Silver Paste Low-Temperature Sintering Resistivity Control
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Solution Overview
Problem
Existing silver pastes used for low-temperature sintering of conductive films exhibit variability in resistivity, making it difficult to achieve conductivity equivalent to bulk silver, which is a challenge for practical applications such as flexible displays and fine electronic circuits.
Innovation Solution
A silver paste containing a polyethyleneimine skeleton as a protective agent, combined with silver nanoparticles and additives like amine and amide functional groups, is used to stabilize the silver nanoparticles and achieve consistent resistivity in low-temperature sintering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional silver paste is used for low-temperature sintering, then sintering temperature is reduced, but resistivity becomes inconsistent and conductivity deteriorates
Solution Approach 1:
The patent modifies the chemical composition parameters of the silver paste by incorporating specific organic compounds with amine or amide functional groups alongside polyethyleneimine. This compositional parameter change enables the paste to achieve stable resistivity (1.5×10^-6 to 5.0×10^-6 Ω·cm) at low sintering temperatures (100-150°C), resolving the contradiction between temperature reduction and reliability maintenance
Solution Approach 2:
The patent creates a composite silver paste system combining metallic silver nanoparticles with organic compounds (polyethyleneimine and amine/amide functional group compounds). This composite structure allows the organic components to control nanoparticle aggregation and sintering behavior, achieving both low-temperature processing and consistent electrical properties
2Use of energy by stationary object
If metal nanoparticles are used for fine wiring, then processing cost and energy are reduced, but conductivity equivalent to bulk silver cannot be achieved
Solution Approach 1:
The patent changes the chemical environment parameters around silver nanoparticles by introducing organic compounds with specific functional groups. These parameter changes facilitate low-temperature sintering (reducing processing energy) while controlling nanoparticle aggregation to achieve conductivity within 1.5×10^-6 to 5.0×10^-6 Ω·cm, resolving the contradiction between energy reduction and conductivity maintenance
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 silver paste produces a conductive film with resistivity comparable to bulk silver, ensuring consistent conductivity and adhesion to substrates, even at low temperatures, thus addressing the variability issue and enhancing its applicability.
Implementation Method 1
fixing the metal as nanoparticles in the dispersion... by means of the strong reducing ability, coordinate bonding force, and electrostatic interaction of the polyalkyleneimine chain
Implementation Method 2
fixing the metal as nanoparticles in the dispersion... by means of the strong reducing ability, coordinate bonding force, and electrostatic interaction of the polyalkyleneimine chain
Implementation Method 3
heating a coating film or printed matter at a low temperature of about 150° C.... conductivity equivalent to that of bulk silver can be obtained by heating a coating film or printed matter at a low temperature
Data Source
AI summary
A problem is to provide a silver paste which can produce, without variation in resistivity value, a conductive silver coating film exhibiting resistivity substantially equivalent to the resistance value of bulk silver in low-temperature sintering. The problem is solved by providing a silver paste including a silver nanoparticle aqueous dispersion prepared by using a compound having a polyethyleneimine skeleton as a protective agent, a compound having a functional group reactable with nitrogen atoms in the polyethyleneimine, and at least one compound selected from the group consisting of a compound having an amine functional group and a compound having an amide functional group.