If I was to use contact cleaner on some connectors, Would this have a better or worst impact then using 100% alcohol? Does contact cleaner leave Residue?
The 100% alcohol would be considered as the ideal material to clean any electronic contacts as they evaporate quickly and leave no residue behind.
But the only problem with them is "100% pure alcohol is too expensive". (Its also one of the most explosive components.) So normally the manufacturer mix alcohol with other components (which might or might not be volatile) so that the cost and dangers can be minimized. Still alcohol is the main content of contact cleaners.
However the best solution for you would be to be reasonable with both cost and the materials used in the product that you want to buy. You can always check about the ingredient components that are used to make a cleaner. Depending on your design requirement you can purchase a specific one.
Nobody would advice you to go for 100% pure alcohol only unless you want to clean some really expensive equipment that has gold platting over the contacts.
See Kaz's answer-as-a-comment:
"contact cleaner" isn't a specific substance; it a marketing label. Some contact cleaners evaporate, others leave something behind, like some sort of lubricant or oleic acid. – Kaz May 13 '14 at 3:29
Just now I used Isopropyl Rubbing Alcohol (70% USP) from the pharmacy, because it's what I had on hand, and it seemed to work fine--the 30% water evaporates almost instantly, which leads me to believe that any rust/oxidation it causes will be minimal. The 70% stuff seems to be more prevalent in stores.
Contact cleaners' additives are designed to keep the contacts sliding nicely. There's a sage-sounding discussion of it at the end of this article, starting at
Curiously, there is virtually no difference in contact resistance between lubricated and unlubricated contacts.
(There, the author is talking about electrical resistance, not sliding friction).