Conductive Paste Low-Temperature Curing for Solar Cell Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Thermosetting conductive pastes used for forming electrodes in semiconductor devices, particularly solar cells, often require high-temperature processing to achieve low specific resistance, which can damage sensitive materials and is inefficient, whereas high-temperature firing pastes have higher specific resistance and are not suitable for low-temperature applications.
Innovation Solution
A conductive paste composition comprising conductive components, epoxy resin, imidazole, solvent, and optionally phenol resin and coupling agents, optimized to achieve low specific resistance and adhesiveness, allowing for low-temperature processing (≤250°C) and forming electrodes with low specific resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thermosetting conductive paste is used to form electrodes, then adhesiveness is improved, but specific resistance increases (worsens)
Solution Approach 1:
The invention changes the chemical composition parameters of the conductive paste by incorporating specific ratios of spherical conductive particles (40-70 wt%), flaky conductive particles (20-40 wt%), and nanoscale conductive particles (10-30 wt%), along with imidazole-based curing agents and epoxy resins. This multi-parameter composition adjustment enables the paste to achieve both low specific resistance (≤10 μΩ·cm) and high adhesiveness without requiring high-temperature processing
Solution Approach 2:
The invention creates a composite conductive paste system that combines three types of conductive particles with different morphologies and sizes (spherical, flaky, and nanoscale), along with epoxy resin and imidazole-based curing agents. This composite structure allows the paste to simultaneously achieve low specific resistance through multiple conduction pathways and high adhesiveness through the epoxy matrix, resolving the contradiction between these two properties
2Reliability
If high temperature firing is used to reduce specific resistance, then electric characteristics are improved, but material degradation occurs
Solution Approach 1:
The invention changes the processing temperature parameter from conventional high-temperature firing (550-900°C) to low-temperature curing (room temperature to 250°C). This is achieved by modifying the chemical composition to include imidazole-based curing agents that enable low-temperature crosslinking of epoxy resin, thereby reducing thermal stress and preventing material degradation while still achieving low specific resistance (≤10 μΩ·cm)
Solution Approach 2:
The invention replaces the thermal-mechanical firing process with a chemical curing process. Instead of relying on high-temperature thermal energy to sinter and conduct particles together, the invention uses imidazole-based curing agents to chemically crosslink the epoxy resin matrix at low temperatures, which binds the conductive particles into a cohesive network. This chemical substitution eliminates the harmful high-temperature effects while achieving equivalent or superior electrical properties
3Reliability
If high temperature processing is used to achieve low specific resistance, then electric characteristics are improved, but processing efficiency decreases
Solution Approach 1:
The invention changes the processing temperature parameter from 550-900°C to room temperature to 250°C, and reduces processing time from prolonged high-temperature firing to rapid low-temperature curing. The imidazole-based curing agents enable the epoxy resin to crosslink and set quickly at low temperatures, achieving low specific resistance (≤10 μΩ·cm) within minutes or hours rather than requiring extended high-temperature processing, thereby significantly improving production efficiency
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 enables the formation of electrodes with low specific resistance and improved adhesiveness at low temperatures, suitable for sensitive materials and high-efficiency solar cells, while avoiding material degradation from high-temperature processing.
Implementation Method 1
a conductive film is formed by curing the resin component to bond silver particles to each other
Implementation Method 2
heating at a relatively low temperature of room temperature (about 20°C.) to about 250°C.
Data Source
AI summary
A conductive paste, for forming an electrode of a solar cell, includes (A) a conductive component, (B) an epoxy resin, (C) an imidazole and (D) a solvent. An amount of (C) the imidazole in the conductive paste is 0.1 to 1.0% by weight based on 100% by weight of the conductive paste excluding (D) the solvent.