Finger Hold Down after Placing

[mcbPalisade]

In a lot of videos I've seen where fine pitch parts are placed by LitePlacer a hand comes in and the IC is "digitally" (couldn't resist) held down by a finger.

Since I'm not to this stage yet why is this done? I'm assuming it is necessary for some reason.

Thanks

[JuKu]

These are not my videos, but I’m guessing that they are testing the machine and not having paste. If there is no glue or something similar, the parts could move when the nozzle goes up. A finger works; I use spray-on post-it type glue to simulate the stickiness of the paste.

[mcbPalisade]

That makes sense, bare board -> hold down part.

Solder paste on board -> part is held in place by adhesion.

Thanks