Magnetic shielding structure

Abstract

The utility model discloses a magnetic shielding structure which is applied to the field of chip packaging. According to the utility model, the four inclined diamagnetic side walls which are mutually connected and the diamagnetic cover plate which is integrally connected with the four diamagnetic side walls are arranged at the periphery of the diamagnetic gasket, and the substrate, the diamagnetic gasket, the four inclined diamagnetic side walls and the diamagnetic cover plate form a closed space, so that a static magnetic field of a magnetic chip placed in the closed space is shielded; due to the fact that the four diamagnetic side walls which are mutually connected in the circumferential direction are adopted, magnetic fields in all directions of the magnetic chip can be shielded, and the magnetic shielding efficiency is greatly improved; and the inclined side wall is adopted, so that the shielding efficiency can be effectively improved, the vertical shielding effect can be greatly improved, and the horizontal shielding effect can be maintained at the same time. Meanwhile, the magnetic chip is connected with the substrate in the hollow area of the diamagnetic gasket by adopting a flip-chip bonding scheme, so that the problem that lead bonding cannot be carried out due to more side walls is solved.

Description

Technical Field

[0001] The utility model relates to the field of chip packaging, in particular to a magnetic shielding structure. Background Art

[0002] Magnetic random access memory (MRAM) includes two magnetic layers: a magnetic reference layer and a magnetic free layer. When the two magnetic layers are in the same direction, the element is in a low resistance state, representing a logic 0; when the two layers are in opposite directions, the element is in a high resistance state, representing a logic 1. Since the magnetic free layer is less stable, its magnetic moment direction can be changed in a variety of ways to achieve data writing. MRAM uses different orientations of magnetic moments to achieve a storage mechanism for recording data information, making it superior to other storage technologies in terms of high-speed reading and writing, number of writes, and non-volatility.

[0003] However, the external magnetic field will significantly affect the stability of the magnetic free layer. If the stability of the magnetic free layer is increased, the write voltage will be increased, thereby reducing the number of writes to the component or causing write errors. If the stability of the magnetic free layer is reduced, errors in the data stored in the chip will occur. Therefore, it is necessary to effectively shield the external magnetic field of MRAM. At present, the main idea of ​​external magnetic field shielding is to construct a high magnetic permeability loop to wrap the chip so that the magnetic field at the chip is reduced, but the shielding efficiency of this solution is generally low. Therefore, how to improve the shielding efficiency of the external magnetic field is a technical problem that technicians in this field currently need to solve. Utility Model Content

[0004] In view of this, an object of the present invention is to provide a magnetic shielding structure for improving the shielding efficiency of the external magnetic field.

[0005] In order to solve the above technical problems, the utility model provides a magnetic shielding structure, comprising: a substrate; an anti-magnetic gasket is arranged on the surface of the substrate; the anti-magnetic gasket is provided with a hollow area; a magnetic chip is flip-chip bonded to the surface of the substrate through the hollow area;

[0006] The surface of the antimagnetic gasket is provided with four interconnected antimagnetic side walls along the circumferential direction; the angles between the four antimagnetic side walls and the substrate are all less than 90°; the ends of the four antimagnetic side walls facing away from the antimagnetic gasket are connected to the antimagnetic cover plate as a whole to form an antimagnetic shielding cover; the substrate, the antimagnetic gasket and the antimagnetic shielding cover form an enclosed space surrounding the magnetic chip.

[0007] Optionally, the hollow area is provided in the middle of the antimagnetic gasket.

[0008] Optionally, inside the enclosed space formed by the substrate, the antimagnetic gasket and the antimagnetic shielding cover, glue is coated at the connection positions between the four antimagnetic side walls and the antimagnetic gasket.

[0009] Optionally, the anti-magnetic side wall and / or the anti-magnetic cover plate is provided with a through hole facing the interior of the anti-magnetic shielding cover.

[0010] Optionally, the gap between the magnetic chip and the substrate is filled with glue.

[0011] Optionally, the glue is insulating glue.

[0012] Optionally, the anti-magnetic gasket is a gasket made of soft magnetic material; the anti-magnetic side wall is a side wall made of soft magnetic material; and the anti-magnetic cover plate is a cover plate made of soft magnetic material.

[0013] Optionally, the included angle between the antimagnetic side wall and the substrate is 45°.

[0014] Optionally, a protruding column is provided on the upper surface of the substrate; a vertical conductive trace is provided inside the protruding column, and a solder joint is provided on the top of the protruding column; the solder joint is connected to the vertical conductive trace; the vertical conductive trace is connected to the solder ball on the lower surface of the substrate through the conductive trace inside the substrate;

[0015] The size of the hollow area is greater than or equal to the diameter of the protruding column; the protruding column passes through the hollow area and is higher than the surface of the antimagnetic gasket; the electrode of the magnetic chip is bonded to the solder joint.

[0016] Optionally, the size of the hollow area is larger than the size of the magnetic chip; the magnetic chip is located in the hollow area; the electrodes of the magnetic chip are bonded to the solder joints on the upper surface of the substrate; the solder joints on the upper surface of the substrate are connected to the solder balls on the lower surface of the substrate through conductive traces inside the substrate.

[0017] It can be seen that the utility model includes: a substrate; an antimagnetic gasket is arranged on the surface of the substrate; the antimagnetic gasket is arranged with a hollow area; the magnetic chip is flip-chip bonded to the surface of the substrate through the hollow area; the surface of the antimagnetic gasket is provided with four interconnected antimagnetic side walls along the circumferential direction; the angles between the four antimagnetic side walls and the substrate are all less than 90°; the ends of the four antimagnetic side walls facing away from the antimagnetic gasket are connected to the antimagnetic cover plate as a whole to form an antimagnetic shielding cover; the substrate, the antimagnetic gasket and the antimagnetic shielding cover form an enclosed space surrounding the magnetic chip. The utility model is provided with four interconnected inclined antimagnetic side walls and an antimagnetic cover plate connected to the four antimagnetic side walls around the antimagnetic gasket. A closed space is formed by the substrate, the antimagnetic gasket, the four inclined antimagnetic side walls and the antimagnetic cover plate to shield the static magnetic field of the magnetic chip placed inside. Since four antimagnetic side walls are interconnected along the circumferential direction, the magnetic field of the magnetic chip in all directions can be shielded, which greatly improves the magnetic shielding efficiency; and the use of inclined side walls can also effectively improve the shielding efficiency, which can not only greatly improve the vertical shielding effect, but also maintain the horizontal shielding effect at the same time. At the same time, since the magnetic chip is connected to the substrate by a flip-chip bonding solution in the hollow area of ​​the antimagnetic gasket, the problem that wire bonding cannot be performed due to too many side walls is solved. In addition, the magnetic shielding structure is easy to install and can be compatible with existing packaging equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0019] Figure 1 A schematic structural diagram of a magnetic shielding structure provided by an embodiment of the utility model;

[0020] Figure 2 A cross-sectional view of a magnetic shielding structure provided by an embodiment of the utility model;

[0021] Figure 3 A schematic structural diagram of another magnetic shielding structure provided by an embodiment of the utility model;

[0022] Figure 4 A cross-sectional view of another magnetic shielding structure provided by an embodiment of the utility model;

[0023] Figure 5 A schematic diagram of the relationship between the inclination angle of the anti-magnetic side wall and the shielding efficiency provided in an embodiment of the utility model.

[0024] The following are the descriptions of the reference numerals:

[0025] 1-substrate; 2-antimagnetic shielding cover; 21-antimagnetic side wall; 22-antimagnetic cover plate; 221-through hole; 3-MRAM chip; 41-metal solder joint; 42-metal routing; 43-solder ball; 5-antimagnetic gasket. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is only a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0027] A magnetic shielding structure provided by an embodiment of the utility model may include: a substrate; an anti-magnetic gasket is provided on the surface of the substrate; the anti-magnetic gasket is provided with a hollow area; a magnetic chip is flip-chip bonded to the surface of the substrate through the hollow area;

[0028] The surface of the antimagnetic gasket is provided with four interconnected antimagnetic side walls along the circumferential direction; the angles between the four antimagnetic side walls and the substrate are all less than 90°; the ends of the four antimagnetic side walls facing away from the antimagnetic gasket are connected to the antimagnetic cover plate as a whole to form an antimagnetic shielding cover; the substrate, the antimagnetic gasket and the antimagnetic shielding cover form a closed space surrounding the magnetic chip.

[0029] This embodiment does not limit the specific position of the hollow area. In order to improve the shielding effect of magnetic fields in all directions, a hollow area can be set in the middle position of the anti-magnetic gasket in this embodiment. This embodiment does not limit the specific number of hollow areas, and the corresponding number of hollow areas can be selected according to the specific method of flip-chip bonding between the magnetic chip and the substrate; for example, the anti-magnetic gasket can be provided with a hollow area so that the magnetic chip can be directly bonded to the solder joints on the upper surface of the substrate; the anti-magnetic gasket can also be provided with multiple hollow areas, and the hollow areas correspond to the positions of the solder joints one by one; in this case, the magnetic chip is located on the surface of the anti-magnetic gasket and is bonded to the solder joints in each hollow area.

[0030] This embodiment does not limit the specific connection method between the anti-magnetic gasket and the substrate. For example, glue may be coated at the connection position between the anti-magnetic gasket and the substrate to fix the anti-magnetic gasket and the substrate together. This embodiment does not limit the specific type of glue, which may include but is not limited to insulating glue.

[0031] This embodiment does not limit the specific connection method of the anti-magnetic side wall and the anti-magnetic cover plate. For example, the four anti-magnetic side walls and the anti-magnetic cover plate may be an integrated structure; or glue may be coated at the connection position of the four anti-magnetic side walls and the anti-magnetic cover plate to fix the anti-magnetic shielding cover and the anti-magnetic cover plate with glue. This embodiment does not limit the specific type of glue, which may include but is not limited to insulating glue.

[0032] This embodiment does not limit the specific connection method of the anti-magnetic shielding cover and the anti-magnetic gasket. For example, the anti-magnetic shielding cover may be surrounded by a plastic packaging material, and the enclosed space formed by the substrate, the anti-magnetic gasket and the anti-magnetic shielding cover may be filled to fix the anti-magnetic shielding cover and the anti-magnetic gasket together through the plastic packaging material. Alternatively, the connection positions of the four anti-magnetic side walls and the anti-magnetic gasket may be coated with glue to fix the anti-magnetic shielding cover and the anti-magnetic gasket together through the glue. This embodiment does not limit the specific type of glue, and may include but is not limited to insulating glue.

[0033] Furthermore, in order to facilitate the flow of the plastic encapsulation material, the anti-magnetic side wall and / or the anti-magnetic cover plate in this embodiment may be provided with a through hole facing the inside of the anti-magnetic shielding cover. It should be noted that when the anti-magnetic shielding cover is encapsulated with the plastic encapsulation material, the encapsulation material can enter the enclosed space formed by the substrate, the anti-magnetic gasket and the anti-magnetic shielding cover through the through holes on the anti-magnetic side wall and / or the anti-magnetic cover plate, which can replace the air in the enclosed space to form a sealed environment on the one hand; on the other hand, the connection position of the anti-magnetic side wall and the anti-magnetic gasket can be further fixed from inside the enclosed space.

[0034] The present embodiment does not limit the specific type of antimagnetic gaskets, for example, the antimagnetic gaskets may be metal soft magnetic material gaskets such as tinplate gaskets or silicon steel gaskets; the present embodiment does not limit the specific type of antimagnetic side walls, for example, the antimagnetic side walls are metal soft magnetic material side walls such as tinplate side walls or silicon steel side walls; the present embodiment does not limit the specific type of antimagnetic cover plates, for example, the antimagnetic cover plates are metal soft magnetic material cover plates such as tinplate cover plates or silicon steel cover plates.

[0035] This embodiment does not limit the specific value of the angle between the antimagnetic side wall and the substrate, and any angle less than 90° can be selected according to actual conditions. For example, the angle between the antimagnetic side wall and the substrate can be 18°, 42° or 45°.

[0036] This embodiment does not limit the specific method of flip-chip bonding between the magnetic chip and the substrate. For example, the following two methods can be used:

[0037] (1) The size of the hollow area is larger than that of the magnetic chip; the magnetic chip is located in the hollow area; the electrodes of the magnetic chip are bonded to the solder joints on the upper surface of the substrate; the solder joints on the upper surface of the substrate are connected to the solder balls on the lower surface of the substrate through the conductive traces inside the substrate. This embodiment does not limit the specific type of solder joints, which may include but are not limited to metal solder joints. This embodiment does not limit the specific type of conductive traces, which may include but are not limited to metal traces.

[0038] (2) A protruding column is provided on the upper surface of the substrate; a vertical conductive trace is provided inside the protruding column, and a solder joint is provided on the top of the protruding column; the solder joint is connected to the vertical conductive trace; the vertical conductive trace is connected to the solder ball on the lower surface of the substrate through the conductive trace inside the substrate; the size of the hollow area is greater than or equal to the diameter of the protruding column; the protruding column passes through the hollow area and is higher than the surface of the antimagnetic gasket; the electrode of the magnetic chip is bonded to the solder joint. This embodiment does not limit the specific type of solder joint, which may include but is not limited to metal solder joints. This embodiment does not limit the specific type of conductive trace, which may include but is not limited to metal traces. This embodiment does not limit the specific type of conductive trace, which may include but is not limited to metal traces.

[0039] It should be noted that the anti-magnetic gasket in structure (2) only needs to set a hollow area at the position corresponding to the protruding column, which greatly reduces the area required for opening, and the magnetic shielding efficiency is higher than that of structure (1).

[0040] Furthermore, in order to firmly fix the magnetic chip on the substrate, the gap between the magnetic chip and the substrate in this embodiment can be filled with glue to bond the magnetic chip to the substrate by the glue. This embodiment does not limit the specific type of glue, which may include but is not limited to insulating glue.

[0041] The present embodiment does not limit the specific type of magnetic chip, which may include but is not limited to an MRAM chip.

[0042] Based on the above embodiments, the utility model is provided with four interconnected inclined antimagnetic side walls and an antimagnetic cover plate connected to the four antimagnetic side walls around the antimagnetic gasket. A closed space is formed by the substrate, the antimagnetic gasket, the four inclined antimagnetic side walls and the antimagnetic cover plate to shield the static magnetic field of the magnetic chip placed inside. Since four antimagnetic side walls are interconnected along the circumferential direction, the magnetic field of the magnetic chip in all directions can be shielded, which greatly improves the magnetic shielding efficiency; and the use of inclined side walls can also effectively improve the shielding efficiency, which can not only greatly improve the vertical shielding effect, but also maintain the horizontal shielding effect at the same time. At the same time, since the magnetic chip is connected to the substrate by a flip-chip bonding solution in the hollow area of ​​the antimagnetic gasket, the problem of being unable to perform wire bonding due to too many side walls is solved. In addition, the magnetic shielding structure is easy to install and can be compatible with existing packaging equipment.

[0043] The above magnetic shielding structure and the preparation process of the magnetic shielding structure are explained below with reference to specific examples.

[0044] Please refer to Figure 1 and Figure 2 , Figure 1 A schematic structural diagram of a magnetic shielding structure provided by an embodiment of the utility model; Figure 2 A cross-sectional view of a magnetic shielding structure provided by an embodiment of the utility model. In this embodiment, there is a metal solder joint 41 in the middle area of ​​the upper surface of the substrate 1, which is connected to the solder ball 43 on the lower surface of the substrate 1 through the metal wiring 42 inside the substrate 1; the anti-magnetic gasket 5 is placed on the substrate 1, the middle part of the anti-magnetic gasket 5 is hollowed out, the size of the hollowed-out area is larger than the size of the MRAM chip 3, and the magnetic chip is located in the hollowed-out area; four interconnected anti-magnetic side walls 21 and an anti-magnetic cover plate 22 connecting the four anti-magnetic side walls 21 are arranged on the anti-magnetic gasket 5; the anti-magnetic gasket 5, ... The material of the magnetic side wall 21 and the anti-magnetic cover plate 22 is soft magnetic material; the angle between the four anti-magnetic side walls 21 and the substrate 1 is less than 90°; a through hole 221 is provided on the anti-magnetic cover plate 22 to facilitate the flow of the plastic packaging material; the anti-magnetic side wall 21 and the anti-magnetic cover plate 22 are integrally formed to form an anti-magnetic shielding cover 2; the MRAM chip 3 is flip-chip bonded to the metal solder joint 41 on the upper surface of the substrate 1, and is located in the space enclosed by the above-mentioned substrate 1, the anti-magnetic gasket 5, the four anti-magnetic side walls 21 and the anti-magnetic cover plate 22.

[0045] Please refer to Figure 3 and Figure 4 , Figure 3 A schematic structural diagram of another magnetic shielding structure provided by an embodiment of the utility model; Figure 4A cross-sectional view of another magnetic shielding structure provided for an embodiment of the utility model. In this embodiment, the solder joint on the upper surface of the substrate 1 protrudes to form a column; a vertical metal trace 42 is provided inside the protruding column, and a metal solder joint 41 is provided on the top of the protruding column; the metal solder joint 41 is connected to the vertical metal trace 42; the vertical metal trace 42 is connected to the solder ball 43 on the lower surface of the substrate 1 through the metal trace 42 inside the substrate 1; the anti-magnetic gasket 5 is placed on the substrate 1, and the anti-magnetic gasket 5 and the corresponding area of ​​the protruding column are hollowed out, and the size of the hollowed-out area is greater than or equal to the diameter of the protruding column, which greatly reduces the area required for opening, thereby having a higher magnetic shielding efficiency; the protruding column passes through the hollowed-out area and is higher than the surface of the anti-magnetic gasket 5 to ensure that the electrode of the MRAM chip 3 can be connected to the The metal solder joint 41 at the top of the protruding column is in contact; four antimagnetic side walls 21 connected to each other and an antimagnetic cover plate 22 connecting the four antimagnetic side walls 21 are arranged on the antimagnetic gasket 5; the antimagnetic gasket 5, the antimagnetic side walls 21 and the antimagnetic cover plate 22 are made of soft magnetic material; the angle between the four antimagnetic side walls 21 and the substrate 1 is less than 90°; a through hole 221 is arranged on the antimagnetic cover plate 22 to facilitate the flow of the plastic packaging material; the antimagnetic side walls 21 and the antimagnetic cover plate 22 are integrally formed to form an antimagnetic shielding cover 2; the MRAM chip 3 is flip-chip bonded to the metal solder joint 41 at the top of the protruding column, and is located in the space surrounded by the above-mentioned substrate 1, the antimagnetic gasket 5, the four antimagnetic side walls 21 and the antimagnetic cover plate 22.

[0046] The above two magnetic shielding structures can be prepared by the following steps:

[0047] 1. Install the antimagnetic gasket 5 on the substrate 1 and cure it; the curing method may be glue bonding;

[0048] 2. Turn the chip upside down and bond it to substrate 1;

[0049] 3. Fill and solidify the bottom of the chip; the solidification method can be glue bonding;

[0050] 4. Install the antimagnetic shielding cover 2 on the gasket and cure it; the curing method may be plastic packaging.

[0051] Please refer to Figure 5 , Figure 5 A schematic diagram of the relationship between the inclination angle of the anti-magnetic side wall and the shielding efficiency provided by an embodiment of the utility model. Figure 5The change of normalized shielding efficiency with the tilt angle shown in the figure shows that, compared with the vertical antimagnetic side wall, the four-sided tilted antimagnetic side wall solution adopted in this embodiment can improve the vertical shielding efficiency by 66% and the horizontal shielding efficiency by 1% when the tilt angle of the antimagnetic side wall (i.e. the angle between the antimagnetic side wall and the substrate) is 42°; when the tilt angle is 18°, the vertical shielding efficiency can be improved by about 200% and the horizontal shielding efficiency only decreases by 1%. It can be seen that the use of the tilted antimagnetic side wall in this embodiment can greatly improve the vertical shielding effect while maintaining the horizontal shielding effect.

[0052] The magnetic shielding structure provided by the embodiment of the utility model is applied. Four interconnected inclined antimagnetic side walls and an antimagnetic cover plate connected to the four antimagnetic side walls are arranged around the antimagnetic gasket. A closed space is formed by the substrate, the antimagnetic gasket, the four inclined antimagnetic side walls and the antimagnetic cover plate to shield the static magnetic field of the magnetic chip placed inside. Since four antimagnetic side walls are interconnected in the circumferential direction, the magnetic field of the magnetic chip in all directions can be shielded, which greatly improves the magnetic shielding efficiency. The use of inclined side walls can also effectively improve the shielding efficiency, which can not only greatly improve the vertical shielding effect, but also maintain the horizontal shielding effect at the same time. At the same time, since the magnetic chip is connected to the substrate by a flip-chip bonding solution in the hollow area of ​​the antimagnetic gasket, the problem of wire bonding being unable to be performed due to too many side walls is solved. In addition, the magnetic shielding structure is easy to install and can be compatible with existing packaging equipment.

[0053] The above is a detailed introduction to a magnetic shielding structure provided by the present invention. For those skilled in the art, according to the idea of ​​the embodiments of the present invention, there may be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A magnetic shielding structure, characterized in that: include: substrate; The surface of the substrate is provided with an anti-magnetic gasket; the anti-magnetic gasket is provided with a hollow area; The magnetic chip is flip-chip bonded to the surface of the substrate through the hollow area; The surface of the antimagnetic gasket is provided with four interconnected antimagnetic side walls along the circumferential direction; the angles between the four antimagnetic side walls and the substrate are all less than 90°; the ends of the four antimagnetic side walls facing away from the antimagnetic gasket are connected to the antimagnetic cover plate as a whole to form an antimagnetic shielding cover; the substrate, the antimagnetic gasket and the antimagnetic shielding cover form an enclosed space surrounding the magnetic chip.

2. The magnetic shielding structure according to claim 1, characterized in that: The hollow area is arranged in the middle of the antimagnetic gasket.

3. The magnetic shielding structure according to claim 1, characterized in that: Inside the enclosed space formed by the substrate, the anti-magnetic gasket and the anti-magnetic shielding cover, glue is coated at the connection positions of the four anti-magnetic side walls and the anti-magnetic gasket.

4. The magnetic shielding structure according to claim 3, characterized in that: The anti-magnetic side wall and / or the anti-magnetic cover plate are provided with a through hole facing the inside of the anti-magnetic shielding cover.

5. The magnetic shielding structure according to claim 3, characterized in that: The gap between the magnetic chip and the substrate is filled with glue.

6. The magnetic shielding structure according to claim 5, characterized in that: The glue is insulating glue.

7. The magnetic shielding structure according to claim 1, characterized in that: The anti-magnetic gasket is a gasket made of soft magnetic material; the anti-magnetic side wall is a side wall made of soft magnetic material; and the anti-magnetic cover plate is a cover plate made of soft magnetic material.

8. The magnetic shielding structure according to claim 1, characterized in that: The included angles between the antimagnetic side wall and the substrate are both 45°.

9. The magnetic shielding structure according to any one of claims 1 to 8, characterized in that: The upper surface of the substrate is provided with a protruding column; a vertical conductive trace is provided inside the protruding column, and a soldering point is provided on the top of the protruding column; the soldering point is connected to the vertical conductive trace; the vertical conductive trace is connected to the solder ball on the lower surface of the substrate through the conductive trace inside the substrate; The size of the hollow area is greater than or equal to the diameter of the protruding column; the protruding column passes through the hollow area and is higher than the surface of the antimagnetic gasket; the electrode of the magnetic chip is bonded to the solder joint.

10. The magnetic shielding structure according to any one of claims 1 to 8, characterized in that: The size of the hollow area is larger than that of the magnetic chip; the magnetic chip is located in the hollow area; the electrodes of the magnetic chip are bonded to the solder joints on the upper surface of the substrate; the solder joints on the upper surface of the substrate are connected to the solder balls on the lower surface of the substrate through the conductive traces inside the substrate.

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