made by electroplating on the plane where the lower surface of the molding layer is located.

7. The Z-axis magnetic field sensor as described in claim 5, characterized in that, The second shielding layer is a single piece of soft magnetic material, and the upper surface of the second shielding layer is also provided with side-blocking soft magnetic material strips around the magnetoresistive die.

8. The Z-axis magnetic field sensor as described in claim 1, characterized in that, The magnetoresistive type in the magnetoresistive die is XMR magnetoresistive, and XMR includes at least TMR, AMR, and GMR.

Images