Silver Carboxylate Paste for High Resolution Conductive Traces
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Solution Overview
Problem
Existing silver paste technologies for electronic devices face challenges in achieving high resolution and high conductivity conductive traces due to the size of silver flakes and low conductivity, leading to economic inefficiencies as devices miniaturize.
Innovation Solution
A conductive paste composition comprising branched metal carboxylates, linear metal carboxylates, and an aromatic hydrocarbon solvent, which is free of polymer binder, offering high viscosity and high conductivity without the need for thick metal layers, enabling high resolution printing and low resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If silver flakes based on thick film technology are used, then conductivity is achieved, but manufacturing precision deteriorates due to flake size (10 to 100 micrometers) preventing high resolution traces
Solution Approach 1:
The patent changes the physical state of silver from flake form to dissolved ionic form (silver carboxylate). This parameter change allows the silver to be deposited in a soluble state and then reduced to fine particles or continuous film during firing, achieving both high conductivity and high resolution traces below 125 micrometers that were previously impossible with flake-based pastes
Solution Approach 2:
The patent introduces organic carboxylate ligands (such as acetate, propionate, or stearate) as intermediary compounds. These ligands form soluble complexes with silver ions, enabling the silver to be transported in solution and deposited uniformly. The carboxylate acts as a mediator that facilitates both solubility and controlled reduction to achieve fine conductive features
2Reliability
If thick layers are deposited to achieve low resistance, then conductivity is improved, but loss of substance increases due to large amount of silver flake material required
Solution Approach 1:
The patent changes the deposition parameter from thick layer to thin layer by utilizing the soluble nature of silver carboxylate. The dissolved silver can penetrate and form conductive pathways more efficiently, achieving low resistance with significantly reduced silver material consumption compared to thick flake-based deposits
Solution Approach 2:
The patent creates a molecular-level distribution pattern of silver through the soluble carboxylate complex, which then reduces to form conductive networks. This molecular copying approach is far more material-efficient than the macroscopic flake placement method, reducing silver usage while maintaining conductivity
3Ease of manufacture
If polymer binder is used in silver paste, then ease of manufacture is improved, but electrical conductivity deteriorates due to insulating properties of polymer
Solution Approach 1:
The patent extracts and removes the polymer binder component from the paste formulation entirely. By using silver carboxylate dissolved in organic solvent, the paste achieves manufacturability without polymer, and the subsequent reduction process creates conductive metal structures free from insulating polymer matrices that plague conventional pastes
Solution Approach 2:
The patent creates a composite system using silver carboxylate complex (silver ion + carboxylate ligand) dissolved in organic solvent. This composite approach replaces the traditional silver flake + polymer binder composite, achieving both ease of deposition and high conductivity through the soluble complex that reduces to pure metal or metal-rich conductive structures
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 composition allows for the formation of high resolution conductive features with low resistance and reduced metal usage, making it economically viable for electronic devices by providing sufficient metal content and conductivity through solubility and viscosity adjustments.
Implementation Method 1
a branched metal carboxylate, a gelling agent, wherein the gelling agent is a linear metal carboxylate, and an aromatic hydrocarbon solvent in which the branched metal carboxylate is soluble
Implementation Method 2
a gelling agent, wherein the gelling agent is a linear metal carboxylate
Implementation Method 3
heating the deposited composition to a temperature from about 80° C. to about 250° C. to form the conductive features on the substrate
Data Source
AI summary
A paste composition includes a branched metal carboxylate, a solvent in which the branched metal carboxylate is soluble and a gelling agent, wherein the gelling agent is a linear metal carboxylate. The paste solvent may be an aromatic hydrocarbon solvent. The paste compositing may be free of polymeric binder. The paste may be used in forming conductive features on a substrate, including by screen printing or offset printing.