JP2019012087A - Sensor - Google Patents

Abstract

To provide a magnetic shield package capable of increasing sensor sensitivity even while reducing influence of magnetic noise from outside.SOLUTION: The sensor comprises a magnetic device, a pressure detection element provided below the magnetic device, a first magnetic material provided at a lower part of the pressure detection element and having a first opening at least in a part right under the pressure detection element, a second magnetic material covering the magnetic device, and a substrate provided below the pressure detection element and having an electrode on a surface different from a surface on which the pressure detection element is provided. At least one of the first magnetic material and the second magnetic material is made of metal and at least one of wires electrically connected to a terminal of the pressure detection element is electrically insulated from the first magnetic material and the second magnetic material.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a magnetic shield package.

  Sensors using magnetic devices are affected by external magnetic noise. Therefore, a magnetic shield package has been proposed in which the magnetic effect is reduced by enclosing the magnetic device with a magnetic shield member.

JP 2009-36579 A

  When a pressure detection element that detects sound waves is installed in the magnetic shield package, if the opening is not provided at an appropriate position in the magnetic shield package, sound waves cannot be efficiently propagated in the package, and pressure detection is not possible. Sensitivity cannot be increased.

  Accordingly, an object of the present invention is to provide a magnetic shield package that can increase the sensitivity of a sensor while reducing the influence of external magnetic noise.

  In order to achieve the above object, a magnetic shield package according to an embodiment of the present invention is provided with a magnetic device, a first magnetic shield member provided below the magnetic device, and the first magnetic shield member. A second shield member that covers the magnetic device, and an opening is provided either at a position that does not contact the outer periphery of the first magnetic shield member or at the upper surface of the second magnetic shield member. .

The magnetic shield package which concerns on the 1st Embodiment of this invention. The magnetic shield package which concerns on the 1st Embodiment of this invention. The graph showing the relationship between the thickness of the 1st adhesive agent of the magnetic shielding package which concerns on the 1st Embodiment of this invention, and a magnetic field shielding effect. FIG. 3 is a top perspective view of the opening of the first magnetic shield member and the opening of the package substrate of the magnetic shield package according to the first embodiment of the present invention. The magnetic shield package which concerns on the modification 1 of the 1st Embodiment of this invention. The magnetic shield package which concerns on the modification 1 of the 1st Embodiment of this invention. The magnetic shield package which concerns on the modification 2 of the 1st Embodiment of this invention. The magnetic shield package which concerns on the 2nd Embodiment of this invention. The magnetic shield package which concerns on the modification 1 of the 2nd Embodiment of this invention. The magnetic shield package which concerns on the modification 2 of the 2nd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
1A and 1B are a perspective view (FIG. 1A) and a cross-sectional view (FIG. 1B) of a magnetic shield package according to a first embodiment of the present invention. The magnetic shield package 1 according to the first embodiment includes a package substrate 10, a first magnetic shield member 11, a second magnetic shield member 12, a pressure detection element 13, a magnetic device 14, and an integrated circuit 15. FIG. 2 shows a top view of the magnetic shield package 1 with the second magnetic shield member 12 removed.

  The magnetic shield package 1 is used for converting sound waves and the like into electrical signals. The magnetic device 14 is an element such as a GMR (Giant Magneto Resistance) element whose electrical performance such as resistance is changed by an external magnetic field or an external pressure. The magnetic device 14 is disposed on the pressure sensing element 13.

  The pressure detection element 13 is constituted by a MEMS (Micro Electro Mechanical System) element or the like obtained by processing Si. The pressure detection element 13 receives an external sound wave and vibrates. When the pressure sensing element 13 vibrates, stress is applied to the magnetic device 14 and electrical performance such as resistance of the magnetic device changes. In this way, sound waves and the like can be converted into electrical signals.

  The electrical performance of the magnetic device 14 changes due to the influence of unnecessary magnetic noise from the outside. Therefore, the inside of the magnetic shield package 1 is magnetically shielded by surrounding the magnetic device 14 with the first magnetic shield member 11 and the second magnetic shield member 12. Thereby, the influence of the unnecessary magnetic field noise on the magnetic device 14 can be reduced. However, if the pressure detection element 13 and the magnetic device 14 are completely covered by the first magnetic shield member 11 and the second magnetic shield member 12, sound waves cannot be efficiently propagated into the package. Therefore, an opening 11 h is provided in the first magnetic shield member 11. The opening 11h will be described in detail later.

  The configuration of the magnetic shield package 1 will be described. The package substrate 10 is a glass epoxy substrate such as FR4. The package substrate 10 includes one or more wiring layers. The package substrate 10 may be an LGA (Land Grid Array) type or a BGA (Ball Grid Array) type. The example shown in FIG. 1 is an LGA type package substrate 10 provided with a first wiring layer 10a and a second wiring layer 10b. The second wiring layer 10b is used as an electrode. The first wiring layer 10a and the second wiring layer 10b are connected by a via 10c.

  A first magnetic shield member 11 and a second magnetic shield member 12 are provided on the package substrate 10. A plate-like first magnetic shield member 11 is bonded onto the package substrate 10. On the first magnetic shield member 11, a magnetic shield member 12 that covers the upper and side surfaces of the magnetic device 14 is provided. Thus, the first magnetic shield member 11 and the second magnetic shield member surround the magnetic device 14. In FIG. 1, the first magnetic shield member 11 has a plate shape, and the second magnetic shield member 12 is shown as having a shape obtained by removing one surface from a rectangular parallelepiped. The shapes of the member 11 and the second magnetic shield member 12 are not limited to this. It is only necessary that the first magnetic shield member 11 and the second magnetic shield member 12 can surround the periphery of the magnetic device 14.

  The material of the first magnetic shield member 11 and the second magnetic shield member 12 may be soft magnetic materials such as iron, carbon steel, silicon steel, and permalloy. The material of the first magnetic shield member 11 and the second magnetic shield member 12 may be the same or different.

  The magnetic field shielding effect of the magnetic shield package 1 is determined by the relative permeability μr and the thickness tm of the first and second magnetic shield members 11 and 12. When the thickness tm of the magnetic shield member is expressed in millimeters, a magnetic field shielding effect of 10 dB or more can be obtained when the product of the relative permeability μr and the thickness tm is 10 or more.

  The first magnetic shield member 11 and the second magnetic shield member 12 are bonded by, for example, a first adhesive 16. When the first adhesive 16 uses magnetic particles having a relative permeability of 2 or more, the magnetic path of the first magnetic shield member 11 and the second magnetic shield member 12 is connected, and the magnetic field shielding effect is enhanced. it can.

  FIG. 3 is a graph showing the relationship between the thickness of the first adhesive 16 and the magnetic field shielding effect. The case where a nonmagnetic adhesive was used as the first adhesive 16 was compared with the case where an adhesive containing magnetic particles having a relative permeability of 20 was used. When a non-magnetic adhesive was used, the magnetic shielding effect was 48 dB or less when the thickness of the first adhesive 16 was 3 μm or more, and the magnetic shielding effect was 34 dB when the thickness was 30 μm. On the other hand, when an adhesive containing nonmagnetic particles was used, a high magnetic field shielding effect of 48 dB or more was obtained when the thickness of the first adhesive 16 was 30 μm or less. Also from this comparison result, it can be seen that when an adhesive containing magnetic particles is used as the first adhesive 16, a higher magnetic shielding effect can be obtained than when a nonmagnetic adhesive is used.

  The magnetic particles used for the first adhesive 16 may be a mixture of microparticles having a diameter of 1 μm to several tens of μm, nanoparticles having a diameter of several nm to several tens of nm, or both. For example, microparticles mainly composed of iron and nickel such as iron, permalloy, ferrite, and sendust, and nanoparticles such as iron, iron oxide, and iron platinum are conceivable. The binder of the particles may be an epoxy resin, silicone, or the like, and may be selected from the good bondability between the first magnetic shield member and the second magnetic shield member. As the first adhesive 16, a non-acidic adhesive such as silicone or a conductor adhesive such as an insulator, silver paste, or solder can be used.

  Further, the first magnetic shield member and the second magnetic shield member may be bonded with, for example, a double-sided tape, in addition to being bonded with an adhesive using magnetic particles having a relative magnetic permeability of 2 or more. .

  The pressure detection element 13 is provided on the first magnetic shield member 11. The pressure detection element 13 and the magnetic shield member 11 are bonded by the second adhesive 17. As the second adhesive 17, a nonmagnetic adhesive such as silicone that does not contain magnetic particles, a nonmagnetic conductor adhesive such as an insulator, silver paste, or solder is used.

  On the pressure sensing element 13, one or a plurality of magnetic devices 14 are provided. By providing a plurality of magnetic devices 14, sensitivity to sound waves can be improved. The magnetic device 14 is electrically connected to the integrated circuit 15 via wiring and wires 18 provided on the pressure detection element 13. An analog signal detected using the pressure detection element 13 and the magnetic device 14 is input to the integrated circuit 15.

  The integrated circuit 15 processes the input analog signal and outputs a digital signal. The digital signal output from the integrated circuit 15 passes through the wire 18 or the package substrate and is output to the electrode 10b. Since it is necessary to connect the wire 18 to the package substrate, the first magnetic shield member 11 is provided with an opening 11i through which the wire 18 is passed, as shown in FIG. The integrated circuit 15 of this embodiment is disposed in a space surrounded by the first magnetic shield member 11 and the second magnetic shield member 12, but the first magnetic shield member 11 and the second magnetic shield member 11 It can also be arranged outside the space surrounded by the magnetic shield member 12.

  Next, the opening 11h provided in the first magnetic shield member 11 will be described. The opening 11 h is provided below the pressure detection element 13. By providing the opening 11 h below the pressure detection element 13, sound waves can be efficiently propagated into the magnetic shield package 1. Further, an opening 10 h of the package substrate 10 is provided below the opening 11 h of the first magnetic shield member 11.

  FIG. 4 is a top perspective view of the opening 11 h of the first magnetic shield member 11 and the opening 10 h of the package substrate 10. In FIG. 4, the opening 11 h of the first magnetic shield member 11 is indicated by a solid line, and the opening 10 h of the package substrate 10 is indicated by a broken line. The package substrate 10 is provided with an opening 10h made of, for example, a circular opening. The opening 11h of the first magnetic shield member 11 may be a circular opening (for example, concentric with the package substrate 10) as shown in FIG. 4A, or a fan-shaped opening as shown in FIG. 4B. May be an opening formed of a plurality of circular openings having a smaller area than the opening of the package substrate 10 as shown in FIG. 4C, or a package as shown in FIG. It may be a mesh-shaped opening made up of a plurality of openings whose area is sufficiently smaller than the opening of the substrate 10. The dimensions of the opening 11h of the magnetic shield member and the opening 10h of the package substrate 10 shown in FIG. 4A are designed in consideration of the thickness of the package substrate, the space of the diaphragm, etc. so that Helmholtz resonance does not occur. The size of each opening 11h of the first magnetic shield member 11 in FIG. 4D is preferably 1/1000 or more of the wavelength of the sound wave at the maximum frequency to be sensed. Specifically, when the maximum frequency is 10 kHz, the wavelength is 3.4 cm. Therefore, when the diameter of the opening or the dimension of the shortest side is 1/1000 or more, it is preferable to set it to 34 μm or more. The shape of the opening is not limited to the above, and may be an ellipse, a polygon, a square, a rectangle, a diamond, a triangle, a star, or the like.

  The opening 10h may be larger than the opening 11h, and the opening 11h may be larger than the opening 10h. Circular openings such as those shown in FIGS. 4A and 4C may be opened by a drill, or may be processed by punching or etching. Moreover, the openings as shown in FIGS. 4B and 4D may be processed by punching or etching.

  4A to 4D, the magnetic shielding effect is 39.8 dB in the case of FIG. 4A, 49.4 dB in the case of FIG. 4B, and FIG. In this case, it was 49.5 dB, and in the case of FIG. 4D, it was 49.8 dB. In other words, the opening 11h composed of a plurality of openings smaller than the opening 10h of the package substrate 10 can obtain a higher magnetic field shielding effect than the same circular opening 11h as the opening 10h of the package substrate 10.

  Such a magnetic shield package 1 can be used for an acoustic sensor using a magnetic device such as a GMR element, a current sensor for measuring magnetic field strength, and a magnetic shield package for MRAM (Magnetoresistive random access memory).

(Modification of the first embodiment)
FIG. 5 is a cross-sectional view of a magnetic shield package according to a modification of the first embodiment of the present invention. In FIG. 5, the same components as those in FIG. The magnetic shield package 2 according to this modification has a configuration in which a third magnetic shield member 21 is added to the magnetic shield package according to the first embodiment. FIG. 6 is a perspective view of the magnetic shield package 2 with the second magnetic shield member 12 removed.

  The third magnetic shield member 21 is disposed on the first magnetic shield member 11 and surrounds the pressure sensing element 13 and the magnetic device 14 in all directions. The third magnetic shield member 21 is not provided above the pressure detection element 13 and the magnetic device 14 in order to pass the wire 18 connecting the pressure detection element 13 and the integrated circuit 15. Alternatively, a third magnetic shield member 21 may be provided above the pressure detection element 13 and the magnetic device 14 in a portion that does not hinder wire bonding.

  The third magnetic shield member 21 is bonded to the first magnetic shield member 11 using the third adhesive 22. As the third adhesive 22, a nonmagnetic adhesive such as silicone that does not contain magnetic particles, or a nonmagnetic conductor adhesive such as an insulator, silver paste, or solder is used. By providing the third magnetic shield member 21 in this way, the magnetic shield effect around the magnetic device 14 can be further enhanced.

  The presence / absence of the third magnetic shield member 21 and the use of a nonmagnetic adhesive as the third adhesive 22 will be described using magnetic field analysis results. (1) When the third magnetic shield member 21 is not disposed (first magnetic shield package 1), and (2) in the second magnetic shield package 2, the nonmagnetic third adhesive 22 having a thickness of 50 μm is used. The magnetic field shielding effect was compared between the case where 3 magnetic shield members were bonded and the case where (3) the second magnetic shield package 2 was bonded with an adhesive containing 10 μm thick magnetic particles.

  At this time, the first magnetic shield member 11, the second magnetic shield member 13, and the third magnetic shield member 21 are permalloy having a relative permeability of 5000, and the first magnetic shield member 11 and the second magnetic shield member 13. The thickness was set to 0.2 mm. As the first adhesive 16, an adhesive containing magnetic particles having a thickness of 10 μm and a relative permeability of 20 was used. The opening 11h of the first magnetic shield member 11 has a shape as shown in FIG. The third magnetic shield member 21 had a height of 0.5 mm, an outer periphery of a 1.2 mm square, and an inner periphery of a 0.8 mm square.

  As a result, (1) when the third magnetic shield member 21 was not disposed, the magnetic field shielding effect was 49.5 dB. (2) When the third magnetic shield member was bonded to the second magnetic shield package 2 with the nonmagnetic third adhesive 22 having a thickness of 50 μm, the result was 56.5 dB. (3) When the second magnetic shield package 2 was adhered with an adhesive containing magnetic particles having a thickness of 10 μm, it was 51.5 dB. That is, by arranging the third magnetic shield member, the magnetic field shielding effect is increased. In particular, when the non-magnetic adhesive is used as the third adhesive 22, the magnetic adhesive is used. It was shown that the magnetic field shielding effect is higher than that.

(Modification 2 of the first embodiment)
FIG. 7 is a perspective view (FIG. 7A) and a cross-sectional view (FIG. 7B) of a magnetic shield package according to Modification 2 of the first embodiment of the present invention. In the magnetic shield package 5 shown in FIG. 7, the same components as those of the magnetic shield package 1 shown in FIG. As shown in FIG. 7, the magnetic shield package 5 is provided with an opening 12 h in the second magnetic shield member 12 instead of the first magnetic shield member 11.

  FIG. 7 shows the magnetic shield package 5 when the opening 12 h is provided immediately above the integrated circuit 15. However, the opening 12 h is not limited to the position directly above the integrated circuit 15, and may be provided anywhere on the second magnetic shield member 12. However, if the second magnetic shield member 12 is provided on a surface that does not contact the first magnetic shield member 11 and does not contact the outer periphery, the opening can be easily processed. The opening 12h may have any shape such as a circle, an ellipse, a polygon, a square, a rectangle, a diamond, a triangle, and a star. Further, similarly to the opening portion 11h described with reference to FIG. 4, the opening portion 12h may be composed of one opening or a plurality of openings.

  Furthermore, the second modification of the first embodiment may be combined with the first modification. That is, a third magnetic shield member 21 that surrounds the pressure detection element 13 and the magnetic device 14 of the magnetic shield package 5 may be provided.

(Second Embodiment)
FIG. 8 is a cross-sectional view of a magnetic shield package according to the second embodiment of the present invention. The magnetic shield package 3 according to the second embodiment includes a package substrate 30, a first magnetic shield member 31, a second magnetic shield member 32, a pressure detection element 13, a magnetic device 14, an integrated circuit 15, and solder balls 39. Have. Since components such as the pressure detection element 13, the magnetic device 14, and the integrated circuit 15 are the same as those of the magnetic shield package 1 of the first embodiment, the same reference numerals are given and detailed description thereof is omitted.

  In the magnetic shield package 3, the first magnetic shield member 31 is provided under the package substrate 10. Then, the second magnetic shield member 32 surrounds the four sides of the package substrate 10 and is bonded to the first magnetic shield member 31 using the first adhesive 16. Accordingly, the first magnetic shield member 31 and the second magnetic shield member 32 can surround the magnetic device 14, and the influence of unnecessary magnetic noise from the outside can be reduced. Further, as described in the first embodiment, when the first adhesive 16 is made of an adhesive having a relative permeability of 2 or more including magnetic particles, the magnetic field shielding effect can be enhanced.

  The package substrate 30 is mounted with solder balls 39 in order to take out the electrodes to the outside of the magnetic shield package 3. For this reason, an opening 31j is also provided in a portion of the first magnetic shield member 31 immediately below the solder ball 39. For example, the diameter of the solder ball 39 is 0.3 mm, and the diameter of the opening 31j is 0.6 mm.

  The magnetic shield package 3 may be subjected to an insulator surface treatment for the purpose of preventing a short circuit with the circuit wiring and for the purpose of providing resistance to corrosion. Polyimide or the like is used as the material for the surface treatment.

  Also in this embodiment, the same modification as the modification of the first embodiment is possible. As shown in FIG. 9, the magnetic shield package 4 according to Modification 1 further includes a third magnetic shield member 21, and the third magnetic shield member 21 is disposed on the package substrate 30, and the pressure detection element. 13 and the magnetic device 14 are arranged so as to surround the four sides. The third magnetic shield member 21 and the package substrate 30 are bonded using a third adhesive.

  Further, as shown in FIG. 10, the magnetic shield package 6 according to the modified example 2 is provided with an opening 32 h in the second magnetic shield member 32. The position where the opening 32h is provided may be anywhere on the second magnetic shield member 32. The opening 32h may be composed of one opening or a plurality of openings, and the opening may have any shape. Furthermore, Modification 1 and Modification 2 may be combined.

  Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1, 2, 3, 4, 5, 6 ... Magnetic shield package, 10, 30 ... Package substrate, 10a, 30a ... First wiring layer, 10b, 30b ... Second wiring layer, 10c, 30c ... Via, 10h , 12h, 30h, 32h ... opening, 11, 31 ... first magnetic shield member, 11h, 31h ... opening, 11i ... opening, 12, 32 ... second magnetic shield member, 13 ... pressure sensing element, DESCRIPTION OF SYMBOLS 14 ... Magnetic device 15 ... Integrated circuit 16 ... 1st adhesive agent 17 ... 2nd adhesive agent 18 ... Wire, 31j ... Opening part, 39 ... Solder ball

Claims (7)

A magnetic device;
A pressure sensing element provided under the magnetic device;
A first magnetic body provided below the pressure detection element, and having a first opening provided at least in part immediately below the pressure detection element;
A second magnetic body covering the magnetic device;
A substrate provided below the pressure sensing element and provided with electrodes on a surface different from the surface on which the pressure sensing element is provided;
At least one of the first magnetic body and the second magnetic body is made of metal,
At least one of the wirings electrically connected to the terminal of the pressure sensing element is electrically insulated from the first magnetic body and the second magnetic body;
Sensor.   The sensor according to claim 1, wherein the first magnetic body is provided with a hole through which wiring is passed.   The sensor according to claim 1, wherein the first magnetic body has a plate shape.   The sensor according to claim 1, wherein an opening is provided in the second magnetic body.   The sensor according to claim 4, wherein a plurality of openings are provided in the second magnetic body.   The sensor according to claim 4, further comprising an integrated circuit electrically connected to the pressure sensing element.   The sensor according to claim 6, wherein at least one of wirings electrically connected to a terminal of the integrated circuit is electrically insulated from the first magnetic body and the second magnetic body.

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