I’ve been using surface mount components on my boards for a while now and using a syringe and needle to deposit solder paste has worked fairly well. But it’s a pain using that technique for fine-pitched components. I ran across https://www.oshstencils.com/ and decided it was time to try using a solder stencil. A copy of my board’s paste mask was uploaded to the site and a few days (maybe a week) later, I received the solder stencil.
Below are the results of using my first SMD solder stencil. I was as careful as possible throughout the process. And either it was that, or beginners luck, but I really didn’t run into any problems and the results turned out great… even the fine-pitch components worked perfectly.
First, several boards were placed around the board to be pasted, to provide a level surface around the edges of the board. Then the stencil was placed on top of the board and carefully aligned with the component pads. Next, a thick bead of solder paste was deposited onto the stencil, along the top width of the board. I also rechecked the stencil alignment at this point. Finally, while holding the stencil securely in place, the paste was pulled across the face of the stencil with a squeegee.
During the first pull, the squeegee was held at around a 45 degree angle to the face of the board, which ensured a nice even paste coverage. Then the squeegee was pulled back across the face at an almost 90 degree angle, which removed most of the excess paste.
![Stencil after applying solder paste](http://random.engineer/wp-content/uploads/2014/12/canctrl-secio1-solderpaste.jpg)
Still holding the stencil firmly at one end, it was pulled up and away from the board starting at the other end, so as not to smear the paste.
![Board after solder paste has been applied](http://random.engineer/wp-content/uploads/2014/12/canctrl-secio1-pasted.jpg)
The next step was to place the components onto the board. I usually start with the smallest components first (resistors, capacitors, etc), then move on to the larger ones.
![All SMD components have been placed](http://random.engineer/wp-content/uploads/2014/12/canctrl-secio1-placedcomponents.jpg)
Now it’s into the reflow oven!
![The Preheat Phase](https://random.engineer/wp-content/uploads/2014/12/canctrl-secio1-reflow-preheat.jpg)
![The Soak Phase](https://random.engineer/wp-content/uploads/2014/12/canctrl-secio1-reflow-soak.jpg)
![The Reflow Phase](https://random.engineer/wp-content/uploads/2014/12/canctrl-secio1-reflow-reflow.jpg)
Once the reflow was complete, the board was removed from the oven and allowed to cool a bit.
![A successfully reflowed board!](https://random.engineer/wp-content/uploads/2014/12/canctrl-secio1-cooled.jpg)
So, an initial success with solder stencils. I’ve got a few more designs in the queue and am looking forward to seeing how those turn out as well.