Quality assurance

AN4428

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DocID025706 Rev 1

Figure 9. Actual pick-and-place nozzle used in ST manufacturing facilities

Finally, other parameters must be rigorously controlled for the proper handling of the device:

the force of the vacuum and the pressure of the nozzle on top of the microphone package.

The pressure of the nozzle depends on the velocity and the height during the picking of the

device but also depends on the force set for the placement of the nozzle on the safe area.

To correctly control the forces involved during the pick-and-place process, the following

indications must be respected:

 Usually the picker is set to a minimum distance from the component (100-200 µm)

 Recommended placement force on the safe area is below 500 g

1.4

Pre-shipment

The flowchart below represents the back-end process from testing to shipment. Basically

the devices are tested according to electrical and acoustic parameters (ATE), they are

placed in a tray, then they are placed in a reel using the automatic pick-and-place machine

and finally the microphones are packaged and shipped to the customer.

Figure 10. Back-end process flow

a.

1 kPa = 0.145 psi (lb/in²) = 0.0102 kgf/cm² = 0.0098 atm maximum allowed pressure on microphone package

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