Silver Paste Composition for Conductivity and Printability
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Solution Overview
Problem
Conventional silver pastes face a trade-off between achieving high electrical conductivity and good printability, with high metal powder content leading to dense films but poor printability, and the addition of other components to prevent migration compromising conductivity.
Innovation Solution
A silver paste with a high silver powder content, specific particle size distribution, copper content, binder resin percentage, and dry film density, optimized to maintain high conductivity and printability while minimizing migration through controlled copper addition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the content of metal powder in the electrically conductive paste is increased to obtain high electrical conductivity, then the electrical conductivity is improved, but the printability is deteriorated
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution parameters (D10, D50, D90 values) and specific surface area of the silver powder, along with the binder resin content ratio, to achieve optimal paste viscosity and flow characteristics that enable good printability while maintaining high metal powder content for electrical conductivity
Solution Approach 2:
The patent uses a composite material approach by combining silver powder with specific binder resin components in optimized ratios, creating a paste formulation that balances the contradictory requirements of high metal content for conductivity and appropriate viscosity for printability
2Manufacturing precision
If the content of metal powder is increased to form a dense coating film, then the coating film density is improved, but the printability is sacrificed
Solution Approach 1:
The patent achieves dense coating film formation while maintaining printability by changing the particle size distribution parameters of the silver powder, specifically optimizing D10, D50, and D90 values to enable better packing density in the coating film without compromising paste processability
Data Source
AI summary
The present invention provides a silver paste, containing at least a silver powder, a binder resin, and an organic solvent, in which a content of the silver powder based on the silver paste is 80.00 to 97.00% by mass, D10 is 1.00 to 3.00 μm and D50 is 3.00 to 7.00 μm, where D10 and D50 respectively represent a 10% value and a 50% value of a volume-based cumulative fraction obtained by laser diffraction particle size distribution measurement of the silver powder, the silver powder has a specific surface area of 0.10 to 0.30 m2/g, the silver powder has a copper content of 10 to 5000 ppm by mass, a content of the binder resin based on the silver powder is 0.430 to 0.750% by mass, and the silver paste has a dry film density of 7.50 g/cm3 or more.