Lead-Free Silver Paste for Solar Cell Contact Penetration
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Solution Overview
Problem
Conventional solar cell technologies face challenges in achieving improved electrical performance and efficient manufacturing methods for semiconductor devices, particularly in forming effective electrical contacts between conductive materials and semiconductor substrates.
Innovation Solution
A thick film composition comprising electrically conductive silver, lead-free glass frits, and organic media is applied to semiconductor substrates, where the organic medium is removed upon firing, allowing the silver and glass frits to sinter and penetrate insulating films, forming a robust electrical contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If lead-free glass frits are used instead of conventional lead-based materials, then environmental compatibility and safety are improved, but the penetration capability through insulating films and bonding effectiveness may deteriorate
Solution Approach 1:
The patent modifies the chemical composition parameters of glass frits by replacing lead oxide with alternative oxides such as bismuth oxide, zinc oxide, and boron oxide in specific ratios. This parameter change maintains the melting and penetration characteristics necessary for reliable electrical contact while eliminating toxic lead content, thus resolving the contradiction between environmental safety and contact reliability
Solution Approach 2:
The invention creates composite glass frit formulations combining multiple oxide components (Bi2O3, ZnO, B2O3, SiO2, etc.) that work synergistically to achieve both non-toxicity and effective penetration through insulating films. The composite structure allows the material to exhibit both environmental compatibility and sufficient reactivity to penetrate SiNx layers and form reliable bonds with silver and semiconductor substrates
2Reliability
If thick film composition penetrates insulating films during firing, then electrical contact is improved, but the complexity of the manufacturing process increases
Solution Approach 1:
The patent combines multiple functions into a single firing step: the organic vehicle is removed, the glass frit melts and penetrates the insulating film, and the silver forms electrical contact all in one thermal processing step. This merging of operations simplifies the overall manufacturing process while achieving reliable electrical contact, resolving the contradiction between contact quality and process complexity
Solution Approach 2:
The invention utilizes phase transitions of the glass frit material during firing - transitioning from solid to liquid state at specific temperatures to enable penetration through the insulating film, then re-solidifying to form a stable bond. This phase transition mechanism enables automatic penetration without requiring additional mechanical or chemical processing steps, maintaining process simplicity while ensuring contact reliability
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
This approach enhances the electrical performance of solar cells by creating reliable and efficient electrical contacts, improving the overall efficiency and reliability of the solar cell devices.
Implementation Method 1
upon firing, the one or more insulating films is penetrated by components of the thick film composition and the organic medium is removed
Implementation Method 2
the silver and glass frits to sinter and penetrate insulating films, forming a robust electrical contact
Data Source
AI summary
Embodiments of the invention relate to a silicon semiconductor device, and a conductive silver paste for use in the front side of a solar cell device.