SMT Solder Paste

SMT Solder Paste – TENSAN TS-501 Mid-Temperature Lead-Free Solution

In modern electronics manufacturing, not all assemblies can withstand the high peak temperatures required by standard SAC305 solder paste. Heat‑sensitive components, flexible PCBs, and multi‑step reflow processes demand an SMT solder paste that can form reliable solder joints at lower temperatures without compromising quality.

TENSAN SMT solder paste – TS‑501 is engineered to meet this exact need. Formulated with a Sn‑Ag1‑Bi35 alloy, this solder paste delivers excellent wetting and soldering performance at a significantly lower melting point than conventional SAC alloys, protecting thermal‑sensitive components while maintaining production efficiency. Whether you run a high‑volume line or a specialised assembly process, this SMT solder paste provides the thermal protection and process stability you require.

What Is TENSAN TS‑501 SMT Solder Paste?

TS‑501 is a lead‑free, no‑clean SMT solder paste designed for assembly processes that require:Lower reflow temperatures – Bismuth‑containing alloy reduces melting point to protect heat‑sensitive componentsExcellent printability – Type 4 powder (20–38 μm) ensures consistent deposit volume and shape retentionReliable soldering – Advanced flux chemistry provides strong wetting and low voidingNo‑clean convenience – Clear, minimal residue that supports ICT testing without cleaningLong stencil life – Stable rheology maintains print performance over extended production shiftsCost‑effective alloy – Lower silver content (1.0%) combined with bismuth reduces material costs

Key Specifications

Alloy Composition & Physical Properties

Chemical & Electrical Properties

Physical Properties

Test methods conform to IPC J‑STD‑004, IPC J‑STD‑005, JIS Z 3284, and Bellcore GR78‑CORE standards.

Why Choose TENSAN TS‑501 as Your SMT Solder Paste?

1. Unique Bi35 Alloy for Lower Reflow Temperatures

TS‑501 uses a Sn‑Ag1‑Bi35 alloy that offers:

• Lower melting point than SAC305, reducing thermal stress on components
• Ideal for assemblies with temperature‑sensitive parts such as LEDs, plastic connectors, and flexible PCBs
• Supports step‑soldering processes where a lower‑temperature solder paste is required for secondary reflow

This SMT solder paste formulation provides the reliability of SAC alloys at a more forgiving temperature profile, making it the preferred solder paste for thermal‑sensitive applications.

2. Excellent Print Performance with Type 4 Powder

With Type 4 powder size (20–38 μm), TS‑501 delivers:

• Consistent paste volume transfer for fine‑pitch applications
• Sharp edge definition and minimal slump after printing
• Compatibility with both standard and fine‑pitch stencil designs (down to 0.25 mm / 10 mil)

Whether you use an automated solder paste printer or manual equipment, this SMT solder paste adapts to your process requirements.

3. No‑Clean, Low‑Residue Formulation

The flux system is designed to leave clear, non‑conductive residue that:

• Supports ICT (In‑Circuit Test) without post‑reflow cleaning
• Eliminates cleaning process steps, reducing chemical costs and cycle time
• Maintains high surface insulation resistance even under humid conditions (SIR > 1.7 × 10⁹ Ω)

The no‑clean design makes this solder paste ideal for high‑volume production where efficiency is paramount.

4. Long Stencil Life and Stable Viscosity

TS‑501 maintains consistent viscosity for:

• Over 8 hours on stencil under normal production conditions (22°C, 50% RH)
• Reduced stencil cleaning frequency and less paste waste
• Stable printing performance across entire production shifts

This stability ensures that your SMT solder paste printer operates at peak efficiency with minimal interruptions, maximising uptime and yield.

5. Excellent Wetting and Solder Joint Quality

Despite its lower melting point, this Sn‑Ag‑Bi solder paste provides:

• Strong wetting on ENIG, OSP, HASL, and other PCB surface finishes
• Bright, well‑formed solder fillets with minimal defects
• Reliable mechanical and electrical connections for consumer and industrial applications

6. High Electrical Reliability

With SIR values exceeding 1.7×10⁹ Ω (IPC) and 6.4×10¹² Ω (Bellcore), and passing 500‑hour electromigration testing, TS‑501 ensures long‑term electrical stability even in humid environments – a critical requirement for any high‑quality SMT solder paste.

Recommended Application Parameters

Stencil Design Guidelines

Stencil Technologies: Electroformed and laser‑cut stencils with electro‑polishing provide optimal printing characteristics. "Roof‑shaped" aperture designs help reduce solder balling between components.

Printing Conditions

Reflow Profile (Recommended)

Note: The lower peak temperature of this mid‑temperature SMT solder paste provides a protective thermal environment for heat‑sensitive components while still delivering strong, reliable solder joints. Adjust profiles based on your specific reflow oven and PCB assembly requirements.

Storage and Handling Guidelines for This Solder Paste

Important: Do not mix leftover solder paste with fresh paste in the same container. Always warm up this SMT solder paste in its sealed container to prevent moisture condensation, which can cause spattering during reflow.

Alloy Composition Overview

Typical Applications for This SMT Solder Paste

TS‑501 is ideal for applications requiring lower reflow temperatures:

• LED Lighting – Protects LED chips and phosphor layers from thermal degradation
• Consumer Electronics – Smartphones, tablets, wearables with heat‑sensitive components
• Automotive Electronics – Sensors, lighting modules, ECUs
• Flexible PCBs – Prevents warpage and delamination of flexible substrates
• Step‑Soldering Processes – Secondary reflow after high‑temperature SAC assembly
• Telecommunications – RF modules, base station components

Quality Assurance

Every batch of TENSAN TS‑501 is accompanied by a Certificate of Analysis confirming:

• Model and batch number
• Alloy composition (Sn‑Ag1‑Bi35)
• Flux content (wt%)
• Viscosity at 25°C

Our manufacturing processes ensure consistent product quality from lot to lot, giving you confidence in every production run with this SMT solder paste.

Frequently Asked Questions

Q: What makes TS‑501 different from SAC305 solder paste?

A: TS‑501 includes 35% bismuth, which lowers the melting point significantly. This reduces thermal stress on heat‑sensitive components and supports step‑soldering processes. It is a specialised SMT solder paste for temperature‑sensitive applications.

Q: Is TS‑501 compatible with standard solder paste printers?

A: Yes. This Type 4 solder paste is compatible with all standard SMT printing equipment.

Q: Do I need to use a specific solder paste mixer for this product?

A: A standard planetary or centrifugal mixer is recommended for 1–3 minutes to ensure uniform mixing after cold storage.

Q: What is the powder type for this solder paste?

A: This product uses Type 4 powder (20–38 μm), suitable for fine‑pitch printing down to 0.25 mm pitch.

Q: Can TS‑501 be used for nitrogen reflow?

A: Yes, it performs well in both air and nitrogen reflow environments.

Q: Is TS‑501 RoHS compliant?

A: Yes, this lead‑free SMT solder paste fully complies with RoHS Directive requirements.

Q: What is the recommended storage temperature for this solder paste?

A: Store at 5–10°C. Do not freeze. At room temperature, it can be kept for up to 15 days.

Conclusion

For manufacturers dealing with heat‑sensitive components, flexible substrates, or multi‑step reflow processes, TENSAN TS‑501 offers the ideal SMT solder paste solution.

This mid‑temperature solder paste delivers:

• Lower reflow temperatures to protect thermal‑sensitive components
• Type 4 powder for consistent, fine‑pitch print performance
• No‑clean, low‑residue convenience for efficient production
• Proven reliability across consumer, automotive, and LED applications
• High SIR and electromigration resistance for long‑term stability

By choosing TENSAN TS‑501 as your SMT solder paste, you achieve reliable soldering results while extending component life and reducing thermal defects – all at a cost‑effective price point.

Trust TENSAN TS‑501 – the solder paste that protects your components and your process.

Contact Information

TENSAN VIETNAM CO., LTD

TS10 Road, Tien Son Industrial Park, Bac Ninh Province, Vietnam

Tel: +84‑222‑650‑8818

Email: mark@sztensan.com

For alternative alloys or custom packaging, please contact your local TENSAN sales office.