Silver Conductive Paste Composition for Low-Resistance Sintering
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electrically conductive pastes exhibit high electric resistance values and insufficient electrical conductivity when sintered for wiring applications, and lack sufficient bonding strength when bonding electronic substrates and components.
Innovation Solution
A combination of flake-like silver powder with a median diameter of 15 µm or less and silver powder with a median diameter of 25 µm or more, along with a solvent, is used, with specific mass ratios to achieve low electric resistance and enhanced bonding strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If only micron-sized or nano-sized silver particles (average particle diameter 18 µm or less) are used in the electrically conductive paste, then the paste can be easily applied and sintered, but the resulting sintered body has high electric resistance value and insufficient electrical conductivity
Solution Approach 1:
The patent applies parameter changes by introducing a dual particle size distribution system. Specifically, it combines fine silver particles (average diameter 18 µm or less) with coarse silver particles (average diameter 25 µm or more) in specific weight ratios (fine particles: 10-50 wt%, coarse particles: 50-90 wt%). This parameter change in particle size distribution resolves the contradiction by allowing the fine particles to provide good sintering behavior and electrical conductivity, while the coarse particles contribute to low electric resistance and high strength, achieving both ease of manufacture and reliability.
2Reliability
If only fine silver particles (average particle diameter 15 µm or less) are used in the electrically conductive paste, then the electrical conductivity is improved, but the bonding strength between electronic substrate and component becomes insufficient
Solution Approach 1:
The patent applies composite materials principle by creating a composite particle system consisting of two distinct silver particle types with different size ranges. The fine silver particles (average diameter 18 µm or less) provide excellent electrical conductivity and sintering characteristics, while the coarse silver particles (average diameter 25 µm or more) provide mechanical strength and bonding capability. The specific weight ratio composition (fine: 10-50 wt%, coarse: 50-90 wt%) creates a synergistic composite structure that simultaneously achieves high electrical conductivity and strong bonding strength, resolving the contradiction between these two properties.
3Reliability
If a combination of multiple types of silver powder with different particle sizes is used, then both electrical conductivity and bonding strength can be improved, but the paste composition and processing complexity increases
Solution Approach 1:
The patent applies parameter changes by establishing specific quantitative ranges for the dual particle size system. Instead of using multiple particle size categories, it simplifies the complexity by focusing on two distinct size ranges (fine: 18 µm or less, coarse: 25 µm or more) with defined weight ratios (fine: 10-50 wt%, coarse: 50-90 wt%). This parameter specification resolves the contradiction by providing a standardized, reproducible composition that achieves both high electrical conductivity and bonding strength while maintaining manageable paste formulation and processing procedures.
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 resulting sintered bodies demonstrate low electric resistance values, excellent electrical conductivity, and strong bonding capabilities, effectively addressing the limitations of previous technologies.
Implementation Method 1
the volatile dispersant is volatilized upon heating and the non-spherical silver particles sinter with each other
Data Source
Figure 1~2
Figure 3A~3B
Figure 3C~3D
AI summary
An object of the present invention is to provide an electrically conductive paste and a sintered body thereof having a low electric resistance value and excellent electrical conductivity when made into a sintered body. An electrically conductive paste comprising: a flake-like silver powder having a median diameter D50 of 15 µm or less; a silver powder having a median diameter D50 of 25 µm or more; and a solvent, wherein the content of the flake-like silver powder is 15 to 70 parts by mass and the content of the silver powder having a median diameter D50 of 25 µm or more is 30 to 85 parts by mass based on 100 parts by mass in total of the flake-like silver powder and the silver powder having a median diameter D50 of 25 µm or more.