Wire Saw Slice Separation With Thermal Shape Deviation Control
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Solution Overview
Problem
Conventional wire saw methods for separating slices, such as lap slicing and grind slicing, face limitations in achieving high flatness and plane parallelism, particularly in the semiconductor industry, where demanding requirements necessitate improved precision and control over shape deviations during the cutting process.
Innovation Solution
The method involves a wire saw with a wire frame made of moving wire sections and an adjusting device, where the wire gate is stretched between two wire guide rollers, each mounted between a fixed and a floating bearing. The method includes tempering the fixed bearing with a cooling liquid according to a temperature profile correlated with a correction profile, and simultaneously displacing the workpiece along its axis, to adjust operating parameters like feed speed, working liquid flow, and wire tension, thereby controlling shape deviations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional wire saw methods (lap slicing or grind slicing) are used to separate discs, then the cutting process can be carried out with standard equipment, but the flatness and plane parallelism of the cut discs deteriorate due to shape deviations
Solution Approach 1:
The invention changes physical parameters (temperature of fixed bearings, axial position of floating bearings, feed rate, wire tension) during the cutting process to compensate for shape deviations. By dynamically adjusting these parameters based on real-time measurements of disc shape, the system achieves high flatness and parallelism without requiring fundamentally different cutting equipment.
Solution Approach 2:
The invention replaces purely mechanical adjustment systems with a hybrid system that uses thermal fields (cooling fluid for fixed bearings) to achieve precise positional control. The thermal expansion/contraction of fixed bearings provides a controlled mechanism for adjusting wire guide roller positions, supplementing mechanical displacement of floating bearings.
2Stability of the object's composition
If the position of wire guide rollers is kept fixed during cutting, then the device operation is simple, but shape deviations occur due to thermal expansion and mechanical instability
Solution Approach 1:
The invention implements a closed-loop feedback system where the actual shape of cut discs is measured and used to adjust cutting parameters for subsequent discs. The measured form deviations feed back into the control system, which modifies temperature profiles, bearing positions, and feed rates to compensate for identified shape errors, achieving high precision through iterative correction.
Solution Approach 2:
The invention transforms the static wire guide roller positioning system into a dynamic one where positions are continuously adjusted during cutting. Floating bearings are displaced axially in real-time, and fixed bearing temperatures are modulated, allowing the system to adapt to thermal expansion and mechanical drift while maintaining form accuracy.
3Manufacturing precision
If single measures (either temperature control or workpiece displacement) are used to correct shape deviations, then the control system is simple, but the displacement amplitude and control bandwidth are insufficient to achieve high precision
Solution Approach 1:
The invention merges two independent control mechanisms (temperature control of fixed bearings and axial displacement of floating bearings) into a coordinated dual-control system. Both mechanisms work simultaneously and complementarily to correct shape deviations, providing greater total displacement amplitude and extended control bandwidth than either mechanism could achieve alone.
Solution Approach 2:
The invention creates a composite control system that combines thermal control (affecting fixed bearing dimensions) with mechanical control (directly displacing floating bearings). This composite approach leverages the strengths of both thermal and mechanical fields to achieve precise, multi-dimensional correction of wire guide roller positions and workpiece alignment.
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 minimizes shape deviations by combining temperature control of the wire guide rollers and workpiece displacement, achieving greater displacement amplitudes and control bandwidths than single-measure methods, resulting in improved flatness and parallelism of cut discs.
Implementation Method 1
tempering the fixed bearings with a cooling fluid
Implementation Method 2
tempering the fixed bearings with a cooling fluid according to a temperature profile
Implementation Method 3
the floating bearings are axially displaced by tempering the fixed bearings with a cooling fluid
Implementation Method 4
hard materials that act abrasively on the workpiece
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A method for cutting a plurality of discs from workpieces (4) using a wire saw during a sequence of cutting operations subdivided into initial cuts and subsequent cuts, wherein the wire saw comprises a wire frame (2) made of moving wire segments of a saw wire (3) and an adjusting device (12), and the wire frame (2) is tensioned in a plane between two wire guide rollers (1), each of the two wire guide rollers (1) being mounted between a fixed bearing (5) and a floating bearing (6). According to one embodiment, the method comprises, during each of the cutting operations, feeding the respective workpiece (4) through the wire frame (2) at a feed rate by means of the adjusting device (12) along a feed direction perpendicular to a workpiece axis and perpendicular to the plane of the wire frame (2) in the presence of a working fluid and hard materials that act abrasively on the workpiece (4).characterized by the following during each of the cutting operations: feeding the workpiece (4) through the wire screen (2) while simultaneously axially displacing the floating bearings (5) by tempering the fixed bearings (6) with a cooling fluid according to a first temperature profile, which specifies the temperature of the cooling fluid as a function of a cutting depth and correlates with a first correction profile, which specifies the displacement of the floating bearings (5) as a function of the cutting depth; feeding the workpiece (4) through the wire screen (2) while simultaneously displacing the workpiece (4) along the workpiece axis by means of an adjusting element according to a second correction profile, which specifies the displacement of the workpiece (4).wherein the first and second correction profiles are directed against a form deviation; determining the form deviation during each of the cutting operations and/or before each of the cutting operations; and, depending on the cutting depth, adjusting operating parameters such as the feed rate, the amount of working fluid supplied to the wire creel (2) per unit of time, the temperature of the working fluid, the wire speed, the wire consumption per cutting operation and the wire tension.