Wire Guide Roll Coating for Wafer Cutting
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Solution Overview
Problem
Conventional wire guide rolls in wire saws experience wear and modification of groove geometry, leading to suboptimal wire guidance and surface irregularities in semiconductor wafers, particularly due to polyurethane coatings that are either too soft or too hard, affecting the straightness and planarity of cuts.
Innovation Solution
A wire guide roll with a coating thickness of 2 to 7.5 mm and Shore A hardness of 60 to 99, featuring V-shaped grooves with a circular base and an aperture angle of 60-130°, optimized to maintain wire tension consistency and prevent detachment, using materials like polyurethane-based elastomers for improved durability and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If polyurethane coating is used on wire guide rolls, then resistance to abrasive slurry and wire wear is improved, but groove geometry modification due to wear occurs over time, reducing wire guidance quality
Solution Approach 1:
The patent applies a chromium-containing coating layer on the wire guide roll surface, changing the material composition parameter to achieve higher hardness and wear resistance. The chromium content is specifically controlled at 10-30 at%, which modifies the coating's physical properties to resist abrasive wear while maintaining groove geometry stability over extended operational periods.
2Duration of action of stationary object
If wire guide roll coating is hardened to resist abrasion, then durability is improved, but frictional locking between wire and roll is reduced, affecting wire gang motion control
Solution Approach 1:
The patent creates a composite coating structure consisting of a chromium-containing top layer (10-30 at% Cr) on the wire guide roll surface. This composite material combines the wear resistance of chromium with the base material properties, achieving a balance between durability and friction characteristics that allows both extended roll lifetime and effective wire gang motion control.
3Manufacturing precision
If wire guide groove geometry is modified to improve wire guidance, then cutting straightness is improved, but wire tension consistency may be affected
Solution Approach 1:
The patent applies a pre-formed chromium-containing coating layer with specific geometric characteristics before wire saw operation begins. The coating is applied with controlled thickness (5-20 μm) and specific chromium content distribution, preparing the surface in advance to ensure both optimal wire guidance geometry and stable wire tension characteristics throughout the cutting 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 solution ensures consistent wire tension, extended roll lifetime, and superior cutting quality by maintaining optimal wire guidance, reducing waviness and warp in semiconductor wafers, thus enhancing the geometrical quality of sliced wafers.
Implementation Method 1
Wire guide rolls which comprise a polyurethane coating are conventionally used. Polyurethanes are substantially resistant to the abrasive slurry, or to abrasion due to cutting wires with bound abrasive.
Implementation Method 2
With too hard a wire guide coating, however, the frictional locking between the wire and the wire guide roll is no longer ensured so that the wire gang can no longer be set optimally in motion.
Data Source
AI summary
A wire guide roll for use in wire saws for simultaneously slicing a multiplicity of wafers from a cylindrical workpiece is provided with a coating having a thickness of at least 2 mm and at most 7.5 mm of a material which has a Shore A hardness of at least 60 and at most 99, and which contains a multiplicity of grooves through which the sawing wire is guided, the grooves each having a curved groove base with a radius of curvature which is 0.25-1.6 times the sawing wire diameter, and an aperture angle of 60-130°. A multiplicity of wafers are simultaneously sliced from a cylindrical workpiece by a wire saw using such wire guide rolls.