RMA Solder Paste

RMA Solder Paste – TENSAN TS-503 Rosin Mildly Activated Solution

In the world of electronics assembly, the choice of solder paste flux chemistry is as critical as the alloy itself. Rosin Mildly Activated (RMA) solder paste has long been the industry standard for applications requiring a balanced combination of excellent wetting, reliable soldering performance, and manageable residue characteristics. TENSAN TS‑503 is an RMA Solder Paste engineered to meet these demands while offering the added benefits of a medium‑temperature, low‑silver Sn‑Ag0.3‑Bi35 alloy. This advanced solder paste delivers superior wetting, low voiding, and stable printability – with a flux system that leaves clear, soft, non‑corrosive, and non‑conductive residues. As a true RMA Solder Paste, TS‑503 is the preferred solder paste for manufacturers who require reliable soldering performance across a wide range of applications, from LED lighting and consumer electronics to automotive and telecommunications assemblies.

What Is RMA Solder Paste?

RMA Solder Paste (Rosin Mildly Activated) is a type of solder paste that uses a rosin‑based flux with mild activators. Unlike highly activated (RA) fluxes that can leave corrosive residues, RMA flux is designed to be non‑reactive and non‑corrosive at room temperatures, becoming active only when heated to remove light surface oxides from metals such as copper.

Key characteristics of high‑quality RMA Solder Paste include:

• Balanced activity – Mild activation provides excellent wetting without excessive residue
• Clear, soft residue – Non‑corrosive and non‑conductive, supporting ICT testing
• Wide process window – Accommodates various alloys and reflow profiles
• Cleanability – Residues can be removed with standard cleaning agents if required
• IPC classification – Typically classified as ROL0, ROL1, ROM0, or ROM1 under IPC J‑STD‑004

TENSAN TS‑503 embodies all these characteristics, making it a versatile and reliable RMA Solder Paste for modern SMT assembly.

What Is TENSAN TS-503 RMA Solder Paste?

TENSAN TS‑503 is a lead‑free, RMA Solder Paste designed for SMT assembly processes that demand medium‑temperature reflow and reliable soldering performance. This advanced solder paste is formulated with:

• Sn‑Ag0.3‑Bi35 alloy – Low‑silver, bismuth‑containing alloy for medium‑temperature reflow
• RMA flux system – Rosin Mildly Activated, providing excellent wetting and clear, non‑corrosive residue
• Type 4 powder (20–38 μm) – Optimised for fine‑pitch printing down to 0.25 mm
• Lower reflow temperature – Peak 210–230°C, protecting heat‑sensitive components
• Full RoHS compliance – 100% lead‑free, meeting global environmental standards

As an RMA Solder Paste, TS‑503 is trusted by manufacturers who demand consistent, reliable soldering performance across diverse applications. The solder paste delivers the ideal balance of activity, residue characteristics, and process stability.

Alloy Composition & Physical Properties

Chemical & Electrical Properties

Physical Properties

Why Choose TENSAN TS-503 as Your RMA Solder Paste?

1. RMA Flux – Balanced Activity for Reliable Soldering

The flux system in TS‑503 is a true Rosin Mildly Activated (RMA) formulation, providing the ideal balance of activity and residue characteristics. This RMA Solder Paste delivers:

• Excellent wetting – Mild activators effectively remove surface oxides without excessive aggressiveness
• Clear, soft residue – Non‑corrosive and non‑conductive, supporting ICT testing
• Low voiding – Optimised flux chemistry minimises gas entrapment during reflow
• Wide process compatibility – Performs reliably across a range of reflow profiles and board finishes

As an RMA Solder Paste, TS‑503 is classified as ROL1 under IPC J‑STD‑004, confirming its low residue and non‑corrosive nature.

2. Low‑Silver, Medium‑Temperature Alloy – Protects Components

TS‑503 uses a Sn‑Ag0.3‑Bi35 alloy that significantly reduces the melting point compared to standard SAC305. The peak reflow temperature of 210–230°C protects heat‑sensitive components such as LEDs, plastic connectors, and flexible substrates from thermal degradation. This makes this RMA Solder Paste the ideal choice for assemblies that cannot tolerate high temperatures, while still providing strong, reliable joints.

3. Excellent Printability – Consistent Fine‑Pitch Performance

With Type 4 powder (20–38 μm), TS‑503 delivers:Consistent paste volume transfer for fine‑pitch applications down to 0.25 mmSharp edge definition and minimal slump after printingCompatibility with both standard and fine‑pitch stencil designsWhether you use an automatic printer or manual equipment, this solder paste adapts to your process requirements, ensuring high first‑pass yields.

4. Clear, Testable Residue – Flexible Processing Options

The RMA flux system leaves a clear, soft residue that is non‑corrosive and non‑conductive. This residue:

• Supports ICT (In‑Circuit Test) without interfering with probe contact
• Can be left in place for many applications, functioning effectively as a no‑clean residue
• Is easily removed with standard cleaning agents if required for specific applications

This flexibility makes TS‑503 a versatile RMA Solder Paste suitable for both no‑clean and clean‑required assemblies.

5. Long Stencil Life and Stable Viscosity

TS‑503 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 RMA Solder Paste printer operates at peak efficiency with minimal interruptions.

6. High Electrical Reliability – Essential for Long‑Term Performance

With SIR exceeding 1.7×10⁹ Ω (IPC) and 6.4×10¹² Ω (Bellcore), and passing 500‑hour electromigration testing, TS‑503 ensures that the residue left by this solder paste does not compromise long‑term reliability – even in humid environments. This makes it a trusted RMA Solder Paste for automotive, telecommunications, and industrial applications.

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)

The lower peak temperature of this RMA 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

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

Alloy Composition Overview

Typical Applications for This RMA Solder Paste

TS‑503 is ideal for applications requiring reliable soldering performance and medium‑temperature reflow:

• 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
• General SMT Assembly – Where RMA flux characteristics are preferred

As a versatile RMA Solder Paste, TS‑503 is trusted by manufacturers across these diverse industries.

Quality Assurance

Every batch of TENSAN TS‑503 is accompanied by a Certificate of Analysis confirming:

• Model and batch number
• Alloy composition (Sn‑Ag0.3‑Bi35)
• Flux type (RMA – Rosin Mildly Activated)
• Powder size distribution (Type 4, 20–38 μm)
• Flux content (wt%)
• Viscosity at 25°C

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

Frequently Asked Questions

Q: What is the difference between RMA and no‑clean solder paste?

A: RMA Solder Paste uses rosin‑based flux with mild activators that leave a clear, soft residue. This residue can be left in place or cleaned if required. No‑clean solder pastes use synthetic fluxes designed to leave minimal residue that is specifically intended to remain on the board. TS‑503's RMA flux offers excellent wetting while providing flexible residue management options.

Q: Is TS‑503 compatible with standard SMT equipment?

A: Yes. This solder paste works with all standard automatic and semi‑automatic printers, as well as standard reflow ovens. Its Type‑4 powder supports fine‑pitch printing down to 0.25 mm.

Q: Does TS‑503 require post‑reflow cleaning?

A: Not necessarily. The RMA flux residue is non‑corrosive and non‑conductive, and can be left in place for many applications. However, if your application requires it, the residue can be easily removed with standard cleaning agents. This flexibility makes TS‑503 a versatile RMA Solder Paste.

Q: What is the shelf life of this RMA Solder Paste?

A: Six months from production date when stored at 5–10°C. At room temperature, it can be kept for up to 15 days.

Q: Can TS‑503 be used for nitrogen reflow?

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

Q: What industries commonly use this RMA Solder Paste?

A: TS‑503 is widely used in LED lighting, consumer electronics, automotive, flexible PCB, and telecommunications manufacturing – anywhere that reliable RMA flux performance and medium‑temperature reflow are required.

Conclusion

For manufacturers who demand the reliability of RMA flux chemistry combined with medium‑temperature processing, TENSAN TS‑503 is the definitive RMA Solder Paste solution. This solder paste offers excellent wetting, stable viscosity, clear and non‑corrosive residue, and proven electrical reliability – all at a cost‑effective low‑silver composition.

By choosing TS‑503, you select an RMA Solder Paste that:

• Delivers balanced RMA flux activity for reliable soldering performance
• Protects heat‑sensitive components with lower reflow temperatures (210–230°C peak)
• Provides consistent, fine‑pitch print performance with Type‑4 powder
• Offers flexible residue management – can be left in place or cleaned
• Ensures long‑term reliability with high SIR and electromigration resistance
• Meets full RoHS compliance as a lead‑free product
• Reduces material costs with low silver content (0.3–0.5%)

Upgrade to TENSAN TS‑503 – the RMA Solder Paste that combines performance, protection, and cost efficiency.

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