In a way, I knew this already - but lifting the stencil after paste application is one of the seemingly simple steps that can mess up all the work you put into alignment and spreading the paste. If the stencil is flat on the board / work surface, it's almost impossible to lift it without shifting.
Since I'll be making many of these boards I decided to create a little jig. What we need:
- a piece of smooth (sealed? don't know what it's called) chipboard
- a piece of cardboard with the same thickness as the PCB
- the alignment pegs I had shown in an earlier log
The chipboard is drilled to make room for the pegs and a pair of screws, and the cardboard gets a cutout for the PCB:
Then I though about the lifting problem described above, and added an extra cutout before gluing it to the chipboard. Here it's shown with PCB and pegs:
And now with stencil - still aligns very well:
When paste application is done, I can hold down the stencil with a finger, remove the pegs and lift the stencil without harming the paste job.
There's still one major drawback: When the pegs are removed, nothing keeps the PCB from shifting because the cardboard isn't fitted tightly. Maybe next time.