Assembling some panels for the shop
Aug 19 2019
about 3 years ago
It was time this weekend to assemble some more modules to replenish the stock for the shop.
I wanted to share a bit of the process, so you can see what goes into manufacturing your Swiss-made modules!
Setting up for stenciling
Stenciling is the first step of the process. The point here is to deposit some solder paste on the raw PCB panels through a stainless steel stencil.
With the help of a squeegee, the solder paste is pushed through the stencil and accurately applied to the PCB panel.
OSH Stencils produce the stencils that I use to manufacture your modules. Their quality is perfect and consistent, and they offer very good support.
Digi-Key Switzerland supply the components with which I build your modules. Their selection of parts seems just endless and always in stock. Plus, their support is outstanding.
I was not paid to say any of this. I honestly enjoy working with these people - they are the best.
After completing this first step, the panels have all their solder pads covered in paste. The texture is similar to toothpaste, but I don't recommend brushing your teeth with it...
Pick & place
Now comes the most time-consuming part: placing every component on the panels.
Every single resistor, capacitor, IC chip, etc... They are simply "dropped" into place, right into the paste. The toothpaste-like consistency and texture will actually maintain the components in place until they are soldered.
For this, I use simple tweezers and some patience. After about two hours, all components are in place.
Well... ALMOST all components :)
Some components are not included at this stage and will be individually soldered later on. These are the through-hole components (large capacitors, 3.5mm stereo jacks) and sensitive components (mini-joysticks, switches, buttons) that risk being damaged by the heat during reflow.
Hot air reflow
Once the components are all sitting comfortably in solder paste, the next step is to expose the panels to enough heat for the paste to reflow.
The temperature must be carefully controlled to follow as accurately as possible the reflow profile of the solder paste's specification.
For this I use an Aoyue hot air station with a wide nozzle and low-speed flow.
After a few minutes the reflow is complete and everything is soldered into place. Unless extreme caution is applied during stenciling, some solder bridges will appear during reflow.
Now comes the time to clean up those solder bridges, as well as touch up any small defects that may have resulted from the reflow soldering step.
When heated, the wick magically sucks away any excess solder through capillary action.
Once everything is reflowed, I finally add the remaining components and solder them by hand with the same WT1010 station.
After this, only one last step is still necessary: cleaning the panels.
I dip the panels in some alcohol (IPA, not vodka...) and gently rub them with a medium-soft toothbrush.
And that's it! The panels are now ready to be broken into individual modules for packaging and shipping :)
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