The effects of an electric field shield on the electric field noise and neutralizing current of a corona discharge air ionizer were investigated as a means to prevent soft errors during quality control inspections. The neutralizing current and noise voltage were measured for shielded and nonshielded air ionizers using a charged plate monitor. The use of an electric field shield decreased both the neutralizing current and the noise voltage. Therefore, neutralizing current to noise voltage ratio was calculated to evaluate the effect of the shield on the neutralization performance, and this ratio was several times higher for the shielded air ionizer than for the nonshielded air ionizer.

Corona discharge air ionizers are widely used during quality control inspections to neutralize the static electricity on electronic devices because the electric field generated by static charge can lead to soft errors. However, an air ionizer may act as a source of noise, which can also lead to soft errors, because it creates a large number of ions that generate a high‐intensity electric field. The soft errors of a CMOS inverter in a large‐scale integration (LSI) were investigated in a minienvironment in which an AC corona discharge air ionizer was operated. The LSI mounted on a printed circuit board was placed 500 mm under the air ionizer, which was operated with a peak‐to‐peak voltage of 15 kV at frequencies of 1‐50 Hz. The noise in the output voltage, which is a source of soft errors, of the CMOS inverter decreased with increasing operating frequency. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Corona‐discharge air ionizers have been used to neutralize static electricity on electronic devices during manufacturing and/or inspection processes. The neutralization performance, that is, the neutralizing current density (JW) and the electric field (EW), in work area depends on the operating conditions. Methods for estimating the neutralization performance are required to check them without stopping the production lines. In this paper, we propose an estimation method using an equivalent circuit simulation called the Simulation Program with Integrated Circuit Emphasis (SPICE) for estimating the behavior of positive and negative ions in the generation, transportation, and work areas. In the simulation, the ion generation characteristics are simulated by diodes and resistors. The transportation and accumulation of the ions are simulated by resistors and capacitors, respectively. The annihilation of ions by recombination is simulated by a circuit composed of capacitors and resistors. The simulation results are in good agreement with the experimental results when the distance between the emitter of the air ionizer and the work area is varied. © 2019 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

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