Microfabrication and Characterization of Metal-Embedded Thin-Film Thermomechanical Microsensors for Applications in Hostile Manufacturing Environments

Choi, Hongseok; Datta, Aniruddha; Cheng, Xiaomin; Li, Xiaochun

doi:10.1109/jmems.2006.872235

Cited by 28 publications

(10 citation statements)

References 14 publications

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“…Recently, thermomechanical phenomena were studied by the use of embedded thin-film sensors for various manufacturing processes [18][19][20][21][22][23][24]. Two types of thin-film microsensors, K-type TFTC, and K-type thermocouple based TETP, were designed and fabricated for in-situ temperature measurement of ultrasonic welding process to better understand the process [18,22].…”

Section: Introductionmentioning

confidence: 99%

Transient Temperature and Heat Flux Measurement in Ultrasonic Joining of Battery Tabs Using Thin-Film Microsensors

Li¹,

Choi²,

Ma³

et al. 2013

Journal of Manufacturing Science and Engineering

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Process physics understanding, real time monitoring, and control of various manufacturing processes, such as battery manufacturing, are crucial for product quality assurance. While ultrasonic welding has been used for joining batteries in electric vehicles (EVs), the welding physics, and process attributes, such as the heat generation and heat flow during the joining process, is still not well understood leading to time-consuming trial-and-error based process optimization. This study is to investigate thermal phenomena (i.e., transient temperature and heat flux) by using micro thin-film thermocouples (TETC) and thin-film thermopile (TETP) arrays (referred to as microsensors in this paper) at the very vicinity of the ultrasonic welding spot during joining of three-layered battery tabs and Cu buss bars (i.e., battery interconnect) as in General Motors's (GM) Chevy Volt. Microsensors were first fabricated on the buss bars. A series of experiments were then conducted to investigate the dynamic heat generation during the welding process. Experimental results showed that TETCs enabled the sensing of transient temperatures with much higher spatial and temporal resolutions than conventional thermocouples. It was further found that the TETPs were more sensitive to the transient heat generation process during welding than TETCs. More significantly, the heat flux change rate was found to be able to provide better insight for the process. It provided evidence indicating that the ultrasonic welding process involves three distinct stages, i.e., friction heating, plastic work, and diffusion bonding stages. The heat flux change rate thus has significant potential to identify the insitu welding quality, in the context of welding process monitoring, and control of ultrasonic welding process. The weld samples were examined using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS) to study the material interactions at the bonding interface as a function of weld time and have successfully validated the proposed three-stage welding theory.

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Section: Introductionmentioning

confidence: 99%

Transient Temperature and Heat Flux Measurement in Ultrasonic Joining of Battery Tabs Using Thin-Film Microsensors

Li¹,

Choi²,

Ma³

et al. 2013

Journal of Manufacturing Science and Engineering

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“…This design, therefore, decreases the sensitivity and response time of the TC. Thin-film TCs on the other hand, promises a fast response rate and high accuracies as a consequence of the absence of airgaps in the thermocouple materials, but they are very challenging to fabricate [15,16]. With all these challenges, further research is needed to develop special TCs of improved performances and longevity to meet the ever-growing demands of industries.…”

Section: Introductionmentioning

confidence: 99%

Performance Characteristics of Custom Thermocouples for Specialized Applications

2021

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This work reports the performance characteristics of custom thermocouples developed for use in elevated temperatures such as metal casting operations. The scope of this research is limited to thermocouples designed using pyrolytic graphite (PG) as the primary thermoelement in connection with aluminum, copper, steel, and tungsten. The Seebeck coefficients of the sensors were determined from experimental data after heating to ~500 °C. Cooling from ~500 °C to room temperature enabled us to compare the characteristic behaviors of the sensors from the obtained near-linear responses in the voltage-temperature plots. Tungsten being a refractory metal produced the highest sensitivity of the sensors. The sensitivity of the PG-tungsten thermocouple upon heating measured up to 26 μV/°C and a slightly lower value of 24.2 μV/°C was obtained upon cooling. Conversely, the PG-steel thermocouple rather produced the lowest Seebeck coefficients of 13.8 μV/°C during heating and 14.0 μV/°C for the cooling experiments though steel has a high melting temperature than most of the other thermoelements.

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“…Aluminum has a CTE of about 21 × 10 −6 K −1 , whereas silicon-based sensors have a CTE of 2.6 × 10 −6 K −1 . This inconsistency between the two materials results in high failure rates caused by thermally induced mechanical stress during the cooling of the cast component [ 2 , 3 , 4 ].…”

Section: Introductionmentioning

confidence: 99%

A Combined Thin Film/Thick Film Approach to Realize an Aluminum-Based Strain Gauge Sensor for Integration in Aluminum Castings

Tiedemann

Lepke

Fischer

et al. 2020

Sensors

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There is currently a large demand for aluminum components to measure the mechanical and thermal loads to which they are subjected. With structural health monitoring, components in planes, vehicles, or bridges can monitor critical loads and potentially prevent an impending fatigue failure. Externally attached sensors need a structural model to obtain knowledge of the mechanical load at the point of interest, whereas embedded sensors can be used for direct measurement at the point of interest. To produce an embedded sensor, which is automatically encapsulated against environmental influence, the sensor must be able to withstand the boundary conditions of the host component’s manufacturing process. This embedding process is particularly demanding in the case of casting. Previous work showed that silicon-based sensors have a high failure rate when embedded in cast aluminum parts and that using aluminum as a substrate is preferable under these circumstances. In the present paper, we present the fabrication process for the combination of a thick-film insulation and a thin-film strain gauge sensor, on such an aluminum substrate. The sensor is capable of withstanding high temperatures of at least 600 °C for over 20 min and a subsequent embedding in a gravity die casting process.

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Microfabrication and Characterization of Metal-Embedded Thin-Film Thermomechanical Microsensors for Applications in Hostile Manufacturing Environments

Cited by 28 publications

References 14 publications

Transient Temperature and Heat Flux Measurement in Ultrasonic Joining of Battery Tabs Using Thin-Film Microsensors

Transient Temperature and Heat Flux Measurement in Ultrasonic Joining of Battery Tabs Using Thin-Film Microsensors

Performance Characteristics of Custom Thermocouples for Specialized Applications

A Combined Thin Film/Thick Film Approach to Realize an Aluminum-Based Strain Gauge Sensor for Integration in Aluminum Castings

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