Plate resists Solder stop lacquers Notation printing In its basic form, the screen-printing process is very simple. A screen fabric with uniform meshes and opening is stretched and fixed on a solid frame of metal or wood. The circuit pattern area open, while the meshes in the rest of the area is closed. In the actual printing step, ink is forced by the moving squeeze thorough the open meshes onto the surface of the material to be printed. The ink deposition, in a magnified cross section, shows the shape of a trapezoid. Pattern transfer onto the Screen There are two different methods in use, and each method has its own advantages and disadvantages. With the direct method, the screen is prepared by coating a photographic emulsion directly onto the screen fabric and exposing it in the pattern area. The indirect method makes use of a separate screen process film, supported on a backing sheet. The film on its backing sheet that is there after pressed onto the screen fabric and sticks there. Finally, the backing sheet is peeled off, opening all those screen meshes, which are not covered by the film pattern. The direct method provides very durable screen stencils with a higher dimensional accuracy but the finest details are not reproduced. The indirect method is more suitable for smaller series and where the finest details to be reproduced. The indirect method is faster but dimensionally less accurate
Plate resists Solder stop lacquers Notation printing In its basic form, the screen-printing process is very simple. A screen fabric with uniform meshes and opening is stretched and fixed on a solid frame of metal or wood. The circuit pattern area open, while the meshes in the rest of the area is closed. In the actual printing step, ink is forced by the moving squeeze thorough the open meshes onto the surface of the material to be printed. The ink deposition, in a magnified cross section, shows the shape of a trapezoid. Pattern transfer onto the Screen There are two different methods in use, and each method has its own advantages and disadvantages. With the direct method, the screen is prepared by coating a photographic emulsion directly onto the screen fabric and exposing it in the pattern area. The indirect method makes use of a separate screen process film, supported on a backing sheet. The film on its backing sheet that is there after pressed onto the screen fabric and sticks there. Finally, the backing sheet is peeled off, opening all those screen meshes, which are not covered by the film pattern. The direct method provides very durable screen stencils with a higher dimensional accuracy but the finest details are not reproduced. The indirect method is more suitable for smaller series and where the finest details to be reproduced. The indirect method is faster but dimensionally less accurate
85295912-Energy-Metering-Circuit-Using-GSM-Semi-Report.docx