SMT process recommendations

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27/10/2024

Stencil life can be lengthened by using a continuous replacement method for keeping the solder paste in a fresh condition. By simply adding new paste to the stencil as you use it, you can lengthen the life of the paste without degradation of tack or reflow characteristics. Solder paste volume on the stencil also has a relationship to how long the solder paste will last. It is recommended to have adequate solderpaste volume on the stencil so that a 1/4" to 1/2" roll of solder paste is in front of the squeegee at all times. This volume leads to better print definition as well.The effects of time on reflow and tack characteristics for solder paste that has been printed on a PCB are greatly influenced by the environmental conditions of the manufacturing facility. The general recommendation is to keep the time between printing and reflow down to a minimum so solderability characteristics are not sacrificed.

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