Pure Copper Sheet Composition for Grain Growth Suppression
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Solution Overview
Problem
Existing pure copper sheets used in electrical and electronic components face issues with crystal grain coarsening during heat treatment, leading to nonuniformity and reduced hot workability, especially when joined with ceramic substrates at high temperatures.
Innovation Solution
A pure copper sheet composition with 99.96% Cu, 9.0-100.0 mass ppm Ag, Sn, and Fe, and controlled impurities like S, Mg, Sr, Ba, Ti, Zr, Hf, and Y, with specific crystal plane orientations and strain energy management, to suppress crystal grain growth and ensure high electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pure copper is used to achieve high electrical conductivity and heat radiation, then electrical conductivity is improved, but crystal grains become coarse during heat treatment
Solution Approach 1:
The invention changes the chemical composition parameters of copper by precisely controlling the content of impurity elements (Ag: 0.001-100 ppm, Sn: 0.001-100 ppm, Fe: 0.001-100 ppm, S: 0.003-30 ppm) to achieve the desired crystal grain growth suppression effect while maintaining high electrical conductivity
Solution Approach 2:
The invention uses trace impurity elements as intermediary substances that segregate at crystal grain boundaries during heat treatment, acting as barriers to prevent crystal grain coarsening while having minimal impact on electrical conductivity
2Stability of the object's composition
If sulfur content is increased to suppress crystal grain coarsening, then crystal grain size is controlled, but hot workability significantly deteriorates
Solution Approach 1:
The invention optimizes the sulfur content parameter within a specific range (0.003-30 ppm) to achieve the minimum effective concentration for crystal grain boundary segregation, thereby suppressing crystal grain coarsening while minimizing the negative impact on hot workability
3Ease of manufacture
If heat treatment is performed at high temperature to join copper to ceramic substrate, then joining is achieved, but crystal grains become coarse and nonuniform
Solution Approach 1:
The invention performs preliminary action by controlling the compositional parameters and crystal grain size before heat treatment, ensuring that the copper material has optimized impurity content and initial crystal structure that resist coarsening during subsequent high-temperature joining processes
Solution Approach 2:
The invention changes the material parameters by precisely controlling impurity element concentrations to create a composition that maintains crystal grain stability during high-temperature heat treatment required for copper-ceramic joining
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 effectively prevents crystal grain coarsening and nonuniformity after heat treatment, maintaining high electrical conductivity and hot workability, suitable for high-current and heat radiation applications.
Implementation Method 1
there is an element having a crystal grain growth-suppressing effect of suppressing the coarsening of crystal grains by being present at crystal grain boundaries
Data Source
AI summary
A pure copper sheet has a composition including 99.96 mass % or more of Cu, 9.0 mass ppm or more and less than 100.0 mass ppm of a total content of Ag, Sn, and Fe, and inevitable impurities as a balance, in which an average crystal grain size of crystal grains on a rolled surface is 10 μm or more, the pure copper sheet has crystals in which crystal planes parallel to the rolled surface are a {022} plane, a {002} plane, a {113} plane, a {111} plane, and a {133} plane, and diffraction peak intensities of the individual crystal planes that are obtained by X-ray diffraction measurement by a 2θ/θ method on the rolled surface satisfy I {022}/(I {022}+I {002}+I {113}+I {111}+I {133})≤0.15, I {002}/I {111}≥10.0, and I {002}/I {113}≥15.0.