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Electronic manufacturing industry
Tin-Silver-Copper Alloy : Unlocking the Potential of Key Material

In the realm of materials science and engineering, the quest for optimal combinations of properties has been an enduring pursuit. From ancient times to the present day, the development of alloys has played a pivotal role in meeting the diverse needs of industries and technologies. Among the plethora of alloys that have emerged, the Tin-Silver-Copper (SAC) alloy stands out as a remarkable example of innovation and practicality.

Comprising tin, silver, and copper in carefully balanced proportions, SAC alloy exemplifies the synergy achieved by combining different elements to yield enhanced performance characteristics. Its versatile applications span across a multitude of industries, from electronics to energy, owing to its exceptional conductivity, reliability, and durability.

Table of Contents

Definition of Tin-Silver-Copper Alloy

Tin-silver-copper alloy, abbreviated as SAC, is a metallic alloy composed of tin (Sn), silver (Ag), and copper (Cu) in specific proportions. Typical compositions include SAC305 (Sn96.5Ag3.0Cu0.5), SAC405 (Sn95.5Ag4.0Cu0.5), among others. This alloy not only inherits the advantages of individual metal components, such as the low melting point of tin, excellent solderability, high conductivity and oxidation resistance of silver, and the high strength and thermal stability of copper but also achieves optimization and upgrade of comprehensive performance through synergistic effects between elements, making it an ideal lead-free solder substitute.

Definition of Tin-Silver-Copper Alloy

Physical and Chemical Properties of Tin-Silver-Copper Alloy

Tin-silver-copper alloy exhibits a series of critical physical and chemical characteristics that profoundly impact its practical performance:

Melting Point: Compared to traditional lead-containing solders, tin-silver-copper alloy has a higher melting point (approximately 217°C), which helps reduce creep deformation of solder joints at high temperatures, enhancing the long-term stability of solder joints.

Hardness: Due to the addition of silver and copper, the hardness of tin-silver-copper alloy is significantly increased, facilitating the improvement of shear strength and fatigue resistance of solder joints.

Ductility: Tin-silver-copper alloy possesses good ductility, ensuring thorough filling of gaps during soldering to form uniform and dense solder joints, reducing the occurrence of welding defects such as voids and cracks.

Conductivity: The high conductivity of silver endows tin-silver-copper alloy with excellent electrical conductivity, conducive to the efficient operation of electronic products, particularly suitable for applications requiring high-frequency and high-speed signal transmission.

Coefficient of Thermal Expansion: The coefficient of thermal expansion of tin-silver-copper alloy matches well with many commonly used electronic component materials (such as ceramics, glass, silicon, etc.), reducing the risk of solder joint failure due to thermal stress.

Main Applications of Tin-Silver-Copper Alloy

Main Applications of Tin-Silver-Copper Alloy

In the Electronics Industry: Lead-Free Soldering and Electronic Component Manufacturing

1.1 Lead-Free Soldering Materials:

(1) Electronic Packaging: Tin-silver-copper alloy plays a core role in the packaging of integrated circuits (ICs). Its high melting point (217°C to 227°C) and excellent wetting properties ensure the stability of solder joints in high-temperature working environments, preventing solder joint failure caused by excessive thermal stress. For example, in advanced packaging technologies such as ball grid array (BGA), chip scale package (CSP), and flip-chip package (FC), tin-silver-copper solder paste or solder balls are used to achieve high-density and high-reliability connections between chips and substrates. Compared to lead-containing solder, tin-silver-copper alloy exhibits better resistance to creep deformation, effectively reducing the risk of solder joint fatigue fracture during long-term use.

(2) Circuit Board Soldering: During the assembly process of printed circuit boards (PCBs), tin-silver-copper alloy solder wires and solder pastes are widely used in surface-mount technology (SMT) and through-hole technology (THT). Its lower tendency for oxidation and excellent solder wetting ensure a strong connection between components and PCBs. Additionally, lower void rates and higher solder joint strength enhance the overall reliability of the circuit. Moreover, tin-silver-copper alloy performs better than lead-containing solder in processes such as reflow soldering and wave soldering, especially suitable for the manufacturing of modern electronic products with high density and fine pitch.

1.2 Electronic Component Manufacturing:

(1) Connectors: Tin-silver-copper alloy is indispensable in the production of connector contacts. Its high conductivity and excellent wear resistance ensure efficient current transmission and long-term stable contact, reducing contact resistance, minimizing heat generation, and enhancing signal integrity. The application of tin-silver-copper alloy is particularly crucial in high-speed data transmission interfaces (such as USB, HDMI, PCIe) and high-voltage power connectors, helping prevent contact damage caused by electromigration.

(2) Relays: Tin-silver-copper alloy is commonly used for relay contacts to maintain stable contact resistance and arc erosion resistance during frequent switching. Its excellent fatigue resistance allows relays to maintain stable performance over millions of cycles, extending their lifespan.

(3) Sensors: In various types of sensors (such as temperature, pressure, and position sensors), tin-silver-copper alloy can be used to manufacture contact pieces, pins, and other components. Its good oxidation resistance and corrosion resistance help ensure sensors accurately transmit signals in complex environments over the long term, while also complying with environmental regulations restricting hazardous substances.

Energy Industry: Solar Photovoltaics and Wind Power Generation

2.1 Solar Photovoltaic Modules:

(1) Cell Interconnection: In the interconnection process of solar cell strings, tin-silver-copper alloy paste is used to produce solder ribbons, achieving low-resistance and high-reliability connections between solar cells. Its excellent thermal stability and corrosion resistance help resist the challenges of thermal cycling and humidity aging during long-term outdoor service of photovoltaic modules, improving the long-term power output of the modules.

(2) Junction Box Soldering: Tin-silver-copper alloy solder is used for soldering wires to terminals inside the junction box, as well as for soldering busbars to the junction box cover plate, ensuring efficient current transmission and waterproof sealing. This is crucial for enhancing the overall efficiency and durability of the modules.

2.2 Wind Power Generation Equipment:

(1) Electrical Connections: In the complex electrical systems inside wind turbines, tin-silver-copper alloy is used for welding at key locations such as generator windings, inverter connections, and cable joints, ensuring the stability and safety of electrical connections in the wide temperature and high vibration environment of wind turbines.

(2) Bearing Protection: In the bearing systems of large wind turbines, tin-silver-copper alloy can be used as anti-electrocorrosion coatings for the inner and outer rings of bearings, preventing electrochemical corrosion caused by current leakage and extending the bearing lifespan, ensuring the efficient operation of the equipment.

Communication Technology: 5G Communication and Optical Fiber Communication

3.1 5G Communication Equipment:

(1) Base Station Antennas: In the welding of key components such as RF modules and power amplifiers in 5G base station antennas, tin-silver-copper alloy ensures low loss and high stability of high-frequency signal transmission. Its excellent heat dissipation performance also helps reduce equipment operating temperatures, improving system reliability.

(2) RF Modules: Packaging and soldering of microwave devices, filters, switches, and other components in radio frequency front-end modules (RFEM) rely on tin-silver-copper alloy. Its outstanding electrical and thermal properties provide a solid foundation for 5G equipment to achieve high-speed, wide-band, multi-frequency communication.

(3) High-Speed Data Transmission Cables: During the termination process of high-speed transmission cables (such as Cat 6A, Cat 7, Cat 8) connectors, tin-silver-copper alloy solder ensures low impedance and low crosstalk connections between cables, meeting the high-bandwidth, low-latency transmission requirements.

3.2 Optical Fiber Communication:

(1) Fiber Optic Connectors: Precision components such as ferrules and sleeves in fiber optic connectors are often made of tin-silver-copper alloy, ensuring high precision during fiber alignment, thus achieving low insertion loss and high return loss optical performance due to its excellent dimensional stability and low thermal expansion coefficient.

(2) Optical Modules: Tin-silver-copper alloy solder is used in the packaging of lasers, detectors, discrete optical components, and other components in optical transceiver modules to achieve high-precision, high-reliability heat sinking and pin soldering, ensuring stable operation of optical modules during high-speed data transmission.


In conclusion, the Tin-Silver-Copper alloy stands as a testament to the ingenuity of human endeavor in materials science and engineering. Its remarkable properties and versatile applications have propelled it into the forefront of modern technology, shaping the landscape of industries such as electronics, energy, and communications. From lead-free soldering in electronic components to high-speed data transmission in telecommunications, SAC alloy continues to play an indispensable role in enabling innovation and progress.


Tin-Silver-Copper (SAC) alloy is a metallic alloy composed of tin (Sn), silver (Ag), and copper (Cu) in specific proportions. It is widely used in various industries due to its desirable properties and versatility.

SAC alloy exhibits excellent conductivity, thermal stability, mechanical strength, and resistance to corrosion. These properties make it suitable for applications requiring reliable electrical connections and high-performance soldering.

SAC alloy is commonly used in electronics manufacturing for lead-free soldering of electronic components, such as printed circuit boards (PCBs), connectors, and semiconductor devices. It is also utilized in the energy industry for solar photovoltaics, wind power generation, and other renewable energy applications.

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