battery corrosion?

Have 96 Accord 2.2L and lately have had a big problem with battery cable corrosion. Have to clean all the time! It has a maintenance free battery less than 6 months old. I am using brass type connectors. Any ideas for a cause and cure? Thanks

Cause - don't know. But, after thoroughly cleaning the posts and terminals (use hot water and detergent), and using a wire brush or emery cloth to remove tatrnish, dry off and smear with Vaseline.