2L FPC have coverlay, with green solder mask on assemble area.

What’s the function FPC solder ink on this design?  

FPC solder ink is used instead of the original covering film, its role is the same as the covering film.  

It mainly plays the following roles:  

1, FPC soft plate ink printed on the circuit board surface copper foil line, isolated from the contact between the copper foil and the outside world, play a surface insulation role.   

2, the circuit board welding ink completely solidified, can be very good to prevent the conductive foreign body fell into the line caused by short circuit.  

3, FPC circuit board welding ink has resistance to electroplating, resistance to tin, resistance to gold, SMT can also play a good role in welding.