Reliability analysis of smartwatch
01 Aug 2017-pp 1011-1015
TL;DR: In this paper, the effect of temperature and humidity on the electronic circuit of a smartwatch has been analyzed using a real case, and it was found that 125°C has been a critical temperature for the smartwatch, above which the sealed plastic case ruptured easily.
Abstract: The reliability of electronics products has become a serious problem due to the increasingly harsh environmental conditions when the products are in use. Due to demand on greater performance and higher integration in microelectronic devices, the electronics industry has been seeking suitable components, packaging and cooling techniques to achieve low-cost and high-reliability. This paper presents the experimental verifications to analyze the effect of temperature and humidity on the electronic circuit as well as evaluating the device reliability, using Xiaomi Band 2 as a real case. It is found that 125°C has been a critical temperature for the smart watch, above which the sealed plastic case ruptured easily. However, 150°C has been found to be the temperature to burst the battery. Cold storage test with a temperature of − 70°C shows that low-temperature will only cause the smartwatch to hibernate, even for up to 400 hours, after which the device will be restored to work under a room temperature. Humidity has been found to be a crucial factor in damaging the device, which changes the rubber ring and plastic case into brittle and corrodes the interconnects on printed circuit board. Further investigation into the microstructure evolution of interconnects has found that the highly accelerated stress test has caused serious cracks in solder joints and electronic components, such as, resistors and capacitors. In short, the smartwatch can work under harsher environment than the designated environmental conditions in the product manual.
Citations
More filters
TL;DR: The review shows that the demand rate of SWs in India is less as compared to other countries, but the overall rate of demand is not as expected.
20 citations
TL;DR: The approach followed in this study consists of a mathematical model based on the centre of mass of the human body, the inertia of a person in motion and the human gait speed that emulates the presence of a people inside the building when an emergency takes place.
Abstract: This article presents a comprehensive study of human physiology to determine the impact of body mass index (BMI) on human gait. The approach followed in this study consists of a mathematical model based on the centre of mass of the human body, the inertia of a person in motion and the human gait speed. Moreover, the study includes the representation of a building using graph theory and emulates the presence of a person inside the building when an emergency takes place. The optimal evacuation route is obtained using the breadth-first search (BFS) algorithm, and the evacuation time prediction is calculated using a Gaussian process model. Then, the risk of the building is quantified by using a non-sequential Monte Carlo simulation. The results open up a new horizon for developing a more realistic model for the assessment of civil safety.
6 citations
Cites background from "Reliability analysis of smartwatch"
...For instance, some Xiaomi products (My Band 2, 3 and My Body Composition Scale) [11] allow customers to keep track of daily activities and, through a mobile application, consult several health indicators such as BMI, body fat, bone mass and muscle mass in a reliable and safe way....
[...]
01 Aug 2019
TL;DR: The root causes of this failure have been determined, the failure mechanisms have been discussed and the pertinent countermeasures have also been proposed.
Abstract: In this paper, a failure case of the smartphones with an internationally renowned brand has been reported. In detail, after this batch of smartphones have been launched to the market, they encounter with the problems of scrambling display or no display frequently, and therefore have to be recalled and cause economic losses as high as nearly 4 million dollars. Through the preliminary analysis, the printed circuit board assembly (PCBA) has been determined as the faulty component. But what is the root cause and which process has the causes occur in should be further clarified, i.e., in the manufacturing of the printed circuit board (PCB) or in the assembling of PCBA? In this context, comprehensive failure analysis has been performed on the PCBA and PCB of the failed smartphones. Based on the results, the root causes of this failure have been determined, the failure mechanisms have been discussed and the pertinent countermeasures have also been proposed.
3 citations
Cites methods from "Reliability analysis of smartwatch"
...So far, the failure analysis of PCB and PCBA was mainly focused on in design, drilling, plated through hole (PTH), electroless nickel/immersion gold (ENIG)[9], soldering mask [7], reflow soldering [1, 8], finite element analysis [2, 3, 6] and other processes [10]....
[...]
TL;DR: In this article, a failure analysis of printed circuit board (PCB) for smartphones with abnormal display problems like scramble display or no display during service and had to be recalled is presented.
Abstract: The submitted paper is mainly concerned with the cracking of blind and buried vias of printed circuit board (PCB) for smartphones which were encountered with abnormal display problems like scramble display or no display during service and had to be recalled.,To found out the root causes of this failure and dissolve this commercial dispute, comprehensive failure analysis was performed on the printed circuit board assemblies (PCBAs) and PCBs of the failed smartphone, such as macrograph and micrograph observation, chemical compositions analysis, thermal performance testing and blind via pull-off experiment, which finally helped to determine the causes. Besides that, the failure mechanisms were discussed in detail, and pertinent countermeasures were proposed point by point.,It was found that the PCB blind vias cracking was the main reason for the scramble display or no display of the smartphone, and the incomplete cleaning process before copper plating was the root cause of the blind vias cracking.,Achievement of this paper would not only help to provide the solid evidence for determining the responsibility of this commercial dispute but also lead to a better understanding of the failure mechanisms and prevention methods for similar failure cases of other advanced mobile phones.,Most failure analysis researches of PCBAs only focused on the unqualified products from manufacturing, while this paper addressed a failure analysis case of PCBAs products for smartphones from actual services, which was relatively rarely reported in the past.
2 citations
18 Jun 2019
TL;DR: In this article, a 125 kHz wireless energy and 25 kbps data transfer system for a wearable device is presented, where the wireless transfer link is through a coupled transformer, and the mismatch between measured and simulated coupling value is within 3 %.
Abstract: This paper presents a 125 kHz wireless energy and 25 kbps data transfer system for a wearable device. In this system, the wireless transfer link is through a coupled transformer. The model of a coupled transformer is discussed, and the mismatch between measured and simulated coupling value is within 3 %. For a wearable scenario, the coupled transformer is designed to fit the bending degree of the wrist. The designed transformer achieves a best coupling factor of 0.42 with ±15mm displacement tolerance. The wireless data link can support 25 kbps data transfer in ASK modulation, and the system wireless power transfer link achieves a 40% efficiency in the optimized position, which fits the application requirement.
References
More filters
01 Nov 2016
TL;DR: In this article, a qualitative and quantitative analysis is performed using surrogate reliability data in order to compare the different electrical power take off mechanisms employed, in particular hydraulic, direct drive and turbine based generation systems.
Abstract: Using generic defined wave energy converters, sub-system block diagrams and reliability diagrams are developed. Devices have common aspects such as moorings or seabed fixings, but the method of electrical power conversion can differ depending upon the device. Reliability analysis is applied to the different electrical power take off mechanisms employed, in particular hydraulic, direct drive and turbine based generation systems. Both a qualitative and quantitative analysis is performed using surrogate reliability data in order to compare the different systems. Critical components are identified and the failure modes analysed in order to provide guidance to improve component design.
19 citations
01 Nov 2016
TL;DR: In this article, the authors investigated the TSV leakage current in metal-insulator-semiconductors and studied MOSFET device characteristics to manage manufacturing quality based on stress propagation of Cu-TSVs by thermal loading in the operating temperature range (−50 to 80 °C) and relatively high process temperature range (250 to 400 °C).
Abstract: For 3D-LSI devices using the through silicon via (TSV) process, there are many reliability issues regarding the large thermal-mechanical stress and deformation volume changes caused by mismatch of the thermal expansion coefficients (CTEs) between the Cu and Si substrate in the device active area. In this paper, we investigated the TSV leakage current in metal-insulator-semiconductors and studies MOSFET device characteristics to manage manufacturing quality based on stress propagation of Cu-TSVs by thermal loading in the operating temperature range (−50 to 80 °C) and relatively high process temperature range (250 to 400 °C). The stress induced leakage current and MOSFET mobility change showed a relationship between expansion and contraction deformation of Cu under the thermal loading conditions. These results show that Cu/Si interface formation quality is high although there is major TSV metallization. Furthermore, it was found that precise estimation is important to designing the keep out zone (KOZ) in consideration of the real operating temperature.
5 citations
"Reliability analysis of smartwatch" refers background in this paper
...Thus, it is more vulnerable for electronic products to damage since they encounter more severe electromigration reliability challenge and other problems, for example, copper and silicon will experience deformation volume change and thermal-mechanical stress under thermal effect [6]....
[...]
07 Aug 2002
TL;DR: In this paper, the authors examined the effects of thermoshock testing, high temperature aging and humidity aging on the contact resistance and the adhesion of new CSMAs on OSP copper, Sn/Pb alloys and even 100 percent tin.
Abstract: Conductive Surface Mount Adhesives (CSMAs) are an alternative to traditional solders used in the electronics industry. CSMAs provide an environmentally friendly alternative to conventional Sn/Pb metal solders offering additional attractive technical advantages including low temperature processing, fine pitch capability and better resistance to thermal cycling. The two major limitations of CSMAs have been their instability on common electronic metals such as copper and Sn/Pb solder and their performance under impact testing. Recent experimental work published by National Starch Corporate Research in collaboration with Georgia Institute of Technology has shown that the unstable contact resistance of CSMAs on copper and solder is due to electrochemical corrosion of these metals under adverse conditions. Based on the above fundamental understandings, Emerson & Cuming have been developing some new and unique formulas which exhibit exceptional contact resistance stability on previously unstable metal surfaces including OSP copper, Sn/Pb alloys and even 100 percent tin. Much progress has also been made in the area of mechanical performance. Recent advances in contact resistance stability have been incorporated along with the advances in impact performance to create novel materials. This paper examines the effects of thermoshock testing, high temperature aging and humidity aging on the contact resistance and the adhesion of these new formulas.
4 citations
TL;DR: In this article, the reliability of printed-circuit-card assemblies was evaluated using thermal shock, humidity, and power-temperature cycling, and a model was developed for interpreting a long term, high temperature life-test.
Abstract: This article describes the work done in evaluating the reliability of a printed-circuit-card assembly. Some assemblies went through thermal shock, humidity, and power-temperature cycling. A model was developed for interpreting a long term, high temperature life-test. Two iterations of the life test took place as part of the evaluation. A short term, intermediate temperature life-test of a relatively large number of assemblies preceded release to manufacturing.
4 citations
"Reliability analysis of smartwatch" refers background in this paper
...The build and test methodology is expected to generate confidence in reliability to satisfy the provided conditions [4]....
[...]
01 May 2016
TL;DR: In this paper, the authors provide a new modeling approach for the simulation of thermo-electro-mechanical stress effects within PCBs (printed circuit boards) and electronic packages, which can be used to correctly predict deflection (warpage), mean time to failure, and defects per million for boards with packages that have been surface mounted using a solder reflow process.
Abstract: The authors provide a new modeling approach for the simulation of thermo-electro-mechanical stress effects within PCBs (printed circuit boards) and electronic packages. Difficult design challenges created by these effects occur throughout the full range of the product lifecycle, from the concept phase when determining a device's footprint to the analysis of reliability failures encountered after manufacturing. Given the ever-shrinking form factors of modern electronic devices and the ever-increasing chip power densities, determining mechanical deflection and stress states in thermo-electro-mechanical devices has never been more challenging. The implementation of new technology form factors, such as 2.5D interposers, will continue to push the thermal envelope, making the use of predictive modeling technologies even more critical when designing future electronic products. This paper explains the challenges and opportunities in preparing ECAD (electrical CAD) geometries for use with solvers traditionally associated with MCAD (mechanical CAD) geometries. The authors describe a new method of intelligently simplifying the ECAD geometry, which in turn greatly simplifies the MCAD model discretization. The result is a thermo-electro-mechanical stress model that benefits from fast modeling and significantly shorter solution times, but that is still highly accurate. The method can be used to correctly predict deflections (warpage), mean time to failure, and defects per million for boards with packages that have been surface mounted using a solder reflow process.
4 citations
Additional excerpts
...Many new approaches, including electrical CAD geometry, can be adopted to predict the mean time to failure and defections [8]....
[...]