Silver Powder Orientation for Fine Low-Resistance Electrode Printing
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Solution Overview
Problem
The challenge is to reduce the wire width of electrode wiring from approximately 25 μm to 15 μm or less while maintaining the integrity of the wires and reducing the resistance of the electrode wiring during printing.
Innovation Solution
A silver powder and a mixed silver powder are developed, where the silver powder consists of particles with a main surface region oriented towards the (111) plane or a plane close to it, with a specific KAM value and aspect ratio, and the mixed silver powder includes these particles mixed with micro silver powder to enhance specific surface area and filling ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional silver powder is used for printing fine wires, then the wire width can be reduced to 15 μm or less, but the resistance of the electrode wiring increases and wire integrity deteriorates
Solution Approach 1:
The invention applies local quality by controlling the crystallographic orientation of silver particles at the local level. Specifically, particles with the (111) plane oriented in the stacking direction are used, which creates favorable conditions for plastic deformation and sintering at the particle level, thereby improving wire integrity and reducing resistance while enabling fine wire printing
Solution Approach 2:
The invention changes the crystallographic parameter of the silver particles by selecting particles where the (111) plane is oriented in the stacking direction and controlling the KAM value to be 1.0 or less. This parameter change in crystal orientation enables the particles to deform and sinter more effectively during printing, resolving the contradiction between fine wire formation and maintaining low resistance
2Reliability
If highly crystalline silver powder with low KAM value is used, then particle deformation is restricted, but mixing with micro silver powder improves filling ratio and reduces resistance
Solution Approach 1:
The invention uses composite materials by mixing silver particles with specific crystal orientation (low KAM value, (111) plane oriented) with micro silver powder. This composite approach combines the advantages of both particle types: the oriented particles provide structural integrity and low deformation, while the micro powder fills gaps and improves packing density, thereby reducing resistance without sacrificing manufacturability
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 developed silver and mixed silver powders achieve low-resistance electrode wiring when printing fine wires, enabling the formation of conductive patterns with reduced line resistance.
Implementation Method 1
silver particles whose main region of a silver particle upper surface is a (111) plane or a plane close to the (111) plane, wherein a KAM value of the silver particles is 0.4 or more and 1.0 or less
Implementation Method 2
a KAM value of the silver particles is 0.4 or more and 1.0 or less
Implementation Method 3
applying strain to a highly crystalline silver powder that includes, as 30% or more of all particles, silver particles whose main region of a silver particle upper surface is a (111) plane or a plane close to the (111) plane, a KAM value of the silver particles being less than 0.4, wherein the strain is applied by applying mechanical energy until the KAM value of the silver particles becomes 0.4 or more and 1.0 or less
Implementation Method 4
the highly crystalline silver powder is obtained by adding an ascorbic acid-based reducing agent to a silver chelate complex solution after the silver chelate complex solution is prepared by addition of an amino acid
Implementation Method 5
an aspect ratio yielded by dividing a median diameter on a volume basis according to laser diffraction by an average thickness of the silver particles in cross-sectional measurement
Data Source
AI summary
Obtained are a silver powder and a mixed powder that can achieve low-resistance electrode wiring when printing wires, and a conductive paste using these powders. The silver powder includes, as 20% or more and less than 95% of all particles, silver particles whose main region of the silver particle upper surface is the (111) plane or a plane close to the (111) plane. The KAM value of the silver particles is 0.4 or more and 1.0 or less.