Our board supplier changed our board surface finish on a prototype to flat solderable tin (FST) because of the PWB thickness (.125"). The pads seem to be contaminated, particularly on second side pass through reflow. The solder appears to draw into the center of the pads. Has anyone any experience with this? I was wondering if our screen cleaner was affecting the process. It seems to leave a greasy film on the screen, but the instructions don't require a water rinse. Thanks in advance...
Statement: This post is only the personal view of the author and does not represent the opinions of ALLPCB.com.