Grinding Workpiece Surface Roughness Uniformity
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Solution Overview
Problem
Conventional grinding methods for plate-shaped workpieces, such as wafers, result in differing surface roughness between the central and outer circumferential portions, affecting mechanical strength and requiring a method to minimize these differences.
Innovation Solution
A grinding method involving two distinct grinding steps with adjusted relative tilts and speeds of the chuck table and grinding wheel, where the first step thins the central portion and the second step focuses on reducing surface roughness of the outer circumferential portion by altering the tilt and speed settings to ensure uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If in-feed grinding is used to thin the workpiece, then productivity is improved, but surface roughness uniformity deteriorates
Solution Approach 1:
The grinding process is divided into multiple separate grinding steps, each with specific tilt settings. The first grinding step uses a first tilt setting to grind the central portion, while the second grinding step uses a second tilt setting to grind the outer circumferential portion. This segmentation allows each step to optimize for its specific region, improving overall surface roughness uniformity while maintaining productivity.
Solution Approach 2:
The tilt setting of the grinding wheel is dynamically adjusted between different grinding steps. By changing the tilt angle from the first tilt setting to the second tilt setting, the process adapts to different regional requirements of the workpiece, enabling uniform surface roughness across both central and outer circumferential portions.
2Device complexity
If single tilt setting grinding is used, then device complexity is reduced, but surface roughness uniformity deteriorates
Solution Approach 1:
The grinding process employs dynamic adjustment of the tilt setting between different steps. The tilt setting is changed from the first tilt setting to the second tilt setting to address different regional requirements, achieving uniform surface roughness without requiring complex multi-axis control systems.
Solution Approach 2:
The grinding process uses periodic alternation between different tilt settings. By alternating between the first tilt setting for central portion grinding and the second tilt setting for outer circumferential portion grinding, the method achieves uniform surface quality through simple periodic parameter changes rather than continuous complex control.
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
This method effectively reduces the surface roughness difference between the central and outer circumferential portions of the workpiece, enhancing mechanical strength and uniformity compared to conventional methods.
Implementation Method 1
moving the holding surface and the grindstones relatively closer to each other to bring the grindstones into abrasive contact with the workpiece to thereby grind the workpiece
Data Source
AI summary
A method of grinding a workpiece includes a first grinding step of adjusting the relative tilt of a chuck table and a grinding wheel to a first state and bringing grindstones into abrasive contact with the workpiece to grind the workpiece, and a second grinding step of adjusting the relative tilt of the chuck table and the grinding wheel to a second state that is different from the first state and bringing the grindstones into abrasive contact with the workpiece to grind the workpiece. In the second grinding step, the workpiece is ground under a condition for causing the workpiece to have a smaller surface roughness than that in the first grinding step.