All stencils are made with high-quality Polyimide and Stainless Steel. We use only the industry-leading Stainless Steel, explicitly designed for stencils.
Stainless Steel: 0.0007″ Laser spot size, 0.001″ minimum aperture size.
Polyimide Film: 0.003″ Laser spot size, 0.005″ minimum aperture size.
Polyimide has a lower precision rate due to the way it is processed and its ability to withstand heat during the cutting process. Minor variances will occur when the material reacts to the laser. Paste release is excellent, but this material should be limited to a small number of uses and with components 0402 or bigger.
The minimum aperture size for Polyimide is 0.005″ vs. 0.001″ for Stainless Steel. Polyimide also has a natural curl in the material caused by the way the film is manufactured; this is outside of our control. Stainless Steel provides the ultimate in precision and quality, with a 0.0007″ spot size, and exceptional paste release with a truly flat surface. If you want the absolute best reflow experience, there is no comparison, Stainless Steel is the superior material.