Small amount of detergent, gentle cycle, no heat dry is what I do.
Then I put it in the oven for 12 hours at minimum temp 200 degrees or whatever.
As a note, at my work where we manufacture super high end circuit boards we use an industrial dishwasher like apparatus to wash boards and then a conveyorized drying apparatus. Later we use an industrial oven at 235 degrees for two hours to ensure that boards are dry and moisture free.