Stepped Stencil Technology
Stepped stencils have gained increasing importance in electronic assembly production. They are used when the paste quantity applied can no longer be adequately regulated via adaptation of the apertures. A further field of application is compensation of height differences on the board surface, which can result e. g. from labels or excessively high via hole pluggings. Height differences are compensated by recesses on the stencil underside.
Artificial jumps and resulting smearing of the print are thus prevented.
Micrograph of a Step
The smooth transition between the steps, avoiding deposition and hardening of the paste, is crucial. In the further production process, steps with << sharp edges >> may result in doctoring in of hardened paste resiudes and thus in clogging of neighbouring apertures.