The secret lies in the holes

Problem: . It is a particular need in the foil stencil printing of solder paste onto fine featured PCBs. Any distortion is liable to lead to the solder paste being deposited in the wrong places Solution: Tecan in Weymouth has a patented system for tensioning foil stencils. It is available either as Single Directional Tensioning or 4 Directional Tensioning. It consists of stencils with large fixing holes etched in their sides which fit over pins in printing frames. Stencils are held on the pins by clamp bars, coupled with a subsequent levered cam action to provide the tension. The secret of the success of the method, however, lies in patterns of fine holes etched into the sides of the stencils, just inside the frames. Applying tension ensures that any yielding or stretching which does take place, is restricted to the perforated regions, leaving the central areas with the printing pattern areas unchanged. Applications: The base technique is applicable to the mounting of any screen or membrane that needs to be held in place without distortion or damage. Screen printing is the obvious other application but the method looks equally appropriate for the better mounting of filter screens or osmotic or other semi permeable membranes. Put a stretchy region round the inside edges and the main area should always be tensioned just right. Tecan are also leaders in multi-level stencil technology, suitable for mixes of components with fine pitch devices that require little paste, and surface mount connectors and power components that require more paste. TS Tecan Components