While in no way decrying what JDW has settled on, I point out that anhydrous anything, by definition, has not water enough in it to dissolve polar materials. The inorganic (and organic—nothing to do with food faddism) non-polarized portions of capacitor electrolyte (the gelling agents) and the ionized molecules and ions (duh ...) dissolve in and are carried away best by the ionic solvent 'water'.
Truly anhydrous ethanol is so avid for water that it will imbibe water from the air, so making and keeping anhydrous ethanol anhydrous is an expensive pastime. The eutectic mixture of ethanol (what results from distilling a water/alcohol mixture) is about 92% ethanol, so you can see that solutions of ethanol in water (and water in ethanol) on either side of 92% ethanol are not stable, tending up or down towards the magic 92%.
Where anhydrous ethanol (and other liquids that can dissolve water) come into their own is as the last rinse, because they can remove remnant water from nooks and crannies (eg under surface mounted ICs and other components) more quickly than can simple evaporation of water. Ethanol, or a higher (longer-chain) aliphatic alcohol that does not deplete the logic-board's lacquer, then comes into its own. As I wrote in another post, commercial board-cleaning is usually done by sonicating boards in water containing suitable detergents, followed by rigorous rinsing. That's cheap and effective. If remnant water is dissolved off a board, as opposed to wiping or blowing it off, time can be saved. However, 98% ethanol is much cheaper for the purpose than is the fiendishly expensive 100% ethanol, or the not-much-cheaper 99.5% ethanol. Acetone is (relatively) cheap, and also infinitely miscible with water. However, it is dangerously flammable and probably can play merry Hell with board lacquers. In the end, one does what works, and swallows the cost, or seeks a less costly equivalent process.
The number of boards to be dealt with at any one time will influence the choice between quick and cheap.
de
Truly anhydrous ethanol is so avid for water that it will imbibe water from the air, so making and keeping anhydrous ethanol anhydrous is an expensive pastime. The eutectic mixture of ethanol (what results from distilling a water/alcohol mixture) is about 92% ethanol, so you can see that solutions of ethanol in water (and water in ethanol) on either side of 92% ethanol are not stable, tending up or down towards the magic 92%.
Where anhydrous ethanol (and other liquids that can dissolve water) come into their own is as the last rinse, because they can remove remnant water from nooks and crannies (eg under surface mounted ICs and other components) more quickly than can simple evaporation of water. Ethanol, or a higher (longer-chain) aliphatic alcohol that does not deplete the logic-board's lacquer, then comes into its own. As I wrote in another post, commercial board-cleaning is usually done by sonicating boards in water containing suitable detergents, followed by rigorous rinsing. That's cheap and effective. If remnant water is dissolved off a board, as opposed to wiping or blowing it off, time can be saved. However, 98% ethanol is much cheaper for the purpose than is the fiendishly expensive 100% ethanol, or the not-much-cheaper 99.5% ethanol. Acetone is (relatively) cheap, and also infinitely miscible with water. However, it is dangerously flammable and probably can play merry Hell with board lacquers. In the end, one does what works, and swallows the cost, or seeks a less costly equivalent process.
The number of boards to be dealt with at any one time will influence the choice between quick and cheap.
de