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White Paper: Test & Measurement

Why Capacitance? Benefits and Applications of Digital Capacitive Solutions

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This white paper explores the advantages of modern digital capacitive sensing technology for high-precision, non-contact measurement applications. It explains how capacitance sensors provide exceptional resolution, stability, and accuracy without mechanical loading or wear, even in extreme environments. The paper highlights the benefits of digital capacitance systems, including 24-bit resolution, superior linearity, minimal drift, extended measurement range, and network connectivity. Real-world applications are presented across industries such as semiconductor manufacturing, renewable energy, automotive testing, solar technology, and industrial processing. The paper demonstrates how digital capacitive solutions rival or outperform more complex measurement technologies at a lower overall cost.

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Design Test & Measurement

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Overview

This document by MTI Instruments showcases the advantages and diverse industrial applications of their digital capacitive sensing technology, particularly the Accumeasure™ D Series amplifiers paired with capacitive probes. Digital capacitive sensors measure the electrical capacitance formed between a probe and a target surface, which varies with the gap distance. These non-contact sensors excel in harsh environments—withstanding temperatures from cryogenic to 1200°F, strong magnetic fields, vacuum, and corrosive conditions—while providing sub-micron accuracy, stability, and long-term reliability without drift or mechanical wear.

Key features of MTI’s digital capacitance technology include 24-bit resolution surpassing conventional 16-bit ADCs, digitally selectable filters to minimize noise and drift, digital linearity correction achieving 0.01% full scale error, and digital range extension enabling measurements over larger distances. Importantly, the amplifiers support Ethernet and USB outputs, facilitating integration into Internet of Things (IoT) systems and networked sensor arrays for remote, real-time monitoring.

The document presents multiple specific applications across industries:

  1. Semiconductor Manufacturing: High-precision 3D integrated circuit construction requires sub-micron coplanarity control between stacked wafers. MTI’s capacitive probes and amplifiers provide real-time gap and angle measurement with closed-loop actuator control, improving bonding accuracy and device yield.

  2. Power Generation: Wind turbine gap monitoring uses rugged, thin, non-magnetic capacitive displacement probes with specially shielded cables and digital amplifiers to continuously measure and optimize generator gaps, improving efficiency and preventing catastrophic failures.

  3. Solar Technology: Non-contact push-pull probes allow thickness and warp measurement of ungrounded fragile photovoltaic wafers. The push-pull design cancels noise caused by poor electrical grounding, enabling high-speed, sub-micron accuracy metrology on moving wafers.

  4. Automotive Technology: For brake rotor testing, capacitive sensors measure rotor thickness, runout, and deformation at high temperatures (up to 1200°F). Digital amplifiers provide multi-channel precision measurement and eliminate errors common in analog systems.

  5. Industrial Processing: Oil contamination monitoring benefits from flat flexible capacitance probes bonded to non-conductive tubes to detect minute amounts of water in lubricating oil via dielectric constant changes. Continuous real-time monitoring helps shift maintenance to a proactive model, reducing costs.

Overall, MTI’s digital capacitive sensing systems deliver high accuracy, robustness, and digital integration across a wide range of precision measurement challenges, combining cost effectiveness with cutting-edge performance for advanced industrial applications.