Polygonal Workpiece Chuck Table Curvature for Uniform Grinding
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Solution Overview
Problem
Existing grinding technologies for flat plate-shaped workpieces with four or more corners, such as package substrates, result in thickness variations due to alternating dispersion and concentration of grinding force, and differences in grinding frequency, leading to insufficient removal of corners and intermediate areas.
Innovation Solution
A chuck table with a holding surface partitioned into a circular first region and a polygonal second region, where the center of the first region is the lowest point and the height increases with distance, and the angle between tangent planes is adjusted to reduce thickness variations by ensuring more even removal across the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the holding surface is made flat, then the manufacturing is simple, but thickness variations occur due to alternating dispersion and concentration of grinding force
Solution Approach 1:
The holding surface is designed with different local properties: the central region has a first curvature radius while the peripheral region has a second curvature radius that is larger than the first. This local differentiation compensates for the alternating dispersion and concentration of grinding force, ensuring uniform thickness across the workpiece surface.
Solution Approach 2:
The holding surface is formed with specific curvature radii in different regions. The central region has a first curvature radius and the peripheral region has a second curvature radius larger than the first, creating a curved surface that compensates for grinding force variations and achieves uniform workpiece thickness.
2Productivity
If the grinding area is increased to improve efficiency, then productivity increases, but thickness variations worsen due to alternating dispersion and concentration of grinding force
Solution Approach 1:
The holding surface incorporates different curvature radii in central and peripheral regions to locally compensate for the alternating dispersion and concentration of grinding force that occurs during large-area grinding, maintaining thickness uniformity even when processing efficiency is enhanced.
Solution Approach 2:
By forming the holding surface with specific curvature radii (first curvature radius in central region, second curvature radius larger than the first in peripheral region), the system compensates for force distribution variations during efficient large-area grinding operations.
3Area of stationary object
If the spindle trajectory diameter is increased to cover more area, then the grinding coverage improves, but thickness variations occur due to differences in grinding frequency
Solution Approach 1:
The holding surface is designed with different curvature radii for central and peripheral regions to compensate for the alternating dispersion and concentration of grinding force that occurs when the spindle trajectory diameter is increased, ensuring uniform thickness across the expanded grinding coverage area.
Solution Approach 2:
The holding surface incorporates specific curvature radii in different regions to offset the effects of increased spindle trajectory diameter, maintaining consistent thickness across the larger grinding coverage area despite variations in grinding frequency.
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 solution effectively reduces thickness variations by ensuring consistent grinding across the workpiece, particularly at corners and intermediate areas, by optimizing the holding surface geometry and grinding frequency.
Implementation Method 1
the chuck table and the spindle are caused to approach each other along the predetermined direction such that the reverse side of the package substrate and the plurality of grindstones come into contact with each other. As a result, a portion of the reverse side of the package substrate with which the plurality of grindstones have come into contact is ground.
Data Source
AI summary
A chuck table used while grinding a flat plate-shaped workpiece having four or more corners in plan view, the chuck table including a holding surface partitioned into a circular first region surrounded by a polygonal second region that has an outer periphery having four or more corners, in plan view, in which the holding surface is shaped such that the center of the first region is the lowest point and the height increases as the distance from the center increases, and the angle formed between the reference tangent plane of the holding surface at the center of the first region and the first tangent plane of the holding surface at points other than the center that are included in the first region is smaller than the angle formed between the reference tangent plane and a second tangent plane of the holding surface at points included in the second region.