In cutting-edge optical systems such as space telescopes and high-power lasers, thin-film heaters and temperature sensors on lens mounts and frames are core components ensuring equipment performance. These components are connected to power and control circuits via tiny wires, and the quality of their soldering directly affects the accuracy of temperature control and system stability. Ultrasonic soldering irons, with their unique technological advantages, have become the ideal choice for this field.
The core competitiveness of ultrasonic soldering irons stems from their soldering principle, which combines thermal effects with ultrasonic vibration. Unlike traditional tools, it uses high-frequency vibration to create cavitation in liquid solder, directly removing the oxide film from copper core wires and circuit board pads without relying on flux. This characteristic is crucial for optical systems—flux residue can cause circuit corrosion, while the ultrasonic cleaning effect enables reliable connections without chemical contamination, especially suitable for the needs of long-life equipment such as space telescopes.
Precise control of the soldering process is key to achieving reliable connections. In terms of materials, Sn-Ag-Cu series lead-free solders are the preferred choice due to their combination of low melting point and high strength. Their copper content enhances wettability with the copper core of the conductor, while the silver element improves the solder joint's oxidation resistance. Strict adherence to specifications is required during operation: the wire stripping length should be controlled within 3-5 mm to avoid damage to the copper core; the soldering iron tip should contact the pad at a 45-degree angle, and the temperature should be stabilized at around 350℃ using the equipment's real-time temperature control function to prevent pad detachment due to high temperature. For micro-wires with a diameter of less than 0.1 mm, a microscope must be used, and the amount of solder should be precisely controlled with a pointed soldering iron to avoid bridging and short circuits.
Quality control is implemented throughout the entire soldering process. Before soldering, the pads and conductors must be thoroughly cleaned with alcohol to remove oil and oxide layers; during soldering, the equipment's automatic frequency adjustment function compensates for load changes to ensure stable soldering energy; after soldering, the solder joint morphology is inspected using a magnifying glass, and the acceptable standard is a smooth, conical shape without defects such as pores or cracks, and the continuity of the circuit is verified through a continuity test. Due to the heat-sensitive nature of optical systems, the solder joints must be allowed to cool naturally after soldering to prevent internal stress caused by rapid cooling from affecting component precision.
In the manufacturing of optical equipment that demands extreme precision, ultrasonic soldering irons have achieved "cleanliness, precision, and reliability" in soldering fine wires. This technology not only solves the problems of contamination and deformation associated with traditional soldering but also ensures the stability of the temperature control system through process controllability, providing crucial process support for the development of cutting-edge optical instruments.
