Copper Particle Coating for Low-Temperature Sintering
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Solution Overview
Problem
Conventional copper particles require high-temperature sintering due to the high decomposition temperature of surface treatment agents like fatty acids and aliphatic amines, leading to increased sintering start temperature and resistance of the conductor film, and poor adhesion to resin sheets.
Innovation Solution
Copper particles coated with a copper salt of an aliphatic organic acid as the surface treatment agent, which lowers the sintering start temperature, suppresses oxidation and aggregation, and improves adhesion, using specific aliphatic organic acids like lauric acid and stearic acid with preferred carbon atom ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional surface treatment agents like fatty acids or aliphatic amines are used, then the copper particles can be coated to prevent oxidation, but the sintering temperature must be kept high to remove the organic matter from the surface treatment agent
Solution Approach 1:
The invention changes the chemical composition parameter of the surface treatment agent from conventional fatty acids or aliphatic amines to a copper salt of an aliphatic organic acid. This parameter change fundamentally alters the decomposition characteristics, allowing the surface treatment agent to be removed at lower temperatures while maintaining its oxidation prevention function during storage and handling.
2Object-generated harmful factors
If high-temperature sintering is performed to remove surface treatment agents, then organic matter can be removed from the surface, but the resistance of the conductor film increases and adhesion to resin sheets deteriorates
Solution Approach 1:
By changing the surface treatment agent to a copper salt of an aliphatic organic acid, the decomposition temperature parameter is reduced. This allows organic matter to be removed at lower sintering temperatures (150-250°C), thereby preventing the increase in conductor film resistance and maintaining good adhesion to resin sheets that would otherwise occur at high temperatures.
3Stability of the object's composition
If conventional surface treatment agents are used, then copper particles can be stabilized, but the sintering start temperature increases
Solution Approach 1:
The invention changes the chemical composition of the surface treatment agent to a copper salt of an aliphatic organic acid, which modifies the thermal decomposition characteristics. This parameter change enables the particles to remain stable during storage and handling while lowering the sintering start temperature, as the copper salt decomposes at lower temperatures compared to conventional organic surface treatment agents.
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 use of copper salt of aliphatic organic acid as a surface treatment agent enables copper particles to be sintered at lower temperatures, reducing the resistance of the conductor film and enhancing adhesion to resin sheets, resulting in improved low-temperature sinterability and conductive properties.
Implementation Method 1
a surface treatment agent containing a copper salt of an aliphatic organic acid is applied to a surface of the core particles
Implementation Method 2
firing of the copper particles coated with the surface treatment agent, such as a fatty acid or an aliphatic amine, may be performed under high-temperature conditions to remove organic matter from the surface treatment agent
Data Source
AI summary
Copper particles are provided that each include a core particle made of copper and a coating layer that coats the surface of the core particle, wherein the coating layer is made of a copper salt of an aliphatic organic acid. It is also preferable that the copper particles have an infrared absorption peak in a range of 1504 to 1514 cm−1 and no infrared absorption peak in a range of 1584 to 1596 cm−1. It is also preferable that, in thermogravimetric analysis of the copper particles, the temperature at which the ratio of the mass loss value to the mass loss value at 500° C. reaches 10% is from 150° C. to 220° C. A method is also provided for producing copper particles, the method including bringing core particles made of copper into contact with a solution containing a copper salt of an aliphatic organic acid to thereby coat the surface of the core particles.