Printing screen units and method of fabricating the same

A method of fabricating a printing screen unit, comprising:

• forming an aperture in a first mesh, wherein threads, providing warp and weft, of the first mesh are aligned so as to be in first and second orthogonal directions;
• locating a second mesh over the aperture in the first mesh, wherein threads, providing warp and weft, of the second mesh are aligned so as to have acute angles of between 0 degrees and 45 degrees to the respective ones of the first and second orthogonal directions of the first mesh;
• attaching the second mesh to the first mesh so as to provide a mesh printing screen;
• tensioning the printing screen by applying a first tension to the printing screen using an external tensioning assembly;
• disposing a supporting frame to the printing screen, wherein sides of the supporting frame are displaceable;
• attaching the printing screen to the sides of the supporting frame while maintaining the printing screen at the first tension;
• following attachment of the printing screen to the supporting frame, removing the first tension applied to the printing screen;
• whereby the sides of the supporting frame are displaced by the first tension in the printing screen, whereby the printing screen has a second, residual tension lower than the first tension.

A method of screen printing patterns of deposits on workpieces, comprising:

• using a printing screen unit comprising a mesh printing screen and a supporting frame which is attached to the printing screen, wherein the printing screen comprises a first, outer mesh which is attached to sides of the supporting frame and includes an aperture therein, and a second, inner mesh which is attached to the outer mesh,
• wherein threads, providing warp and weft, of the inner mesh are aligned so as to have acute angles of between 0 degrees and 45 degrees to the respective sides of the supporting frame, and optionally threads, providing warp and weft, of the outer mesh are aligned so as to have acute angles of between 0 degrees and 10 degrees to the respective sides of the supporting frame, optionally being substantially orthogonal to the sides of the supporting frame, wherein the printing screen has a residual tension which is provided by tensioning the printing screen by an external tensioning assembly to a first tension when the printing screen is attached to the supporting frame, and releasing the first tension following attachment of the printing screen to the supporting frame, such that sides of the supporting frame are displaced by the first tension to leave the printing screen with the residual tension which is lower than the first tension;
• tensioning the printing screen unit in a frame assembly to a second tension higher than the residual tension;
• and
• printing patterns of deposits on workpieces using the printing screen unit tensioned in the frame assembly.

A method of fabricating a printing screen unit, comprising:

• providing a printing screen comprising a mesh, wherein threads, providing warp and weft, of the mesh are aligned so as to be in first and second orthogonal directions;
• disposing the printing screen over a supporting frame, wherein the supporting frame comprises first and second pairs of interface members which provide sides of the supporting frame and the interface members are configured so as to be resiliently deflectable on application of tension thereto by external tensioning mechanisms, and the threads of the mesh are aligned so as to have acute angles of between 0 degrees and 30 degrees to the respective sides of the supporting frame;
• attaching the printing screen to the sides of the supporting frame while maintaining the printing screen at a first tension;
• and
• following attachment of the printing screen to the supporting frame, removing the first tension applied to the printing screen, whereby the printing screen has a second, residual tension lower than the first tension.