General technical requirements: Frame: The frame size is determined according to the requirements of the printing machine. Take the DEK265 and MPM UP 3000 models as an example. The frame size is 29ˊ 29ˊ, and the aluminum alloy frame size is 1.5ˊ1.5ˊ.
Stretching net: It adopts red rubber + aluminum tape method. In the joint of aluminum frame and glue, it should be evenly coated with a protective paint. At the same time, in order to ensure sufficient tension and good flatness of the stencil, it is recommended that the stainless steel plate retain 25mm-50mm from the inner side of the frame.
Benchmark: Opens in a 1:1 manner according to the size and shape provided by the PCB data, and is semi-transparent on the reverse side of the printing. At the corresponding coordinates, the entire PCB is opened at least two reference points.
Opening requirements:
1.41. The position and size ensure high opening accuracy and open in strict accordance with the specified opening.
1.42. The size of the independent opening should not be too large, the width should not be greater than 2mm, and the 0.4mm bridge should be placed in the middle of the pad size larger than 2mm, so as not to affect the strength of the stencil.
1.43. The open area must be centered.
5, character: For the convenience of production, it is recommended to engrave the following characters in the lower left or lower right corner of the stencil: Model; T; Date; stencil production company name.
6. Thickness of the stencil: In order to ensure the printing amount and welding quality of the solder paste, the surface of the stencil is smooth and uniform, and the thickness is uniform. The thickness of the stencil refers to the above table, and the thickness of the stencil should meet the requirements of the finest pitch QFP BGA.