1,862 research outputs found
A 0.25mm<sup>2</sup> Resistor-Based Temperature Sensor with an Inaccuracy of 0.12°C (3σ) from -55°C to 125°C and a Resolution FOM of 32fJK<sup>2</sup>
No full textTemperature sensors based on Wheatstone bridges, e.g. [1,2], have recently achieved higher resolution and greater energy efficiency than conventional BJT-based sensors [3]. However, this comes at the expense of area, making them less attractive in industrial applications. This paper presents a Wheatstone-bridge sensor that uses a zoom-ADC architecture to reduce area (by 3x over [2]) and achieve state-of-the-art energy-efficiency for an integrated temperature sensor. After a 1st-order fit and a systematic non-linearity correction [2,4], it also achieves state-of-the-art inaccuracy: 0.12°C (3σ) over the full military temperature range (-55°C to 125°C).Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic InstrumentationMicroelectronic
A CMOS Dual-RC frequency reference with ±250ppm inaccuracy from -45°C to 85°C
No full textTo comply with wired communication standards such as USB, SATA and PCI/PCI-E, systems-on-chip require frequency references with better than 300ppm accuracy. LC-based references achieve 100ppm accuracy [1], but suffer from high power consumption (∼20mW). Thermal diffusivity (TD) references require less power (∼2mW), at the expense of less accuracy (1000ppm) [2]. RC-based references offer the lowest power consumption, but their accuracy is typically limited to ∼0.1% [3]. In RC relaxation oscillators, comparator offset and delay are the major sources of inaccuracy [4,5]. References based on frequency-locked loops (FLLs) circumvent these by locking an oscillator's frequency to the time-constant of an RC filter, but their accuracy is then limited by the nonlinear temperature dependency of on-chip resistors [3,6].Session 3.3 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Instrumentation(OLD)Applied Quantum ArchitecturesMicroelectronic
A twenty-five-year-old eucalyptus tree in a eucalyptus grove at the L.J. Rose Ranch, ca.1900
No full textPhotograph of a twenty-five-year-old eucalyptus tree in a eucalyptus grove at the L.J. Rose Ranch, ca.1900. The barks on the trunk is pealing off to reveal the smooth surface underneath. The ground is littered with fallen leaves. Shrubs and grass cover the area in the background where other trees stand.; "Under the ownership of Leonard John Rose, the Sunny Slope Ranch live location was a showplace of orchards and vineyards, drawing as many as two to three hundred visitors a day. Rose learned how to grow grapes without irrigation, and the ranch became known for its brandy and fine wines." -- unknown author.; "The Old Grapevine holds a small segment of the original vine whose trellised branches once covered 10,000 square feet. It was a popular local gathering place where refreshments were served under the vine. Started as a cutting from the "Mother Vine" at the Mission, many local vineyards began from cuttings of this vine. L.J. Rose of Sunnyslope Ranch, just north and east of San Gabriel, started with such cuttings and grafted on many varieties of grapes new to this area. He later helped begin many a vineyard in Northern California. The San Gabriel Winery was among the worlds largest in the late 1800's, until a blight wiped out the vineyards and oranges became the main agricultural crop of the area. Today the park is once again a popular place for weddings, parties and social gatherings." -- unknown author
Failure and Delamination in Microelectronic Packages
No full textThin layers of dissimilar materials are used in most microelectronic components in order to achieve special functional requirements. Generally, the interface between two adjacent materials forms a weak link, not only because of the relatively low delamination strength, but also because of the existing mismatch in thermo-mechanical properties, such as Young’s modulus, coefficient of thermal expansion, hygro-swelling, and vapor pressure induced expansion. Residual stresses from the production processes and initial strains due to the changing thermal and humidity conditions together with acting mechanical loading form the crack driving factors for interface delamination. Failure of interface induces decreased reliability of microelectronic components. Nowadays, interfacial delamination forms one of the key reliability issues in the microelectronic industry and therefore is getting more and more attention. The analysis of a laminate structure with a crack along the interface is central to the characterization of the delamination toughness. The delamination toughness is highly dependent to temperature, moisture and mode mixity. In recent years, several studies were directed at the determination of the delamination behavior of Cu-EMC interfaces. In the event that moisture sensitivity was included in these studies, the temperature had to be limited to below 100oC. This limitation reduces the applicability of the toughness data obtained in a number of reliability studies of micro-electronic components. This is due to the fact that, in preconditioned (humid) micro-electronic components the interface delamination often occurs above this temperature limit. In many cases the damage is initiated during heating up in subsequent production steps, where temperatures can reach far above 100oC. Therefore the present research focuses on interface delamination measurements, especially interested in harsh environment (humidity combined with temperatures above the 100oC limit). In this thesis the thermal-mechanical properties of epoxy molding compounds in dry conditions are first investigated. The coefficient of thermal expansion and bulk modulus were measured via a dilatometer (PVT apparatus). DMA experiments in relaxation mode as well as in multi frequency mode were employed for obtaining the viscoelastic master curve and corresponding shift factors. Secondly, the thermo-mechanical properties of EMC during cure were studied. The volumetric contraction of the material during the curing period was measured via a PVT test. Furthermore the increasing shear modulus of the EMC because of the progressing cure was established through DMA experiments. For the dry state, the previous two-material characterization steps are sufficient to be able to interpret the measurement results of delamination tests via FEM simulation. For the humid state with T> 100 °C, in the delamination measurements the effect of (trapped) steam at the interface should be compensated by performing the measurements in a pressure chamber. Therefore, in a third step a pressure vessel surrounding the delamination test setup is designed and built. For the sake of simplicity the humid delamination measurements with T> 100 °C were only performed under full steam pressure (=relative humidity is 100%). The functionality of the setup has been verified by the measurement of the viscoelastic creep compliance of an EMC in dry state and to compare this with the result from measurements obtained from a commercially available measurement instrument. In order to be able to perform delamination measurements a mixed-mode bending setup is installed in the pressure vessel. Interfacial delamination measurements for a EMC-Cu lead frame interface (as obtained from a real production process) are subsequently performed for dry conditions as well as under pressurized steam conditions(= relative humidity 100%). A (I / II) mixed mode mechanical load is applied to the test sample, in which the initial stress state due to the manufacturing and the steam pressure (relative humidity 100%) is already present, in order to initiate and propagate the delamination. In conclusion: This dissertation shows that the temperature, the mix mode and the humidity under these conditions (T> 100 °C and 100% relative humidity) results in a significant effect on the delamination properties of interfaces. As far as known to the author, here for the first time a good insight on the impact of this harsh environment on the delamination properties is presented.Precision and Microsystems EngineeringMechanical, Maritime and Materials Engineerin
A 280μW dynamic-zoom ADC with 120dB DR and 118dB SNDR in 1kHz BW
No full textMicro-power ADCs with high linearity and dynamic range (DR) are required in several applications, such as smart sensors, biomedical imaging, and portable instrumentation. Since the signals of interest are then often small (tens of μν) and slow (<1kHz BW), such ADCs should also exhibit low offset and flicker noise. Noise-shaping SAR [1] and incremental ADCs [2] have been proposed for such applications, but their DR is limited to about 100dB. Although the ΔΣ modulator (ΔΣM) proposed in [3] achieves 136dB DR, it is at the expense of high power consumption (12.7mW). The incremental zoom ADC proposed in [4] combines a coarse SAR ADC and a fine ΔΣ ADC to efficiently achieve 119.8dB DR, but is limited to DC signals. The dynamic zoom ADC in [5] solves this problem, but requires external filtering to cope with out-of-band interference. This paper describes an interferer-robust dynamic zoom ADC that consumes 280μW while achieving 120.3dB DR and 118.1dB SNDR in 1kHz BW, resulting in a Schreier FoM of 185.8dB. It also achieves a maximum offset of 30μν and a 1/f corner of 7Hz. These advances are achieved by the combination of dynamic error-correction techniques, an asynchronous SAR ADC and a fully differential inverter-based ΔΣ ADC.Session 14.5 Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Instrumentation(OLD)Applied Quantum ArchitecturesMicroelectronic
L.J. Emory Publishing Co.: Expansion to U.S. Regional Midwest and The Netherlands
No full textNational bestselling author Serena B. Miller owns the rights to her published works in Amish fiction, historical romance, mystery and children’s works. The L.J. Emory publishing company partnered with a marketing class in an agency project to develop marketing research instruments. The company deployed the instruments, gathered the data and approached the SSU Marketing program in the School of Business for participation in a second agency project to use the data to build a strategic plan. BUMK 4000 Marketing Management students evaluated the data and presented a package and live proposal to the company owners suggesting new ways to expand in the U.S. Midwest and a pilot project to expand internationally, targeting The Netherlands. The proposal included sample social media posts, email drip campaign messages and related promotional materials in English and Dutch
Two men with their arms wrapped around a 25-years-old eucalyptus tree at the L.J. Rose Ranch, ca.1900
No full textPhotograph of two men with their arms wrapped around a 25-years-old eucalyptus tree at the L.J. Rose Ranch, ca.1900. The men, leaning against the tree and holding hands, have their free arm wrapped around the large tree. The barks on the trunk is pealing off and revealing the smooth surface underneath. The ground is littered with fallen leaves. Shrubs and trees are visible in the background.; "Under the ownership of Leonard John Rose, the Sunny Slope Ranch live location was a showplace of orchards and vineyards, drawing as many as two to three hundred visitors a day. Rose learned how to grow grapes without irrigation, and the ranch became known for its brandy and fine wines." -- unknown author.; "The Old Grapevine holds a small segment of the original vine whose trellised branches once covered 10,000 square feet. It was a popular local gathering place where refreshments were served under the vine. Started as a cutting from the "Mother Vine" at the Mission, many local vineyards began from cuttings of this vine. L.J. Rose of Sunnyslope Ranch, just north and east of San Gabriel, started with such cuttings and grafted on many varieties of grapes new to this area. He later helped begin many a vineyard in Northern California. The San Gabriel Winery was among the worlds largest in the late 1800's, until a blight wiped out the vineyards and oranges became the main agricultural crop of the area. Today the park is once again a popular place for weddings, parties and social gatherings." -- unknown author
Computational modelling of rubber-like materials under monotonic and cyclic loading
No full textThe simulation of rubber-like material behaviour by means of the finite element method has been described in this study. Proper material models for the numerical description of static hyper-elasticity, the ideal Mullins effect and the Mullins effect with permanent deformation were proposed, respectively. The second focus of this study was the verification of numerical constitutive models by means of experimental evidence. It was concluded that Gao's model with only two parameters describes the mechanical behaviour of rubber-like material adequately. The model parameters estimated from simple tension are valid for other loading conditions (compression and shear) if the specimens are made of the same material. This property is crucial for the general use of Gao's elastic model. The present work demonstrated that both the continuum damage mechanics model and the pseudo-elastic model combined with Gao's elastic model are capable of simulating the Mullins effect in their own characteristic way. The pseudo-elastic model significantly simplifies the identification of model parameters. Finally, combination of the pseudo-elastic concept and Gao's model was used to construct a specific model for the description of Mullins effect with permanent deformation. The evolution of stress softening, the permanent deformation and all turning points in the numerical simulations were reproduced well compared to experimental data.Civil Engineering and Geoscience
Surface Modification of Titanium and Polyimide Sheet for Adhesive Bonding
No full textMajor industrial sectors like automotive, aerospace and others are increasingly using polymer composites in their structural parts. Polyimide sheet and adhesives, are high performance polymers. They are widely used in various engineering applications due to their excellent thermal, mechanical and chemical properties and their resistance to radiation and fire. Unfortunately, the surface of polyimide like any other polymer is inert and exhibits poor adhesion properties. It is established that for successful application of polymeric composite materials to form structural parts using adhesive bonding, they need to have special surface properties like hydrophilicity. The surface modification of polymers and metals play a predominant role in enhancing the surface energy for improved adhesion properties. The aerospace industry is giving special attention to surface modification of titanium which could enhance the adhesive bond durability. In general, surface modification of titanium is carried out by chromic acid anodization. In this thesis work, an alternative surface preparation technique of titanium is investigated which could be of the interest for future research. We propose to modify the surface of titanium by plasma ion implantation, This is clean and solvent free technique, which could possibly be of interest to the aerospace industry in terms of adhesive bond strength and durability. It is also noted that in search of the long term durability and efficient service performance in the context of the future generation of aerospace structures, there is an increasing need of metal-polymer composites. Therefore, work of particular relevance to this project has been on the improvement of high performance polymer-titanium composites through high performance adhesive bonding. Several methods may be employed for modifying the surfaces of polymers and metals, which range from wet chemical processes to dry physical processes. Dry processes, like electrical treatment by exposure to plasma have received special attention because of the uniformity of these surface modifications, its precise control and the absence of chemical hazards. It is now well known that the plasma treatment creates physical and chemical changes such as cross linking, degradation, formation of free radicals, oxygen ions functionalisation and etching. A high temperature resistant and thermally stable polyimide adhesive as supplied by Creative materials Inc. was selected. TGA, DSC and FTIR analyses of this high performance polyimide adhesive were performed. After analysis, the polyimide adhesive is used as the standard adhesive for joining and testing materials in this project. There are mainly two types of surface treatments i.e. mechanical treatment and atmospheric pressure plasma treatment, that are combined in the present research. The grit blasting and atmospheric pressure plasma treatment time is optimized to get optimum values of surface roughness and surface energy. When these surfaces with optimum values of surface roughness and surface energy are joined together using the PI adhesive, a remarkable increase in the value of the adhesive bond strength during lap-shear testing is obtained. The bond strength is increased by two and half times compared to the lap-shear test results of untreated surfaces. The characterization of untreated and treated titanium surfaces with XPS, SEM, a surface roughness profiler and a contact angle analyser is performed. The Lap-shear test results suggest that the bond strength increases with an increase in surface energy. The surface roughness profiler results show that the surface energy increases with an increase in surface roughness. FTIR results suggest that the surface energy increases with a decrease in carbon contents and an increase in oxygen contents in the top layers of the titanium surface. The characterisation of the polymer surface after exposure to plasma reveals that the polar component of the surface energy increases due to chain scission and oxidation, leading to generation of polar groups such as C-O, C=O & COO on the polymer surface. Therefore, the total surface energy also increases, leading to enhanced adhesion. AFM analysis of polyimide sheet indicates that there is an increase in surface energy with an increase in surface roughness. In the last part of this research work, the effects of the moisture and high temperature on the adhesive bond strength of the modified surfaces is investigated. At high temperature and relative humidity conditions, moisture ingression in the adhesive bond line takes place at a faster pace than at room temperature. The modified surface adhesive bonds retain their bond strength at high temperature, while heated in dry environment. In case of moisture pre–condition at elevated temperature before lap-shear testing, the bond loses the improved bond strength, possibly due to the attack of polar water molecules on the interface bonds of titanium and polyimide adhesive. The present work aims to contribute to the knowledge and understanding of several aspects of the surface treatment of metals and polymers for adhesive bonding in high temperature applications. Different problems related to the surface treatment and adhesive bonding for high temperature application has been discussed. Efforts are made to evaluate the performance of the adhesive bonds between modified titanium and polyimide at elevated moisture and temperature conditions. The present work has produced some encouraging results to perform further research on surface treatment methods for coating and high temperature adhesive material for different aerospace applications.Precision and Microsystems EngineeringMechanical, Maritime and Materials Engineerin
A finite element approach to nonlinear thin shell analysis
No full textMechanical Maritime and Materials Engineerin
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