Benefits of Solder Paste Stencils
Soldering with a stencil can largely save time and improve efficient during the whole PCB manufacturing process. Though solder components by hand is ok, working with SMD components presents an entirely new challenge for our clumsy hands with smaller contact pad connections. When using a solder paste stencil, you get the following benefits:
Uniformity-- Even amount of solder paste across every SMD pad on your PCB can be guaranteed.
Efficiency-- You can apply solder paste to your entire board all at once instead of one pad at a time.
Reliability-- You’ll get a reliably assembled board since each pad receives the same amount of solder paste.
Using a solder paste stencil is a rapid process and requires just a couple swipes of a credit card to apply a nice, even coating to all of the SMD pads on your PCB. That’s why you can find this method used by hobbyist and manufacturers.
Currently, after your board is fabricated by PCB manufacturer, they will then apply a layer of solder paste on all of your SMD based board. Once the paste is applied, your board will then be placed in a pick-and-place machine where all of the SMD components are set. Here, the flux in the solder paste keeps all of the components in place until the board is cooked.
With all of the SMD components on your board, it will then go through either a reflow soldering or wave soldering oven. In a wave soldering process, your PCB passes over a wave of molten solder which melts all of the solder on your board. This Is the ideal manufacturing process when you have both through-hole and SMD components on your PCB. The alternative is reflow soldering, where your board is sent through a large industrial oven with reflow heat applied to the top of your board, which melts the solder on your SMD pads.