It's other way around! Iron age did not result in Bronze Age collapse, it was caused by it. Iron has been known for a long time before the collapse, and widely accessible. It was little used because iron at that era was an inferior, substitute material (and is a pain in the ass to make because it involves first producing charcoal to achieve high temperatures). It only became stronger and comparably durable to bronze around 2nd century BC, in late Roman Republic. But the Collapse made long-distance transportation of inputs for bronze production impossible because centralised governments one could depend on for predictable rules and security, vanished. It forced people to turn to then-inferior iron, and start using and eventually, improving it, but it still remained inferior to bronze even in Classic Greece.