Conductive Metal Paste with Self-Heating Protective Agent
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Solution Overview
Problem
Conductive metal pastes face issues with low adhesion to base materials due to the presence of ceramic particles or binder, which inhibit fusion and reduce conductivity, and existing methods to improve adhesion are costly and restrictive, either increasing production costs or requiring additional steps and surface modifications that may not be feasible.
Innovation Solution
A conductive metal paste with metal fine particles coated by a protective agent that generates 500 J or more of heat per unit mass at 200° C. to 300° C., allowing for improved adhesion and fusion with the base material, eliminating the need for additional additives and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If ceramic particles or binder are added to improve adhesion, then adhesion to base material is improved, but conductivity is reduced due to inhibition of metal particle fusion
Solution Approach 1:
The invention removes ceramic particles and binder resin from the conductive paste formulation, using only metal fine particles and protective agents. This extraction of harmful insulating components resolves the contradiction by allowing metal particles to fuse directly, maintaining conductivity while achieving adhesion through the protective agent's heat generation and chemical reactivity with the base material.
Solution Approach 2:
The invention changes the protective agent from conventional low-heat-generation materials to specific compounds (amines, carboxylic acids, sulfonic acids) that generate 500 J/g or more of heat. This parameter change in heat generation capability enables the protective agent to both prevent aggregation and provide adhesion through thermal diffusion and chemical bonding, eliminating the need for ceramic particles or binder resin.
2Stability of the object's composition
If conventional protective agents are used to prevent aggregation, then particle stability is improved, but adhesion to base material remains low
Solution Approach 1:
The invention changes the protective agent's heat generation parameter from conventional low values to 500 J/g or more. This parameter change enables the protective agent to provide both particle stability during storage and strong adhesion after heating, as the high heat generation promotes diffusion and chemical bonding with the base material while preventing aggregation during storage through adsorption.
Solution Approach 2:
The protective agent serves dual functions: preventing particle aggregation during storage and providing adhesion to the base material after heating. This self-service capability eliminates the need for separate adhesion promoters or ceramic particles, as the same protective agent performs both functions through its heat generation and chemical reactivity.
3Strength
If additional adhesion promoters or base layers are added, then adhesion is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The invention removes the need for additional adhesion promoters, binder resin, and base layers by using only metal fine particles and protective agents. This extraction simplifies the formulation and manufacturing process while maintaining strong adhesion through the protective agent's heat generation and chemical bonding capabilities.
Solution Approach 2:
The protective agent performs multiple functions: preventing particle aggregation during storage, enabling low-temperature sintering through heat generation, and providing adhesion to the base material through chemical bonding. This multi-functionality eliminates the need for separate adhesion promoters or base layers, reducing process complexity and manufacturing cost.
4Temperature
If metal fine particles are used for low-temperature sintering, then sintering temperature is reduced, but adhesion to base material is insufficient
Solution Approach 1:
The invention changes the protective agent's heat generation parameter to 500 J/g or more, which enables low-temperature sintering while providing sufficient adhesion. The high heat generation promotes diffusion and chemical bonding with the base material at low temperatures, resolving the contradiction between low sintering temperature and adequate adhesion.
Solution Approach 2:
The protective agent provides both the heat necessary for low-temperature sintering and the adhesion to the base material. This self-service capability eliminates the need for high external heating temperatures while maintaining strong adhesion, as the protective agent's decomposition heat and chemical reactivity simultaneously enable sintering and bonding.
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 conductive metal paste achieves high adhesion and conductivity by self-heating during calcination, reducing production time and costs, and eliminating the need for additional adhesion promoters, while maintaining a smooth film with minimal cracks or holes.
Implementation Method 1
an amount of heat generated per unit mass (g) of the metal fine particle is not less than 500 J at a temperature of an external heat source temperature in a range of 200° C. to 300° C. when being calcined by the external heat source
Implementation Method 2
a phenomenon that a melting point is depressed due to a rapid increase in a surface area with respect to particle volume (hereinafter, referred to as melting point depression) is known in metal fine particle. Therefore, diffusion of the metal fine particles at an interface between particles occurs at a temperature lower than the melting point of bulk metal, and a metal bond is formed by progression of fusion
Implementation Method 3
it is essential to suppress the aggregation or fusion of metal fine particles by coating the surface thereof with an organic substance called protective agent which exhibits adsorption properties
Data Source
AI summary
A metal fine particle for a conductive metal paste includes a protective agent covering a surface of the metal fine particle. An amount of heat generated per unit mass (g) of the metal fine particle is not less than 500 J at a temperature of an external heat source temperature in a range of 200° C. to 300° C. when being calcined by the external heat source. The protective agent includes at least one selected from the group consisting of dipropylamine, dibutylamine, triethylamine, tripropylamine, tributylamine, butanethiol, pentanethiol, hexanethiol, heptanethiol, octanethiol, nonanethiol, decanethiol, undecanethiol and dodecanethiol. The content of the protective agent is in a range of 0.1 to 20% by mass with respect to the mass of the metal fine particle.