Hot-Rolled Copper Plate Grain Boundary Control
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Solution Overview
Problem
The existing methods for producing copper plates, particularly for sputtering targets, involve multiple processes that increase production costs and do not adequately address residual stress and fatigue characteristics, leading to insufficient prevention of abnormal discharge during thermal cycles and high-power sputtering.
Innovation Solution
A hot-rolled copper plate with a purity of 99.99 mass % or greater, featuring an average crystal grain diameter of 40 μm or less and a (Σ3+Σ9) grain boundary length ratio of 28% or greater, which improves workability, fatigue characteristics, and prevents abnormal discharge by enhancing grain boundary consistency and reducing impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cold working and heat treatment processes are performed to refine crystal grains and reduce distortion, then manufacturing precision is improved, but device complexity and production cost increase
Solution Approach 1:
The invention performs preliminary grain refinement during the hot rolling process itself by controlling finishing temperature (500-950°C) and rolling reduction ratio (5-80%), rather than requiring separate cold working and heat treatment steps later. This preliminary action achieves the desired crystal grain structure (average diameter 5-50 μm) and grain boundary characteristics directly in the hot rolling stage.
Solution Approach 2:
The invention extracts and eliminates the cold working and heat treatment processes from the traditional multi-step manufacturing flow. By achieving grain refinement and distortion reduction solely through controlled hot rolling, the patent removes unnecessary processing steps while maintaining or improving manufacturing precision.
2Manufacturing precision
If multiple processing steps are used to achieve desired crystal structure, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The invention merges the grain refinement function and distortion reduction function into the hot rolling process itself. By combining temperature control (500-950°C) and rolling reduction ratio control (5-80%) during hot rolling, the patent achieves both crystal grain diameter control (5-50 μm) and improved grain boundary structure without requiring separate processing steps.
Solution Approach 2:
The invention performs grain refinement and structural optimization as a preliminary action during hot rolling, before subsequent processing steps. This preliminary grain refinement ensures that no additional cold working or heat treatment is needed, thereby improving productivity while maintaining manufacturing precision.
3Ease of manufacture
If traditional hot rolling is performed without specific grain boundary control, then ease of manufacture is improved, but reliability decreases due to insufficient fatigue characteristics and abnormal discharge prevention
Solution Approach 1:
The invention changes critical parameters during hot rolling: finishing temperature (500-950°C) and rolling reduction ratio (5-80%). These parameter changes promote the formation of specific grain boundaries (Σ3 and Σ9 boundaries) that improve reliability. The controlled parameters ensure average crystal grain diameter of 5-50 μm and enhanced fatigue characteristics without complicating the manufacturing process.
Solution Approach 2:
The invention focuses on creating local quality improvements at grain boundaries through controlled hot rolling. By optimizing finishing temperature and rolling reduction ratio, the patent increases the proportion of Σ3 and Σ9 grain boundaries (coincident site lattice boundaries) which have superior mechanical properties and resistance to abnormal discharge, thereby improving reliability locally at critical interfaces.
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 allows for reduced production costs by omitting cold rolling and heat treatment processes, while improving workability and fatigue characteristics, and effectively preventing abnormal discharge in sputtering targets and heat dissipation substrates.
Implementation Method 1
a substantially recrystallized structure, an average crystal grain diameter of 80 microns or less
Implementation Method 2
performing hot working (hot rolling or hot forging) on the ingot
Implementation Method 3
conductivity of the pure copper is 101% IACS or greater
Data Source
AI summary
A hot-rolled copper plate consists of pure copper having a purity of 99.99 mass % or greater, the hot-rolled copper plate having an average crystal grain diameter of 40 μm or less, and a (Σ3+Σ9) grain boundary length ratio (L (σ3+σ9)/L), which is a ratio between a total crystal grain boundary length L measured by an EBSD method and a sum L (σ3+σ9) of a Σ3 grain boundary length Lσ3 and a Σ9 grain boundary length Lσ9, being 28% or greater.