Transparent and Fine Film Stencils with Functional Coating for Advanced Surface Mount Technology

Area of Science:

• Materials Science
• Manufacturing Engineering

Background:

• Miniaturization in electronics demands thinner, more durable stencils for advanced surface mount technology (SMT).
• Conventional metal stencils face limitations in achieving the required precision for fine-pitch applications.

Purpose of the Study:

• To develop a transparent, thin film stencil for fine-pitch SMT processes.
• To enhance solder paste printing accuracy and reduce defects using a novel stencil material and fabrication method.

Main Methods:

• Fabrication of a transparent stencil using a clear polyimide film.
• Application of a functional diamond-like carbon (DLC) coating layer.
• Utilizing a nanosecond pulse laser for precise, burr-free aperture creation.
• Incorporating electrostatic discharge (ESD) properties into the DLC coating.

Main Results:

• Achieved high-quality, burr-free apertures via a thermally stable laser-cutting process.
• Demonstrated enhanced solder paste printing accuracy with significantly fewer solder joint defects.
• The DLC coating provided smooth aperture surfaces and sidewalls, ensuring high solder paste release and mechanical durability.
• The developed stencil offers a low-cost, easily fabricated alternative to conventional metal stencils.

Conclusions:

• The transparent polyimide film stencil with DLC coating is suitable for fine-pitch SMT.
• This technology enables improved printing accuracy, reduced defects, and enhanced stencil durability.
• Presents a cost-effective and scalable solution for mass production in fine-pitch SMT.