IPC-7527, "Requirements for Solder Paste Printing," establishes industry-standard visual criteria for evaluating solder paste deposits, covering defect definitions for classes 1 through 3. Released in 2012, this 23-page document aids in identifying printing errors early to mitigate 60–70% of SMT defects, offering specific benchmarks for deposit shape, misalignment, and slumping. The standard, available in PDF, covers both manual inspection and automated 3D SPI system programming. For more details, visit IPC Store. ANSI Webstore IPC-7527 Solder Paste Printing Standards | PDF - Scribd
: Requires continued performance and extended life; uninterrupted service is desired but not critical. ipc-7527 pdf
Having the is one thing; implementing it is another. Here is a checklist derived directly from the standard to improve your stencil printing process. "Requirements for Solder Paste Printing