Micro-motion magnetic suspension Z-axis driving device

Abstract

The embodiment of the invention discloses a micro-motion magnetic suspension Z-axis driving device which comprises a voice coil motor stator assembly, a voice coil motor rotor assembly and a magnetic suspension gravity compensation assembly, and the magnetic suspension gravity compensation assembly comprises a dynamic magnetic force assembly and a static magnetic force assembly. The dynamic magnetic assembly and the static magnetic assembly are respectively connected with the voice coil motor stator assembly and the voice coil motor rotor assembly; the magnetizing directions of the dynamic magnetic assembly and the static magnetic assembly are opposite; repulsive force generated by the magnetic suspension gravity compensation assembly in the Z-axis direction is equal to the sum of gravity of the load, the voice coil motor rotor assembly and the static magnetic force assembly. Through cooperative work of magnetic suspension guiding, permanent magnet constant force compensation and coil dynamic magnetic field compensation, negative influences of load changes on Z-axis dynamic response and control precision are effectively overcome, and the overall efficiency and the product yield of semiconductor device packaging and testing are remarkably improved.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and in particular to a micro-motion magnetic levitation Z-axis drive device. Background Technology

[0002] High-precision Z-axis motion has become a critical component in semiconductor device packaging and testing. However, the unique vertical motion direction of Z-axis drives makes them significantly sensitive to different loads in terms of dynamic response and control accuracy, especially for micro-motion Z-axis drives with short Z-axis strokes that require even higher control precision. Changes in load (such as changing different test probes, workpiece holders, or samples) directly alter the forces acting on the Z-axis, disturbing the original control parameters and thus affecting overall positioning accuracy and work efficiency.

[0003] Traditional Z-axis drive mechanisms use a guide rail and slider (such as a ball bearing guide) in conjunction with a cylinder for load compensation. However, due to frictional resistance and the nonlinearity of the cylinder itself, this method is insufficient to meet increasingly stringent micro / nano-level precision requirements. Traditional Z-axis drive mechanisms have the following drawbacks: (1) Traditional Z-axis drive devices often use combined guide rail sliders, which have inherent frictional resistance and are easily affected by tiny dust particles, reducing the smoothness of motion and repeatability of positioning accuracy.

[0004] (2) The gravity of the load on the Z-axis drive device is its most important constant external force, which directly affects the torque and control accuracy required for the drive. Although the traditional cylinder compensation method can offset part of the gravity, the cylinder itself has problems such as friction, leakage and hysteresis, making it difficult to achieve a constant, frictionless compensation force.

[0005] (3) Changes in load, such as changing workpieces or fixtures, will cause dynamic changes in the gravity acting on the Z-axis. If the compensation force is constant, the control system of the drive device will be unable to maintain an ideal working state when the load changes, and the control accuracy will drop rapidly. Summary of the Invention

[0006] The technical problem to be solved by the embodiments of the present invention is to provide a micro-motion magnetic levitation Z-axis drive device to improve the Z-axis control accuracy.

[0007] To address the aforementioned technical problems, this invention provides a micro-motion magnetic levitation Z-axis drive device, comprising a voice coil motor stator assembly, a voice coil motor mover assembly, and a magnetic levitation gravity compensation component for gravity compensation of the voice coil motor mover assembly and the load on the voice coil motor mover assembly. The magnetic levitation gravity compensation component includes a dynamic magnetic component and a static magnetic component arranged at relative intervals, which are respectively connected to the voice coil motor stator assembly and the voice coil motor mover assembly. The magnetization directions of the dynamic magnetic component and the static magnetic component are opposite, generating repulsive forces in the horizontal and Z-axis directions. The repulsive force in the Z-axis direction generated by the magnetic levitation gravity compensation component is equal to the sum of the gravity of the load, the voice coil motor mover assembly, and the static magnetic component.

[0008] Furthermore, the static magnetic component includes magnet A, and the dynamic magnetic component includes magnet B and a magnetic compensation unit. The magnetic compensation unit consists of an iron core and a compensation coil. Magnets A and B are staggered relative to each other, with a preset distance between them.

[0009] Furthermore, the magnetic levitation gravity compensation component comprises four sets, which are arranged symmetrically on all four sides.

[0010] Furthermore, the voice coil motor stator assembly includes a base, a voice coil motor stator, and a support component. The voice coil motor stator and the support component are respectively disposed on the base. The dynamic magnetic components of the four sets of magnetic levitation gravity compensation components are respectively disposed on the front, back, left, and right sides of the support component. The voice coil motor mover assembly includes a top plate, a voice coil motor mover, and four sets of magnetic steel connectors. The top plate is connected to the voice coil motor mover, and the four sets of magnetic steel connectors are respectively connected to the top plate. The static magnetic components of the four sets of magnetic levitation gravity compensation components are respectively disposed on the four sets of magnetic steel connectors.

[0011] Furthermore, a core slot is provided on magnet B, with the front end of the core located in the core slot and the compensation coil correspondingly located on the rear end of the core.

[0012] Furthermore, the magnetic center lines of magnet B and the magnetic compensation unit are on the same straight line.

[0013] Furthermore, the device adjusts the direction and magnitude of the current in the compensation coil according to the load size, so that the repulsive force generated by the magnetic levitation gravity compensation component in the Z-axis direction is equal to the sum of the gravity of the load, the voice coil motor mover assembly, and the static magnetic component.

[0014] Furthermore, the repulsive force F in the Z-axis direction generated by the magnetic levitation gravity compensation component z satisfy: F z = F 恒 +K0·N·I; Among them, F 恒The repulsive force in the Z-axis direction generated between magnet A and magnet B is given by K0, which is a proportionality constant, N is the number of turns of the compensation coil, and I is the current flowing through the compensation coil. I is positive when a positive current flows and negative when a reverse current flows.

[0015] The beneficial effects of this invention are as follows: 1. This invention utilizes the interaction force between permanent magnets to suspend the voice coil motor's mover assembly and the load on it, completely eliminating mechanical contact and friction. This invention significantly improves the smoothness of motion, sensitivity, and nanometer-level repeatability, effectively overcoming the precision bottleneck of traditional mechanical guidance. The suspended state of the drive device not only significantly reduces frictional resistance caused by external contact, but more importantly, it effectively isolates vibration transmission from the machine base, thereby greatly improving positioning accuracy, repeatability, and micro-motion accuracy.

[0016] 2. This invention utilizes a constant magnetic field generated by a fixed permanent magnet to create a repulsive force, thereby providing constant compensation for the gravitational force generated by the Z-axis load. This magnetic compensation method is frictionless, leak-free, and has a fast response speed, enabling more precise and stable countermeasures against the effects of gravity. This lays a solid foundation for subsequent dynamic control and avoids the accuracy loss associated with cylinder compensation methods.

[0017] 3. This invention, based on the constant magnetic field compensation of a permanent magnet, introduces a controllable coil. By applying currents of different magnitudes and directions, the coil can generate an adjustable dynamic magnetic field. This dynamic magnetic field is superimposed on the constant magnetic field generated by the permanent magnet, and together they act on the Z-axis, thereby achieving: (1) Dynamically adjustable compensation force: By precisely controlling the current of the coil, the magnitude and direction of the total compensation force can be changed in real time to adapt to the instantaneous changes in the load.

[0018] (2) Constant force + dynamic force integration: The compensation force consists of gravity compensation (provided by permanent magnet) of the constant part and dynamic compensation (coil current control) of the dynamic part.

[0019] (3) High robustness: Even if the load changes significantly, the performance and control accuracy of the drive device can be maintained without loss by dynamically adjusting the coil current, which is especially critical for scenarios where the client load changes frequently. Attached Figure Description

[0020] Figure 1 This is a three-dimensional structural diagram of the micro-motion magnetic levitation Z-axis drive device according to an embodiment of the present invention.

[0021] Figure 2 This is an exploded view of the micro-motion magnetic levitation Z-axis drive device according to an embodiment of the present invention.

[0022] Figure 3This is a top view of the micro-motion magnetic levitation Z-axis drive device according to an embodiment of the present invention.

[0023] Figure 4 yes Figure 3 Sectional view at point CC.

[0024] Figure 5 This is a three-dimensional structural diagram of the support member according to an embodiment of the present invention.

[0025] Figure 6 This is an exploded view of the magnetic levitation gravity compensation component according to an embodiment of the present invention.

[0026] Figure 7 This is a top view of the internal structure of the micro-motion magnetic levitation Z-axis drive device according to an embodiment of the present invention.

[0027] Figure 8 This is a schematic diagram of the structure of magnet A and magnet B in an embodiment of the present invention.

[0028] Explanation of icon numbers 10. Voice coil motor stator assembly; 11. Base; 12. Voice coil motor stator; 13. Support component; 14. Screw; 15. Round hole; 20. Voice coil motor mover assembly; 21. Top plate; 22. Voice coil motor mover; 23. Magnet connector; 30. Magnetic levitation gravity compensation assembly; 31. Magnet A; 32. Magnet B; 33. Iron core; 34. Compensation coil; 35. Bolt; 36. Iron core slot. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] In this embodiment of the invention, directional indicators (such as up, down, left, right, front, back, etc.) are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicator will also change accordingly.

[0031] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0032] Please refer to Figures 1 to 8 The micro-motion magnetic levitation Z-axis drive device of this invention includes a voice coil motor stator assembly, a voice coil motor mover assembly, and a magnetic levitation gravity compensation assembly.

[0033] The magnetic levitation gravity compensation component guides the movement of the voice coil motor mover assembly and compensates for the gravity load on the voice coil motor mover assembly. The magnetic levitation gravity compensation component includes dynamic magnetic components and static magnetic components arranged at relative intervals. The dynamic magnetic components and static magnetic components are respectively connected to the voice coil motor stator assembly and the voice coil motor mover assembly.

[0034] The dynamic magnetic component and the static magnetic component are arranged side-by-side and staggered vertically, with their magnetic center lines horizontal. The magnetization directions of the dynamic and static magnetic components are opposite (either NN or SS, generating a repulsive force between like poles), and their staggered arrangement generates repulsive forces in both the horizontal and Z-axis directions. The horizontal repulsive force keeps the dynamic and static magnetic components spaced apart, achieving contactless and frictionless motion guidance. The repulsive force in the Z-axis direction generated by the magnetic levitation gravity compensation component is equal to the sum of the weights of the load, the voice coil motor actuator assembly, and the static magnetic component. In practice, multiple sets of magnetic levitation gravity compensation components are used, i.e., two or more sets, symmetrically arranged. This invention, through three technical solutions—magnetic levitation guidance, magnetic gravity compensation, and coil dynamic magnetic field compensation—achieves excellent dynamic performance and extremely high control precision in the Z-axis drive device under different load conditions.

[0035] In practical implementation, the magnetic levitation gravity compensation component can also adopt two sets of dynamic magnetic components and static magnetic components (this structure is more complex and the number of components increases). The two sets of dynamic magnetic components and static magnetic components are set horizontally and vertically opposite to each other (magnet A and magnet B are opposite but not separated). The horizontally opposite dynamic magnetic components and static magnetic components provide a horizontal repulsive force F1, and the vertically opposite dynamic magnetic components and static magnetic components provide a vertical repulsive force F2.

[0036] In one implementation, the static magnetic component includes magnet A, and the dynamic magnetic component includes magnet B and a magnetic compensation unit. The magnetic compensation unit consists of an iron core and a compensation coil. Magnets A and B are staggered relative to each other, with a preset distance between their opposite sides. The preset distance is preferably set between 0.005mm and 0.01mm. The dynamic magnetic component and the static magnetic component generate repulsive forces in the Z-axis direction and the horizontal direction. The horizontal repulsive force keeps magnets A and B spaced apart, achieving contactless and frictionless motion guidance between them. Please refer to... Figures 7-8 Since magnet B remains fixed, not only will a normal repulsive force F1 be generated between magnet A and magnet B, but also a tangential repulsive force F2 will be generated. F2 is the constant force component that compensates for gravity.

[0037] The magnet B has a core slot, preferably racetrack-shaped. The front end of the core is located in the core slot, and the compensation coil is located on the rear end of the core. The core is fixed to the support member by bolts. The magnetic center lines of magnet B and the magnetic compensation unit are on the same straight line.

[0038] In one implementation method, the magnetic levitation gravity compensation assembly includes four sets, which are arranged symmetrically in pairs facing each other. The four sets of magnetic levitation gravity compensation assemblies generate equal repulsive forces in the four directions: front, back, left, and right.

[0039] The voice coil motor stator assembly includes a base, a voice coil motor stator, and a support. The voice coil motor stator and support are screwed onto the base, with the voice coil motor stator located in the center of the support. Four sets of dynamic magnetic components are bolted to the front, back, left, and right sides of the support. The support has grooves to accommodate magnet B and the compensation coil; a central hole accommodates the voice coil motor stator, and the voice coil motor mover is located within the stator. The voice coil motor stator contains the voice coil motor coil, and the voice coil motor mover contains the voice coil motor magnet. This invention places all components with coils on the base to prevent the wires connected to the coils from moving.

[0040] The voice coil motor mover assembly includes a top plate, a voice coil motor mover, and four sets of magnet connectors. The top plate is connected to the voice coil motor mover, and the four sets of magnet connectors are correspondingly connected to the top plate. The four sets of static magnetic components are respectively set on the four sets of magnet connectors.

[0041] As one implementation method, the micro-motion magnetic levitation Z-axis drive device adjusts the direction and magnitude of the current in the compensation coil in real time according to the load size, so that the total repulsive force generated by each magnetic levitation gravity compensation component in the Z-axis direction is equal to the sum of the gravity of the load, the voice coil motor mover assembly, and the static magnetic force assembly.

[0042] The travel distance of the micro-motion magnetic levitation Z-axis drive device in this embodiment of the invention is typically ±1mm. Therefore, the fluctuation of the repulsive force in the Z-axis direction of the voice coil motor mover at different positions can be ignored.

[0043] If the motion stroke is large, the micro-motion magnetic levitation Z-axis drive device will adjust the direction and magnitude of the current in the compensation coil in real time according to the offset distance and the load size, so that the total repulsive force generated by each magnetic levitation gravity compensation component in the Z-axis direction is equal to the sum of the gravity of the load, the voice coil motor mover assembly and the static magnetic force assembly.

[0044] As one implementation method, the repulsive force F generated by the magnetic levitation gravity compensation component in the Z-axis direction z satisfy: F z = F 恒 +K0·N·I; Among them, F 恒 F2 is the repulsive force generated between magnets A and B in the Z-axis direction. K0 is a comprehensive proportionality constant, with units of N / (turns·A), determined by the core parameters (μ, L, S), the magnetic field characteristics of magnet B, the air gap size, and the structural layout of the device. It is a constant and can be obtained through experimental testing. N is the number of turns in the compensation coil, and I is the current flowing through the compensation coil (A). I ​​is positive when a forward current flows and negative when a reverse current flows. N is a design parameter, and the product of K0 and N can be changed by adjusting N to adapt to the design requirements of Z-axis drive devices with different load ranges (e.g., for large load Z-axis drives, the number of turns N can be increased to improve the compensation force per unit current).

[0045] When a direct current is applied to the compensation coil, a magnetic field is generated in the iron core. When the direction of the magnetic field generated in the iron core is the same as the direction of the magnetic field of magnet B, the two magnetic fields are superimposed, increasing the total elastic force. The total elastic force equals the constant force plus the compensation force. If the direction of the current is reversed, and the direction of the magnetic field generated in the iron core is opposite to the direction of the magnetic field of magnet B, the two magnetic fields are subtracted, decreasing the total elastic force. The total elastic force equals the constant force minus the compensation force. When the load is greater than the set value (increases), the coil compensation force is directed upwards, and the current is precisely controlled to compensate for the increased load. When the load equals the design value, the current is 0. When the load is less than the set value (decreases), the coil compensation force is directed downwards, and the current is precisely controlled to compensate for the decreased load.

[0046] This invention achieves dynamic adaptation of the compensating force by adjusting the magnetic field superposition effect through coil current. The key formulas and explanations are as follows: (1) Basic formula for total compensation force: Total elastic force (F) z = Constant force compensation part (F) 恒 ± Coil dynamic compensation force (F) 补 ); Signing rules: When the magnetic field of the compensation coil is in the same direction as the magnetic field of magnet B, take "+" (total elastic force increases); when the magnetic field of the compensation coil is in the opposite direction to the magnetic field of magnet B, take "-" (total elastic force decreases).

[0047] (2) Constant force compensation part (F) 恒 )definition: F 恒 = Tangential repulsive force (F2) generated between magnet A and magnet B.

[0048] Source: The repulsive force between the same poles of fixed magnet A and magnet B (with opposite magnetization directions and set opposite to each other) is used to counteract the basic gravity of the moving part of the drive device.

[0049] (3) Coil dynamic compensation force (F) 补 Load adaptation formula: F 补∝ I × B (I is the magnitude and direction of the current flowing through the coil, and B is the magnetic field strength generated by the coil) (∝ means "proportional to").

[0050] Load adaptation logic: When the load exceeds the design value (load increases): a positive current is applied to the coil, F 补 Direction upward, F 补 = Load increment (precisely offsetting the increased load portion), at which point F z = F 恒 + F 补 ; When the load equals the design value: coil current I = 0, F 补 = 0, at this time F z = F 恒 ; When the load is less than the design value (load decreases): reverse current is applied to the coil, F 补 Direction downwards, F 补 = Load reduction (precisely offsetting the reduced load portion), at this time F z = F 恒 - F 补 .

[0051] (4) Prerequisites for levitation force balance (and conditions for compensating force coordination): The four sets of magnetic levitation gravity compensation components are arranged in pairs in a symmetrical configuration. The sum of the horizontal normal repulsive forces ΣF1 generated by them forms a balanced horizontal constraint, ensuring a stable air gap between magnets A and B without contact. This air gap provides a frictionless levitation foundation for the tangential repulsive force F2 along the vertical Z-axis. Furthermore, the threshold of ΣF1 must match the design value of the gravity plus load of the moving part of the worktable to prevent air gap displacement from causing magnetic levitation failure.

[0052] Specifically, the design of ΣF1 must meet the engineering threshold that prevents the horizontal air gap from being squeezed and deviated. Its minimum design value must be greater than or equal to the equivalent squeezing force of the total vertical gravity on the horizontal air gap, that is, ΣF1 ≥ gravity of the moving part of the worktable + load design value. However, in actual engineering design, ΣF1 is an interference design, and is taken as 1.2 to 2 times (gravity of the moving part of the worktable + load design value), that is, ΣF1 = K × (gravity of the moving part of the worktable + load design value), where K ∈ [1.2, 2].

[0053] This invention constructs a comprehensive, high-precision Z-axis dynamic compensation system through the coordinated operation of magnetic levitation guidance, permanent magnet constant force compensation, and coil dynamic magnetic field compensation. This system effectively overcomes the negative impact of load variations on Z-axis dynamic response and control accuracy, significantly improving the overall efficiency and product yield of semiconductor device packaging and testing.

[0054] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A micro-motion magnetic levitation Z-axis drive device, comprising a voice coil motor stator assembly and a voice coil motor mover assembly, characterized in that, It also includes a magnetic levitation gravity compensation component for gravity compensation of the voice coil motor mover assembly and the load on the voice coil motor mover assembly. The magnetic levitation gravity compensation component includes a dynamic magnetic component and a static magnetic component arranged at relative intervals. The dynamic magnetic component and the static magnetic component are respectively connected to the voice coil motor stator assembly and the voice coil motor mover assembly. The magnetization directions of the dynamic magnetic component and the static magnetic component are opposite, and they generate repulsive forces in the horizontal direction and the Z-axis direction. The repulsive force generated by the magnetic levitation gravity compensation component in the Z-axis direction is equal to the sum of the gravity of the load, the voice coil motor mover assembly, and the static magnetic component.

2. The micro-motion magnetic levitation Z-axis drive device as described in claim 1, characterized in that, The static magnetic component includes magnet A, and the dynamic magnetic component includes magnet B and a magnetic compensation unit. The magnetic compensation unit consists of an iron core and a compensation coil. Magnets A and B are staggered relative to each other, with a preset distance between them.

3. The micro-motion magnetic levitation Z-axis drive device as described in claim 2, characterized in that, The magnetic levitation gravity compensation components consist of four sets, arranged symmetrically on all four sides.

4. The micro-motion magnetic levitation Z-axis drive device as described in claim 3, characterized in that, The voice coil motor stator assembly includes a base, a voice coil motor stator, and a support component. The voice coil motor stator and the support component are respectively mounted on the base. The dynamic magnetic components of the four sets of magnetic levitation gravity compensation components are respectively mounted on the front, back, left, and right sides of the support component. The voice coil motor mover assembly includes a top plate, a voice coil motor mover, and four sets of magnet connectors. The top plate is connected to the voice coil motor mover, and the four sets of magnet connectors are respectively connected to the top plate. The static magnetic components of the four sets of magnetic levitation gravity compensation components are respectively mounted on the four sets of magnet connectors.

5. The micro-motion magnetic levitation Z-axis drive device as described in claim 2, characterized in that, The magnet B has a core slot, with the front end of the core located in the core slot and the compensation coil located on the rear end of the core.

6. The micro-motion magnetic levitation Z-axis drive device as described in claim 5, characterized in that, The magnetic center lines of magnet B and the magnetic compensation unit are on the same straight line.

7. The micro-motion magnetic levitation Z-axis drive device as described in claim 2, characterized in that, The device adjusts the direction and magnitude of the current in the compensation coil according to the load size, so that the repulsive force generated by the magnetic levitation gravity compensation component in the Z-axis direction is equal to the sum of the gravity of the load, the voice coil motor mover assembly, and the static magnetic component.

8. The micro-motion magnetic levitation Z-axis drive device as described in claim 7, characterized in that, The repulsive force F in the Z-axis direction generated by the magnetic levitation gravity compensation component z satisfy: F z = F 恒 +K0·N·I; Among them, F 恒 The repulsive force in the Z-axis direction generated between magnet A and magnet B is given by K0, which is a proportionality constant, N is the number of turns of the compensation coil, and I is the current flowing through the compensation coil. I is positive when a positive current flows and negative when a reverse current flows.

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