An ultra-high-impedance voltmeter performs contact measurements with virtually no charge transfer to or from the ESD-sensitive item.
Electrostatic discharge (ESD) has the potential to destroy a device. And yet, most products intended to measure site-specific voltage on ESD-sensitive devices actually transfer charge upon contact. Though the ESD riddle has continually gnawed at the industry, one company claims to have the answer
Trek Inc. (Medina, NY) has introduced an ultra-high-impedance voltmeter designed to perform contact measurements with virtually no charge transfer to or from the measured ESD-sensitive item. The Model 800 Infinitron features a high input impedance of more than 1016 Ω and low input capacitance measuring less than 10–15 F. ESD transfer is averted because the ultrahigh resistance offers infinite impedance loading.
The company cites the need for contact ESD measuring in real time as one of the motivations behind constructing the voltmeter. With a response time of less than 3.5 millisecond for a 100-V step change, the product is equipped to operate in real-time situations. The firm also notes that accurate and site-specific measurements may help determine causes and effects of ESD issues, leading to improved and more resilient products.
“Using the Infinitron, our ability to accurately measure voltage at a surface, by contact, without affecting the charge of the surface, and without causing an ESD event, has generated true excitement in the electrostatic community,” says Bruce Williams, chief designer of the product.
The voltmeter features a handheld contact probe configured to measure voltage on the ESD-sensitive object. Probe tips are available in round, flat, and pointed shapes, while tip sizes range from 1.27 to 0.76 mm. Measurement capabilities range from 0 to ±100 V dc, or peak ac at ±0.1% accuracy.
Additional features of the voltmeter include an LCD screen with LED back light that shows readings along with time and date, a zero button that provides zeroing of the input, and a hold mode that retains LCD information.