Back-Contact Solar Cell Interconnects Using Wire Bonding
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Solution Overview
Problem
Existing solar cell module technologies face challenges in efficiently interconnecting solar cells while maintaining high reliability and cost-effectiveness.
Innovation Solution
The use of a string of crystalline silicon solar cells interconnected using conductive interconnect wires with wedge bonds, and the employment of interconnect boards with conductive layers and solder joints to electrically connect solar cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional soldering methods are used to interconnect solar cells, then reliable electrical connection is achieved, but manufacturing complexity and cost increase due to additional solder materials and processes
Solution Approach 1:
The patent extracts and eliminates the solder material and soldering process from the interconnection system by using wire bonding technology. The wire bonding method creates direct metallurgical bonds between solar cell contacts without requiring additional solder, thereby reducing manufacturing complexity while maintaining reliable electrical connections.
Solution Approach 2:
The patent replaces the thermal-mechanical soldering process with an ultrasonic wire bonding process. Instead of using heat and molten solder to create joints, the invention uses ultrasonic vibration energy to forge metallurgical bonds between the wire and solar cell contacts, eliminating the need for solder materials and associated manufacturing complexity.
2Productivity
If wire bonding with ultrasonic welding is used to interconnect solar cells, then manufacturing throughput and efficiency are improved, but the complexity of the bonding process increases
Solution Approach 1:
The patent applies preliminary action by pre-positioning the wire on the solar cell contacts and using fixtures to hold cells in precise alignment before the ultrasonic bonding process. This preliminary setup enables high-speed automated bonding operations, improving manufacturing throughput while the automation itself manages the process complexity.
Solution Approach 2:
The patent utilizes parameter changes in the ultrasonic bonding process, specifically controlling vibration frequency, amplitude, and bonding time to optimize both productivity and bond quality. By precisely controlling these parameters, the system achieves high throughput while maintaining consistent, reliable connections without requiring overly complex process management.
3Reliability
If multiple wedge bonds are used per interconnect wire, then electrical connection reliability is enhanced, but manufacturing time and process complexity increase
Solution Approach 1:
The patent implements continuity of useful action by performing multiple wedge bonds in a continuous ultrasonic bonding sequence without interrupting the manufacturing flow. The automated system executes multiple bonds per wire in rapid succession, enhancing reliability while minimizing the time penalty through uninterrupted processing.
Solution Approach 2:
The patent applies preliminary action by pre-programming the bonding sequence and positions, allowing multiple wedge bonds to be executed in an optimized, predetermined pattern. This preparation enables the system to perform multiple bonds efficiently without significantly increasing manufacturing time, as the process parameters and paths are established in advance.
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 efficiency and reliability of solar cell interconnection, reduces manufacturing costs by eliminating the need for additional solder, and allows for higher throughput in solar module production.
Implementation Method 1
ultrasonic wire bonding each interconnect wire to a bond pad on the first solar cell and a bond pad on the second solar cell, the ultrasonic wire bonding forms wedge bonds
Data Source
AI summary
A solar cell module with interconnect wires wire-bonded to back-contact solar cells. A solar cell module using an interconnect board to electrical interconnect back-contact solar cells. The interconnect board may also contain a bypass diode and circuitry to connect the bypass diode to solar cells of the module.