Maintenance Interval
Maintenance intervals specifying how often the bottom of a stencil is cleaned during the printing process prevent the accumulation of stray solder paste. The underside wipe frequency is set based on the pitch of the components and the type of solder paste being used. It ensures that the apertures remain clear and that no paste is transferred to the solder mask between the pads.
Defect Prevention
As the printer operates, small amounts of paste inevitably squeeze between the stencil and the board. If the underside wipe frequency is too low, this excess material builds up and causes shorts or solder balls after reflow. High density boards with fine pitch parts require more frequent cleaning to maintain a high level of print precision.
Process Throughput
Optimizing the underside wipe frequency involves a trade off between the speed of the line and the risk of quality failures. Every cleaning cycle adds time to the production of a board and consumes cleaning rolls and solvent. Modern printers use automatic inspection systems to trigger a wipe only when they detect a certain level of contamination on the stencil.
This data driven approach reduces unnecessary downtime while protecting the integrity of the solder joints. Consistent monitoring of the print quality allows the operator to adjust the interval to account for changes in the ambient temperature and humidity. This parameter is a necessary part of the setup for any high volume automated SMT line.
