An aperture defines the shape and size, round, rectangular, oblong or custom, that a Gerber file uses to flash pads or draw traces. The name comes from vector photoplotters, where each aperture is a physical hole in a wheel that shapes the light exposing the film, listed in a separate aperture file. RS-274X embeds the definitions in the Gerber file itself, and stencil designers use the same word for each opening in a solder paste stencil.
Stencil apertures on the QFN thermal pad should be a window pane at about 60 percent, not one big opening.
Also heard as
- D-code
Related terms
Gerber
Standard file format describing each board layer as a 2D image, sent to the fabricator to build the board.
Artwork
Image of each board layer used to make the phototools for fabrication, and by extension the layer data itself.
Stencil
Thin laser-cut metal sheet used to print solder paste onto board pads before parts are placed.