Conclusions

Using this higher bandwidth CPM is a requirement for faster ionizers.  In addition, when the ionizer is placed quite close to the product (and hence the CPM), the displacement current plays a greater role.

For applications in which displacement current plays a significant role in the CPM measurement, it is important for the user to determine whether the details of his handling of the product in the field of an ionizer.  In contrast, handling of the product in the ion current can result in voltage swings which are important.  However, in the case of systems with large robots this is rarely an issue.

The simple test of blocking the ionizer with a dielectric as shown in Figures 5-7 is highly recommended as an easy method to assess the contributions to voltage swing from ion and displacement current.

References

(1)               “Analysis of the Electrical Field Effects of AC and DC Ionization Systems for MR Head Manufacturing,” Proceedings of the 1999 ESD Symposium, Vol 21, (1999), pp 3193 – 328.

(2)               L. Levit, A. Wallash, “Measurement of the effects of ionizer imbalance and proximity to ground in MR head handling”, EOS/ESD Symposium, 1998, pp. 375–382

(3)               LB Levit, GG Desai, W. Vosteen, Measurement of ionizer performance—a new approach, EOS-ESD Symposium Proceedings 1999, pp. 124–129


(4) ANSI EOS/ESD S 3.1 EOS/ESD Association “Protection of Electrostatic Discharge Susceptible Items” Rome, N.Y. 2000.