Glass-frit bonding of silicon strain gages on large thermal-expansion-mismatched metallic substrates

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Half-bridge silicon strain gauges are widely used in the fabrication of diaphragm-type high-pressure sensors, but in some applications, they suffer from low output sensitivity because of mounting position constraints. Through a special design and fabrication approach, a new half-bridge silicon strain gauge comprising one arc gauge responding to tangential strain and another linear gauge measuring radial strain was developed using Silicon-on-Glass (SiOG) substrate technology. The tangential gauge consists of grid patterns, such as the reciprocating arc of silicon piezoresistors on a thin glass substrate. When two half-bridges are connected to form a full bridge with arc-shaped gauges that respond to tangential strain, they have the advantage of providing much higher output sensitivity than a conventional half-bridge. Pressure sensors tested under pressure ranging from 0 to 50 bar at five different temperatures indicate a linear output with a typical sensitivity of approximately 16 mV/V/bar, a maximum zero shift of 0.05% FS, and a span shift of 0.03% FS. The higher output level of pressure sensing gauges will provide greater signal strength, thus maintaining a better signal-to-noise ratio than conventional pressure sensors. The offset and span shift curves are quite linear across the operating temperature range, giving the end user the advantage of using very simple algorithms for temperature compensation of offset and span shift.

Section: Discussionmentioning

confidence: 99%

Section: Gauge Chips and Diaphragm Assemblymentioning

confidence: 99%

Half-Bridge Silicon Strain Gauges with Arc-Shaped Piezoresistors

Han,

Min,

Lee

et al. 2023

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“…One arc-shaped gauge chip and two linear gauge chips were attached to the steel diaphragm using a glass frit to evaluate their properties and the feasibility of using these sensing elements to measure high pressure. Although several organic epoxies could also have been used instead of glass frit to attach the silicone gauge to the metal diaphragm, they negatively affected the mechanical and electrical properties of the sensor, such as creep, hysteresis, nonlinearity, reproducibility, long-term reliability, and operating temperature range [ 25 , 26 ]. The glass frit bonding process consisted of three steps: glass frit screen printing, initial dry, and first and second firing.…”

Section: Strain Gauge Fabrication and Bondingmentioning

confidence: 99%

Reciprocating Arc Silicon Strain Gauges

Han

Min²,

Kim

et al. 2023

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Currently, silicon-strain-gauge-based diaphragm pressure sensors use four single-gauge chips for high-output sensitivity. However, the four-single-gauge configuration increases the number of glass frit bonds and the number of aluminum wire bonds, reducing the long-term stability, reliability, and yield of the diaphragm pressure sensor. In this study, a new design of general-purpose silicon strain gauges was developed to improve the sensor output voltage while reducing the number of bonds. The new gauges consist grid patterns with a reciprocating arc of silicon piezoresistors on a thin glass backing. The gauges make handling easier in the bonding process due to the use of thin glass for the gauge backing. The pressure sensors were tested under pressure ranging from 0 to 50 bar at five different temperatures, with a linear output with a typical sensitivity of approximately 16 mV/V/bar and an offset shift of –6 mV to 2 mV. The new approach also opens the possibility to extend arc strain gauges to half-bridge and full-bridge configurations to further reduce the number of glass frit and Al wire bonds in the diaphragm pressure sensor.

“…In order to evaluate the electrical performance of the Si strain gauge, two-gauge chips were bonded using glass frit [26,27] along the radial direction of a circular metal diaphragm, as shown in Figure 5b. After bonding, the sensing elements (Figure 5b) were subjected to the following temperature cycle: thermal aging → pressure aging → calibration.…”

Section: Glass Frit Bonding and Assemblymentioning

confidence: 99%

Enhancement of Withstand Voltage in Silicon Strain Gauges Using a Thin Alkali-Free Glass

Kim

Han

Park

et al. 2020

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We present a cost-effective approach to produce silicon strain gauges that can withstand very high voltage without using any complex package design and without sacrificing any sensor performance. This is achieved by a special silicon strain gauge structure created on an alkali-free glass substrate that has a high breakdown voltage. A half-bridge silicon strain gauge is designed, fabricated, and then tested to measure its output characteristics. The device has a glass layer that is only 25–55 µm thick; it shows it is able to withstand a voltage of over 2000 V while maintaining a high degree of linearity with correlation coefficients higher than 0.9990 and an average sensitivity of 104.13. Due to their unique electrical properties, silicon strain gauges-on-glass chips hold much promise for use in advanced force and pressure sensors.