So, about the other recommended PCB manufacturer for the ZeroPhone, OSH Park. DirtyPCBs is China-based, whereas OSH Park is USA-based. Indeed, if you look at the OSH Park website, you can see that the service is overall more geared toward professional commercial users, and they may provide some nicer services that DirtyPCBs doesn’t provide. Prices? Prices appear to be about the same as DirtyPCBs, and that being said, they are for sure more expensive than your hand-made cardboard circuit board options.
20190104/https://wiki.zerophone.org/index.php/Sourcing_ZeroPhone_parts
20190104/https://oshpark.com
Again, I reiterate, because this is important! “Solder mask” is effectively another name for “conformal coating” of a circuit board so that stray conductive objects cannot short out the traces on the board. The second Wikipedia article is the article on “robotic pick and place” machines for surface-mount devices. Again, due to the cost of setting up these machines, they are still generally only available for larger production runs, and small runs of custom designs must be done manually.
20190104/https://en.wikipedia.org/wiki/Solder_mask
20190104/https://en.wikipedia.org/wiki/SMT_placement_equipment