Foam Density Measurement: Capacitance Sensors vs. Nuclear Gauges
This application note from MTI Instruments compares two technologies for measuring foam density: capacitance sensors and nuclear gauges. It examines the basic operating principles of each technology and explains why capacitance measurement is recommended for in-line measurement during foam manufacturing. Capacitance Sensors Capacitive probes are non-contact devices that use electric fields to measure foam density. In combination with a thickness value, a density measurement may be calculated. These probes consist of a capacitance sensor inside of a protective housing and are part of a larger measurement system that includes amplifiers, cables, and software. With parallel plate capacitance, the capacitance probe [...]
TESTING CHARGE AMPLIFIER GAIN AND FREQUENCY RESPONSE WITH A SIGNAL GENERATOR
[Application Note 40518] Piezoelectric transducers produce small electrical charges in response to pressure. Their sensitivity, ruggedness, and stability at high temperatures make them an essential building block of many accelerometers and pressure sensors. Applications include turbine vibration measurement (accelerometers) and combustion dynamics monitoring (pressure sensors). Typically, the high-impedance charge output produced by a piezoelectric transducer must be conditioned and amplified before transmission across system cabling to the data acquisition and measurement instrumentation. This conversion is accomplished with a device called a charge amplifier. Problem Over time, a charge amplifier’s signal response can drift. Damage to the charge amplifier or associated [...]
THICKNESS INFORMATION OF COMPOSITE MATERIALS
Composite materials consist of two or more materials which include a substrate or base material such as paper, cotton cloth, or glass cloth along with a resin or adhesive such as epoxy, melamine, or silicone. To make a thermoset laminate, the base material is coated with the adhesive so that layers of material can be pressed under heat and pressure into sheet form. The Problem: Composite material thickness needed to be verified prior to forming or machining. Due to the size of the sheets typical measurement techniques were not suitable. A consistent method to accurately measure the board thickness [...]
Capacitance Sensing vs. Strain Gauge Sensing Application Note
Capacitance Sensing vs. Strain Gauge Sensing Application Note Capacitance probes that are embedded in piezo flexure stages can provide significantly greater accuracy than strain gauges. Although some minor mounting modifications are required, capacitance probes with picoscale positioning provide higher linearity, greater long-term stability, and better direct measurement. Capacitance sensors cost more, however, and are limited by sensing distance. Therefore, strain gauge sensors remain a good choice for applications where cost is a consideration, sensing distances are larger, and high resolution or high accuracy are required. In a recent application note, MTI Instruments examines the differences between capacitance probes and [...]
TIRE TREAD INSPECTION WITH 1D LASER SENSOR
Tire manufacturers wants to satisfy their customers, and protect themselves from liabilities, manufacturers are moving to 100% tire inspection for defects and abnormalities. Defects not only cause potential safety issues but they can also introduce unwanted vibration into the vehicle suspension system. Belts can be overlapped, or not cover the complete tire surface, causing weak or bubbled areas and imbalances. The tread depth can be too shallow, leading to decreased service life. An uneven tire can cause excessive runout and vibration. MTI was approached by a major manufacturer requesting a solution to measure tread depth, runout and blistering. They [...]
Using Capacitance Sensors for Non-Conductive Material Measurement GalleryUsing Capacitance Sensors for Non-Conductive Material Measurement
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Using Capacitance Sensors for Non-Conductive Material Measurement
Non-Conductive Material Measurement with Capacitance Sensors Capacitance sensors are non-contact devices that can be used to obtain position, thickness, and dynamic measurements with a high degree of precision, accuracy, and resolution. Capacitive measurement is used with electrically-conductive materials such as metals but can also be used to measure non-conductive materials such as glass, sapphire, and many plastics. Even if a non-conductive material is relatively inexpensive (such as closed cell foam), manufacturers want to avoid errors that can result in significant waste across high volumes. Importantly, capacitance measurement is also used with semi-insulating materials such as gallium arsenide (GaAs) and [...]
Semiconductor Wafer Lapping and Displacement Measurement
Semiconductor Wafer Lapping and Displacement Measurement Semiconductor Semiconductor Wafer Manufacturing Displacement Description Semiconductor Wafer Lapping and Displacement Measurement This application note explains how MTI’s Accumeasure technology was used with a lapping machine to measure displacement (wafer material removal) and determine the new semiconductor wafer thickness. Changes in electrical capacitance (displacement) were measured and then directly converted into a 24-bit digital reading to obtain precise digital thickness measurements. During lapping, a wafer of known start thickness is placed on a rotary lapping table. The backside of the wafer faces downward and toward [...]
Torque Converter
Industry Automotive Applications Torque Converter Measurement Type Surface Description Since minute defects in the torque converter casing wall thickness can result in unacceptable and dangerous torque converter expansion, a precision measurement system was needed to measure the impeller hub displacement and thus the torque converter axial displacement. An AC dynamometer would be required to spin the torque converter at a high rate of speed while a fast response hydraulic system is needed to pressurize the converter to pressures up to 150 psi. MTI’s MicroTrak laser sensor was selected because it offered [...]
Why Demand for SiC Wafers is Soaring and Durable GalleryWhy Demand for SiC Wafers is Soaring and Durable
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Why Demand for SiC Wafers is Soaring and Durable
Silicon carbide (SiC) wafers are in high demand, particularly in high-temperature applications. Silicon carbide (SiC), a semiconductor material made of both silicon and carbon, can withstand extreme temperatures of up to 2700°C. Often referred to as carborundum, SiC’s unique properties also make it a key material in non-electronic applications such as bulletproof vests, extrusion dies, sandpaper, and high-performance disc brakes. In the electronics industry, SiC wafers are crucial for devices operating under high temperatures, high voltages, or both. For example, they are used in electric vehicle (EV) power electronics, 5G communication systems, and LED technology, making SiC a material [...]
Wafer Stress Analysis Using the 300iSA
Wafer Stress Analysis Using MTI Instruments Proforma 300iSA Wafer processing involves several stages that can lead to mechanical changes in the wafer structure. These changes, or stresses, may result in deformities, making the wafer either unusable or only marginally usable. To evaluate these stresses and determine the wafer's quality, wafer stress measurement is essential. The Proforma 300iSA wafer characterization tool offers a powerful solution for wafer stress analysis. It allows for the analysis of a wafer both before and after processing. By comparing these two states, the Proforma 300iSA effectively evaluates the wafer's stress levels and mechanical alterations, providing [...]