Revolutionary Lead-Free Flux Soldering Paste
High-strength, low-temperature performance for environmentally conscious electronics manufacturing
The Environmental Imperative for Lead-Free Solutions
Lead and its compounds are toxic substances that pose significant risks to human health and environmental integrity. As global awareness of environmental issues has grown, nations worldwide have implemented stringent regulations to address the ecological impact of electronic products, specifically restricting lead usage in electronic manufacturing processes.
This global movement toward lead-free green manufacturing has prompted research institutions and enterprises to invest heavily in developing alternative materials. Among these innovations, our advanced flux soldering paste represents a significant breakthrough in balancing performance requirements with environmental responsibility.
The transition to lead-free production isn't merely a regulatory compliance issue—it's a commitment to sustainable manufacturing practices that protect both workers and the broader ecosystem from harmful exposure to toxic substances commonly found in traditional soldering materials.
Addressing Limitations in Current Solder Technology
Currently, the most commonly used low-melting-point lead-free solders are based on Sn-Bi alloys with additional alloying elements. While these represent an improvement over lead-based alternatives, they present several significant limitations that compromise performance and reliability.
Wide Melting Range
The low-temperature solder has a relatively large melting range, creating challenges in consistent application and bonding.
Structural Defects
During the solidification process, dendrite segregation and coarse grain formation frequently occur, weakening the bond structure.
Stress Imbalance
Uneven stress distribution within the solder joint often leads to delamination and premature failure.
Performance Trade-offs
Many existing formulations sacrifice either thermal performance, mechanical strength, or cost-effectiveness.
These limitations are particularly problematic in precision electronics manufacturing, where reliability and performance are critical. Our advanced flux soldering paste has been specifically engineered to overcome these challenges while maintaining the environmental benefits of lead-free technology.
Our Innovative Solution
Key Innovation
By introducing Indium (In) into the traditional Sn-Bi solder system, we've developed a flux soldering paste with superior performance characteristics while maintaining a lead-free composition.
A Breakthrough in Lead-Free Solder Technology
Our high-strength low-temperature lead-free solder and corresponding flux soldering paste represent a significant advancement in electronic joining materials. The innovation centers on the strategic addition of indium (In) to the existing Sn-Bi solder system, creating a formulation that addresses the limitations of previous technologies.
In our proprietary composition, indium constitutes 15% to 45% by mass percentage, carefully balanced with tin (Sn) and bismuth (Bi) to achieve optimal performance characteristics. This precise formulation results in a flux soldering paste that delivers exceptional bonding strength while maintaining a low melting point—critical factors for modern electronics manufacturing.
Optimal Composition Range
The solder alloy powder in our flux soldering paste features the following weight percentage components:
- Tin (Sn): 34% to 36%
- Bismuth (Bi): 38% to 40%
- Indium (In): 24% to 27% (or as needed to reach 100% total)
This carefully calibrated composition forms the foundation of our premium flux soldering paste, delivering a harmonious balance of melting characteristics, mechanical strength, and application properties that exceed industry standards for lead-free alternatives.
Beyond the primary components, our formulation may include trace elements that enhance specific performance attributes, creating a flux soldering paste tailored for demanding electronic manufacturing environments.
Detailed Composition & Specifications
Alloy Composition
Our flux soldering paste incorporates a precise blend of primary metals and carefully selected trace elements to optimize performance. In addition to the primary Sn-Bi-In matrix, the solder alloy powder may contain one or more of the following elements:
| Element | Weight Percentage Range | Function |
|---|---|---|
| Silver (Ag) | 0.1～0.3wt% | Enhances strength and wettability |
| Copper (Cu) | 0.1～0.5wt% | Improves mechanical properties and reliability |
| Zinc (Zn) | 0.2～0.5wt% | Enhances wettability and mechanical performance |
| Aluminum (Al) | 0.1～0.4wt% | Forms protective oxide layer, improving oxidation resistance |
| Gallium (Ga) | 0.05～0.25wt% | Enhances oxidation resistance and surface wettability |
| Phosphorus (P) | 0.01～0.1wt% | Improves oxidation resistance and wettability |
Environmentally Safe Composition
Our flux soldering paste is completely free of lead (Pb) and cadmium (Cd), eliminating公害问题 (public hazard issues) associated with traditional solder materials and ensuring compliance with global environmental regulations.
Thermal Properties
A critical advantage of our flux soldering paste is its carefully controlled thermal characteristics, which make it ideal for sensitive electronic components that cannot withstand high temperatures.
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Liquidus Temperature:
75℃～100℃
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Solidus Temperature:
70℃～90℃
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Controlled Melting Range:
Minimized temperature difference between liquidus and solidus for improved bonding
Key Benefits & Performance Advantages
Low Melting Temperature
With a liquidus temperature between 75℃～100℃, our flux soldering paste is ideal for heat-sensitive components, reducing thermal stress during manufacturing processes.
Superior Mechanical Strength
The optimized Sn-Bi-In composition significantly improves shear strength and tensile strength of solder joints compared to conventional lead-free alternatives.
Excellent Pad Adhesion
Our flux soldering paste demonstrates superior adhesion to various pad materials, ensuring reliable connections even in demanding environments.
Enhanced Oxidation Resistance
Strategic addition of elements like Ga, P, and Al creates protective oxide layers, significantly improving the oxidation resistance of our flux soldering paste.
Improved Wettability
Trace elements including Ag, Zn, and Cu enhance the wetting properties of our flux soldering paste, ensuring uniform coverage and reliable bonding.
Environmentally Friendly
Completely free of lead and cadmium, our flux soldering paste supports green manufacturing initiatives while complying with global environmental regulations.
Performance Characteristics Explained
Our high-strength low-temperature lead-free flux soldering paste consists primarily of an alloy formed by three metal elements: bismuth, tin, and indium. This unique combination delivers a precisely controlled melting point (liquidus temperature) between 75℃～100℃.
The solidus and liquidus temperatures of our Bi-Sn-In fusible alloy flux soldering paste increase with Bi content or Bi/In ratio. The hardness of the fusible alloy solder increases linearly with Bi content or Bi/In ratio, but decreases significantly with increased Sn and In content.
By optimizing the Sn content and Bi/In ratio in our formulation, we've achieved significant improvements in the shear strength and tensile strength of alloy solder joints. This careful balance ensures our flux soldering paste delivers exceptional mechanical performance in demanding applications.
The strategic addition of trace elements further enhances the structural and mechanical properties of our flux soldering paste, creating a material that outperforms conventional lead-free alternatives across multiple performance metrics.
Applications & Use Cases
Consumer Electronics
Ideal for smartphones, tablets, laptops, and wearable devices where heat sensitivity and miniaturization demand a high-performance flux soldering paste that can create reliable joints in compact spaces.
Automotive Electronics
Perfect for under-hood electronics and infotainment systems where temperature resistance and mechanical reliability are critical, our flux soldering paste delivers consistent performance in harsh environments.
Medical Devices
Meets the stringent reliability and biocompatibility requirements of medical electronics, where our flux soldering paste ensures consistent performance in life-critical applications.
Aerospace & Defense
Our flux soldering paste meets the rigorous performance standards required for aerospace and defense applications, delivering reliable performance in extreme temperature fluctuations and high-vibration environments.
Implementation Example
In a specific implementation, our flux soldering paste was formulated with the following composition by mass percentage:
- Bismuth (Bi): 39%
- Tin (Sn): 36%
- Zinc (Zn): 0.2%
- Aluminum (Al): 0.15%
- Copper (Cu): 0.1%
- Phosphorus (P): 0.15%
- Indium (In): Remaining percentage (to reach 100%)
This specific formulation of our flux soldering paste demonstrated exceptional performance characteristics, including:
Thermal Performance
Liquidus temperature: 87℃
Solidus temperature: 79℃
Mechanical Strength
Shear strength: 32 MPa
Tensile strength: 41 MPa
Wettability
Spread ratio: 85%
Contact angle: 22°
Reliability
Thermal cycle performance: 1000+ cycles
Humidity resistance: 96 hours @ 85°C/85% RH
This implementation demonstrates how our flux soldering paste can be tailored to specific application requirements while maintaining superior performance across all critical metrics.
Advancing Electronics Manufacturing With Superior Materials
Our high-strength low-temperature lead-free flux soldering paste represents a significant advancement in electronic joining technology, offering superior performance while supporting environmental sustainability initiatives.
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