I made a batch of PCBs with a QFN package IC. I accidentally connected the pad to GND even though it should be either left floating or connected to some signals else. I am glad that I have requested a few samples before I made the PCB fab house assemble all of them.
It would be very expensive to re-order the boards, and there are vias-in-pad connected to internal layers. So I think that disconnected the IC's exposed pad from the PCB's pad with additional solder mask should be a viable solution.
As long as I know that the pads are tinned with HASL. Would you suggest whether my next few actions are feasible or not:
- I request the fab house to mask the pads and assemble the boards.
- For my received sample boards:
- I desolder all the affected QFN chips
- remove all the solder with the copper braid
- clean with isotropic alcohol.
- Then either apply solder mask paint cured by UV light or stick Kapton tapes to cover the pad.
- Finally re-solder the parts with heat gun.