Improving Solder Paste Printing With Squircle Aperture Designs

The term “squircle” is a portmanteau, or mashup, of “square” and “circle”. It looks like a square with rounded corners. Mathematically, this shape is known as a superellipse. When it comes to SMT stencil design, a looser definition is often used, and the actual shape is known as a rounded square - generated by separating four quadrants of a circle and connecting them with a straight line.

As it turns out, the squircle is an effective shape for maximizing both solder paste volume in tight spaces and improving transfer efficiency.