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 BGAs

For plated through holes

 

As well as other IPC Requirements like soldermask encapsulation, oxide marks under the soldermask, thickness etc….