Ceramic Resistors Research Articles

Contact‐Based and Proximally Thermosensitive Few‐Layer Graphene Ntc Thermistors with Highly Fast Switching Behavior

AbstractPatterning graphene onto polymeric materials offers benefits in realizing flexible, stretchable, and wearable multifunctional electrodes. However, the employed integration approaches and use of non‐patternable polymers hinder the patterning of graphene at the sub‐millimeter (mm) scale. Serpentine‐shaped thermally active graphene patterns (thermistors) of 500 × 500 µm2 area are reported by the seamless integration of chemical vapor‐deposited graphene (GCVD) into readily available SU‐8 polymer with MEMS‐compatible cleanroom fabrication processes. The thermistor resistance decreases with an increase in graphene temperature changed by local heat conduction or environmental thermal radiations; hence, exhibits a negative temperature coefficient (NTC) of resistance of 0.0012/°C. Furthermore, very fast resistive switching with 1 s response and 3.2 s recovery time is observed under cyclic heating and cooling. Several application scenarios including, monitoring of surface temperature (e.g., kettle and human body), rapid response (0.25 s) to heat conduction and radiations (0.5 s) from human finger at room temperature for contact and touch‐free proximity switching (e.g., turn ON and OFF an LCD display) are demonstrated. Moreover, owing to its small area less than a ceramic resistor enabled to integrate the fabricated thermistor onto a printed circuit board (PCB) to construct a fully packaged thermometer to monitor ambient temperature.

Surface mount multilayer ceramic capacitors as optically stimulated luminescent dosimeters

The choice of dosimetric materials for precise retrospective dose assessment in case of any emergencies is very challenging. Since few decades, electronic components like ceramic resistors, inductors, IC chips, surface mount resistors and inductors have been proven to be suitable candidates for dose estimation using thermoluminesce (TL)/optically stimulated luminescence (OSL) techniques. In this work, OSL technique is applied to study dosimetric properties of surface mount multilayer ceramic capacitors (SM MLCC) available in commonly used instruments like printer, computer mouse, USB flash drive and personal gadgets like mobile phone etc. To understand the OSL process involved, the elemental composition and crystallinity of the SM MLCCs were analyzed using Fourier transform infrared (FTIR) and X-ray diffraction (XRD) techniques. It is found that the main constituent is barium titanate with aluminium silicate as major impurity along with some trace elements and is responsible for the origin of the radiation induced OSL signal. Some important dosimetric characteristics like OSL sensitivity, repeatability, OSL dose response, and OSL signal stability upon storage were studied. The stimulation time was optimized as 50 s and used for all OSL measurements. The dose response was found to be linear from 500 mGy to 15 Gy and simply increased (up to 40 Gy). Fading analysis showed that the OSL signal decreases by ∼ 25 % in 1 day, ∼ 50 % in 4 days, and remained stable after that at least up to 8 days. The dose was recovered using single aliquot regenerative-dose (SAR) technique with very good accuracy. These results of dosimetric studies and validation study suggest that surface mount multilayer ceramic capacitors have potential use as retrospective dosimeters.

Improving electric-energy transmission performance of LixNi1-xO linear ceramic resistors by Li+/Ni3+ ion occupation regulation for pulsed power technology

Linear ceramic resistor receives extensive attention for its great advantages of fast energy transmission in pulsed power technology. However, the research about improving the linear current-voltage characteristics and pulsed charge-discharge speed of LixNi1-xO solid solution is rarely reported. Herein, we fabricated the LixNi1-xO linear ceramic resistors through a solid-phase reaction method, and the effects of the Li+ ion on the microstructure, current-voltage characteristics and pulsed charge-discharge properties were studied. Specifically, the electron holes exchange between divalent and trivalent nickel ions is enhanced by Li substitution, which contributed to the significantly decreasing in nonlinear coefficient (α) and resistivity. On a separate note, the rising edge of pulse charge-discharge is influenced by the linearity of LixNi1-xO ceramic resistors. The closer the nonlinear coefficient is to 1, the shorter the pulsed charge-discharge time is. Meanwhile, the defect dipoles induced by Li substitution may also contribute to the reduction of discharge time of LixNi1-xO linear ceramic resistors. As a result, the Li0.03Ni0.97O linear ceramic resistor with an excellent nonlinear coefficient of 1.03 exhibits extraordinary fast discharge speed (t0.9 = 94.8 ns) at 1.0 kV. The investigation on LixNi1-xO linear ceramic resistors suggests the potential of this material to be applied in the pulsed power system.

A compact nanosecond pulse generator for x-ray radiographies.

A compact nanosecond pulse generator was developed, aiming at producing high-energy flash x rays with a long lifetime. The generator was designed on the basis of a 0.67-ns pulse forming line (PFL), which is charged to ∼700kV by an air core Tesla transformer and switched by a fast spark gap. The Tesla transformer consists of a single turn primary coil surrounding a 44-turn secondary coil using no magnetic cores. 2D magnetostatic and electrostatic simulations were carried out, and the inductance and stray capacitance of the transformer were calculated. The transformer was powered by a 40-nF capacitor bank via a hydrogen thyratron. An effective coupling co-efficiency keff of 0.55 was achieved. The PFL voltage reached its second peak of 680kV in 395ns when the capacitor bank was switched at 25kV. A nanosecond pulse with a peak voltage of 510kV, a peak power of 2.6 GW, and a pulse width of 2.1ns was generated on a 100-Ω ceramic resistor, which is going to be replaced by a vacuum x-ray tube. Since the pulse energy is small, the x-ray tube is expected to have a long lifetime. The generator is 285mm in diameter, 800mm in length, and 35kg in weight, providing a compact means for high-energy x-ray radiographies both in scientific research and industrial applications.

Prognostics and Health Management Features for Large Circuit Boards to Be Implemented Into Electric Drivetrain Applications

Abstract Canary structures being used as early warning indicators represent an important tool for condition and health monitoring of electronic components and systems. In this paper, printed circuit boards (PCBs) with canary structures based on surface mounted device (SMD)-2512 ceramic chip resistors with reduced solder pad sizes were studied. Focus of these investigations was set on thermomechanical and mechanical stresses caused by passive thermal cycling as well as by vibrational loads. For this purpose, experimental methods such as deformation analysis and accelerated aging tests as well as finite element (FE) based methods were applied. In addition, an outlook on the implementation of these canary structures into dual inverter electronic control boards for electrical powertrain applications will be given.

Ceramic based electronic component as retrospective radiation dosimeter

Surface mount electronic devices (like resistors, capacitors, and inductors) extracted from the portable electronic devices (mobile phones, USB drives, etc.) have been studied for dose reconstruction using luminescence techniques for radiological or nuclear emergencies. In this work, carbon coated ceramic resistors removed from the electronic instruments are analyzed using thermo luminescence (TL) technique for the retrospective dose reconstruction. TL measurements on beta irradiated ceramic resistors exhibited one major dosimetric peak at around 540 K in addition to three other low temperature peaks. A linear beta dose response has been observed from 1 Gy to 125 Gy with Minimum Detectable Dose (MDD) of 0.1 Gy. The dose response is found to be supralinear below 1 Gy. The fading studies have been carried out and investigated up to 30 days. The important kinetic parameters for the material like TL trap depth, frequency factor and order of kinetics are evaluated by deconvolution method.

Design and optimization of cost-effective coldproof portable enclosures for polar environment

Based on the International Electrotechnical Commission standards, 
 the electronic devices in the industrial class (e.g., integrated circuits or batteries) can only operate at the ambient temperature between -40°C and 85°C. For the human-involved regions in Alaska, Northern Canada, and Antarctica, extreme cold condition as low as -55°C might affect sensing electronic devices utilized in the scientific or industrial applications. In this paper, we propose a design and optimization methodology for the self-heating portable enclosures, which can warm up the inner space from -55°C for encasing the low-cost industrial-class electronic devices instead of expensive military-class ones to work reliably within their allowed operating temperature limit. Among the other options, ceramic thermal resistors are selected as the heating elements inside the enclosure. The placement of the thermal resistors is studied with the aid of thermal modelling for the single heating device by using the curve fitting technique to achieve uniform temperature distribution within the enclosure. To maintain the inner temperature above -40°C but with the least power consumption from the thermal resistors, we have developed a control system based on the fuzzy logic controller. For validation, we have utilized COMSOL Multiphysics software and then one prototyped enclosure along with the fuzzy control system. Our experimental measurement exhibits its efficacy compared to the other design options.

SAM Theory and Case Studies in Reliability and Counterfeit Detection

Abstract This article reviews the basic principles of scanning acoustic microscopy (SAM) and presents several case studies demonstrating its use in failure analysis and counterfeit detection. The FA case studies show how SAM is used to detect delamination, cracking, and manufacturing defects in ceramic chip capacitors and resistors, voids in a full-bridge rectifier, and a radiation-induced defect in a microprocessor. In cases involving counterfeit ICs, CSAM images reveal the presence of an abnormality on component packages, evidence of relabeling, and popcorn fractures indicative of the use of excessive heat and force to dislodge components from circuit board assemblies.

Frequency compensation for resistive voltage divider using specially shaped inner conductor

The main factor that slows down the high-frequency response of a resistive voltage divider (RVD) is the distributed stray capacitance (Cg) between the high-voltage-arm (HVA) and the grounded conductors, due to the charging and discharging of Cg through the high resistance RH of the HVA with characteristic time RHCg. Based on a RVD consisted of ceramic tube resistors, a compensation method utilizing the distributed capacitance between a specially shaped inner conductor and the HVA was proposed in this paper, which is more compact than grading rings and can work well with grounded shielding. The method was verified by electromagnetic simulation, which indicated a bandwidth improvement from 3 MHz to more than 1 GHz for the prototype RVD with grounded shielding. Experimental results showed that the 10%–90% rise time for a step input was improved by the compensating electrode from ∼90 ns to 1.25 ns. The main drawback of the method is the possible degradation of insulation when precise compensation is required.

Ceramic resistors as optically stimulated luminescent retrospective dosimeters

Application of optically stimulated luminescence (OSL) as a retrospective dosimetric technique is studied using ceramic resistors available in commonly used instruments like personal computers, printers, household electronic appliances etc. In order to understand the OSL process the composition of the ceramic resistors was analysed using XRD, FTIR and ED-XRF techniques and it is found to have hydrated calcium aluminium silicate as the major constituent along with trace impurities for the origin of radiation induced OSL. The important retrospective dosimetric characteristics like its OSL sensitivity, reproducibility, OSL dose response and stability of the signal upon storage after exposure have been studied. The dose response was found to be linear from 100 mGy to 5 Gy. It is also observed that the OSL signal decreases by 30% in the first 3 days and thereafter there is negligible fading up to 30 days. The correlation between TL and OSL signals in the material was also studied. Using Single Aliquot Regenerative (SAR) technique, the dose was recovered with very good accuracy. These dosimetric studies showed that carbon film ceramic resistors have potential use as emergency dosimeter.

Effect of PCB cracks on thermal cycling reliability of passive microelectronic components with single-grained solder joints

Lead-free tin-based solder joints often have a single-grained structure with random orientation and highly anisotropic properties. These alloys are typically stiffer than lead-based solders, hence transfer more stress to printed circuit boards (PCBs) during thermal cycling. This may lead to cracking of the PCB laminate close to the solder joints, which could increase the PCB flexibility, alleviate strain on the solder joints, and thereby enhance the solder fatigue life. If this happens during accelerated thermal cycling it may result in overestimating the lifetime of solder joints in field conditions. In this study, the grain structure of SAC305 solder joints connecting ceramic resistors to PCBs was studied using polarized light microscopy and was found to be mostly single-grained. After thermal cycling, cracks were observed in the PCB under the solder joints. These cracks were likely formed at the early stages of thermal cycling prior to damage initiation in the solder. A finite element model incorporating temperature-dependant anisotropic thermal and mechanical properties of single-grained solder joints is developed to study these observations in detail. The model is able to predict the location of damage initiation in the PCB and the solder joints of ceramic resistors with reasonable accuracy. It also shows that the PCB cracks of even very small lengths may significantly reduce accumulated creep strain and creep work in the solder joints. The proposed model is also able to evaluate the influence of solder anisotropy on damage evolution in the neighbouring (opposite) solder joints of a ceramic resistor.

The improvement on thermal performance of herbal ball compress

Herbal ball compress is an equipment usually employed in Thai traditional medical treatment to relieve muscular pain. The herbal ball needs to be prepared by steam heating prior to the application in order to extract essential oils from herbal ingredients. This study aims at improving thermal performance of herbal ball so that it can maintain temperature at a suitable level for a particular period of time. In this article, the investigation to facilitate the herbal ball compress usage is performed in various schemes. Adding some materials of high specific heat capacity is one approach. In addition, employing electric powered heat sources such as cable heater, Peltier sheet, ceramic resistor and directly supplied steam are also included in the test. The experimental results revealed that the herbal ball with small water balloons inside can prolong the time duration at a desired temperature range. Direct steam supply system was built by modifying a household electric pan. The experiment demonstrated that the temperature of herbal ball was capably controlled at a desired level through the treatment. It is supposed that the appropriate method could benefit thermal performance of herbal ball compress in regard to temperature control, treatment duration, economical aspect as well as safety circumstance.

Note: A rectangular pulse generator for 50 kV voltage, 0.8 ns rise time, and 10 ns pulse width based on polymer-film switch.

In this article, we describe a rectangular pulse generator, consisting of a polymer-film switch, a tri-plate transmission line, and parallel post-shaped ceramic resistor load, for 50-kV voltage, 0.8-ns rise time, and 10-ns width. The switch and resistors are arranged in atmospheric air and the transmission line can work in atmospheric air or in transformer oil to change the pulse width from 6.7 ns to 10 ns. The fast switching and low-inductance characteristics of the polymer-film switch ensure the fast rising wavefront of <1 ns. This generator can be applied in the calibration of nanosecond voltage dividers and used for electromagnetic pulse tests as a fast-rising current injection source.

&lt;italic&gt; In Situ&lt;/italic&gt; Interconnect Failure Prediction Using Canaries

A physics-of-failure-based canary approach for early identification of solder interconnect failures has been developed. The canary is composed of a resistance path formed by a near-zero ohm ceramic chip resistor soldered to pads designed to produce failure earlier than standard pad resistors, which are the target structures. The time to failure of the canary can be adjusted by adjusting the printed wiring board pad dimensions and, hence, the solder interconnect area. The developed canary approach is demonstrated through temperature cycling of the resistors. The pad width of a standard resistor is reduced by 80%, thereby reducing the interconnect life. The results from the temperature cycling experiment prove that the developed canary approach provides advanced warning of failures of the standard pad resistors. The FEA results suggest that there is a 78% increase in the strain range in the canary resistor, as compared with the standard resistor. The Engelmaier model, a physics-of-failure-based model for solder interconnect life estimation under thermal cycling, is modified to take the solder interconnect area into account. The model provides time to failure estimates for the canary and target structures. A comparison of the results from the Engelmaier model and temperature cycling experiment shows that the model provides a good estimate of time to failure of standard resistors and a conservative estimate of time to failure of the canary resistors.

Processing of La2O3 based rare earth non-linear resistors via combustion synthesis

Non Linear ceramic Resistor (NLR) was processed using ZnO-La2O3 rare earth composition via combustion technique involving urea and glycine as organic fuels. The La2O3 NLR ceramic was sintered at 1300 °C/ 3 h that showed dense microstructures with average grain size of 1 μm. The current v/s voltage characteristics of La2O3 NLR were compared among the fuels. In addition to that the combustion chemistry of urea and glycine was monitored via C-H-N-S analysis and the functional property was assessed by UV-Vis analysis. The I-V analysis confirmed that the La2O3 NLR ceramic prepared with urea fuels exhibits only a linear resistor behavior whereas an excellent non-ohmic nature was obtained in glycine fuels. The grain-grain boundary property was further examined by impedance analysis. The study brought out a promising, eco-friendly rare earth composition for obtaining high-energy NLR ceramics.

R-BENCH TOOL을 이용한 상용차용 정전용량 방식의 연료 센서의 소프트웨어 검증 평가

최근 차량이 기계장치 중심에서 전기전자 장치 중심으로 발전하고 있으며, 상용차량 역시 전기전자 장치가 증대되고 있다. 정전용량 방식의 연료 센서는 연료의 레벨을 정전용량 값으로 측정하여 센서 내 MCU 를 통해 연산과정을 거쳐 최종 전압값의 신호로 출력해 주는 센서이다. 기존의 세라믹 저항을 이용한 센서보다 내구성이나 연료 측정 정확성이 향산된 진보된 센서로 센서에 대한 소프트웨어 검증을 위하여 가변 커패시터 보드를 제작하여 R-BENCH TOOL 을 통해 test case 를 자동으로 생성시킨 후 연료센서의 소프트웨어 검증을 시도하였다. 또한 결론으로 98% 이상의 높은 소프트웨어의 신뢰도가 있음을 확인하였다.

Fatigue of Solder Interconnects in Microelectronic Assemblies under Random Vibration

This study investigates vibration fatigue durability of solder interconnects of surface mount electronic IC packages under harmonic and random excitation, through accelerated stress testing and physics-of-failure (PoF) simulations. The solder material of interest is Sn3.0Ag0.5Cu. The test vehicle consists of several HVQFN (Heat-sink Very-thin Quad Flat-pack No-leads) components soldered onto a Printed Wiring Board (PWB). The fatigue damage accumulation rates under ED random vibration excitation is found to be much higher than under harmonic vibration excitation, for equivalent RMS responses of PWB. To understand the reasons for such discrepancy we use FEA-based modeling. For simplicity of modeling we use a simple PWB with a simple Leadless Ceramic Resistor (LCR) component. We use a multiscale FEA modeling approach where the global analysis provides insights into the PWB modal response under the given excitation and can be conducted in the frequency-domain or in the time-domain. The local FEA model allows us to establish a transfer function between PWB curvature (flexural strain) in the vicinity of the critical component and equivalent strain in the critical region of the critical solder joint. al analysis is conducted to investigate the PWB mode shapes and natural frequencies, and they are compared with the measured strain time history, to understand the modal participation factors under both harmonic and ED random vibration excitation. The failure data is found to correlate well with the modal participations. Multiscale finite-element (FE) simulations are conducted to assess the dynamic response of the critical interconnects. This is done with two steps, first using a FE global analysis in the frequency domain for the global response consisting of all participating modes. Participation factors for individual modes are estimated from the global response, using numerical filtering methods. Inverse FFT is used to convert the frequency-domain response into the time-domain response histories for each dominant mode. In the second step, dynamic FE local analysis is conducted to obtain the transfer function between the PWB flexure and the strain in the critical solder interconnect for each dominant mode. Finally, rainflow cycle counting and Coffin-Manson fatigue model are used to estimate durability model constants and to compare fatigue damage accumulation rates under harmonic versus ED random vibration excitation.

Reliability of SMD interconnections on flexible low-temperature substrates with inkjet-printed conductors

This work dealt with potential reliability issues in inkjet-printed electronics. The aim was to increase our understanding of how failures occur in hybrid electronic structures that utilize inkjet printing. A future goal in this field will be to enable expansion of this product area from low-life-expectancy and -performance products to high-life-expectancy and -performance products.In this work the reliability of isotropically conductive adhesive interconnections between 0402- and 0805-sized ceramic resistors and three types of flexible substrates was investigated. The use of low-temperature ink material (curing temperature 150°C) allows new, inexpensive substrates to be introduced into the process. In addition, the interconnection reliability of a more complex low-temperature cofired ceramic module attached to a flexible substrate with ball grid array interconnections was investigated.Reliability testing was carried out in a thermal cycling test chamber in a 0–100°C temperature range. Daisy-chain resistances of the samples were monitored with a datalogger during the cycling. Besides optical inspections, the interconnections were analyzed with X-ray microscopy. Also scanning acoustic microscopy was used to observe crack propagation. Finally, scanning electron microscopy was used to detect failure mechanisms.The two main failure mechanisms of the chip resistor components were loss of adhesion at the ICA/component terminal cladding interface and cracking of matte tin cladding of the component. For the tested LTCCs it was noted that breakdowns of interconnections occurred because of fractures on the module side of the interconnection—in most cases in the solder/intermetallic compound interface—and not because of ICA fractures or ink delamination on the substrate side.

Surface finish effect on reliability of SAC 305 soldered chip resistors

PurposeThe purpose of this paper is to assess the long‐term reliability of lead‐free Sn96.5Ag3.0Cu0.5 (SAC305) under accelerated temperature cycling (ATC) conditions. Test vehicles consisted of commercial 2512 ceramic chip resistors soldered to printed circuit boards (PCBs) using three different Pb‐free surface finishes: organic solderability preservative (OSP), immersion silver (IAg) and electroless nickel immersion gold (ENIG).Design/methodology/approachTwo populations of solder joints were monitored continuously during a thermal cycle of 0°C to 100°C with a ramp rate of 10°C/min and a 30 min dwell at the temperature extremes. One population was cycled to 2,500 cycles, the other population was cycled to 8,250 cycles. Failures were defined in accordance with the IPC‐9701A industry test guidelines and failure data are reported as characteristic life, η. Microstructural evolution was characterised using metallographic techniques and back‐scattered scanning electron microscopy (SEM). Fractography was performed on post‐cycled resistors to determine failure mechanisms.FindingsThe results showed that the lifetime of the chip resistors could be ranked as follows: OSP&gt;ENIG&gt;IAg after 8,250 thermal cycles, when&gt;73 per cent of the population had failed. It was found that the relative performance of OSP finishes improved with longer periods of cycling. This was attributed to diffusion of copper into the bulk solder and which subsequently, over time, acted as a dispersion strengthening mechanism. The relatively poor performance of IAg finishes was attributed to void formation.Originality/valueThe paper provides new and valuable information to end‐users about the long‐term reliability of lead‐free solder on three commonly used lead‐free surface finishes. The performance of each surface finish is explained in terms of microstructural evolution and void formation.

Effects of Extended Dwell Time on Thermal Fatigue Life of Ceramic Chip Resistors

The understanding of the effects of temperature cycling parameters, such as dwell and ramp times, mean cyclic temperature, and temperature range, on the fatigue life of solder interconnects is critical for qualification and reliability testing. After the solder achieves complete stress relaxation, a further increase in dwell time does not decrease the fatigue life of solder interconnects. Studies have shown that an increase in dwell time beyond a certain limit (10–20 minutes) has no effect on the fatigue life of eutectic tin-lead solder when cycled at peak cycle temperatures at or above 100°C. The duration of stress relaxation is longer in SnAgCu and SnCu solders than in eutectic tin-lead solder, resulting in higher creep damage accumulation and thereby reducing the fatigue life of solder interconnects. Experimental data for modeling of the effects of extended dwell time (beyond 60 minutes) on the temperature cycling reliability of tin-silver-copper solders is limited. In this study, forty 2512 ceramic chip resistors soldered onto an FR4 board using SAC105, SAC305, SN100C, and eutectic SnPb solders were subjected to temperature cycling tests with dwell time durations of 10 and 120 minutes, respectively. Resistors soldered on standard and narrow pads were compared to study the effects of pad size on thermal fatigue reliability. In eutectic SnPb-soldered narrow pad resistors, the increase in dwell time to 120 minutes did not change the cycles to failure. However, SnPb-soldered standard pad resistors showed a decrease in fatigue life with the increase in dwell time. For SAC105- and SAC305-soldered narrow and standard pad resistors, the 120-min dwell decreased the thermal fatigue life, compared to the 10-min dwell. The thermal fatigue life of SN100C-soldered narrow pad resistors increased when the dwell time was increased to 120 minutes, while that of the standard pad decreased. In the case of narrow pad resistors, extended dwell may be have annealed the SN100C solder, making it more robust to solder fatigue.