The panel is then sprayed with a chemical, which develops the part of the image that is black on the phototool, this is the part of the soldermask, which is not polymerised.
As we are following the creation of a BGA it now looks like the following
At this point the developed soldermask image is inspected to ensure it complies with the default IPC Class 2, or IPC Class 3 if stated on the job card
For SMT Devices
For plated through holes
As well as other IPC Requirements like soldermask encapsulation, oxide marks under the soldermask, thickness etc….