2-1-1 Product Introduction

No-clean lead-free solder paste is a core soldering material for surface mount technology (SMT) that combines environmental friendliness, high reliability and production efficiency. It is formulated by uniformly mixing lead-free solder alloy powder with a specially developed no-clean flux. Its key advantage lies in eliminating the need for post-soldering cleaning while preventing lead pollution, perfectly meeting the environmental and high-efficiency requirements of modern precision electronics manufacturing. It has become the mainstream choice in the field of electronic assembly.

I. Basic Composition

A. Lead-Free Solder Powder

The mainstream alloy system is SnAgCu (SAC305/SAC0307). Low-temperature SnBi and high-temperature SnSb grades are also available. Melting points range from 138°C to 240°C, with lead content below 0.1% (1000 ppm), fully complying with lead-free standards and free from lead toxicity hazards.

B. No-Clean Flux

Adopting a low-active organic formulation free of lead and other hazardous substances, combined with special activators and film-forming agents, it is designed with “no-clean” as the core objective. It focuses on controlling residue content and corrosiveness, ensuring excellent wettability as well as low post-soldering residue, non-corrosiveness and high insulation.

II. Core Properties

1. Environmentally Compliant, Green & SafeStrictly conforms to RoHS 2.0/3.0, REACH and other international environmental regulations. Free of hazardous substances such as lead, cadmium and mercury, it is suitable for electronic manufacturing with high environmental standards, ensuring a safe production environment and user protection.

2. No-Clean Core, Simplified ProcessProduces minimal, transparent post-soldering residues with high insulation resistance (meeting ANSI/J-STD-004 ROLO). No water washing or solvent cleaning is required; products can directly undergo ICT testing and conformal coating. This greatly saves production time and cleaning costs, and reduces risks of PCB deformation and component damage.

3. Excellent Printability for Precision AssemblyHigh thixotropy (thixotropic index 4.2–4.5) enables continuous printing without stencil clogging or slumping. With outstanding transfer printing performance, it is ideal for fine-pitch precision components including 0201, 01005, BGA and QFN, compatible with high-speed SMT automated production lines and featuring long printing life.

4. Stable Soldering Quality & High ReliabilityStrong wettability ensures full, bright and uniform solder joints with low void ratio (≤5% for premium products). Excellent thermal fatigue resistance and electrochemical migration resistance prevent cold joints, detachment and short circuits during long-term use, guaranteeing product service life.

5. Easy to Use & Strong CompatibilityStable under normal temperature storage and operation, easy to open and stir. Compatible with both air and nitrogen reflow soldering processes with a wide process window, suitable for soldering various PCBs.

III. Application Fields

Widely used in electronic product assembly with high demands for environmental protection, efficiency and reliability, including:

1. Consumer electronics: mobile phones, tablets, laptops, power supplies, home appliance mainboards

2. Automotive electronics: electronic control units (ECU), lamp modules, automotive sensors

3. Telecommunication equipment: 5G modules, communication base stations, network equipment, servers

4. Industrial control, medical electronics, precision instruments, aerospace supporting electronic products

IV. Comparison with Traditional Solder Paste

2-1-3 Flux Chemical Composition

2-1-4 Properties