Why does a wafer grinding spindle need vibration measurement?

The wafer grinding spindle directly affects grinding accuracy, surface flatness, and process stability. If the spindle or spindle motor shows increased vibration, imbalance, mechanical wear, or unstable operation, wafer surface quality may decline, grinding may become uneven, yield may decrease, and equipment downtime may occur. Therefore, vibration measurement helps understand spindle operating conditions and serves as an important basis for predictive maintenance and quality management.

Why should measurement not only be performed on the spindle cover?

Grinding spindles are usually protected by a cover housing. If the sensor is only installed on the spindle cover, the measurement signal may be affected by background vibration, housing structure, and environmental interference, making it less accurate. Actual measurement results show that the motor body is closer to the spindle dynamic source and can more clearly capture grinding operation signals, making it more suitable for long-term monitoring.

Where is the best measurement location for a wafer grinding spindle?

According to the measurement results in this case, the axial direction of the spindle cover is easily affected by background interference, so the motor body is a better measurement location. The motor body is closer to the spindle operation source, can clearly reflect dynamic signals during grinding, and is convenient for establishing load measurement comparison baselines and long-term trend management.

Why compare no-load and loaded conditions for wafer grinding spindles?

No-load measurement can serve as the equipment baseline to eliminate background vibration and machine interference. Loaded measurement can observe how actual grinding pressure, grinding slurry, and working conditions affect spindle vibration. By comparing no-load and loaded conditions, users can determine whether abnormalities come from the equipment itself, grinding conditions, or process load changes.

How do VMS-PH and VMS-RM support predictive maintenance for grinding spindles?

VMS-PH Equipment Dynamic Analyzer can be used for dynamic analysis at different measurement locations and under no-load and loaded conditions, helping identify the most suitable sensor installation position. VMS-RM Rotor Quality Management System can continuously monitor machine vibration broadband values and spectrum values, establish trend-based management baselines, and detect spindle condition changes early as a basis for predictive maintenance.

Case

Application

FAQ

Support

How to Perform Measurement on Wafer Grinding Spindle?

Q: Does grinding slurry affect the dynamic signal of the grinding spindle?

Yes. In this case, water and grinding slurry were compared as grinding media, and the results showed that the dynamic signal of grinding slurry was slightly higher than that of water. This indicates that different grinding media change spindle force and vibration conditions. Therefore, grinding media, process conditions, and load status should be considered during long-term monitoring interpretation.

Case｜How to Perform Measurement on Wafer Grinding Spindle?

During the grinding process, the spindle, which significantly affects wafer quality, is often covered by a protective casing that may introduce noise into measurement data. How should the measurement be conducted?

Semiconductor Grinding Process

The semiconductor grinding process is a crucial step in semiconductor manufacturing, typically used for refining and leveling different layers on semiconductor wafers. The primary goal of semiconductor grinding is to produce thin wafer layers and ensure flatness and surface quality between layers. Advanced packaging technologies, in particular, require better heat dissipation performance, and grinding helps manufacture thinner wafers, thereby improving heat dissipation and enhancing the performance of electronic components.

Grinding processes utilize grinding machinery, including grinding discs, spindles, abrasives, and other components. These machines enable high-precision control to finely grind the wafer surface. Among the grinding equipment, the spindle and the spindle motor are two critical components, and their relationship is crucial to the effectiveness and stability of the grinding process.

The movement of the grinding spindle requires highly precise control to ensure accuracy and surface quality during the grinding process. The spindle motor should provide precise speed and position control to ensure the spindle operates according to the preset parameters. Vibration during the grinding process may negatively impact the final product quality. A good motor should have low vibration and high stability to ensure smooth operation of the grinding spindle.

Therefore, managing the spindle is essential to ensure grinding quality. Since the spindle is the core of the equipment and is covered by a protective casing, attaching a sensor directly to the spindle may introduce background noise interference. How should the measurement be conducted?

Monitoring Explanation

VMS-PH Dynamic Analysis Instrument + VMS-RM Rotor Quality Management System
By using the VMS-PH dynamic analysis instrument to operate under both loaded and unloaded conditions, the optimal sensor installation position can be determined. The VMS-RM rotor quality management system provides long-term monitoring to understand equipment status, enabling trend-based management and serving as a basis for predictive maintenance.

Measurement Status

1. No-load acceleration to 30 rpm dynamic analysis comparison

Result: Excluding background fluctuations, the motor operation remains below 0.03, which can serve as a reference position for load measurement.

2. Load dynamic analysis comparison

Result: Comparing the dynamic analysis from stationary to grinding, using 0.03 as a threshold.
It shows that vibration in 001 is the highest, while 002 is the lowest, with the sequence: H1 ＞ H3 ＞ H4 ＞ H2.

3. Dynamic analysis comparison of different grinding fluids (Measurement location: Motor body)

Grinding medium: Water

Grinding medium: Grinding fluid

Result: The dynamic signal of the grinding fluid is slightly higher than that of water.

4. Dynamic analysis comparison before and after maintenance (Measurement location: Motor body)

Result: After maintenance, the vibration has been reduced to 0.03 mm/s!

5. Machine operation status trend management

Measurement Conclusion

Due to background interference in the spindle cover axial measurement, the motor body is the optimal measurement location. It is the closest to the spindle and provides clear grinding signals. Additionally, the dynamic signal of the grinding fluid is slightly higher than that of water.

By using RM to learn real-time machine vibration broadband values and spectrum as a monitoring reference, machine operation status can be trend-managed. This allows for early detection of machine changes and provides a basis for predictive maintenance.

Rotor Health Monitoring System - Wired

Ensure key production line stability.

FAQ

Why is vibration measurement necessary for wafer grinding spindles?
The wafer grinding spindle directly affects grinding accuracy, surface flatness, and process stability. If the spindle or spindle motor experiences increased vibration, unbalance, mechanical wear, or unstable operation, it may lead to degraded wafer surface quality, uneven grinding, lower yield, and equipment downtime. Therefore, grasping the spindle's operating status through vibration measurement serves as an important basis for predictive maintenance and quality management.

Why shouldn't we only measure the spindle cover during grinding spindle measurement?
The grinding spindle is usually protected by a cover shell. If the sensor is only installed on the spindle cover, it is susceptible to background jitter, shell structure, and environmental interference, resulting in inaccurate measurement signals. Actual measurement results show that the motor body is closer to the dynamic source of the spindle, which can more clearly acquire grinding operation signals, making it more suitable as a long-term monitoring location.

Where is the best measurement position for a wafer grinding spindle?
According to the measurement results in this case, the axial direction of the spindle cover is susceptible to background interference, making the motor body a better measurement position. The motor body is closer to the source of the spindle's operation, clearly reflecting the dynamic signals during the grinding process, and it also facilitates the establishment of load measurement comparison baselines and long-term trend management.

Why compare no-load and loaded states for the wafer grinding spindle?
No-load measurement serves as a baseline for the equipment itself to eliminate background jitter and the machine's own interference. Loaded measurement observes the impact of actual grinding downforce, slurry, and working conditions on spindle vibration. By comparing no-load and loaded states, it can be determined whether abnormalities come from the equipment itself, grinding conditions, or changes in processing load.

Does grinding fluid affect the dynamic signals of the grinding spindle?
Yes. In the case study comparing water and grinding fluid as grinding media, the results showed that the dynamic signals with grinding fluid were slightly higher than with water. This indicates that different grinding media change the force and vibration state of the spindle. Therefore, when conducting long-term monitoring, grinding media, process conditions, and load status should be included in the interpretation criteria.

How do VMS-PH and VMS-RM assist in predictive maintenance for grinding spindles?
The VMS-PH Equipment Dynamic Analyzer can be used for dynamic analysis at different measurement positions under no-load and loaded conditions to help find the most suitable position for sensor installation. The VMS-RM Rotor Quality Management System can continuously monitor the machine's vibration broadband values and spectrum levels over the long term, establish trend management baselines, and detect spindle status changes in advance, serving as a basis for predictive maintenance.