Hi,
what value do you use for solder mask expansion when designing PCB to be manufactured by itead/elecrow/seeed etc?
According to design rules, the minimum soldermask bridge is 0.2mm (7.874mil). I know that solder mask expansion is supposed to compensate for soldermask/copper registration errors and soldermask shrinkage. I've set it to 3mil, but I still can't achieve reliable soldermask between pads of 0.635mm pitch SOP package.
How low can I go with expansion value without risking some catastrpohic misalignment?