Hugo Holden
Veteran Member
If you consider washing a board with water, you might want to consider that not all parts on the pcb are compatible with it. Or compatible with other products too.
Apart from water being more difficult to displace from crevices, and requiring washing with a more volatile solvent anyway (so back to square one and don't require water) there is the occasional part affected by water and lubricants for that matter.
The typical part is the miniature variable capacitor, found in oscillator circuits, and specifically scope Attenuators, This is why you find very specific and strict instructions in Tek manuals about what can and cannot be applied. Also not all potentiometers and pcb switches cope with water as they are not sealed. One of the worst examples would be the CTS brand DIL switches that quickly imbibe a large volume of fluid and hold onto it in their rectangular body and it is very difficult to get it out.
All lubricant compounds have a dielectric constant. If this gets in small variable capacitors it significantly raises the capacitance and completely corrupts the adjustments. People find this out when they spray cleaner-lubricant products into their scope attenuators.
Also, micro-crevices get created, by a component's approximation to the pcb. For example DIL IC's are not too bad in this respect as they sit a fair distance above the pcb surface. Surface mount IC's sit very near or sometimes on the pcb surface. If any water +/- detergents +/-salts gets under them, it can take a very long time to dry out, even with heating because there is only a very thin strip of water in the edge of the film exposed to the atmosphere, and any salts either in the water or detergents, or compounds already on the board, or IC pin surface oxides can have a corrosive effect. Some types of IC sockets sit flat on the board surface, with a gap that will take a thin layer of fluid.
The only time I use water on a board is to leach off leaked electrolyte because contact cleaners cannot do it. Otherwise it is, on the whole, better to avoid water and certainly to avoid the dishwasher and only use a good contact cleaner product.
I think cleaning pcb's in dishwashers, started out because people were lazy, wanted a quick cleaning solution, and didn't have the patience and want to take the time to do the cleaning manually with contact cleaner and cue tips and other tools such as paper strips & tooth picks, it can take a long time on a large board to properly clean. But I think the dishwasher will leave, in some cases, depending on the board, the types of sockets, switches, other components, latent troubles that might not crop up for a few years. But by then the person who used the dishwasher probably on-sold the equipment and somebody else inherits the disaster.
Apart from water being more difficult to displace from crevices, and requiring washing with a more volatile solvent anyway (so back to square one and don't require water) there is the occasional part affected by water and lubricants for that matter.
The typical part is the miniature variable capacitor, found in oscillator circuits, and specifically scope Attenuators, This is why you find very specific and strict instructions in Tek manuals about what can and cannot be applied. Also not all potentiometers and pcb switches cope with water as they are not sealed. One of the worst examples would be the CTS brand DIL switches that quickly imbibe a large volume of fluid and hold onto it in their rectangular body and it is very difficult to get it out.
All lubricant compounds have a dielectric constant. If this gets in small variable capacitors it significantly raises the capacitance and completely corrupts the adjustments. People find this out when they spray cleaner-lubricant products into their scope attenuators.
Also, micro-crevices get created, by a component's approximation to the pcb. For example DIL IC's are not too bad in this respect as they sit a fair distance above the pcb surface. Surface mount IC's sit very near or sometimes on the pcb surface. If any water +/- detergents +/-salts gets under them, it can take a very long time to dry out, even with heating because there is only a very thin strip of water in the edge of the film exposed to the atmosphere, and any salts either in the water or detergents, or compounds already on the board, or IC pin surface oxides can have a corrosive effect. Some types of IC sockets sit flat on the board surface, with a gap that will take a thin layer of fluid.
The only time I use water on a board is to leach off leaked electrolyte because contact cleaners cannot do it. Otherwise it is, on the whole, better to avoid water and certainly to avoid the dishwasher and only use a good contact cleaner product.
I think cleaning pcb's in dishwashers, started out because people were lazy, wanted a quick cleaning solution, and didn't have the patience and want to take the time to do the cleaning manually with contact cleaner and cue tips and other tools such as paper strips & tooth picks, it can take a long time on a large board to properly clean. But I think the dishwasher will leave, in some cases, depending on the board, the types of sockets, switches, other components, latent troubles that might not crop up for a few years. But by then the person who used the dishwasher probably on-sold the equipment and somebody else inherits the disaster.
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