In the process of advancing perovskite solar cell technology towards practical application, the integrated manufacturing of small modules is one of the core links. These modules consist of multiple sub-cells connected in series, and their performance depends not only on the photoelectric conversion efficiency of the sub-cells themselves but also directly on the reliability of the connections between them. Ultrasonic soldering irons, with their unique soldering advantages, have become an ideal choice for the interconnection and packaging of perovskite solar cell modules.
The interconnection requirements of perovskite solar cell modules place stringent demands on soldering technology. Connecting adjacent electrodes in series with sub-cells requires metal wires such as tin-plated copper strips. However, perovskite materials have poor heat resistance, and traditional high-temperature soldering easily leads to thin film decomposition or performance degradation. Furthermore, residual chemical flux can cause interface corrosion, affecting device stability. The solid-state bonding characteristics of ultrasonic soldering are perfectly suited to this scenario—it achieves connection through high-frequency mechanical vibration rather than simply high temperature. The temperature of the soldering area is controllable and flux is not required, fundamentally avoiding thermal damage and chemical contamination to the perovskite layer.
The working mechanism of ultrasonic soldering irons provides technical support for precise connections. The core of this process is to convert a 50Hz low-frequency current into 20-60kHz high-frequency electrical energy, which is then converted into mechanical vibration by a transducer and transmitted to the welding interface through the welding head. Under moderate pressure, the tin-plated copper strip generates intense friction with the electrode surface, which not only breaks and disperses the metal oxide layer but also creates microscopic plastic flow in localized areas, allowing molecules from different metal surfaces to interpenetrate and diffuse, ultimately forming a reliable, gapless solder layer. This dual effect of "vibration cleaning + diffusion connection" ensures low contact resistance between the electrode and the wire, laying the foundation for efficient current transmission in the module.
Precise control of process parameters is crucial for achieving high-quality welding. Heat control must balance solder melting and material protection, typically achieved by adjusting the balance between the soldering iron temperature and vibration energy to avoid excessively high temperatures damaging the perovskite layer or excessively low temperatures leading to insufficient welding. The time parameter directly affects the connection quality; too short a time can easily cause cold solder joints, while too long a time may lead to device performance degradation due to cumulative heat effects. In practice, "energy mode" control is often employed, combined with a step-by-step welding strategy. The welding time is dynamically adjusted based on the cleanliness of the electrode surface to ensure thorough oxide removal and stable interface connections.
In the encapsulation stage, the advantages of ultrasonic soldering irons become even more apparent. They enable reliable connections between metal wires and dissimilar materials such as glass substrates and ceramics. Through vibration cavitation, they expel air bubbles from the solder layer, improving encapsulation sealing, effectively preventing moisture and oxygen intrusion, and extending module lifespan. This versatility allows for synergistic processes of interconnection and encapsulation in perovskite solar cell module manufacturing.
With the iteration of perovskite solar cell technology, the application of ultrasonic soldering irons in small module manufacturing will become more widespread. Their precise and controllable welding characteristics are providing a solid process guarantee for perovskite solar cells to move from the laboratory to commercialization.
