Low-Temperature Conductive Paste for Low-Resistivity Electrodes
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Solution Overview
Problem
Thermosetting conductive pastes typically require high-temperature treatment above 250°C to achieve good adhesion and electrical characteristics, resulting in higher specific resistance compared to high-temperature firing type conductive pastes.
Innovation Solution
A conductive paste comprising a conductive component, a thermosetting resin, a compound with a specific structure as a cationic polymerization initiator, and a solvent, which can be treated at a low temperature of not more than 250°C to form a conductive film with a low specific resistance, using silver or copper particles and a mixture of spherical and flaky particles for enhanced conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thermosetting conductive paste is used, then adhesion and electrical characteristics are improved, but treatment temperature must be increased above 250°C resulting in higher specific resistance
Solution Approach 1:
The invention changes the chemical composition parameters of the conductive paste by incorporating specific organic solvents (ethyl glycol monophenyl ether, butyl carbitol acetate) and controlled amounts of water (0.1-5.0 mass%), along with specific resin ratios (epoxy resin 20-70 parts, phenolic resin 10-50 parts, cellulose resin 10-50 parts per 100 parts silver particles). These parameter changes enable the paste to cure effectively at lower temperatures (not more than 250°C) while maintaining good adhesion and achieving low specific resistance (not more than 10 μΩ·cm), thus resolving the contradiction between treatment temperature and electrical characteristics.
2Reliability
If high-temperature firing type conductive paste is used, then specific resistance is reduced, but treatment temperature must be increased to 550-900°C
Solution Approach 1:
The invention uses a composite resin system combining epoxy resin, phenolic resin, and cellulose resin in specific proportions, along with a multi-component solvent system. This composite material formulation creates a synergistic effect where the phenolic and cellulose resins provide thermal stability and adhesion at lower temperatures, while the epoxy resin contributes to low specific resistance. The composite structure allows the paste to achieve electrical characteristics comparable to high-temperature firing pastes without requiring temperatures above 250°C.
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 conductive paste achieves a low specific resistance and reliable thermal curing at reduced temperatures, suitable for forming electrodes in semiconductor devices and solar cells without thermal degradation.
Implementation Method 1
a compound having a structure of formula (1) as a cationic polymerization initiator
Implementation Method 2
conductive paste containing (A) silver particles
Implementation Method 3
a thermosetting conductive paste that can be used to form electrodes and circuit patterns in devices
Data Source
Figure 1~2
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AI summary
Provided is a thermosetting conductive paste which is able to be processed at low temperature (for example, at 250°C or less), and which enables the achievement of a conductive film that has low resistivity. The conductive paste which contains (A) a conductive component, (B) a thermosetting resin, (C) a compound having a specific structure, and (D) a solvent.