Solder Paste with 63% Tin and 37% Lead (Type 3 and Type 4) for SMD Assembly from China

Solder paste is essential in Surface Mount Device (SMD) assembly, enabling efficient electrical connections between components and the printed circuit board (PCB). One of the widely used compositions is the 63/37 tin-lead solder paste, which contains 63% tin and 37% lead. This composition is eutectic, meaning it has a melting point of around 183°C, melting and solidifying at a single temperature. This property ensures reliable solder joints, critical for high-quality electronics.

For SMD assembly, choosing the right solder paste particle size is crucial, as it affects the application method, print quality, and the resolution of the solder deposits. Solder pastes are available in different types based on particle size, with Type 3 and Type 4 being popular choices for SMD assembly.

Type 3 (Type 3) Solder Paste (63% Tin and 37% Lead)

Type 3 solder paste (63% Tin and 37% Lead) is characterized by particle sizes ranging from 25 to 45 microns. It is often preferred for larger components or where stencil openings are relatively large, such as in coarse pitch applications. Key benefits of Type 3 solder paste include:

Cost-Effective: Type 3 is typically less expensive than finer particle sizes, as the production process for larger particles is less intensive.

Lower Risk of Voiding: Type 3 solder paste (63% Tin and 37% Lead) generally exhibits a lower chance of voiding, which is beneficial for applications requiring high reliability.

Good Print Performance for Standard Stencils: The larger particles in Type 3 paste facilitate good stencil release, making it ideal for printing on standard stencils and in applications where extremely fine deposits are not required.

However, Type 3 solder paste may not be ideal for very fine-pitch applications or when extremely small component footprints are involved. Its larger particle size limits its ability to pass through finer stencil apertures, potentially causing inconsistent deposition in high-density PCB layouts.

Type 4 (Type 4) Solder Paste (63% Tin and 37% Lead)

Type 4 solder paste (63% Tin and 37% Lead) features smaller particle sizes, typically in the 20 to 38-micron range, making it suitable for finer-pitch applications. Key advantages of Type 4 solder paste include:

Improved Print Quality for Fine-Pitch Components: Type 4 is ideal for SMD assembly where smaller components and tighter pitches are involved. The smaller particles allow for better coverage and more consistent solder deposits in narrow stencil openings.

Reduced Solder Balling: The finer particle distribution helps reduce solder ball formation, leading to a cleaner, higher-quality finish.

Enhanced Stencil Release in Fine Apertures: Type 4 offers better stencil release properties than Type 3 for fine pitch areas, contributing to more precise solder paste application in high-density designs.

While Type 4 solder paste (63% Tin and 37% Lead) offers precision, it is generally more costly than Type 3 due to the need for finer particle sorting and processing. Additionally, Type 4 paste may be more prone to oxidation if not handled and stored properly, as the higher surface area of finer particles can increase susceptibility to degradation over time.

Choosing Between Type 3 and Type 4 Solder Paste (63% Tin and 37% Lead)

The choice between Type 3 and Type 4 solder paste (63% Tin and 37% Lead) depends primarily on the application requirements, including component size, pitch, and cost constraints. Type 3 is often suitable for general SMD applications with larger components and standard pitches, offering a balance of performance and cost-effectiveness. In contrast, Type 4 is the preferred option for high-density PCB designs where finer pitch and smaller components are common, providing more consistent print quality and better solder deposit accuracy.

In summary, 63/37 tin-lead solder paste remains a popular choice for its reliability in SMD assembly, with Type 3 and Type 4 offering different benefits for specific applications. Understanding the distinctions between Type 3 and Type 4 solder paste allows manufacturers to optimize solder joint quality and assembly efficiency according to the demands of each project.

If you are looking for Solder Paste with 63% Tin and 37% Lead (Type 3 and Type 4) for SMD Assembly from China, please contact us.

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