What is stencil printing? Learn about solder paste stencil printing: how it works, stencil types, quality parameters and its importance in the SMT process.
What is Stencil Printing?
Stencil printing is a process where solder paste is applied through the openings of a stainless steel stencil onto the solder pads of a circuit board.
Stencil printing is the first and one of the most critical steps in the SMT manufacturing process. Solder paste is deposited through a precision-cut stainless steel stencil onto the pads of the PCB. The quality of this print largely determines the quality of the subsequent solder joints — it is estimated that over 60% of all soldering defects can be traced back to paste printing.
Process and Application
The stencil is made from thin stainless steel sheet (typically 100–150 µm thick) with laser-cut openings. During printing, a squeegee moves across the stencil, pressing solder paste through the apertures onto the board.
Key quality parameters include squeegee speed, squeegee pressure, separation speed (snap-off), stencil cleaning and environmental conditions. Print results are typically monitored in real time by SPI (Solder Paste Inspection).
Frequently Asked Questions
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