Metal Oxide-Attached Silver Powder for Stronger Conductive Paste Adhesion
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Solution Overview
Problem
Conductive pastes containing low-melting point metals struggle to achieve high adhesive strength with underlying layers, leading to electrode separation issues, especially at high aspect ratios, due to uneven distribution of metal oxide particles caused by differences in specific gravity between silver and metal oxide powders.
Innovation Solution
Attaching a low-melting point metal oxide to the surfaces of silver particles to create a metal oxide-attached silver powder, which is then incorporated into a conductive paste, ensuring even distribution and enhanced adhesive strength by lowering the softening point temperature of glass frit and improving the uniformity of the conductor pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If low-melting point metal oxide powder is mixed with silver particles in conductive paste, then contact resistance is improved, but adhesive strength between conductive pattern and underlying layer decreases
Solution Approach 1:
The patent combines silver particles and low-melting point metal oxide particles into a single composite particle structure, where the metal oxide is attached to the silver particle surface. This merging ensures that both materials function together as one unit, preventing separation during paste application and firing, thereby maintaining both low contact resistance and high adhesive strength.
Solution Approach 2:
The low-melting point metal oxide is pre-attached to the silver particle surfaces before the conductive paste is applied. This preliminary action ensures uniform distribution of the metal oxide throughout the paste, which prevents aggregation during firing and ensures consistent adhesive strength and contact resistance properties in the final conductive pattern.
2Reliability
If aspect ratio of conductive pattern is increased to reduce conductor resistance, then wire thickness is reduced, but adhesive strength decreases leading to electrode separation
Solution Approach 1:
By merging silver particles and metal oxide particles into composite structures, the paste maintains uniform composition even when forming high aspect ratio patterns. This prevents the metal oxide from aggregating or separating during the firing process, ensuring that adhesive strength is maintained throughout the conductive pattern regardless of its aspect ratio.
Solution Approach 2:
The patent changes the physical state of the metal oxide from a separate powder component to a surface-coated layer on silver particles. This parameter change in the material's physical configuration ensures that the metal oxide remains uniformly distributed during paste application and firing, maintaining adhesive strength even when the conductive pattern has high aspect ratio dimensions.
3Strength
If metal oxide powder particles are evenly distributed in conductive paste, then adhesive strength is improved, but particle aggregation occurs due to specific gravity difference
Solution Approach 1:
The patent merges silver particles and metal oxide particles into composite structures where the metal oxide is attached to the silver particle surface. Since silver has higher specific gravity than the metal oxide, the composite particles behave as a single phase with uniform density, preventing aggregation or separation during paste application and firing, thereby maintaining both even distribution and high adhesive strength.
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 approach significantly increases the adhesive strength of the conductive pattern, reduces micro-cracks, and maintains high conductivity, even at high aspect ratios, thereby preventing electrode separation and improving the reliability of the conductive pattern.
Implementation Method 1
Some metal oxides have the effect of lowering the softening point temperature of a glass frit that is mixed with the conductive paste. As a result of the softening point temperature of the glass frit being lowered, when the coating film is fired, glass particles can flow rapidly and migrate to the interface between the film and the substrate to form a strong bond
Implementation Method 2
If the metal oxide powder particles are evenly distributed, a variation occurs in the softening point temperature of the glass, as a result of which, it is expected that the effect of lowering the softening point temperature of the glass frit cannot be effectively exhibited. Furthermore, the inside of the conductive pattern film becomes nonuniform after firing, which may increase the possibility of breakage of the film caused by contact points between different phases.
Data Source
AI summary
A silver powder containing: silver particles; and an adherent that is attached to surfaces of the silver particles and contains a metal oxide that has a melting point lower than a melting point of silver.