Grinding Wheel Inclination Control for Uniform Wafer Thickness
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Solution Overview
Problem
Existing grinding apparatuses struggle to achieve uniform thickness distribution in workpieces due to delayed adjustment of the table rotational axis, leading to unstable processing conditions and increased variations in the grinding result.
Innovation Solution
A grinding apparatus with a chuck table and grinding unit that includes a thickness measuring instrument, an inclination adjusting unit, and a controller to calculate and adjust the necessary inclination of the table rotational axis based on real-time thickness information, using PID or P control to moderate adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the inclination of the table rotational axis is adjusted frequently to achieve uniform thickness distribution, then the manufacturing precision is improved, but the processing stability deteriorates due to excessive adjustments and corrections
Solution Approach 1:
The patent applies partial action by calculating and applying only the necessary adjustment amount rather than maximum adjustment. The adjustment amount calculating section determines the precise inclination adjustment needed based on thickness distribution, avoiding excessive adjustments that would require correction and destabilize the processing conditions.
Solution Approach 2:
The patent implements feedback control where the thickness measuring instrument continuously monitors the workpiece thickness distribution, and this information is fed back to the adjustment amount calculating section. This closed-loop feedback enables precise, stable adjustments that maintain processing stability while achieving uniform thickness distribution.
2Manufacturing precision
If the inclination adjustment is made immediately after detection to reduce variations in processing results, then the manufacturing precision is improved, but the processing stability deteriorates due to repeated excessive adjustments and corrections
Solution Approach 1:
The system calculates the precise necessary adjustment amount based on detected thickness deviations and applies only that amount, avoiding excessive adjustments. This partial action approach reduces variations in processing results while maintaining stability by preventing the need for repeated corrections.
Solution Approach 2:
The patent replaces manual or rough mechanical adjustment with an automated calculation system that determines the precise adjustment amount. The adjustment amount calculating section uses measured thickness data to compute the exact inclination adjustment needed, substituting mechanical trial-and-error with calculated precision.
3Stability of the object's composition
If the grinding process is interrupted to wait for adjustment effects to be reflected before next adjustment, then the processing stability is improved, but the productivity deteriorates due to decreased number of adjustments possible during grinding
Solution Approach 1:
The system performs preliminary calculation of the adjustment amount based on current thickness measurements before executing the adjustment. This preliminary action allows continuous monitoring and adjustment without waiting for full effect manifestation, maintaining both stability and productivity by enabling sequential adjustments during the grinding process.
Solution Approach 2:
The patent enables continuous grinding and continuous adjustment by calculating adjustment amounts based on real-time thickness measurements. The useful action of grinding continues uninterrupted while adjustments are made incrementally, maintaining both processing stability and high productivity throughout the entire grinding process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The apparatus achieves accurate and uniform grinding of workpieces to a predetermined thickness by minimizing excessive adjustments and reducing variations in processing results.
Implementation Method 1
a thickness measuring instrument configured to measure a thickness of the workpiece held by the chuck table
Implementation Method 2
a grinding unit including a spindle having a grinding wheel fitted to a lower end thereof such that a lower surface of the grinding wheel having annularly arranged grinding stones on the lower surface faces the holding surface of the chuck table
Data Source
AI summary
A grinding apparatus includes a chuck table rotatable about a table rotational axis, a grinding unit including a spindle having a grinding wheel fitted to a lower end thereof, an inclination adjusting unit that adjusts inclination of one of or both the table rotational axis and the spindle, a thickness measuring instrument that measures a thickness of a workpiece, and a controller, the controller including a necessary adjustment amount calculating section that calculates an adjustment amount necessary for adjustment of the inclination as a necessary adjustment amount in reference to thickness information of the workpiece being ground, an actual adjustment amount calculating section that calculates an actual adjustment amount by multiplying the necessary adjustment amount by an adjustment rate, and an adjustment control section that adjusts the inclination by the actual adjustment amount.