Chemically etched stencils

Etched stencil, chemical etching, low cost stencil, low density stencil, stepped stencils
Chemically etched stencils

Chemically etched stencils are usually produced from an etchable grade of stainless steel. The resist is applied to the stencil material and the apertures are photographically defined. Chemical etching process is used to etch the material away in unexposed areas resulting in the apertures.

Since etching is carried out from both sides of the foil, process can create a waist within the aperture, although this can be reduced by polishing. The artwork dimensions are not the same as those of the openings to be made because the etchant undercuts the photoresist (over-etching). In order to compensate this issue, the artwork is modified by the stencil manufacturer to reduce the aperture sizes. This compensation in combination with etching produces the rounded corners which are characteristic of etched stencil apertures.

Etching in combination with laser cutting, is used to produce stepped stencils, partially etching areas around apertures where a thinner than normal deposit is required. This construction enables solder paste deposits of different thickness to be produced simultaneously for different types of components.

Material stainless steel SUS304
Thickness 50µm ~ 1.0mm
Minimum pattern 1.3 x thickness
Opening cross-section stencil_cross_etched
Properties - low cost product
- up to 0.5mm pitch (QFP)
Applications - standard quality, low density