Copper Powder Production via High-Pressure Water Atomization
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Solution Overview
Problem
Conventional copper powders used in conductive pastes for forming contact members on ceramic or dielectric substrates face issues with shrinkage mismatch and increased oxygen content when particle diameter is reduced, leading to lower conductivity and shrinkage starting temperature, and existing production methods are inefficient and costly.
Innovation Solution
A method involving rapid cooling and solidification of molten copper by spraying high-pressure water in a non-oxidizing atmosphere to produce copper powder with a small particle diameter and low oxygen content, achieving a high shrinkage starting temperature, which is then used in a conductive paste for forming conductive films.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the particle diameter of copper powder is decreased to form a thin copper layer, then the ability to form thin layers is improved, but the oxygen content increases and shrinkage starting temperature decreases
Solution Approach 1:
The patent changes the production parameters of copper powder by controlling particle diameter within 0.6-5 μm and oxygen content within 0.03-0.5 wt%, achieving a balance between formability and thermal stability. The water atomization process parameters (water jet pressure, flow rate, vertical angle) are optimized to produce fine particles with low oxygen content and high shrinkage starting temperature
Solution Approach 2:
The patent uses a non-oxidizing atmosphere during the water atomization process to prevent oxidation of copper particles. This inert environment protects the fine copper particles from absorbing oxygen, thereby maintaining low oxygen content even at small particle diameters and preserving high shrinkage starting temperature
2Volume of moving object
If conventional water atomizing method is used to produce fine copper powder, then particle diameter is reduced, but oxygen content increases and shrinkage starting temperature decreases
Solution Approach 1:
The patent employs a non-oxidizing atmosphere during water atomization to prevent oxidation of copper particles. This inert environment protects fine copper particles from absorbing oxygen, thereby maintaining low oxygen content even at small particle diameters
Solution Approach 2:
The patent uses high-pressure water atomization (water jet pressure 60-180 MPa, flow rate 80-190 L/min, vertical angle 10-30°) to produce fine copper particles. The hydraulic system efficiently atomizes molten copper into fine particles while the non-oxidizing atmosphere prevents oxygen absorption
3Volume of moving object
If copper powder with small particle diameter is used, then thin copper layers can be formed, but the difference between shrinkage rate of conductive paste and ceramic substrate increases
Solution Approach 1:
The patent optimizes copper powder parameters (particle diameter 0.6-5 μm, oxygen content 0.03-0.5 wt%) to achieve high shrinkage starting temperature (≥500°C). This parameter optimization ensures that the shrinkage behavior of the copper paste matches the ceramic substrate during firing, preventing delamination and cracks
Solution Approach 2:
By maintaining a non-oxidizing atmosphere during production, the patent ensures low oxygen content in fine copper particles, which preserves high shrinkage starting temperature and ensures shrinkage rate compatibility with ceramic substrates during the firing 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 method produces copper powder with a low oxygen content and high shrinkage starting temperature, ensuring better conductivity and adhesion to substrates, while reducing production costs and improving the yield of fine particles.
Implementation Method 1
spraying gas containing ammonia onto the molten metal of copper
Implementation Method 2
rapidly cooled and solidified by spraying a high-pressure water onto the molten metal
Implementation Method 3
rapidly cooling and solidifying the heated molten metal by spraying a high-pressure water onto the heated molten metal
Implementation Method 4
a water atomizing method at a water jet pressure of higher than 60 MPa and not higher than 180 MPa, a water jet flow rate of 80 to 190 L/min. and a water jet vertical angle of 10 to 30°
Data Source
AI summary
While a molten metal of copper heated to a temperature, which is higher than the melting point of copper by 250 to 700° C. (preferably 350 to 650° C. and more preferably 450 to 600° C.), is allowed to drop, a high-pressure water is sprayed onto the heated molten metal of copper in a non-oxidizing atmosphere (such as an atmosphere of nitrogen, argon, hydrogen or carbon monoxide) to rapidly cool and solidify the heated molten metal of copper to produce a copper powder which has an average particle diameter of 1 to 10 μm and a crystallite diameter Dx(200) of not less than 40 nm on (200) plane thereof, the content of oxygen in the copper powder being 0.7% by weight or less.