How to precisely control bonding parameters in a multifunctional gold ribbon bonding machine to ensure connection stability and reliability?
Publish Time: 2026-01-06
In semiconductor packaging processes, wire bonding is a crucial step in achieving electrical interconnection between the internal circuitry of a chip and the external lead frame. As the core equipment in this process, the multifunctional gold ribbon bonding machine precisely connects the chip pads to the lead frame pads using gold or aluminum wires. To ensure high stability and long-term reliability of the connection, precise control of several key parameters during the bonding process is essential. The following systematically explains the control strategies from the perspectives of temperature, pressure, ultrasonic energy, time, and equipment calibration.1. Precise Control of Hot-Pressure ParametersWire bonding typically employs a hot-press ultrasonic bonding method, where the substrate heating temperature directly affects the plastic deformation capacity and interfacial diffusion effect of the metal wires. For gold wire bonding, the typical heating temperature range is 150℃–250℃; while aluminum wire bonding often uses cold ultrasonic bonding at room temperature or slightly above room temperature. Too low a temperature will result in insufficient metal ductility, leading to poor solder joints or weak connections; too high a temperature may damage the chip passivation layer or cause excessive growth of intermetallic compounds. Therefore, the equipment needs to be equipped with a high-precision temperature control system, combined with a real-time feedback mechanism, to ensure that the temperature fluctuation of the heating platform is controlled within ±2℃, and the set value is dynamically adjusted according to the material characteristics.2. Synergistic Optimization of Bonding Pressure and TimeThe pressure and application time applied during the bonding process jointly determine the contact area and deformation degree between the metal wire and the pad. Excessive pressure can lead to chip breakage or pad sinking, while insufficient pressure will prevent the formation of an effective metallurgical bond. Typically, the pressure of the first solder joint in gold ball bonding is between 30–80 cN, and the pressure of the second solder joint is slightly lower. Simultaneously, the bonding time must be matched with the pressure: too short a time will result in insufficient metal diffusion; too long a time may cause "tailing" or wire arc collapse. Modern multi-functional bonding machines achieve millisecond-level time accuracy and micro-Newton-level force control through a closed-loop servo control system, ensuring the consistency of each bonding action.3. Fine Adjustment of Ultrasonic EnergyUltrasonic vibration is a key factor in promoting metal atom diffusion, removing oxide films, and enhancing interfacial bonding. Ultrasonic power, frequency, and amplitude need to be customized based on wire diameter, material, and pad structure. Excessive ultrasonic energy can cause "ultrasonic erosion," damaging the underlying chip structure; insufficient energy will fail to effectively activate the interface reaction. Advanced equipment employs an adaptive ultrasonic control system that dynamically adjusts the output based on real-time bonding feedback, improving the robustness of the process window.4. Equipment Calibration and Process MonitoringBesides parameter settings, the mechanical precision and stability of the equipment itself are equally crucial. The Z-axis repeatability of the bonding head must reach sub-micron levels, and the XY platform motion error should be less than 1μm. Regular laser alignment, force sensor calibration, and ultrasonic transducer performance testing are fundamental to maintaining long-term process stability. Furthermore, an integrated machine vision system can automatically identify solder joint morphology and detect defects. Combined with SPC technology, it can provide real-time monitoring and early warning for key indicators such as bonding strength, wire arc height, and ball diameter consistency.In summary, to achieve highly reliable wire bonding, a multifunctional gold ribbon bonding machine must implement coordinated, precise, and dynamic parameter control across four dimensions: heat, force, acoustics, and time. As semiconductor devices become increasingly miniaturized and denser, higher requirements are placed on the control precision of bonding processes.
