Click here for a description and video that shows a nozzle design from FINETECH which clamps down onto PoP components during rework.
“The PoP soldering head is an easy-to-use tool for reworking stacked devices as a whole in a single reflow process. It uses vacuum-actuated mechanical clamping tweezers which avoid separating the single layers of a PoP during component removal. The PoP soldering head can be easily adapted to different component thicknesses. Furthermore it is possible to adjust the width of the clamping tweezers prior to the process when the rework arm is swiveled down to avoid affecting other components on the PCB (e.g. accidental shifting of neighboring small passives).”
Sounds like this would be great for combating “PoP Quicksand”. That nasty problem that large components have when the vacuum provided by the nozzle isn’t strong enough to lift the package-on-package component back out of the PoP solder paste or dipping flux. Okay, I just made up that term – but it’s pretty descriptive, right?
Conceptually it seems to make a lot of sense, please comment if you have any experience with it!