MEMS microstrip surface-mounted circulator and preparation method thereof

Abstract

The invention provides an MEMS microstrip surface-mounted circulator and a preparation method thereof, and belongs to the technical field of microwave devices, the MEMS microstrip surface-mounted circulator comprises a circulator chip and a magnetic shielding shell, first magnetic steel is arranged on the circulator chip, and a kovar carrier is arranged on the bottom surface of the circulator chip; the magnetic shielding shell is arranged above the circulator chip in a covering manner; second magnetic steel opposite to the first magnetic steel in polarity is arranged in the magnetic shielding shell, and the second magnetic steel and the first magnetic steel are arranged at intervals. Compared with the conventional micro-strip surface-mounted circulator, the MEMS micro-strip surface-mounted circulator disclosed by the invention has the advantages of higher consistency, lower loss and higher power capacity; by adding the positioning columns, the mounting precision of the microstrip surface-mounted circulator is improved, and batch production of the circulator is facilitated; by adding the magnetic shielding shell, the interaction between the circulator and the circulator in the actual mounting process is greatly reduced, and the problem that accurate alignment cannot be achieved due to the interaction between the circulators in the mounting process is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of microwave devices, and in particular relates to a MEMS microstrip surface-mount circulator and a preparation method thereof. Background Art

[0002] As the core device in the communication transceiver system, the circulator has been required to be miniaturized, high-performance, and easy to integrate with the development of the communication system. The surface mount circulator has the technical characteristics of high integration and high reliability based on its mounting process. As the integration of the communication system becomes higher and higher, the circulators between channels in the communication system are often close to each other. As a magnetic passive device, when the distance is close, there must be interaction between circulators. Therefore, in the mounting process of the microstrip surface mount circulator, the interaction between the two will directly affect the mounting accuracy of the microstrip surface mount circulator, and directly affect the mass production of the microstrip surface mount circulator. Therefore, solving the mounting accuracy and mass production of microstrip circulators at high integration has a far-reaching impact on the development of the communication system. In addition, the traditional microstrip surface mount circulator is prepared by thin film circuit technology, which has the problems of low power capacity, large loss and poor consistency. Therefore, it is particularly important to develop a microstrip surface mount circulator with high consistency, small loss and large power capacity. Summary of the invention

[0003] The embodiment of the present invention provides a MEMS microstrip surface-mount circulator and a preparation method thereof, aiming to solve the problems of poor mounting accuracy and poor mass productivity of the existing microstrip surface-mount circulator due to the existence of interactions, as well as the problems of low power capacity and poor consistency when prepared using a thin film circuit process.

[0004] In the first aspect, in order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is: to provide a MEMS microstrip surface-mount circulator, comprising: a circulator chip, on which a first magnetic steel is arranged, and on which a kovar carrier is arranged at the bottom; and A magnetic shielding shell is disposed above the circulator chip; a second magnetic steel having a polarity opposite to that of the first magnetic steel is disposed in the magnetic shielding shell, and the second magnetic steel is spaced apart from the first magnetic steel.

[0005] In combination with the first aspect, in one achievable manner, the second magnetic steel is fixed to the inner top surface of the magnetic shielding shell, and the inner top surface of the magnetic shielding shell simultaneously abuts against the upper surface of the first magnetic steel.

[0006] In combination with the first aspect, in one achievable manner, a positioning column protruding downward is provided at the bottom of the kovar carrier, and the positioning column is embedded in a positioning groove reserved on the circuit board during mounting.

[0007] In combination with the first aspect, in an achievable manner, it includes one circulator chip, or multiple circulator chips, and the multiple circulator chips are integrated on the same silicon substrate to form a multi-circulator chip; the magnetic shielding shell is arranged on the multi-circulator chip, and the magnetic shielding shell is provided with the second magnetic steel corresponding to the first magnetic steel on each circulator chip.

[0008] In combination with the first aspect, in an achievable manner, the circulator chip includes, from bottom to top, the kovar carrier, a first circuit layer, a first silicon base layer, a second circuit layer, a second silicon base layer, a silicon gasket and the first magnetic steel; the first magnetic steel is fixed on the silicon gasket; an opening window is provided on the kovar carrier, a metal ball connected to the first circuit layer is provided in the opening window, and a port pad for welding the metal ball is provided on the first circuit layer; a metallized through hole is provided in the first silicon base layer, and the first circuit layer and the second circuit layer form vertical signal transmission through the metallized through hole.

[0009] In combination with the first aspect, in one achievable manner, a gyromagnetic sheet cavity is provided in the first silicon-based layer, and the gyromagnetic sheet cavity is filled with a gyromagnetic sheet; the first magnetic steel, the silicon gasket and the gyromagnetic sheet are collinear in the upper and lower directions.

[0010] In a second aspect, an embodiment of the present invention further provides a method for preparing a MEMS microstrip surface-mount circulator, the method comprising: Filling the gyromagnetic sheet into the gyromagnetic sheet cavity of the circulator chip, placing a solder sheet between the circulator chip and the Kovar carrier, and then placing the gyromagnetic sheet in a sintering furnace for welding; Pasting a silicon gasket on the sintered circulator chip, pasting a first magnetic steel on the silicon gasket, and putting the silicon gasket into an oven for curing; Mark a preset position on the inner top surface of the magnetic shielding shell, stick the second magnetic steel on the marked position, and then put it into an oven for curing; The solidified magnetic shielding shell is placed over the solidified circulator chip.

[0011] In combination with the second aspect, in one achievable manner, a mark is made at a preset position on the inner top surface of the magnetic shielding shell, a second magnetic steel is pasted at the marked position, and then placed in an oven for curing, including: A laser marking machine is used to mark a preset position of the magnetic shielding shell, and a glue dispenser is used to dispense epoxy glue at the marked position to adhere the second magnetic steel.

[0012] In combination with the second aspect, in one achievable manner, the varable carrier is a magnetic conductive material.

[0013] In combination with the second aspect, in one achievable manner, the gyromagnetic sheet is made of ferrite material.

[0014] Compared with the prior art, the MEMS microstrip surface-mount circulator and the preparation method thereof provided by the present invention have the following beneficial effects: (1) The present invention adopts MEMS technology. Compared with the thin film circuit technology used in conventional microstrip circulators, MEMS technology has higher accuracy and stability. Therefore, MEMS microstrip surface mount circulators have higher consistency than conventional microstrip surface mount circulators. In addition, MEMS microstrip surface mount circulators use silicon as the substrate material, the device loss is small and has good heat dissipation performance. Therefore, the device has a higher power capacity.

[0015] (2) By adding positioning columns at the bottom of the MEMS microstrip surface mount circulator carrier, a limit is provided for the mounting of the circulator. During the actual mounting process, the positioning columns are embedded in the positioning grooves reserved on the circuit board, which increases the limit of the circulator during the mounting process, improves the mounting accuracy of the microstrip surface mount circulator, and facilitates the mass production of the circulator.

[0016] (3) By adding a magnetic shielding shell above the MEMS microstrip surface-mount circulator, the magnetic field of the circulator is confined inside the magnetic shielding shell, which greatly reduces the interaction between the circulators during the actual mounting process of the microstrip surface-mount circulator. This solves the problem of inaccurate alignment caused by the interaction between the circulators during the mounting process of the microstrip surface-mount circulator, thereby improving the mounting accuracy of the circulator. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 A schematic diagram of the structure of a MEMS microstrip surface-mount circulator chip provided in an embodiment of the present invention; Figure 2 A schematic diagram of the structure of a MEMS microstrip surface-mount circulator having a magnetic shielding shell provided in an embodiment of the present invention; Figure 3 A schematic diagram of the structure of a magnetic shielding shell provided by an embodiment of the present invention; Figure 4 A schematic diagram of the structure of a MEMS microstrip surface mount circulator provided in an embodiment of the present invention mounted on a circuit board; Description of reference numerals: 1. kovable carrier; 2. first circuit layer; 3. first silicon-based layer; 4. second circuit layer; 5. second silicon-based layer; 6. silicon gasket; 7. first magnetic steel; 8. metal ball; 9. opening window; 10. metallized through hole; 11. positioning column; 12. magnetic shielding shell; 13. second magnetic steel; 14. closed magnetic field; 15. circuit board; 16. gyromagnetic sheet. DETAILED DESCRIPTION

[0018] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0019] Please also read Figures 1 to 4 The MEMS microstrip surface-mount circulator provided by the present invention is now described. The MEMS microstrip surface-mount circulator comprises: a circulator chip and a magnetic shielding shell 12, wherein a first magnetic steel 7 is arranged on the circulator chip, and a var carrier 1 is arranged on the bottom surface thereof; the magnetic shielding shell 12 is arranged above the circulator chip; a second magnetic steel 13 having a polarity opposite to that of the first magnetic steel 7 is arranged in the magnetic shielding shell 12, and the second magnetic steel 13 is arranged at an interval from the first magnetic steel 7.

[0020] Compared with the prior art, the MEMS microstrip surface-mount circulator provided by the present invention has the following beneficial effects: (1) The present invention adopts MEMS technology. Compared with the thin film circuit technology used in conventional microstrip circulators, MEMS technology has higher accuracy and stability. Therefore, MEMS microstrip surface mount circulators have higher consistency than conventional microstrip surface mount circulators. In addition, MEMS microstrip surface mount circulators use silicon as the substrate material, the device loss is small and has good heat dissipation performance. Therefore, the device has a higher power capacity.

[0021] (2) By adding a magnetic shielding shell 12 above the MEMS microstrip surface-mount circulator, the magnetic field of the circulator is confined inside the magnetic shielding shell 12, which greatly reduces the interaction between the circulators during the actual mounting process of the microstrip surface-mount circulator, solves the problem of inaccurate alignment caused by the interaction between the circulators during the mounting process of the microstrip surface-mount circulator, and improves the mounting accuracy of the circulator.

[0022] (3) The magnetic shielding shell 12 of the present application is placed above the circulator, and includes a metal shell and a second magnetic steel 13. The second magnetic steel 13 is bonded to the inside of the metal shell. The bonding position of the second magnetic steel 13 needs to avoid the position of the first magnetic steel 7 corresponding to the circulator to avoid interference; the polarity of the second magnetic steel 13 should be opposite to the polarity of the first magnetic steel 7, so that two magnetic steels with completely opposite polarities will form a closed magnetic field 14 inside the magnetic shielding shell 12, which greatly reduces magnetic leakage and realizes magnetic shielding of the device.

[0023] In this article, MEMS is the abbreviation of MicroelectroMechanical Systems.

[0024] In some embodiments, see Figure 1 to Figure 2The second magnetic steel 13 is fixed on the inner top surface of the magnetic shielding shell 12 , and the inner top surface of the magnetic shielding shell 12 is also in contact with the upper surface of the first magnetic steel 7 .

[0025] In some embodiments, see Figure 1 to Figure 2 A positioning column 11 protruding downward is provided at the bottom of the kovar carrier 1; the positioning column 11 is embedded in the positioning groove reserved on the circuit board during mounting. By adding the positioning column 11 at the bottom of the kovar carrier 1 of the MEMS microstrip surface mount circulator, a limit is provided for the mounting of the circulator, and the positioning column 11 is embedded in the positioning groove reserved on the circuit board 15 during the actual mounting process, which increases the limit of the circulator during the mounting process, improves the mounting accuracy of the microstrip surface mount circulator, and is conducive to the mass production of the circulator.

[0026] See also Figure 4 During mounting, the positioning column 11 at the bottom of the circulator chip is embedded in the positioning groove reserved on the circuit board 15, and mounted on the circuit board 15 by reflow soldering. By adding the positioning column 11 at the bottom of the MEMS microstrip surface mount circulator carrier 1, the positioning column 11 is embedded in the positioning groove reserved on the circuit board 15 during the actual mounting process, which increases the position limit of the circulator during the mounting process and improves the mounting accuracy of the microstrip surface mount circulator.

[0027] Alternatively, see Figure 1 to Figure 2 The positioning column 11 includes but is not limited to one, two or more; the positioning column 11 and the kovar carrier 1 are an integral structure, made of the same material, and the positioning column can be machined. The positioning column 11 can be in the shape of a cylinder or a square column.

[0028] The MEMS microstrip surface-mount circulator provided in the present application includes at least one circulator chip, that is, the number of circulator chips can be one, or two or more, and multiple circulator chips are integrated on the same silicon substrate to form a multi-circulator chip; a magnetic shielding shell 12 is arranged on the multi-circulator chip, and a second magnetic steel 13 corresponding to the first magnetic steel 7 on each circulator chip is arranged in the magnetic shielding shell 12, so that a closed magnetic field can be formed above each circulator chip.

[0029] For example, when the circulator includes two circulator chips, the two circulator chips are integrated on the same silicon substrate to form a dual circulator chip.

[0030] Therefore, the MEMS microstrip surface-mount circulator provided in the present application includes but is not limited to a circulator, and may also be a dual circulator, a dual isolator, a ring isolator, a dual circulator, a multi-circulator, etc.

[0031] In some embodiments, see Figure 1 to Figure 2The circulator chip includes, from bottom to top, a kovar carrier 1, a first circuit layer 2, a first silicon-based layer 3, a second circuit layer 4, a second silicon-based layer 5, a silicon gasket 6 and a first magnetic steel 7; the first magnetic steel 7 is fixed on the silicon gasket 6; an opening window 9 is provided on the kovar carrier 1, a metal ball 8 connected to the first circuit layer 2 is provided in the opening window 9, and a port pad for welding the metal ball 8 is provided on the first circuit layer 2; a metallized through hole 10 is provided in the first silicon-based layer 3, and the first circuit layer 2 and the second circuit layer 4 form vertical signal transmission through the metallized through hole 10.

[0032] Specifically, the kovar carrier 1 is welded to the lower layer of the first circuit layer 2 by gold-tin sintering, and a port pad is reserved in the first circuit layer 2. The port pad is exposed through an opening window 9 opened on the kovar carrier 1, and the metal ball 8 is welded to the port pad by a ball planting process; in addition, a positioning column 11 is left at the bottom of the kovar carrier 1 by machining, and the positioning column 11 is embedded in the circuit board 15 during the actual mounting process to provide a limit for the circulator; the first silicon base layer 3 has a metallized through hole 10 to provide vertical transmission of the signal; the first silicon base layer 3 has a gyromagnetic sheet cavity for pre-setting the ferrite position, and the gyromagnetic sheet cavity is filled with a gyromagnetic sheet 16, which is a ferrite material. The magnetic field of the magnetic steel acts on the gyromagnetic sheet 16 to provide a bias magnetic field, thereby realizing the circulation effect of the signal.

[0033] In some embodiments, see Figure 1 to Figure 2 A gyromagnetic sheet cavity is provided in the first silicon-based layer 3, and the gyromagnetic sheet cavity is filled with a gyromagnetic sheet 16; the first magnetic steel 7, the silicon gasket 6 and the gyromagnetic sheet 16 are collinear, that is, the first magnetic steel 7, the silicon gasket 6 and the gyromagnetic sheet 16 are in concentric positions in the vertical direction.

[0034] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0035] Based on the same inventive concept, the embodiment of the present application also provides a method for preparing a MEMS microstrip surface-mount circulator, the method comprising: Step 1: Sintering of MEMS microstrip surface mount circulator chip Fill the gyromagnetic sheet 16 into the gyromagnetic sheet cavity of the circulator chip, and place a gold-tin solder sheet of appropriate size between the circulator chip and the kovar carrier 1, align the edges of the circulator chip and the kovar carrier 1, and then place the well-aligned kovar carrier 1 and the circulator chip in a sintering furnace for welding.

[0036] Step 2: Magnetic curing See also Figure 1, use a glue dispenser to apply a proper amount of epoxy glue at the reserved bonding position of the first magnetic steel 7 of the MEMS microstrip surface mount circulator, stick the silicon gasket 6 at this position, and then apply a proper amount of epoxy glue on the silicon gasket 6 to bond the first magnetic steel 7 to the silicon gasket 6. After bonding, place it in a high-temperature oven for curing.

[0037] See also Figure 3 , use a laser marking machine to mark the reserved position of the second magnetic steel 13 in the magnetic shielding shell 12, use a glue dispenser to apply a proper amount of epoxy glue at the reserved position, then bond the second magnetic steel 13 to the reserved position, and finally place it in a high-temperature oven for curing.

[0038] Step 3: Planting the ball See also Figure 1 , a proper amount of solder paste is applied on the port pad in the opening window 9 of the MEMS microstrip surface mount circulator by a dispensing machine, a metal ball 8 is placed on the port pad, and then placed in a reflow oven for reflow, and the metal ball 8 is welded on the port pad.

[0039] Step 4: Install the magnetic shielding shell 12 See also Figure 2 , the solidified magnetic shielding shell 12 is covered on the solidified circulator chip.

[0040] Regarding the material selection of each part, the following examples are given: The kovar carrier 1 is a magnetic conductive material, preferably an iron-nickel alloy.

[0041] The gyromagnetic sheet is made of ferrite material.

[0042] The material of the metal ball 8 is a material suitable for soldering, preferably a high-lead ball.

[0043] Preferably, the first magnetic steel 7 and the second magnetic steel 13 are both samarium cobalt magnetic steels.

[0044] The magnetic shielding shell 12 is made of magnetic conductive material, preferably industrial pure iron.

[0045] The first silicon-based layer 3 and the second silicon-based layer 5 are made of silicon; the first circuit layer 2 and the second circuit layer 4 are made of gold.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A MEMS microstrip surface mount circulator, characterized in that: include: A circulator chip, on which a first magnetic steel (7) is arranged, and on which a kovar carrier (1) is arranged; as well as A magnetic shielding shell (12) is arranged above the circulator chip; a second magnetic steel (13) having a polarity opposite to that of the first magnetic steel (7) is arranged in the magnetic shielding shell (12), and the second magnetic steel (13) is spaced apart from the first magnetic steel (7).

2. The MEMS microstrip surface mount circulator according to claim 1, characterized in that: The second magnetic steel (13) is fixed on the inner top surface of the magnetic shielding shell (12), and the inner top surface of the magnetic shielding shell (12) simultaneously abuts against the upper surface of the first magnetic steel (7).

3. The MEMS microstrip surface mount circulator according to claim 1, characterized in that: A positioning column (11) protruding downward is arranged at the bottom of the kovar carrier (1), and the positioning column (11) is embedded in a positioning groove reserved on the circuit board during mounting.

4. The MEMS microstrip surface mount circulator according to claim 1, characterized in that: It comprises one circulator chip, or comprises a plurality of circulator chips, wherein the plurality of circulator chips are integrated on the same silicon substrate to form a multi-circulator chip; the magnetic shielding shell (12) is arranged on the integrated multi-circulator chip, and the second magnetic steel (13) corresponding to the first magnetic steel (7) on each circulator chip is arranged in the magnetic shielding shell (12).

5. The MEMS microstrip surface mount circulator according to claim 1, characterized in that: The circulator chip comprises, from bottom to top, the kovar carrier (1), a first circuit layer (2), a first silicon-based layer (3), a second circuit layer (4), a second silicon-based layer (5), a silicon gasket (6) and the first magnetic steel (7); the first magnetic steel (7) is fixed on the silicon gasket (6); an opening window (9) is provided on the kovar carrier (1), a metal ball (8) connected to the first circuit layer (2) is provided in the opening window (9), and a port pad for welding the metal ball (8) is provided on the first circuit layer (2); a metallized through hole (10) is provided in the first silicon-based layer (3), and the first circuit layer (2) and the second circuit layer (4) form vertical signal transmission through the metallized through hole (10).

6. The MEMS microstrip surface mount circulator according to claim 5, characterized in that: A gyromagnetic sheet cavity is provided in the first silicon-based layer (3), and the gyromagnetic sheet cavity is filled with a gyromagnetic sheet (16); the first magnetic steel (7), the silicon gasket (6) and the gyromagnetic sheet (16) are collinear in the vertical direction.

7. A method for preparing a MEMS microstrip surface mount circulator, used to prepare the MEMS microstrip surface mount circulator as claimed in any one of claims 1 to 6, characterized in that: The method comprises: Filling the gyromagnetic sheet (16) into the gyromagnetic sheet cavity of the circulator chip, placing a solder sheet between the circulator chip and the Kovar carrier (1), and then placing the gyromagnetic sheet in a sintering furnace for welding; Pasting a silicon gasket (6) on the sintered circulator chip, pasting a first magnetic steel (7) on the silicon gasket (6), and placing the silicon gasket (6) in an oven for curing; Marking a preset position on the inner top surface of the magnetic shielding shell (12), pasting the second magnetic steel (13) to the marked position, and then placing it in an oven for curing; The solidified magnetic shielding shell (12) is covered above the solidified circulator chip.

8. The method for preparing the MEMS microstrip surface mount circulator according to claim 7, characterized in that: Marking a preset position on the inner top surface of the magnetic shielding shell (12), pasting the second magnetic steel (13) on the marked position, and then putting it into an oven for curing, including: A laser marking machine is used to mark a preset position of the magnetic shielding shell (12), and a glue dispenser is used to dispense epoxy glue at the marked position, and the second magnetic steel (13) is adhered.

9. The method for preparing the MEMS microstrip surface mount circulator according to claim 7, characterized in that: The kovar carrier (1) is a magnetic conductive material.

10. The method for preparing the MEMS microstrip surface mount circulator according to claim 7, characterized in that: The gyromagnetic sheet (16) is made of ferrite material.

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