Development of a New Type Saw Wire Fixed Diamond Abrasive Grains with Solder and Ni Electroplating and Its Application to Slicing of Silicon and Sapphire Ingots
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2015-01-01 |
| Journal | Journal of the Japan Society of Powder and Powder Metallurgy |
| Authors | Atsushi Nakahira, Atsushi OKIMURA, Yasuhito HAGIWARA, Takashi NAKANISHI, Masaru Yokota |
| Institutions | The Nakamura Hajime Eastern Institute, Tohoku University |
| Citations | 1 |
| Analysis | Full AI Review Included |
Diamond Fixed Abrasive Saw Wire Development: Technical Analysis and 6CCVD Solutions
Section titled âDiamond Fixed Abrasive Saw Wire Development: Technical Analysis and 6CCVD SolutionsâThis analysis reviews the development of novel diamond abrasive fixed saw wires optimized for high-precision slicing of hard materials, specifically silicon and sapphire ingots, relevant to the solar cell and LED industries. The techniques focus on enhancing the mechanical bonding between the diamond abrasive grains and the substrate wire using specialized brazing alloys and electroless/electroplating processes.
Executive Summary
Section titled âExecutive Summaryâ- Core Achievement: Successful development and validation of high-performance fixed diamond saw wires for slicing brittle materials (Polycrystalline Silicon and Sapphire ingots).
- Material Focus: Optimization centered on low-melting-point brazing alloys (Ag-Cu-Sn-Ni) and Pb-free solders (Sn-Ag) combined with Nickel (Ni) addition to maximize mechanical strength (rupture stress and strain).
- Abrasive Functionalization: Diamond grains (40-60 ”m) were pre-treated with Ni-P electroless plating (up to 40 mass% coating) to significantly improve wettability and mechanical interlocking with the solder/braze material.
- Novel Process: A four-step fixation method (HB-Type Saw Wire) utilizing initial Sn-Ag solder temporary fixing followed by a final Ni electroplating step was developed to ensure highly robust diamond embedding.
- Slicing Performance: Using the optimized method, 50 simultaneous slices of a 50.8 mm sapphire ingot achieved excellent dimensional stability, including an average wafer thickness of 546 ± 4.3 ”m and a low Total Thickness Variation (TTV) of 7.9 ± 3.9 ”m.
- Substrate Preservation: Analysis of high-tensile SUS304 wire showed mechanical properties remained largely intact after vacuum heating at 873 K, with hardness reducing by < 10%, confirming the feasibility of the thermal brazing process.
Technical Specifications
Section titled âTechnical SpecificationsâThe following table summarizes the critical hard data extracted from the research regarding material properties and slicing performance.
| Parameter | Value | Unit | Context |
|---|---|---|---|
| Target Wafer Materials | Si, Sapphire, SiC | N/A | High-volume slicing for solar cells and LED package substrates |
| Sapphire Ingot Dimensions | Ă50.8, Length 70 | mm | Processed simultaneously (50 wafers) |
| Final Wafer Thickness (AT) | 546 ± 4.3 | ”m | Average thickness of sliced sapphire (HB-Type) |
| Total Thickness Variation (TTV) | 7.9 ± 3.9 | ”m | Wafer dimensional quality metric |
| Maximum Waviness (WT) | 6.0 ± 1.2 | ”m | Surface quality metric |
| Diamond Abrasive Size Range | 40 - 60 | ”m | Used for S-Type and HB-Type wires |
| Wire Core Diameter (Piano Wire) | 180 | ”m | Brass-coated high-tensile steel |
| H-Type Brazing Alloy Composition | 47.5 Ag-25.5 Cu-27.0 Sn + 1.0 Ni | mass% | Optimized for strength and lower melting point |
| Brazing/Solder Temperature | < 600 | °C | Required process temperature for H-Type alloy |
| Ni-P Coating on Diamond | Ni-7 mass% P | N/A | Applied via electroless plating (hypophosphite method) |
| Solder Mechanical Improvement | Rupture Strain up to 5 | % | Maximum increase achieved with 1.0 mass% Ni addition |
| Wire Hardness Drop (SUS304) | < 10 | % | After vacuum heating at 873 K for 300 s |
Key Methodologies
Section titled âKey MethodologiesâThe study involved two primary methods for diamond fixation: a single-step brazing method (H-Type) and a novel four-step solder/electroplating method (HB-Type). The HB-Type is detailed below as it yielded superior mechanical properties and slicing results.
Abrasive Pre-Treatment Recipe
Section titled âAbrasive Pre-Treatment Recipeâ- Selection: Diamond abrasive grains (40-60 ”m) selected for sawing hard ingots.
- Functionalization: Grains were subjected to Ni-P electroless plating using the hypophosphite method.
- Target Coating: The Ni-P layer comprised Ni-7 mass% P and coated 30 mass% (or up to 40 mass%) of the diamond particle weight to ensure maximum solder wettability and strong mechanical bonding.
Continuous HB-Type Saw Wire Manufacturing Process
Section titled âContinuous HB-Type Saw Wire Manufacturing ProcessâThis process utilized a brass-coated piano wire (180 ”m) and Sn-Ag Pb-free solder (Sn-0.7 Cu mass% alloy).
- 1st Step: Pre-Coating (Solder and Flux Application): High-tension piano wire was cleaned, applied with flux, and pre-coated with the Sn-Ag Pb-free solder alloy.
- 2nd Step: Physical Adhesion: The wire was run through a bath where the Ni-P coated diamond particles were physically adhered to the solder-coated wire surface.
- 3rd Step: Temporary Fixing (Solder Reflow): The wire was heated in a furnace to re-melt (reflow) the Sn-Ag solder. This created stable filet shapes around the diamond particles, temporarily fixing them to the wire substrate.
- 4th Step: Final Fixation (Ni Electroplating): The wire underwent a final strengthening process using Ni electroplating. This metallic layer (thickness of a few ”m) was deposited over the temporary solder fixation, fully embedding the diamond particles and providing the robust mechanical locking necessary for continuous hard material slicing.
6CCVD Solutions & Capabilities
Section titled â6CCVD Solutions & CapabilitiesâThe research successfully demonstrates the potential of complex diamond wire manufacturing for advanced material processing. 6CCVD, an expert provider of MPCVD diamond solutions, is uniquely positioned to supply the foundational materials and specialized engineering services required to replicate, optimize, and scale this technology.
| Paper Requirement/Application | 6CCVD Solution & Capability | Value Proposition |
|---|---|---|
| High-Performance Diamond Abrasives | Single Crystal Diamond (SCD) Material | Supply of high-purity SCD material, superior in uniformity and hardness compared to conventional diamond powders, offering extended tool life and higher cutting speeds for saw wire applications. |
| Large-Area Hard Substrate Fabrication (SiC, Sapphire) | Polycrystalline Diamond (PCD) Wafers up to 125 mm | We provide PCD plates up to 125 mm in diameter, which can serve as wear-resistant dies, counter-materials, or high-thermal-conductivity substrates for processing tools required in the next phase of this research (e.g., SiC processing). |
| Abrasive Surface Functionalization (Ni/Solder Interface) | Custom Metalization Services (Ti, W, Ni, Au, Pt, Cu) | We offer internal, clean-room metalization capabilities. If researchers require more advanced interface layers than simple Ni-P plating (e.g., Ti/W wetting layers for higher temperature brazing or customized adherence), 6CCVD delivers precise, tailored solutions. |
| Saw Wire Geometry & Tooling | Precision Laser Cutting Services | We can laser-cut SCD and PCD materials to complex, precise shapes and dimensions required for new wire guidance rollers, supports, or specialized abrasive forms, with thickness control down to 0.1 ”m. |
| Achieving Sub-10 ”m TTV | Ultra-Fine Polishing (Ra < 1 nm SCD) | Post-processing of sliced wafers demands exceptional surface quality. Our high-precision polishing achieves roughness Ra < 1 nm (SCD) and < 5 nm (Inch-size PCD), critical for subsequent semiconductor or LED fabrication steps. |
| Engineering R&D Support | In-House PhD Material Science Team | 6CCVDâs expert team can assist with material selection for diamond fixed abrasive projects, offering consultation on optimizing diamond grade (SCD vs. PCD), thickness control, and material stability in high-temperature or corrosive environments (like the flux/solder baths described). |
For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.
View Original Abstract
We have carried out research and development of high-performance diamond abrasive grains fixed saw wire for electronic equipment material for wafer fabrication, such as solar cells for silicon and sapphire for the LED package substrate. It advances the prototype of the saw wire, to produce a product in a way that makes a commercial basis. Through these research and development activities, we report on the process that led to the production of silicon wafers for solar cells and sapphire wafers for LED package substrate using novel saw wires fixed diamond abrasive rains with solder and Ni electroplating process.