Tungsten Saw Wire Composition for Thin, Low-Kerf Ingot Cutting
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Solution Overview
Problem
Conventional piano wires used in multi-wire saws for slicing silicon ingots have low elastic modulus and hardness, making them difficult to thin and resulting in high kerf loss during cutting.
Innovation Solution
A metal wire with a tungsten content of at least 90 wt%, a tensile strength of at least 4000 MPa, an elastic modulus of 350 GPa to 450 GPa, and a diameter of up to 60 μm, combined with a rhenium-tungsten alloy to enhance tensile strength and reduce crystal grain size, is used to create a saw wire for improved cutting efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If piano wire is used as saw wire, then the saw wire has sufficient tensile strength, but the elastic modulus and hardness are low, making it difficult to thin the wire
Solution Approach 1:
The patent changes the material parameters by using tungsten as the base material instead of piano wire, achieving a tensile strength of at least 4000 MPa while enabling the wire diameter to be reduced to 60 μm or less. The crystal grain size is controlled to 0.20 μm or less, which contributes to achieving both high strength and thin diameter simultaneously.
Solution Approach 2:
The patent employs a composite structure by adding alloying elements (such as rhenium, iridium, osmium, ruthenium, or nickel) to tungsten, creating a composite material system that achieves superior mechanical properties. This composite approach allows the wire to maintain high tensile strength while being thinned to 60 μm or less, resolving the contradiction between strength and thinness.
2Ease of manufacture
If piano wire is used as saw wire, then the saw wire can be manufactured, but the elastic modulus is low resulting in high kerf loss during cutting
Solution Approach 1:
The patent changes the material parameters by using tungsten with an elastic modulus of at least 350 GPa, which is significantly higher than piano wire. This parameter change directly reduces kerf loss during cutting while maintaining manufacturability through controlled crystal grain size of 0.20 μm or less.
3Ease of operation
If piano wire is used as saw wire, then the saw wire can operate, but the hardness is low making it difficult to achieve thin wire dimensions
Solution Approach 1:
The patent changes the material parameters by using tungsten which inherently provides higher hardness, enabling the wire to be thinned to 60 μm or less while maintaining operational capability. The controlled crystal grain size contributes to achieving both thin dimensions and operational performance.
Data Source
AI summary
A metal wire containing tungsten is provided. A tungsten content of the metal wire is at least 90 wt %. A tensile strength of the metal wire is at least 4000 MPa. An elastic modulus of the metal wire is at least 350 GPa and at most 450 GPa. A diameter of the metal wire is at most 60 μm. An average crystal grain size of the metal wire in a cross-section orthogonal to an axis of the metal wire is at most 0.20 μm.