Solar Cell Metallization Using Thermally Compressed Foil
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Solution Overview
Problem
Current solar cell manufacturing techniques face challenges in increasing efficiency and reducing costs, as existing methods for forming conductive contacts can be complex and inefficient, leading to suboptimal performance and higher production costs.
Innovation Solution
The use of thermally compressed conductive foil with additional metal regions and intermetallic phases to form conductive contacts on solar cells, which reduces contact resistance and improves adhesion, allowing for lower temperature and pressure processes, thereby enhancing solar cell performance and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods for forming conductive contacts are used, then the manufacturing process is simpler, but the contact resistance is higher and adhesion is poorer
Solution Approach 1:
The patent employs a multi-layer composite structure consisting of a first metal region (aluminum or aluminum alloy), a second metal region (nickel, copper, or silver), and an intermetallic phase. This composite material system provides both strong adhesion to the semiconductor substrate and low contact resistance, while the intermetallic phase enhances bonding strength. The composite approach resolves the contradiction by achieving superior contact properties through material composition rather than process complexity.
Solution Approach 2:
The patent applies different metal materials at different locations and interfaces: the first metal region contacts the semiconductor substrate requiring good adhesion, the second metal region provides low resistance pathways, and the intermetallic phase forms at specific interfaces to enhance bonding. This localized optimization of material properties at different interfaces achieves both high reliability and manageable manufacturing complexity.
2Strength
If higher temperature and pressure are applied during contact formation, then adhesion improves, but manufacturing costs and process complexity increase
Solution Approach 1:
The patent utilizes controlled thermal parameters during the formation process to induce intermetallic phase formation at specific temperature ranges. By carefully controlling the heating parameters and duration, the intermetallic phase forms spontaneously at the metal-substrate interfaces, providing strong bonding without requiring excessive temperature or pressure. This parameter optimization achieves high bond strength while maintaining ease of manufacture.
Solution Approach 2:
The intermetallic phase acts as an intermediary layer between the metal regions and the semiconductor substrate, facilitating strong bonding through controlled interdiffusion. This intermediate phase forms during the heating process and provides robust adhesion without requiring high-pressure mechanical bonding, thereby reducing manufacturing complexity and cost while achieving superior bond strength.
3Reliability
If existing conductive contact structures are used, then manufacturing is easier, but electrical conductivity and cohesion are insufficient
Solution Approach 1:
The patent employs a multi-layer composite structure consisting of a first metal region (aluminum or aluminum alloy), a second metal region (nickel, copper, or silver), and an intermetallic phase. This composite material system provides both strong adhesion to the semiconductor substrate and low contact resistance, while the intermetallic phase enhances bonding strength. The composite approach resolves the contradiction by achieving superior contact properties through material composition rather than process complexity.
Solution Approach 2:
The patent applies different metal materials at different locations and interfaces: the first metal region contacts the semiconductor substrate requiring good adhesion, the second metal region provides low resistance pathways, and the intermetallic phase forms at specific interfaces to enhance bonding. This localized optimization of material properties at different interfaces achieves both high reliability and manageable manufacturing complexity.
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 results in improved electrical properties and reduced costs by increasing the cohesion and conductivity of the conductive contacts, leading to more efficient solar cell performance and streamlined manufacturing processes.
Implementation Method 1
a conductive foil thermally compressed to the semiconductor region
Implementation Method 2
heating and applying mechanical force to the conductive foil to form a conductive bond
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
A solar cell (100A) includes a substrate (200) and a semiconductor region (220, 224) disposed in or above the substrate. The solar cell also includes a conductive contact (228) disposed on the semiconductor region with the conductive contact including a conductive foil (134) bonded to the semiconductor region.