A Micromechanical Tooling for Stacking Stable Materials and a MEMS Circulator

Abstract

This application is applicable to the technical field of MEMS circulator production, and provides a micromachining tooling for stable material stacking and an MEMS circulator. The micromachining tooling includes: a sintering bearing bottom plate, an isolation structure, and a magnetic force application structure; the sintering bearing bottom plate is placed below the isolation structure; the MEMS circulator is placed in a cavity enclosed by the sintering bearing bottom plate and the isolation structure; the upper surface of the isolation structure has a plurality of grooves with a preset width, and the magnetic force application structure is placed in the grooves; the magnetic force application structure is used to provide an upward attraction force for the ferrite in the MEMS circulator. This application can prevent sintering failure caused by phenomena such as ferrite skew and chip misalignment, and can improve the sintering yield of the MEMS circulator.

Description

Technical Field

[0001] This application belongs to the technical field of MEMS circulator production, and particularly relates to a micromachining tooling for stable material stacking and a MEMS circulator. Background Art

[0002] When designing a MEMS circulator, in order to ensure the heat dissipation effect under high power, high-temperature solder is usually used to sinter the chip and the heat sink carrier, and the structural form is as Figure 1 shown. Before sintering, the ferrite is pre-placed in the bottom cavity reserved on the chip, and solder and the heat sink carrier are stacked in sequence below. After sintering, it is required that the surfaces of the chip, the ferrite, and the heat sink carrier are parallel to each other, as shown by the dotted line part in Figure 1 , and the solder is completely filled between the chip and the heat sink carrier, with a low sintering void ratio, and finally the qualified sintering of the chip is achieved.

[0003] However, due to processing errors, there are deviations between the actually measured dimensions of the raw materials and the designed dimensions. Multiple ferrites cannot ensure that the thicknesses are exactly the same. Under the action of external gravity, the thinner ferrite will be skewed in the cavity, and it is impossible to ensure the voids of the solder after sintering, resulting in unqualified sintering. Unqualified sintering is one of the main reasons for unqualified production of MEMS circulators, seriously affecting the production yield of MEMS circulators. There are two main reasons for unqualified sintering:

[0004] (1) An unreasonable sintering curve design will cause batch unqualified sintering effects. This failure form can be solved by referring to the industry-standard sintering curve. The standard sintering curve ensures the solder melting effect and the surface wetting effect, greatly improving the welding quality.

[0005] (2) The unstable stacking structure of the tooling at high temperatures will directly cause misalignment and separation between the chip and the heat sink carrier, and at the same time cause the ferrite to be skewed in the cavity, and the forms are as Figure 2 , Figure 3 shown.

[0006] Currently, there is an urgent need to design a suitable production tooling to solve the problem of the unstable stacking structure of the materials of the MEMS circulator at high temperatures. Summary of the Invention

[0007] To overcome the problems existing in the related technologies, the embodiments of this application provide a micromachining tooling for stable material stacking and a MEMS circulator, which can solve the problem of the unstable stacking structure of the materials of the MEMS circulator at high temperatures.

[0008] This application is implemented through the following technical solutions:

[0009] In a first aspect, an embodiment of the present application provides a micromachining tooling for firmly stacking materials, including: a sintering bearing bottom plate, an isolation structure, and a magnetic force application structure;

[0010] The sintering bearing bottom plate is placed below the isolation structure; the MEMS circulator is placed in the cavity enclosed by the sintering bearing bottom plate and the isolation structure;

[0011] The upper surface of the isolation structure has a plurality of grooves with a preset width, and the magnetic force application structure is placed in the grooves; the magnetic force application structure is used to provide an upward attractive force for the ferrite in the MEMS circulator.

[0012] In a possible implementation manner of the first aspect, the cross-section of the sintering bearing bottom plate is in a U-shaped structure;

[0013] The width of the cavity enclosed by the U-shaped structure of the sintering bearing bottom plate is the same as the width of the MEMS circulator; the height of the cavity enclosed by the U-shaped structure of the sintering bearing bottom plate is the same as the height of the MEMS circulator.

[0014] In a possible implementation manner of the first aspect, the bottom surface of the sintering bearing bottom plate is in contact with the heat sink carrier in the MEMS circulator; the thickness of the bottom surface of the sintering bearing bottom plate is greater than the thickness of the heat sink carrier in the MEMS circulator.

[0015] In a possible implementation manner of the first aspect, the number of grooves in the isolation structure is the same as the number of ferrite in the MEMS circulator; the positions of the grooves in the isolation structure correspond to the positions of the ferrite in the MEMS circulator up and down.

[0016] In a possible implementation manner of the first aspect, the isolation structure is a T-shaped structure, including a first part and a second part;

[0017] The first part is located above the second part; the length of the first part is greater than the length of the second part; the thickness of the first part is greater than the thickness of the second part.

[0018] In a possible implementation manner of the first aspect, the grooves are located in the first part.

[0019] In a possible implementation manner of the first aspect, the length of the first part is greater than or equal to the overall length of the sintering bearing bottom plate.

[0020] In a possible implementation manner of the first aspect, the upward attractive force provided by the magnetic force application structure for the ferrite in the MEMS circulator is greater than the gravity of the ferrite itself.

[0021] In a possible implementation manner of the first aspect, the expression for the upward attractive force provided by the magnetic force application structure for the ferrite in the MEMS circulator is:

[0022] F = kB × 2A

[0023] Among them, k is the magnetic force coefficient, B is the magnetic induction intensity at the surface position of the magnetic force application structure on the ferrite, and A is the effective area of the ferrite relative to the magnetic force application structure.

[0024] In a second aspect, an embodiment of the present application provides a MEMS circulator, which is sintered by a micromachining tooling including a stable material stack as described in any item of the first aspect.

[0025] It can be understood that the beneficial effects of the above second aspect can be referred to the relevant descriptions in the first aspect, and will not be elaborated here.

[0026] The beneficial effects of the embodiments of the present application compared with the prior art are as follows:

[0027] In the embodiment of the present application, an upward attraction force is provided for the ferrite by the magnetic force application structure to offset the influence of gravity, which can ensure that the ferrite is horizontally placed in the cavity, effectively prevent the ferrite from tilting in the cavity due to its small size, and limit the relative displacement between the chip in the MEMS circulator and the bottom heat sink carrier through sintering the bearing bottom plate, which can prevent sintering failure caused by phenomena such as ferrite tilting and chip misalignment, and improve the sintering yield of the MEMS circulator.

[0028] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit this specification. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the following drawings are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0030] Figure 1 It is a schematic structural diagram of a qualified MEMS circulator provided by an embodiment of the present application;

[0031] Figure 2 It is a schematic diagram of misalignment and separation of the MEMS circulator provided by an embodiment of the present application;

[0032] Figure 3 It is a schematic diagram of the ferrite tilting in the chip cavity of the MEMS circulator provided by an embodiment of the present application;

[0033] Figure 4 It is a schematic structural diagram of the micromachining tooling with a stable material stack provided by an embodiment of the present application;

[0034] Figure 5 It is a top view of a micromachining tooling with a stable material stack provided by an embodiment of the present application. Detailed implementation manners

[0035] In the following description, for the purpose of illustration rather than limitation, specific details such as specific system architectures, technologies, etc. are presented to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to avoid unnecessary details from interfering with the description of the present application.

[0036] It should be understood that when used in the specification of the present application and the appended claims, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0037] It should also be understood that the term "and / or" used in the specification of the present application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0038] As used in the specification of the present application and the appended claims, the term "if" can be interpreted as "when", "once", "in response to determining", or "in response to detecting" depending on the context. Similarly, the phrase "if determined" or "if detecting [the described condition or event]" can be interpreted as meaning "once determined", "in response to determining", "once detecting [the described condition or event]", or "in response to detecting [the described condition or event]" depending on the context.

[0039] In addition, in the description of the specification of the present application and the appended claims, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0040] The reference to "an embodiment" or "some embodiments" etc. described in the specification of the present application means that a specific feature, structure, or characteristic described in connection with the embodiment is included in one or more embodiments of the present application. Thus, statements such as "in an embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in another way. The terms "comprising", "including", "having", and their variants all mean "including but not limited to", unless otherwise specifically emphasized in another way.

[0041] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0042] Figure 1 The structure of a MEMS circulator in the related art is shown. The raw materials of this structure include a chip, a ferrite, solder, and a heat sink carrier. The requirements for a qualified MEMS circulator are to ensure the stable stacking of the four raw materials before and after sintering, and there should be no horizontal offset of the raw materials during the transfer process or production process, resulting in misalignment or skew, as Figure 2 shown. Before production, it is necessary to ensure the stability of the stacking structure to prevent offset caused by vibration during handling.

[0043] Because there are errors in the processing of raw materials, to reduce the production difficulty, the size of the ferrite must be smaller than the size of the chip pre-set cavity. The ferrite will freely fall due to gravity in the chip pre-set cavity. There are differences in the heights of multiple ferrites. The thinner ferrite will not be squeezed between the chip and the solder in the cavity and is in a free state. The free-state ferrite has a high probability of being slightly skewed in the cavity, as Figure 3 shown, which has a great impact on the sintering effect.

[0044] To solve the above problems, an embodiment of the present application provides the structure of a micromachining tooling for stabilizing the stacking of materials. Referring to Figure 4 , the detailed description of the micromachining tooling for stabilizing the stacking of materials is as follows:

[0045] The micromachining tooling for stabilizing the stacking of materials includes: a sintering carrier bottom plate 100, an isolation structure 200, and a magnetic force application structure 300.

[0046] The sintering carrier bottom plate 100 is placed below the isolation structure 200; the MEMS circulator is placed in the cavity enclosed by the sintering carrier bottom plate 100 and the isolation structure 200.

[0047] The upper surface of the isolation structure 200 has a plurality of grooves with a preset width, and the magnetic force application structure 300 is placed in the grooves; the magnetic force application structure 300 is used to provide an upward attraction force for the ferrite in the MEMS circulator.

[0048] When the MEMS circulator undergoes high-temperature sintering, while the sintering carrier bottom plate 100 ensures the stacked structure of the chip and the heat sink carrier, through the magnetic force action of the magnetic force application structure 300, it ensures that each ferrite is in a horizontal direction inside the cavity. At the same time, a vertical force is provided for the heat sink carrier, so that the upper surface of the heat sink carrier is closely attached to the bottom surface of the ferrite. Under the action of the sintering environment, the solder between the heat sink carrier and the chip melts and fuses with the gold plating on both surfaces. When ensuring that both are closely attached and in a horizontal state, the solder flow rate can be controlled by the temperature, time, and gas environment during sintering. Using the siphon principle, the solder preferentially flows into the gap between the ferrite and the heat sink carrier to ensure the gap filling effect of the solder, and finally achieve the uniformity of the welding height and the sintering void ratio, thereby improving the grounding effect of chip welding and increasing the overall product yield. Therefore, this magnetic force application structure ensures the stability of the stacked structure, the effect of plane parallelism, and the sintering void ratio.

[0049] Specifically, the cross-section of the sintering carrier bottom plate 100 is in a U-shaped structure, as Figure 4 shown. The width of the cavity surrounded by the U-shaped structure of the sintering carrier bottom plate 100 is the same as the width of the MEMS circulator; the height of the cavity surrounded by the U-shaped structure of the sintering carrier bottom plate 100 is the same as the height of the MEMS circulator.

[0050] Exemplarily, the width of the MEMS circulator is generally determined by the lengths of the chip, the solder, and the heat sink carrier. The width of the cavity surrounded by the U-shaped structure of the sintering carrier bottom plate 100 is the same as the width of the MEMS circulator, which can just clamp the chip, the solder, and the heat sink carrier, so that the stacked structure of the chip, the solder, and the heat sink carrier will not be misaligned.

[0051] Exemplarily, the height of the MEMS circulator is generally determined by the thicknesses of the chip, the solder, and the heat sink carrier. The height of the cavity surrounded by the U-shaped structure of the sintering carrier bottom plate 100 is the same as the height of the MEMS circulator. When the isolation structure 200 covers the cavity, it can apply a certain force in the vertical direction of the chip, the solder, and the heat sink carrier, so that the stacked structure of the chip, the solder, and the heat sink carrier will not be skewed.

[0052] Specifically, the bottom surface of the sintering carrier bottom plate 100 is in contact with the heat sink carrier in the MEMS circulator; the thickness of the bottom surface of the sintering carrier bottom plate 100 is greater than the thickness of the heat sink carrier in the MEMS circulator.

[0053] Exemplarily, the thickness of the bottom surface of the sintering carrier bottom plate 100 is relatively large and is not easily burned through during the sintering process, which is beneficial to the formation of the heat sink carrier.

[0054] Specifically, the number of grooves in the isolation structure 200 is the same as the number of ferrites in the MEMS circulator; the positions of the grooves in the isolation structure 200 correspond to the positions of the ferrites in the MEMS circulator up and down.

[0055] Exemplarily, a magnetic force application structure 300 is placed in each groove of the isolation structure 200, such as Figure 4 and Figure 5 shown. Actually, each magnetic force application structure 300 corresponds to each ferrite, which is beneficial for the magnetic force application structure 300 to apply a uniform magnetic force to the ferrite, so that the ferrite is placed horizontally in the chip cavity.

[0056] Specifically, the isolation structure 200 is a T-shaped structure, including a first part 201 and a second part 202. The first part 201 is located above the second part 202; the length of the first part 201 is greater than the length of the second part 202; the thickness of the first part 201 is greater than the thickness of the second part 202.

[0057] Exemplarily, the groove is located in the first part 201, and the first part 201 is mainly used to place the magnetic force application structure 300. The second part 202 is mainly used to seal the cavity and isolate the MEMS circulator in the cavity from the outside of the cavity. The isolation structure 200 is designed as a T-shaped structure, and the second part 202 is as short or thin as possible on the premise of ensuring the overall performance, which is beneficial to reducing the pressure on the sintering carrier plate 100, prolonging the service life, saving materials and controlling costs.

[0058] Specifically, the length of the first part 201 is greater than or equal to the overall length of the sintering carrier plate 100, which is convenient for clamping.

[0059] Specifically, the upward attraction provided by the magnetic force application structure 300 for the ferrite in the MEMS circulator is greater than the gravity of the ferrite itself.

[0060] Exemplarily, the ferrite is subject to gravity downward in the free state, and the gravity expression is:

[0061] G = mg (1)

[0062] Wherein, m represents the mass of the ferrite, and g is the acceleration due to gravity. It can be seen from the above formula that the gravity and the mass are linearly related.

[0063] The expression of the upward attraction F provided by the magnetic force application structure 300 for the ferrite in the MEMS circulator is:

[0064] F = kB×2A (2)

[0065] Wherein, k is the magnetic force coefficient, B is the magnetic induction intensity at the surface position of the ferrite by the magnetic force applying structure 300, and A is the effective area of the ferrite relative to the magnetic force applying structure 300.

[0066] When F > G, that is, when the magnetic force F on the ferrite is greater than its own gravity G, the ferrite will not tilt in the cavity. The magnetic force applying structure 300 provides an upward attraction force for the ferrite to offset the influence of gravity. When there are multiple ferrites with different thicknesses, the corresponding magnetic force applying structures 300 can provide different upward attraction forces for the ferrites to offset their own gravity, that is, it can ensure that different ferrites are horizontally placed in the cavity, effectively preventing sintering unqualified caused by tilting in the cavity due to small size.

[0067] The magnetic force applying structure 300 can limit the displacement of the stacking structure in the horizontal direction, preventing relative displacement between the chip and the bottom heat sink carrier during the movement process, resulting in sintering unqualified.

[0068] It can be seen that the micro-mechanical tooling for stabilizing material stacking provided by the present invention provides an upward attraction force for the ferrite through the magnetic force applying structure 300 to offset the influence of gravity, which can ensure that the ferrite is horizontally placed in the cavity, effectively preventing tilting in the cavity due to small size of the ferrite. By sintering the bearing bottom plate 100, relative displacement between the chip in the MEMS circulator and the bottom heat sink carrier can be restricted, and sintering failure caused by phenomena such as ferrite tilting and chip misalignment can be prevented, improving the sintering yield of the MEMS circulator.

[0069] Moreover, the structural form of the micro-mechanical tooling is simple and stable, and it can withstand high temperatures, improving the sintering efficiency of the MEMS circulator.

[0070] The embodiment of the present application also provides a MEMS circulator, which is sintered by including the micro-mechanical tooling for stabilizing material stacking as described in the above embodiment.

[0071] It should be understood that the magnitudes of the sequence numbers of the steps in the above embodiments do not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0072] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A micromachining tooling for stabilizing material stacking, applied to a sintered MEMS circulator, characterized in that Comprising: A sintered load-bearing bottom plate, an isolation structure, and a magnetic force application structure; The sintered load-bearing bottom plate is placed below the isolation structure; The MEMS circulator is placed in a cavity enclosed by the sintered load-bearing bottom plate and the isolation structure; The upper surface of the isolation structure has a plurality of grooves with preset widths, and the magnetic force application structure is placed in the grooves; The magnetic force application structure is used to provide an upward attraction force for the ferrite in the MEMS circulator. The upward attraction force provided by the magnetic force application structure for the ferrite in the MEMS circulator is greater than the gravity of the ferrite itself, and the upward attraction force provided by the magnetic force application structure for the ferrite in the MEMS circulator varies according to the thickness of the ferrite; Wherein, the isolation structure is a T-shaped structure, including a first part and a second part; The first part is located above the second part; The length of the first part is greater than the length of the second part; The thickness of the first part is greater than the thickness of the second part; The grooves are located in the first part, and the length of the first part is greater than or equal to the overall length of the sintered load-bearing bottom plate.

2. The micromachining tooling for a stable material stack according to claim 1, characterized in that, The cross-section of the sintered load-bearing bottom plate is a U-shaped structure; The width of the cavity enclosed by the U-shaped structure of the sintered load-bearing bottom plate is the same as the width of the MEMS circulator; The height of the cavity enclosed by the U-shaped structure of the sintered load-bearing bottom plate is the same as the height of the MEMS circulator.

3. The micromachining tooling with a stable material stack as claimed in claim 2, wherein The bottom surface of the sintered load-bearing bottom plate is in contact with the heat sink carrier in the MEMS circulator; The thickness of the bottom surface of the sintered load-bearing bottom plate is greater than the thickness of the heat sink carrier in the MEMS circulator.

4. The micromachining tooling with a stacked stable material as claimed in claim 1, wherein The number of grooves in the isolation structure is the same as the number of ferrites in the MEMS circulator; The positions of the grooves in the isolation structure correspond to the positions of the ferrites in the MEMS circulator up and down.

5. The micromachining tooling with a stacked stable material as claimed in claim 1, wherein, The expression for the upward attraction force provided by the magnetic force application structure for the ferrite in the MEMS circulator is: F = kB×2A Wherein, k is the magnetic force coefficient, B is the magnetic induction intensity at the surface position of the ferrite of the magnetic force application structure, and A is the effective area of the ferrite relative to the magnetic force application structure.

6. A MEMS circulator, characterized in that, Sintered by a micromachining tooling including a stable material stack as described in any one of claims 1-5.

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