1090 solder balls with lead free water soluable paste results

Reflow with lead-free 96.5 /3/0.5 No-Clean T4 brown-orange burn color on parts

Electronics Forum | Thu Dec 26 17:13:43 EST 2019 | rgduval

Doesn't really look like no-clean to me...typically, no-clean encapsulates the solder joint after reflow, trapping any organics. This looks like plain-old water soluble flux, that cooked a bit too much in reflow. As you noted, it cleaned up with