As the name suggests, acid core has a corrosive flux core which is used for soldering copper pipes. The acid literally removes the surface layer of the pipe for better bonding of the solder. You definitely don't want that corrosive flux traveling to other parts of the circuitry. Talk about never-ending intermittent problems!
For electronic soldering, use resin-core solder which is less corrosive. Even then, use a cotton swab, saturated with alcohol, to clean up any traces of flux after soldering.
