when we use this word to refer to electric circuits, stress is naturally always цепОчка (basically, it's slang for a simple electric circuit or part of circuit). I am not sure this technical meaning could be of any use to laymen though.

but if you refer to bikes, boats it's supposed to be a цепь (as a mechanism it is supposed to be hard and reliable), while цепочка is perceived as something fragile (so usually it's something of jewelry type).

additionally, if a causal relationship is meant, both words цепочка or цепь are used (цепь событий, etc.)