Wire bonding machine ball micro-deformation control method and system

Abstract

This invention discloses a method and system for controlling the micro-deformation of solder balls in a wire bonding machine, belonging to the field of semiconductor packaging technology. In the high-speed approach phase, a closed-loop position control mode is used to drive the bonding head to a safe suspended position before the contact point. In the contact detection phase, a high-gain position servo mode is switched to, and the rate of change of the force signal is calculated in real time. When the rate of change exceeds a preset threshold, a contact event is triggered, and the current bonding head position is recorded as the force control reference zero point. In the welding phase, a pressure control mode is switched to, and the position feedback of the bonding head is acquired in real time, calculating its position deviation from the force control reference zero point. Based on the position deviation and the total disturbance estimated by the state observer, a compensation force is generated and superimposed on the thrust output by the motor. Depending on the position deviation during the welding process, the system adaptively switches between the pressure control mode and the position control mode once or multiple times. This significantly improves bonding head accuracy, reduces the occurrence of ball defects, and increases product yield.

Description

Technical Field

[0001] This application belongs to the field of semiconductor packaging technology, and in particular relates to a method and system for controlling the micro-deformation of solder balls in a wire bonding machine. Background Technology

[0002] Wire bonding machines, as high-precision, high-speed packaging equipment, have extremely high requirements for wire bonding quality, especially in high-end IC products, where the solder ball shape is often required to be highly consistent, with ball deformation uniformity controlled at around 2-3µm. However, in actual production, during ultrasonic bonding, high-frequency mechanical noise is mixed in with the sensor, which cannot completely filter out the excess noise, making it difficult to extract the true quasi-static pressure value, and the instability of the bonding causes slight deformation. The bonding head, transducer, and Z-axis drive mechanism are not ideal rigid bodies, forming a complex multi-mass block-spring-damping system, which generates parasitic vibration modes that interfere with the true transmission of pressure, resulting in a difference between the instantaneous force acting on the bonding pad interface and the sensor reading or motor command force.

[0003] All of the above anomalies can lead to issues such as bonding head vibration and overshoot of control force, resulting in poor wire bonding sphericity, mainly manifested as large and small balls and aluminum extrusion. Poor sphericity is not just an appearance problem, but a critical defect affecting the product's internal quality and lifespan. Large and small balls can cause problems such as weak mechanical strength and electrical short circuits. Aluminum extrusion can invade and damage the passivation layer under the chip's aluminum pads, leading to problems such as leakage and corrosion. In production, precise control of parameters such as arcing parameters and bonding pressure is required to avoid these problems. Summary of the Invention

[0004] To address the spherical defects (including but not limited to large and small balls, aluminum extrusion, etc.) caused by the inherent physical randomness of the electronic arcing (EFO) process and the limitations of the mechanical control system in the bonding stage in existing wire bonding processes, this application provides a method and system for controlling the micro-deformation of welding balls in a wire bonding machine.

[0005] The technical solution is as follows:

[0006] In a first aspect, a method for controlling micro-deformation of solder balls in a wire bonding machine is provided, comprising the following steps:

[0007] During the high-speed approach phase, as the bonding head moves along the Z-axis toward the chip pad, a closed-loop position control mode is used to drive the bonding head to a safe hovering position before the contact point.

[0008] During the contact detection phase, switch to high-gain position servo mode, calculate the rate of change of the force signal in real time, and trigger contact event determination when the rate of change exceeds a preset threshold, and record the current position of the bearing head as the force control reference zero point;

[0009] Upon entering the welding stage, switch to pressure control mode to control the bonding head to apply a preset welding force to the pads, and obtain the position feedback of the bonding head in real time to calculate its position deviation from the zero point of the force control reference.

[0010] Based on the position deviation and the total disturbance obtained through the state observer, a compensation force is generated and superimposed on the thrust output by the motor;

[0011] Based on the positional deviation during the welding process, at least one adaptive switch is made between the pressure control mode and the position control mode;

[0012] The adaptive switching includes: switching to position control mode when the position deviation exceeds a first set threshold, switching to pressure control mode during the middle of welding, and switching back to position control mode at the end of welding when the contact force approaches the material's upper limit.

[0013] A further technical solution is provided: the formula for calculating the thrust output of the motor in closed-loop position control mode is as follows:

[0014] ;

[0015] in, It is a position command. For speed, For acceleration; The position is fed back by the grating ruler. For the speed of the head; The PID proportional signal for the position loop. The differential gain of the position loop, For acceleration feedforward gain, This is the velocity feedforward gain.

[0016] A further technical solution, in high-gain position servo mode, is to calculate the rate of change of the force signal using the following formula:

[0017] ;

[0018] in, The rate of change of the force signal, This represents the current force sensor signal value. This represents the sampling time interval.

[0019] A further technical solution is that the state observer is based on a system dynamics model that includes the total disturbance, and the system dynamics model is as follows:

[0020]

[0021] in, For equivalent quality, The damping coefficient is... This is the stiffness coefficient. For the acceleration of the head, The total disturbance factor, This refers to the thrust output by the motor.

[0022] A further technical solution is that the compensation force is generated by the following formula:

[0023] ;

[0024] in, Representing a moment, This is the virtual stiffness coefficient. This is the virtual damping coefficient. This represents the time coefficient of the high-pass filter. It is the disturbance compensation coefficient.

[0025] Secondly, a wire bonding machine solder ball micro-deformation control system is provided to implement the above-mentioned wire bonding machine solder ball micro-deformation control method, including:

[0026] The motion control card module is used to generate position commands and force control commands, and execute mixed-mode control algorithms, PID control algorithms, and disturbance observation.

[0027] The drive module, electrically connected to the motion control card module, is used to receive position commands and output drive signals, wherein the drive signals are the power stage current or voltage of the actuator motor;

[0028] The bonding head module is connected to the drive module and is used to move the bonding head along the Z-axis of the pad under the action of the drive signal; it includes a force sensor for detecting the welding force and a grating ruler for detecting the absolute or relative position of the bonding head.

[0029] The bus is communicatively connected to the motion control card module, the drive module, and the connector module to enable data communication between the modules.

[0030] The motion control card module is configured to receive feedback signals from the dynamic force sensor and the grating ruler, control the drive module according to the above control process, and realize adaptive switching between pressure control mode and position control mode.

[0031] In a further technical solution, the motion control card module is a digital signal processor and / or a field-programmable gate array (FPGA). The digital signal processor is used to perform control algorithm logic operations and parameter tuning, and the FPGA is used to implement hardware-level interpolation and high-speed synchronous triggering of position commands for each axis.

[0032] In a further technical solution, the drive module includes a motor, one end of which is connected to the head module for transmission, serving as the direct driving force source for the head module.

[0033] In a further technical solution, the force sensor is a piezoelectric ceramic or strain gauge sensor.

[0034] In a further technical solution, the position signal generated by the grating ruler in pressure control mode is used to construct an active compensation algorithm for disturbance observation and position control assistance.

[0035] The technical solution includes at least the following technical effects:

[0036] This paper presents a method for controlling the micro-deformation of solder balls in wire bonding machines. By constructing a collaborative control system that integrates high-gain position servo precise contact detection, total disturbance feedforward compensation based on a state observer, real-time position deviation feedback compensation, and dynamic switching of multi-stage adaptive control modes, it achieves rapid perception and active suppression of random disturbances such as electronic ignition (EFO) impacts and system nonlinearities. This allows the bonding head to accurately maintain the preset pressure during the welding process to ensure the quality of solder ball formation, while also strongly constraining undesirable displacements to prevent aluminum extrusion and positional deviation. This significantly improves the consistency of solder ball size, shape regularity, and reliability of the welding interface, effectively solving defects such as uneven ball size and aluminum extrusion, and greatly improving the overall yield and stability of the wire bonding process.

[0037] This invention provides a micro-deformation control system for wire bonding machines, constructing a fully closed-loop control system based on multi-modal dynamic switching. The system includes a motion control card module as the computational hub; a high-speed real-time bus, drive module, force sensor, and grating ruler for data exchange and detection; a final actuator bonding module; a drive motor providing high bandwidth and high dynamic response power output; and the final actuator bonding module. A hybrid control strategy is employed to collaboratively optimize and dynamically decouple the traditionally independent pressure and position control loops, which suffer from bandwidth conflicts, in the time and frequency domains through high-order algorithms. This not only avoids the high costs and engineering complexity associated with simply increasing hardware bandwidth but also solves the fundamental problem of interface force control accuracy from a system dynamics perspective. Through this software-defined precise force control paradigm, this invention significantly reduces the process's dependence on extreme hardware performance, achieving optimized and highly consistent stress distribution at the bonding interface on the same hardware platform, thereby effectively improving the reliability of packaged interconnects and overall production yield.

[0038] It should be understood that the above general description and the following detailed description are merely exemplary and do not limit this application. Attached Figure Description

[0039] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0040] Figure 1 A flowchart of a method for controlling micro-deformation of welding balls in a wire bonding machine, provided as a preferred embodiment of this application;

[0041] Figure 2 A structural block diagram of a wire bonding machine ball micro-deformation control system provided in a preferred embodiment of this application;

[0042] Figure 3 A flowchart of a method for controlling micro-deformation of welding balls in a wire bonding machine, provided as another preferred embodiment of this application. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0044] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0045] To address the ball-forming defects (including but not limited to uneven ball size and aluminum extrusion defects) caused by the inherent physical randomness of the electronic arcing (EFO) process and the limitations of the mechanical control system in the bonding stage in existing wire bonding processes, a method for controlling the micro-deformation of the solder balls in a wire bonding machine that integrates pressure control and position control is proposed. This method can smoothly switch to position control by precisely adjusting the distance of the current force during welding pressure control, and then, as needed, can precisely and smoothly switch back to return force control based on the current position. This reduces bonding head jitter and overshoot, effectively improving uneven ball size and aluminum extrusion during the bonding process. This technology significantly improves bonding head accuracy, reduces ball-forming defects, increases product yield, and further enhances equipment reliability and process stability.

[0046] In one embodiment, such as Figure 1 As shown, a method for controlling micro-deformation of solder balls in a wire bonding machine is provided, comprising the following steps:

[0047] During the high-speed approach phase, as the bonding head moves along the Z-axis toward the chip pad, a closed-loop position control mode is used to drive the bonding head to a safe hovering position before the contact point.

[0048] During the contact detection phase, switch to high-gain position servo mode, calculate the rate of change of the force signal in real time, and determine that contact has occurred when the rate of change exceeds a preset threshold, and record the current position of the bearing head as the force control reference zero point.

[0049] Upon entering the welding stage, switch to pressure control mode to control the bonding head to apply a preset welding force to the pads, and obtain the position feedback of the bonding head in real time to calculate its position deviation from the zero point of the force control reference.

[0050] Based on the position deviation and the total disturbance estimated by the state observer, a compensation force is generated and superimposed on the thrust output by the motor.

[0051] Based on the positional deviation during the welding process, at least one adaptive switch is made between the pressure control mode and the position control mode;

[0052] The adaptive switching includes: switching to position control mode when the position deviation exceeds a first set threshold, switching to pressure control mode during the middle of welding, and switching back to position control mode at the end of welding when the contact force approaches the material's upper limit.

[0053] In one embodiment, such as Figure 2 As shown, a wire bonding machine solder ball micro-deformation control system is provided to implement a wire bonding machine solder ball micro-deformation control method. The system includes a motion control card module as the computing center; a high-speed real-time bus, drive module, force sensor, and grating ruler for data exchange and detection; a drive motor that provides high bandwidth and high dynamic response power output; a final actuator assembly module; an XY motion module; and a host computer module.

[0054] The motion control card module generates position and force control commands and executes hybrid mode control algorithms, PID control algorithms, and disturbance observation. As the core processor and algorithm carrier of the system, the motion control card module is preferably a dedicated motion control card based on a high-performance multi-core digital signal processor (DSP) and / or field-programmable gate array (FPGA), responsible for implementing the hybrid mode control, real-time PID control algorithm, disturbance observation, and safety monitoring logic of this invention. The DSP is responsible for performing complex floating-point operations, such as the logical judgment of the hybrid control state machine, online tuning of adaptive PID parameters, and model-based disturbance observer operations; the FPGA is dedicated to hardware-level parallel processing, realizing nanometer-level interpolation of position commands for each axis, high-speed comparator output, and precise hardware triggering and synchronization of multi-channel data acquisition.

[0055] The XY motion module is used to carry the bonding head module and move it in the horizontal plane to the target position directly above the pad. According to the program instructions issued by the motion control card module, it moves at high speed and high precision in the X and Y axis directions, accurately moving the bonding head module directly above the target pad. According to the trajectory instructions issued by the motion control card, it coordinates the movement of the XY module and the Z-axis bonding head.

[0056] The host computer module provides a human-machine interface and a process management hub for editing welding programs, setting parameters, monitoring processes, and managing production data.

[0057] The bus communicates with the motion control card module, drive module, and connector module, enabling data interconnection between modules via a high-speed real-time bus. This bus features microsecond-level cyclic communication cycles and extremely low jitter, ensuring that control commands and sensor feedback are transmitted at extremely high frequency and with extremely low latency, providing the necessary data transmission path for full closed-loop control.

[0058] The drive module is electrically connected to the XY motion module, which in turn is electrically connected to the motion control card. The drive module receives position commands and outputs drive signals, which are the power stage current or voltage of the actuator motor. The drive module includes a motor, one end of which is connected to the drive module, serving as the direct drive force source for the drive module. The drive unit receives command signals from the motion control card, modulates and aligns them, and outputs sufficient power stage current or voltage to drive the actuator motor, achieving rapid and linear control of the output torque.

[0059] Using a linear motor as the direct drive force source for the bonding head features zero transmission backlash, high acceleration, high bandwidth, and smooth thrust. Its high dynamic response characteristics enable the controller to quickly and accurately generate the required fine force, achieving precise force control and rapid mode switching, perfectly meeting the high-precision and high-speed technical requirements of wire bonding machine bonding modules.

[0060] The bonding head module, connected to the drive module and electrically connected to the host computer module, is used to move the bonding head along the Z-axis of the bonding pad under the action of a drive signal. The bonding head module is a highly integrated mechatronic end-effector, incorporating structural mechanics, thermodynamics, and electromagnetics, optimized synergistically to form a precision component. Its structure ensures extremely high axial stiffness while minimizing moving mass and lateral coupling stiffness. In the wire bonding machine, it is responsible for the most important and precise Z-axis movement. As the final convergence point of energy flow, information flow, and material flow in the wire bonding process, it affects the solder joint performance and arc characteristics; therefore, its dynamic characteristics directly determine the boundary capability of the bonding process.

[0061] A dynamic force sensor is preferred for detecting welding force. This dynamic force sensor, based on micro-strain gauges or piezoelectric ceramics, is directly integrated into the bonding module. It measures the normal force at the bonding interface in real time with extremely high response speed (natural frequency up to several kiloHz) and resolution (down to millinewtons). The signal, after being processed by a preamplifier, serves as the core feedback quantity in the pressure closed loop.

[0062] The preferred grating ruler is a high-resolution grating ruler, which serves as a displacement sensor to detect the absolute or relative position of the bearing head. As a position feedback element, the high-resolution grating ruler achieves nanometer-level resolution and is integrated within the bearing head module. It directly measures the absolute or relative displacement of the bearing head, providing feedback for position control mode. Simultaneously, in pressure control mode, its signal is used to construct disturbance observation and implement an active compensation algorithm for position control assistance.

[0063] like Figure 3 As shown, the workflow of the wire bonding machine's micro-deformation control system for welding balls is as follows:

[0064] During the wire bonding process, the motion control card issues high-precision position commands according to the preset motion trajectory. After receiving the position commands, the drive unit outputs the corresponding excitation current to the actuator motor through pulse width modulation or current loop control. At this stage, the bonding module rapidly presses down along the Z-axis under the action of electromagnetic thrust, approaching the target chip pad position with high dynamic response characteristics.

[0065] In high-speed approach mode, the system operates in closed-loop position control mode. The controller, based on the preset position command curve and combined with real-time grating ruler feedback, adopts a composite control strategy of feedforward (velocity, acceleration) and feedback (proportional, derivative) to drive the head to achieve a fast, smooth and overshoot-free motion trajectory until it reaches a preset safe suspension position above the contact point.

[0066] Thrust output by the motor:

[0067] ;

[0068] in, It is a position command. For speed, For acceleration; The position is fed back by the grating ruler. For the speed of the head; The PID proportional signal for the position loop. The differential gain of the position loop, For acceleration feedforward gain, This is the velocity feedforward gain.

[0069] Next, the system switches to high-gain position servo mode, driving the boom to make precise downward movements at extremely low speeds. Simultaneously, the system monitors the force sensor signal in real time and calculates the rate of change of the force signal in real time.

[0070] ;

[0071] in, The rate of change of the force signal, This represents the current force sensor signal value. This represents the sampling time interval.

[0072] When the rate of change of the force signal Exceeding the system's preset contact detection threshold Upon contact, the system immediately triggers a contact event determination, locks the position information of the position sensor at the current moment, i.e., the reading of the high-resolution grating ruler, and records it as the force control reference zero point. Then, the system enters the next phase. The system officially enters the modal adaptive switching phase, and the core task is to dynamically and smoothly switch between pressure control and position control based on the real-time status during the subsequent welding process.

[0073] During the soldering stage, system control switches from a position loop to a pressure control loop, controlling the force applied by the solder head when it contacts the solder joint, ensuring that the contact force is maintained within the process requirements so that the solder ball can be properly soldered onto the pad. This invention implements an active anti-disturbance mechanism based on position feedback in parallel within the force control closed loop, simplifying the solder head module and its actuator into a second-order system.

[0074] The state observer is based on a system dynamics model that includes the total disturbance, and the system dynamics model is as follows:

[0075]

[0076] in, For equivalent quality, The damping coefficient is... This is the stiffness coefficient. For the acceleration of the head, The total disturbance factors (including nonlinear friction, mechanical vibration coupling, stiffness variation, etc.) This refers to the thrust output by the motor.

[0077] The basic discretized form of the state observer designed to estimate the total disturbance that cannot be precisely measured in real time is as follows:

[0078] ;

[0079] in, This is the estimated disturbance value from the previous moment. These are location measurements. It is the observer gain matrix. , and These are the state transition matrix, control input matrix, and output matrix, respectively.

[0080] The system monitors the position of the grating ruler in real time. Compare it with the reference zero point position Positional deviation Defined as:

[0081] ,

[0082] If the position is deviated When the allowable threshold is exceeded, the system switches from pressure control to position control. The position deviation is then recorded. With disturbance estimation Mapped to compensating force ;

[0083] ;

[0084] in, Representing a moment, and For feedforward gain, This is the virtual stiffness coefficient. This is the virtual damping coefficient. This represents the time coefficient of the high-pass filter. It is the disturbance compensation coefficient.

[0085] Compensation force The thrust output by the motor during the force control process Vector superposition is performed to obtain the actual output for position control, thereby actively suppressing disturbances and maintaining force control stability. The control head applies welding force to the solder joint while suppressing undesirable movements of the welding head.

[0086] This system supports real-time dynamic switching between pressure control and position control, with the switching logic consisting of multi-level condition judgments. For example, when the position deviation detected by the encoder exceeds a first set threshold, the system accurately converts the current force into the distance for position control and automatically switches from pressure control mode to position control mode to avoid solder ball deformation or damage caused by overshoot. In the middle of the welding stage, the system automatically switches back from position control mode to pressure control mode to ensure stable welding force. Towards the end of the welding process, when the contact force approaches the material's maximum tolerance, it switches back to position control mode to prevent defects such as solder ball aluminum extrusion and pad damage caused by excessive pressure, ensuring the reliability of the electrical connection. The switching timing, thresholds, and control parameters can be adaptively configured according to different wire bonding materials, solder ball sizes, and process requirements.

[0087] Through the above method, the system achieves a pressure-position hybrid mode dynamic switching bonding head drive mode. While maintaining high-speed production, it detects encoder position and estimates disturbances in real time, dynamically controlling the bonding head force. This technology significantly reduces bonding head force overshoot without increasing additional hardware costs, effectively reducing the occurrence of ball defects and ensuring the appearance and electrical performance of the solder balls, thus enhancing the stability and reliability of the wire bonding machine system.

[0088] This invention addresses the problem of spherical defects (including but not limited to uneven ball size and aluminum extrusion defects) caused by the inherent physical randomness of the electronic arcing (EFO) process and the limitations of the mechanical control system in the bonding stage in existing wire bonding processes. It proposes an innovative method for controlling the micro-deformation of solder balls in wire bonding machines based on dynamic switching of pressure-position hybrid modes. Traditional solutions rely on improving sensor sensitivity, actuator accuracy, and mechanical structural rigidity to suppress noise and parasitic vibrations. However, these methods offer limited marginal improvements and are accompanied by significant non-linear increases in hardware costs, resulting in an imbalance between economic and technical benefits.

[0089] The core of this method lies in reconstructing the control architecture of the bonding process, designing and implementing a novel control strategy that deeply integrates pressure closed-loop feedback and precise position servo control. The system constructs a real-time state observer to dynamically analyze the coupling relationship between the mechanical properties at the bonding interface and the bonding head's motion trajectory. During the critical first solder joint bonding cycle, the controller executes an adaptive mode-switching algorithm based on a preset process phase diagram and real-time acquired multi-source sensor data (including but not limited to piezoelectric dynamic force signals, high-resolution grating ruler displacement information, and ultrasonic transducer impedance spectra).

[0090] Specifically, during the bonding head search and contact phase, the system operates in a high-gain position servo control mode to ensure that the bonding head approaches the pad at a constant and smooth speed, eliminating initial contact force peaks caused by inertial impact or mechanical hysteresis. Once the contact state is reliably detected, the system seamlessly switches to dynamic pressure control mode. At this time, the controller adjusts the force in real time with millinewton resolution, ensuring it strictly tracks the preset ideal pressure curve. Crucially, when the pressure build-up phase approaches the target setpoint, the algorithm predictively introduces a dynamic damping compensation based on position feedforward, essentially embedding a constrained position sub-loop within the pressure closed loop. This proactively suppresses instantaneous impact forces induced by servo system overshoot, mechanical resonance, or interface material yielding from the source of the control command, thereby avoiding defects such as excessive solder ball deformation, plastic flow of the pad aluminum layer, or aluminum extrusion caused by cracking of the underlying passivation layer due to transient overshoot of the bonding pressure.

[0091] The essence of this hybrid control strategy is to collaboratively optimize and dynamically decouple traditionally independent pressure and position control loops with bandwidth conflicts in the time and frequency domains through high-order algorithms. This not only avoids the high costs and engineering complexity associated with simply increasing hardware bandwidth, but also solves the fundamental problem of interface force control accuracy from a system dynamics perspective. Through this software-defined precision force control paradigm, this invention significantly reduces the process's dependence on extreme hardware performance, achieving optimized and highly consistent stress distribution at the bonding interface on the same hardware platform, thereby effectively improving the reliability of packaged interconnects and overall production yield.

[0092] By implementing this invention, the wire bonding machine can maintain extremely high welding speed in a high-speed production environment while reducing the occurrence of ball defects, ensuring the appearance and electrical performance of the solder balls, and effectively improving the process stability and market competitiveness of the equipment in advanced packaging applications.

[0093] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0094] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0095] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0096] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0097] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

Claims

1. A method for controlling micro-deformation of welding balls in a wire bonding machine, characterized in that, include: During the high-speed approach phase, the closed-loop position control mode is used to drive the head to a safe hovering position before the contact point. During the contact detection phase, switch to high-gain position servo mode, calculate the rate of change of the force signal in real time, and trigger contact event determination when the rate of change exceeds a preset threshold, and record the current position of the bearing head as the force control reference zero point; Upon entering the welding stage, switch to pressure control mode to control the bonding head to apply a preset welding force to the pads, and obtain the position feedback of the bonding head in real time to calculate its position deviation from the zero point of the force control reference. Based on the position deviation and the total disturbance obtained through the state observer, a compensation force is generated and superimposed on the thrust output by the motor; Based on the positional deviation during the welding process, one or more adaptive switches are made between the pressure control mode and the position control mode. The adaptive switching includes: switching to position control mode when the position deviation exceeds a first set threshold, switching to pressure control mode during the middle of welding, and switching back to position control mode at the end of welding when the contact force approaches the material's upper limit. The compensation force is generated by the following formula: ； in, Representing a moment, This is the virtual stiffness coefficient. This is the virtual damping coefficient. This represents the time coefficient of the high-pass filter. It is the disturbance compensation coefficient. The position deviation at the current moment, The total disturbance estimated by the state observer at the current time; the compensation force at the current time. The thrust output by the motor during the force control process Vector superposition yields the actual output for position control.

2. The method for controlling micro-deformation of welding balls in a wire bonding machine according to claim 1, characterized in that, In high-gain position servo mode, the formula for calculating the rate of change of the force signal is: ； in, The rate of change of the force signal, This represents the current force sensor signal value. The sampling time interval, Sampling time.

3. A wire bonding machine solder ball micro-deformation control system, used to implement the wire bonding machine solder ball micro-deformation control method as described in claim 1, characterized in that, include: The motion control card module is used to generate position commands and force control commands, and execute mixed-mode control algorithms, PID control algorithms, and disturbance observation. The drive module, electrically connected to the motion control card module, is used to receive position commands and output drive signals, wherein the drive signals are the power stage current or voltage of the actuator motor; The bonding head module is connected to the drive module and is used to move the bonding head along the Z-axis of the pad under the action of the drive signal; the bonding head module includes a force sensor for detecting the welding force and a grating ruler for detecting the absolute or relative position of the bonding head. The bus is communicatively connected to the motion control card module, drive module, and connector module to enable data communication between the modules. The motion control card module is configured to receive feedback signals from the force sensor and the grating ruler, control the drive module according to the wire bonding machine solder ball micro-deformation control method of claim 1, and realize adaptive switching between pressure control mode and position control mode.

4. The wire bonding machine ball micro-deformation control system according to claim 3, characterized in that, The motion control card module is a digital signal processor and / or a field-programmable gate array (FPGA). The digital signal processor is used to perform control algorithm logic operations and parameter tuning, and the FPGA is used to implement hardware-level interpolation and high-speed synchronous triggering of position commands for each axis.

5. The wire bonding machine ball micro-deformation control system according to claim 3, characterized in that, The drive module includes a motor, one end of which is connected to the head module for transmission, serving as the direct drive force source for the head module.

6. The wire bonding machine ball micro-deformation control system according to claim 3, characterized in that, The force sensor is a piezoelectric ceramic or strain gauge sensor.

7. The wire bonding machine ball micro-deformation control system according to claim 3, characterized in that, In pressure control mode, the position signal generated by the grating ruler is used to construct an active compensation algorithm for disturbance observation and position control assistance.

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