Stencils

It is important to start the assembly process with the correct stencil. Choosing the correct thickness and having your apertures cut to match your manufacturing capabilities is essential to the quality of your end product.

At Precision, we supply various thicknesses and sizes of high-quality stainless-steel laser cut stencils, both framed and frameless.

Framed stencils are permanently mounted in a frame using a mesh border to tightly stretch the stencil foil taut in the frame.

Frameless stencils do not need to be permanently glued in a frame as they are designed to work with tensioning systems. They are significantly less expensive than their framed counterpart and require less storage space.

The first requirement to consider when requesting stencils is its thickness. It is important to maintain a minimum aspect ratio of 1:5 between the smallest aperture width and thickness, as this will prevent clogging. If the aspect ratio is less than 1:5, solder paste will tend to remain in the opening.

Aperture design is a crucial step in optimising the print process. Here are a few general recommendations:

• Discrete components: 10% – 20% aperture reductions to avoid occurrence of solder beads.
• Fine pitch components: 5% – 15% aperture reduction to minimize solder balling and bridging.

We can make any necessary aperture adjustments, if required.