Zinc Chloride is a fairly strong acid, and if you don't THOROUGHLY clean that joint of all the residue, it will very quickly rust. It's really not stuff you want to use around electrical connections.
From the product page.
Rubyfluid has been giving superior results for plumbers and workers in brass, copper, tin, steel and stained glass since 1907.
Note they don't mention doing electrical work with it, and that's for a good reason.