Are you struggling with unreliable connections on your PCB due to cold solder joints? Hot air rework is a powerful technique to fix these issues and restore your board's functionality. A cold solder joint forms when the solder does not properly bond the component lead to the pad—typically due to inadequate heat, oxidation, or poor technique. While these joints may look acceptable at first glance, they can become problematic over time, especially when exposed to vibration, thermal. This guide explains what a cold solder joint is, what it looks like, why it happens, and how to reliably identify, fix, and prevent it.