This disclosure describes use of fiducial marks for alignment of solder paste in a solder printing process for manufacture of flexible printed circuits (FPC). Per techniques of this disclosure, two diagonal fiducial marks and a central fiducial mark are placed on a FPC and utilized in the solder printing process for optimal alignment of deposited solder paste. The fiducial marks are placed in a central region of the FPC and have a smaller spacing than conventionally utilized fiducial marks. The central fiducial mark is placed at a location that lies perpendicular to a line connecting the diagonal fiducial marks. Spacing between the fiducial marks is designed to compensate for FPC deformation by limiting the shift in the fiducial marks during deformation of the FPC. During the printing process, the spacing between the FPC and printing stencil is automatically adjusted (scaled) to ensure printing alignment.
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Lu, Daniel and Zhou, Zhixin, "Fiducial Marks for Alignment in Solder Printed Flexible Printed Circuits", Technical Disclosure Commons, (June 15, 2020)