Solder Paste – Automatic Mixer Compatible (Sn42Bi58)

Solder Paste – Automatic Mixer Compatible (Sn42Bi58) – Technical Overview & Application Guide

Specifically engineered to streamline SMT preparation processes, Solder Paste – Automatic Mixer Compatible (Sn42Bi58) combines a high‑reliability flux system with fine spherical Sn42/Bi58 alloy powder. This advanced Solder paste mixer‑friendly product is formulated to achieve rapid, homogeneous mixing with minimal aeration, ensuring consistent viscosity and printability across every batch. Its eutectic composition provides a sharp melting point at 138 °C, enabling energy‑efficient reflow while protecting temperature‑sensitive components – and its robust rheology guarantees that after mixing with any standard Solder paste mixer, the paste delivers identical performance to freshly manufactured material.

Solder Paste Composition

The formulation of Solder Paste – Automatic Mixer Compatible (Sn42Bi58) consists of a eutectic Sn42/Bi58 alloy powder and a specially developed flux system. According to the technical datasheet:

• Alloy composition: Tin 41.5–42.5%, Bismuth 57.5–58.5% – eutectic point at 138 °C (both liquidus and solidus).
• Flux content: 10.0 ± 1.0 wt%, with halogen content < 0.05 wt%.
• Flux composition (wt%):

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

This low‑ionic flux system ensures that Solder Paste – Automatic Mixer Compatible (Sn42Bi58) leaves minimal, non‑conductive residues after reflow, eliminating the need for post‑soldering cleaning while maintaining high surface insulation resistance (SIR) – a critical requirement for no‑clean processes, and one that remains unaffected by the gentle mixing action of a Solder paste mixer.

Optimized Compatibility with Automatic Mixers

Designed to simplify solder paste preparation, Solder Paste – Automatic Mixer Compatible (Sn42Bi58) is specifically tailored for use with centrifugal or planetary Solder paste mixer systems. The paste’s thixotropic index and powder‑flux affinity ensure that after mixing, the viscosity returns precisely to the specified range (180 ± 20 Pa·s) without over‑shearing or overheating. Key benefits for production using a Solder paste mixer:

• Rapid homogenization – Recommended mixing time of just 2–5 minutes (with the container sealed) in an automatic Solder paste mixer, compared to longer manual stirring.
• No viscosity drift – The paste is formulated to withstand the mechanical forces of high‑speed mixing without breaking down the flux structure, ensuring consistent print performance.
• Temperature control – Even during extended mixing cycles, the paste does not experience significant temperature rise, preventing premature activation of the flux.
• Direct transfer – After mixing, the paste can be directly loaded onto the stencil printer without additional adjustment, thanks to its stable rheology.

For operations that rely on automated preparation, this Solder paste mixer‑compatible product reduces human error, improves throughput, and guarantees that every jar delivers the same outstanding printability as the first.

Printing Performance & Process Stability

Once mixed by a Solder paste mixer, Solder Paste – Automatic Mixer Compatible (Sn42Bi58) exhibits excellent printing characteristics across a wide range of equipment. The particle size of 25–45 μm (between Type 3 and Type 4) ensures fine‑pitch capability and consistent release from stencils.

Recommended printing parameters (Table 3 from TDS) – fully applicable after mixing:

Key advantages after using a Solder paste mixer:

• Restored viscosity ensures minimal slump (< 0.2 mm) and sharp edges, preventing bridging even at 0.4 mm pitch.
• The non‑hydrophilic nature allows stable printing at up to 80 % RH, and mixing does not introduce moisture or air bubbles.
• Extended stencil life (> 8 hours) – the paste remains workable throughout the shift, reducing cleaning intervals.

Flux Reliability & Electrical Performance

The flux system in Solder Paste – Automatic Mixer Compatible (Sn42Bi58) employs a low‑ionic activator, passing stringent tests without causing corrosion or electromigration. This makes it ideal for no‑clean applications, and the mixing process does not alter the flux’s chemical integrity – a key validation for any Solder paste mixer‑based preparation.

Low‑Temperature SnBi Alloy Advantages

As a lead‑free product (Pb < 0.001 %), Solder Paste – Automatic Mixer Compatible (Sn42Bi58) fully complies with RoHS directives. Compared to conventional SAC alloys, the Sn42/Bi58 eutectic offers:

• Melting point 138 °C – approximately 80 °C lower than SAC, protecting heat‑sensitive components and substrates while reducing energy consumption.
• Mechanical properties: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/°CExcellent creep resistance and thermal fatigue performance, verified in LED lighting, automotive sensors, and RF modules.

This low‑temperature profile also reduces PCB warpage, and the mixing process – whether manual or via a Solder paste mixer – preserves the alloy’s fine powder morphology, ensuring optimal wetting and joint strength.

Reflow Profile & Process Guidelines

To achieve optimal wetting and minimize voiding, the following reflow profile is recommended for Solder Paste – Automatic Mixer Compatible (Sn42Bi58) – fully compatible with the paste after mixing in a Solder paste mixer:

Handling guidelines specifically for this Solder Paste and your Solder paste mixer:

• Thawing – Allow 4–6 hours at 25 °C before opening the container; never mix cold paste as it may condense moisture.
• Mixing – Use an automatic Solder paste mixer for 2–5 minutes with the container sealed.
•  For manual stirring, 3–6 minutes is sufficient, but an automatic Solder paste mixer is recommended for consistency and time savings.
• Post‑mixing check – Viscosity should return to 180 ± 20 Pa·s; if using a Solder paste mixer with programmable time and speed, follow the manufacturer’s recommended settings for this paste.
• Printing window – Complete printing and placement within 3–6 hours after mixing to maintain optimal tackiness.Storage – Sealed at 0–10 °C, < 75 % RH; shelf life 180 days from manufacture.

Application Scenarios & Supply Capacity

Solder Paste – Automatic Mixer Compatible (Sn42Bi58) has been successfully deployed in mass production across multiple sectors, with many customers adopting automated mixing to enhance efficiency:

• Consumer Electronics – TWS earbuds, smartwatches, and wearables, where the paste’s low‑temperature property and mixer‑compatible formulation ensure consistent quality in high‑mix production.
• LED Lighting – COB modules and automotive lighting, where thermal management is critical, and the Solder paste mixer ensures each batch is perfectly homogenized.
• Automotive Electronics – BMS, sensors, and infotainment, requiring high SIR and reliability; the use of a Solder paste mixer guarantees that every jar meets the same stringent standards.

With over 30 active customers and a monthly production capacity exceeding 2 tons, this Solder paste mixer‑ready product is available with 72‑hour delivery. Our technical team provides mixing parameter recommendations for various Solder paste mixer models (including planetary, centrifugal, and vacuum types) to ensure seamless integration into your SMT line.

• Safety & Handling Compliance
• Contains no regulated hazardous substances (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; mixing in a closed Solder paste mixer container minimizes fume exposure.