Low-Ionic Activator System

Low‑Ionic Activator System – High‑Reliability Solder Flux for SnBi Eutectic Alloys

As a fully compliant solution for environmentally conscious electronics assembly, Low‑Ionic Activator System is a high‑performance Solder flux formulated specifically for Sn42/Bi58 eutectic solder pastes. This advanced Solder flux combines a low‑ionic activator with a carefully balanced resin and solvent system, delivering exceptional printability, minimal residue, and robust electrical reliability – all while meeting the strictest global restrictions on hazardous substances. When used with SnBi alloy powder, this Solder flux enables a sharp melting point at 138 °C, supporting energy‑efficient reflow and protecting temperature‑sensitive components. With a powder particle size of 25–45 μm (spanning Type 3 and Type 4), the Solder flux ensures excellent stencil release and process stability across both conventional and fine‑pitch SMT lines.

Solder Flux Composition

The formulation of Low‑Ionic Activator System consists of a unique blend of hydrogenated rosin, solvents, and activators. According to the technical datasheet, the Solder flux composition (by weight) is:

• Hydrogenated Rosin: 45–48%
• Straight‑chain C9–C12 Aliphatic Alcohol: 20–22%
• Cyclical C12–C16 Ester: 9–15%
• Polymerized Fatty Oil: 4–6%
• Dicarboxylic Acid Activator: 4–8%
• Organic Amine C8–C10: 2–3%
• Antioxidant/Corrosion Inhibitor: 2–3%

This low‑ionic Solder flux system ensures that Low‑Ionic Activator System leaves minimal, non‑conductive residues after reflow, eliminating the need for post‑soldering cleaning while maintaining high surface insulation resistance (SIR) – a critical attribute for any high‑reliability Solder flux product. The halogen content is kept below 0.05 wt%, further enhancing its no‑clean compatibility.

Printing Performance & Process Stability – Enabled by the Solder Flux

Designed for both conventional and fine‑pitch applications, this Solder flux‑based paste features a powder particle size of 25–45 μm, which matches the Type 3 range while overlapping with Type 4. This unique characteristic, combined with the rheology provided by Low‑Ionic Activator System, ensures excellent release from additive‑process stencils. The Solder flux optimizes transfer efficiency and minimizes slump, guaranteeing consistent solder deposit geometry across long production runs – a hallmark of a premium Solder flux formulation.

Recommended printing parameters (Table 3 from TDS) – fully compatible with all major printers:

• Key production advantages delivered by this Solder flux:
• Minimal viscosity change during continuous printing – the robust Solder flux prevents shear degradation, ensuring uniform deposit volume for both fine and coarse apertures.
• Non‑hydrophilic nature – the Solder flux does not absorb moisture even at up to 80 % RH, preventing solder ball defects – a major benefit for users in humid environments.
• Extended stencil life (> 8 hours) – the Solder flux resists drying, reducing cleaning downtime and maximizing throughput.
• Excellent anti‑slump properties (< 0.2 mm) – the Solder flux maintains sharp printed edges, preventing bridging at fine pitches.

Low‑Ionic Activator System employs a low‑ionic activator, passing stringent tests without causing corrosion or electromigration. This makes it an ideal Solder flux for no‑clean assemblies where post‑reflow cleaning is impractical – a key requirement for high‑volume production.

Low‑Temperature SnBi Alloy Advantages – with Environmental Compliance

As a fully compliant Solder flux (Pb < 0.001 % in the alloy), Low‑Ionic Activator System is designed for use with Sn42/Bi58 alloys that meet RoHS, REACH, and other global regulations. Compared to conventional SAC alloys, the SnBi eutectic offers:

• Melting point 138 °C – approximately 80 °C lower than SAC, protecting temperature‑sensitive components and substrates, while reducing energy consumption and thermal stress.
• Mechanical properties (of the soldered joint):Tensile strength: 55 MPa (25 °C) / 28 MPa (100 °C)、Elongation: 13 % (25 °C) / 18 % (100 °C)、Coefficient of thermal expansion: 13.4 × 10⁻⁶/°C
• Excellent creep resistance and thermal fatigue performance, verified in LED lighting, automotive sensors, and RF modules.

The low‑temperature profile reduces PCB warpage – a significant advantage for Solder flux users transitioning from higher‑melting alloys, and the powder size ensures compatibility with both standard and fine‑pitch stencil designs.

Reflow Profile & Process Guidelines

To achieve optimal wetting and minimize voiding, the following reflow profile is recommended for pastes using Low‑Ionic Activator System – applicable regardless of mixing method:

Handling guidelines for this Solder flux‑based paste:

• Thawing – Allow 4–6 hours at 25 °C before opening to prevent moisture condensation.
• Mixing – Stir manually (3–6 minutes) or use a standard mixer (2–5 minutes) until viscosity returns to 180 ± 20 Pa·s. The Solder flux ensures reliable performance after either method.
• Printing‑to‑placement window – Complete component placement within 3–6 hours after printing; the Solder flux maintains tackiness throughout this period.
• Storage – Sealed at 0–10 °C, < 75 % RH; shelf life 180 days from manufacture.

Application Scenarios & Supply Capacity

Low‑Ionic Activator System has been successfully deployed in mass production across multiple sectors, with customers relying on its proven Solder flux performance:

• Consumer Electronics – TWS earbuds, smartwatches, and portable devices, where the Solder flux enables low‑temperature assembly and fine‑pitch printing.
• LED Lighting – COB modules and automotive interior lighting, where thermal management and reliability are critical, and the Solder flux ensures minimal residue and high SIR.
• Automotive Electronics – Battery management systems (BMS), in‑vehicle sensors, and infotainment, requiring high vibration resistance – all delivered by this robust Solder flux.

With over 30 active customers and a monthly production capacity exceeding 2 tons of finished paste, this Solder flux‑based solution is readily available with 72‑hour delivery to support continuous SMT line operations. Our technical team provides on‑site process support to ensure seamless integration of Low‑Ionic Activator System into your existing workflow, with specific guidance for stencil design and reflow optimization.

Safety & Environmental Compliance

• Contains no regulated hazardous substances (RoHS, REACH, Japan Industrial Safety and Health Act).
• Free from organic solvents subject to poisoning prevention regulations.
• In case of skin contact, clean immediately with ethanol‑soaked cotton, then wash with soap and water.
• Adequate ventilation is recommended during reflow to minimize fume exposure – the Solder flux formulation poses no additional toxicity risks.