De-ionized water is generally regarded as an effective cleaning agent for PCB's, as shown here and here. However, removing that water means compressed air, oven, and/or lengthy drying-time. Even if all these are used, water can still be present under (and inside) some components (i.e. transformer housing), possibly contributing to crevice corrosion and other un-desireables.
Similar to the question regarding Vacuum dessication of MSL components, what would the efficacy be of subjecting a washed PCB to low-pressure conditions for accelerated drying?
Most discrete components are solid and homogenous, so should be unaffected. But what about:
- Electrolytic, polymer, polystyrene capacitors
- Sealed non-vacuum items (fuses, relays?)
- Sealed vacuum items (thermionic tubes, neon lamps, etc)
- LCD displays
- Battery cells
Can electrolytics survive vacuum, or will they vent? What about a glass fuse? Are nixie tubes safe in a vacuum? Would an LCD display be altered at all?
Batteries are interesting. One video reports that certain 18650-sized cells may be unaffected by vacuum, while LiPo swells but remains functional. I'd not trust one after this, nor consider coin cells, or vented liquid-electrolyte types. Another video shows a GoPro camera and Fieldpiece temperature probe both operating well under vacuum conditions, however that was of short duration. Real vacuum moisture removal would take an hour or so, depending on ambient temperature.