Wire Saw Slurry Temperature Control for Wafer Warp Reduction
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Solution Overview
Problem
Conventional wire saws face challenges in maintaining a straight slicing trajectory due to thermal expansion of the workpiece and grooved rollers, leading to warp in wafers, as existing cooling methods are insufficient in controlling temperature and displacement, resulting in inflected slicing trajectories and significant warp values.
Innovation Solution
A method where the supply temperature of the slurry is increased from the start to the end of slicing, with a controlled rate of increase, to minimize temperature decrease in the workpiece and reduce displacement of the grooved rollers, thereby maintaining a straight slicing trajectory and reducing warp in the workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the workpiece is cooled with a workpiece cooling means provided in the workpiece holding member, then the generation of heat in the workpiece during slicing is reduced, but the cooling capability is insufficient since the slicing portion is far from the cooling portion and the size of the cooling portion is restricted
Solution Approach 1:
The patent introduces slurry as an intermediary cooling medium that is supplied directly to the slicing portion of the workpiece. The slurry absorbs heat at the cutting interface and transports it away, effectively cooling the workpiece where it is needed most rather than relying on distant cooling mechanisms.
Solution Approach 2:
The patent utilizes hydraulic principles by circulating slurry through the slicing system. The slurry is pumped and supplied under pressure to the slicing zone, enabling efficient heat removal through fluid circulation and exchange at the critical cutting interface.
2Temperature
If the grooved roller is cooled to reduce thermal expansion, then the axial expansion of the grooved roller is reduced, but the relative position between the workpiece and the wire row still changes due to workpiece thermal expansion
Solution Approach 1:
The patent accepts that thermal expansion of the workpiece cannot be completely prevented, but converts this challenge into a manageable parameter by continuously monitoring workpiece temperature and adjusting the slicing trajectory in real-time to compensate for the expansion, thereby maintaining manufacturing precision.
Solution Approach 2:
The patent implements a feedback control system that continuously measures workpiece temperature during slicing and uses this information to dynamically adjust the slicing trajectory and wire tension, compensating for thermal expansion effects and maintaining accurate relative positioning between the workpiece and wire row.
3Manufacturing precision
If the supply temperature of the slurry is increased from the start to the end of slicing, then the temperature decrease near the slicing end is suppressed and the displacement of the grooved rollers is reduced, but the slicing process requires temperature control management
Solution Approach 1:
The patent employs dynamic temperature control by progressively increasing the slurry supply temperature during the slicing process. This dynamic adjustment optimizes cooling effectiveness at different stages of slicing, suppressing temperature decrease near the slicing end and reducing grooved roller displacement while maintaining trajectory straightness.
Solution Approach 2:
The patent changes the temperature parameter of the slurry during the slicing process, increasing it from start to end. This parameter change optimizes the balance between cooling effectiveness and thermal expansion control, improving slicing trajectory straightness without requiring complex additional control mechanisms.
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 approach effectively suppresses temperature decrease near the slicing end and reduces displacement, resulting in improved straightness of the slicing trajectory and reduced warp values without requiring additional mechanisms, enhancing the accuracy and quality of sliced wafers.
Implementation Method 1
a slurry can be supplied to the grooved rollers... Friction that occurs in this case causes generation of heat at a slicing portion of the workpiece... the grooved roller is axially expanded by thermal expansion under frictional heat
Implementation Method 2
Friction that occurs in this case causes generation of heat at a slicing portion of the workpiece... under frictional heat between the wire and the grooved roller
Implementation Method 3
the workpiece is thermally expanded during slicing. Moreover, the grooved roller is axially expanded by thermal expansion
Data Source
AI summary
The present invention is a wire saw in which a wire is wound around a plurality of grooved rollers, the workpiece is sliced into wafers by causing the wire to travel and pressing the workpiece against the wire while a slurry is supplied to the grooved rollers, the wire saw controlling in such a manner that the workpiece is sliced while a supply temperature of the slurry is increased from the start to the end of slicing the workpiece. As a result, there is provided a wire saw in which Warp of the workpiece to be sliced can be improved by suppressing a decrease in a temperature of the workpiece in the vicinity of the slicing end portion of the workpiece and by making an increase in displacement of the grooved roller during slicing straight, that is, by making the slicing trajectory depicted in the workpiece close to a straight line.