An apparatus for mounting semiconductor chips has a pick and place system
arranged stationary in vertical direction for the picking, transport and
placement of a semiconductor chip onto a substrate. The pick and place
system comprises a bondhead with a chip gripper deflectable relative to
the bondhead. The deflection of the chip gripper takes place by means of
a pneumatic drive arranged on the bondhead which has two pressure
chambers separated by a piston, whereby the chip gripper is secured to
the piston. The pressure p.sub.1 prevailing in the first pressure chamber
and the pressure p.sub.2 prevailing in the second pressure chamber are
dynamically controlled by means of a regulator controlled valve system.
The regulator can be operated in two operating modes. In the first
operating mode, the deflection of the chip gripper and/or a variable
derived from it is controlled based on the signal delivered by a position
encoder which measures the deflection of the chip gripper. In the second
operating mode, the pressure p.sub.1 and/or the pressure p.sub.2 and/or
the pressure differential p.sub.1-p.sub.2 is controlled.