Clamshell versus Vertical Lift Printer

MPM AP-27 preferred over MPM AP-20

The issue is release of paste from the stencil. A vertical lift printer kinda snaps the stencil away from the board to complete the print cycle. The inertia and the rheometric properties of the paste make it release from the stencil better than a clam-shell.

But this all depends on what you're doing. For normal pitch, who cares, but as you start thinking about the aspect and area ratios of you apertures, paste release becomes more important.

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Dear Keith.

A vertical lift of stencil or vertical lowering of the PCB is best way to control the separation speed which is essential in fine pitch printing. The clamsheel lifting will give a different separations speed depending on the distance from the turning point.

Checkout: http://www.smtinfocus.com/processguide_printing.html

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