Surface Mount Research Articles

Dynamic Response Characteristics and Fatigue Life Prediction of Printed Circuit Boards for Random Vibration Environments

The study focuses on the analysis of the surface mounted components of the printed circuit boards (PCB) under random vibration loading. The surface mount technology used for the study involves ball grid arrays. In order to predict the fatigue life of the component under certain defense and automotive applications, modal analysis is done by using the finite element method. The results are verified experimentally using JEDEC standards to validate the finite element design used for the study, and random vibration experiments were performed with finite element analysis. The fatigue life of PCB under different random vibration environments is predicted and compared. The fatigue life of PCB is least with jet cargo environment and is maximum with rail cargo environment. The analysis reveals that under the jet cargo environment, more numbers of natural frequency excitations are present. It was found that upon loading, maximum stress was found to be induced at the corner of solder balls for packages mounted in the center of the PCB. Hence, it is suggested to incorporate design modification such that the central area of the PCB must not contain any packaging designs.

Three-dimensional CFD simulation of the stencil printing performance of solder paste

The first step in the surface mount technology is the printing of the solder paste. The amount of solder placed on the cooper pad is important in guaranteeing an acceptable quality of soldering. Experimental works and studies for this process consume time and cost. There is a need for a cost-effective method to study this process. The simulation method has shown as a good alternative method for the solder paste printing process. Thus, this study presents a 3D computer simulation of stencil printing for the deposited volume prediction of solder paste. The volume of fluid (VOF) method integrated with the cross viscosity model was used for the numerical simulation. A widely used industry lead-free solder paste Sn/Ag/Cu (SAC305) of type 3 was utilized. The experimental and simulation results for filling volume of solder paste at different aperture sizes were compared. Results for different aperture sizes show a similar trend and agree well with the experimental results. This study was extended to investigate stencil printing at different squeegee speeds and aperture sizes. The squeegee speed of 35 mm/s provided the highest solder paste volume in the aperture with acceptable printing time.

Remnant Mode Conversion Noise Suppression Using a Surface Mount Device Capacitor

AbstractA novel scheme to suppress the remnant mode conversion noise with a surface mount device (SMD) capacitor on dual back-to-back bent differential lines is proposed. To suppress the remnant mode conversion noise, an additional SMD capacitor is loaded on the differential lines between two bends to equalize even- and odd-mode velocities. The mode conversion noise suppression characteristics of the proposed scheme were analyzed and compared with various schemes. Also, eye diagrams confirmed that the addition of the SMD capacitor suppressed remnant mode conversion noise while preserving differential signal quality in dual back-to-back bent differential lines.

A Study of Micro-crack on Surface Mount IC Package

In integrated circuit (IC) manufacturing industry, package micro-crack and other crack-related flaws are common defect frequently encountered in trim and form process of a surface mount IC package. This paper focused on the prevention of the micro-crack occurrence as it affected the assembly yield performance of the device in focus. Process mapping and defect concentration diagram were done to isolate the location of the defect and the processes involved. Containment and corrective actions were employed to fully narrow down the defect occurrence. Finally, a 99% improvement on defect parts per million (ppm) reduction was observed after implementation of all corrective actions.

Experimental Implementation of a Low-Cost, Fully-Analog Self-Jamming Canceller for UHF RFID Devices

It is quite common for transceivers to operate with the RF receiver and transmitter working on different time slots. Typical applications are radars and transceivers in the field of communications. Generally, the receiver is turned off when the transmitter broadcasts and vice versa. This is done in order to prevent the transmitter from blinding the receiver or causing the RF low noise amplification (LNA) stage to saturate. When keeping a receiver active, some leakage of RF energy is inevitable, and therefore shielding is applied to mitigate spurious signals. However, there are many applications wherein the receiver cannot be turned off. To address these applications, we investigate the design and performance of a fully-analog self-jamming canceller able to operate in UHF (Ultra High Frequency) RFID devices. While the traditional cost to design and build this type of topology can be quite high, our proposal is based on a low-cost physical approach. In addition to using common SMT (Surface Mount Technology) devices, we leveraged a new piece of modular technology offered by X-Microwave which allows designers to easily produce RF solutions with a broad portfolio of modular system drop-in blocks. A prototype was realized and the measured results are in close agreement with theoretical simulations. Significant damping of the leaked signal in the receiving channel was realized.

Overview of microfabricated bolometers with vertically aligned carbon nanotube absorbers

Multi-wall vertically aligned carbon nanotubes (VACNTs) are nearly ideal absorbers due to their exceptionally low reflectance over a broad wavelength range. Integrating VACNTs as bolometer absorbers, however, can be difficult due to their high growth temperature and fragile nature. Despite these challenges, we have microfabricated many different types of VACNT bolometers, ranging from cryogenic optical power primary standards to room temperature satellite-based solar irradiance monitors and broadband infrared microbolometers. Advantages our VACNT bolometers provide over the bolometers they replace vary by application, but can be reduced size and time constant, increased absorption, and/or microfabrication instead of hand assembly. Depending on the application and operating conditions, our VACNT bolometers are designed with a variety of thermistors and weak thermal links. The thermistors used include commercial surface mount chips, superconducting transition-edge sensors, and vanadium oxide (VOx). Weak thermal links include silicon nitride (SiNx) membranes, Si bridges, and laser-cut polyimide. We summarize a wide variety of microfabricated bolometers with VACNT absorbers that measure optical power levels spanning over seven orders of magnitude.

Multi-objective Ensemble of Regression Chains Prediction Algorithm for Pose Correction Errors of Precise Vision-based Printing Equipment

To accurately know the working condition of the Precise Vision-based Printing Equipment (PVPE) and improve its printing accuracy and stability, this paper proposes a multi-objective ensemble of regression chains algorithm to predict the pose correction (position and orientation) errors of PVPE’s alignment platform. Since this algorithm uses XGBoost as a base learner, it’s called XGBoost Ensemble of Regressor Chain (XGB-ERC) prediction algorithm. The algorithm is verified by a test set, which is constructed based on experimental data of PVPE. The experimental result shows that the Mean Absolute Percent Error (MAPE) of this algorithm for pose correction errors x, y and θ is 6.868%, 6.495% and 5.342%, which is 25.1%, 27.6% and 16.8% higher than that of the traditional XGBoost single-objective prediction algorithm. The predicted result of the proposed algorithm can be used to compensate the correction errors of the alignment platform, which will help improve the printing accuracy and stability of PVPE, and promote the development of the field of Surface Mount Technology (SMT).

Electrical Machine Permanent Magnets Health Monitoring and Diagnosis Using an Air-Gap Magnetic Sensor

This study proposes a magnetic sensor design and application for monitoring the health of rotor magnets in permanent magnet (PM) electrical machines through in-situ observation of the air-gap magnetic flux density. The reported device employs the concept of Fibre Bragg Grating (FBG) strain sensing fusion with magnetostrictive material to deliver a machine stator slot wedge integrated sensor that allows straightforward installation and retrofit with no invasive action to core elements of the machine. The sensing theory, design, prototyping, calibration and installation of the proposed magnetic sensing scheme are detailed in the paper. The sensor was installed into an inverter driven surface mount PM synchronous machine (SPMSM) and its performance for in-situ observation of rotor PM magnetization conditions validated in a range of healthy and demagnetised PM conditions tests. The obtained experimental data demonstrate the reported device's capability to enable recognition of rotor PMs' magnetisation level and thus their health monitoring. Finally, a fault index is proposed and experimentally validated that allows the application of in-situ magnetic sensor measurements for relative quantification of PM demagnetization fault severity.

Development of low-silver content SAC0307 solder alloy with Al2O3 nanoparticles

The present study is focused on the development of low Ag content 99Sn-0.3Ag-0.7Cu (SAC0307) solder alloy with Al2O3 nanoparticles reinforcement. The effects of multiple reflow cycles and the addition of Al2O3 nanoparticles in 0.01, 0.05, 0.1, 0.3 and 0.5 percentages by weight on microstructure development and mechanical strength of the solcder joint were first investigated. The addition of ceramic nanoparticles in 0.01-0.5 wt% range resulted in 15-40% increase in the wetting area and about 10-55% increase in the microhardness of the solder. The shear strength of nanoparticles reinforced SAC0307 solder joint increased by 11-53% under multiple reflow conditions. Nano-composite solder joints containing 0.01 and 0.05 wt% Al2O3 nanoparticles showed superior shear strength and improved ductility for two reflow cycles. Hence, these nano-composites were selected and tested for their performance and joint reliability. The surface mount 2220 capacitor joint assemblies with the selected nano-composites reflowed on bare copper and Ni–P coated Cu substrates were investigated. The reliability of the solder joint was assessed by determining the joint shear strength under varying temperature environments. The nano-composite with 0.05 wt% nanoparticles addition resulted in maximum joint reliability compared to monolithic solder. The Ni–P coating on the Cu substrate significantly hindered the IMC growth at the joint interface under different thermal conditions. The joint strength improved by about 26% for samples reflowed on Ni–P surface finish compared to that on bare Cu metallization. The Weibull analysis of the joint shear strength under all thermal conditions suggest that the addition of Al2O3 nanoparticles in very small amounts to SAC0307 solder and the presence of Ni–P surface finish on Cu substrate significantly enhances the performance and reliability of solder joints. In terms of both quality and reliability, the newly developed low-silver content SAC0307+0.05Al2O3 nano-composite is an effective alternate lead-free solder that can be used in microelectronics industry in place of high-silver content Sn–Ag–Cu solders.

A Data-Flow Oriented Deep Ensemble Learning Method for Real-Time Surface Defect Inspection

Real-time surface defect inspection plays an important role in the quality control of automated production. For the surface defect inspection, flowing data are a common data form in the automated pipeline production. Although flowing data provide rich information for surface defect inspection, there are still a lot of dynamic distribution challenges caused by the flowing data, such as the domain shift phenomenon and imbalanced training data. However, many existing industrial inspection solutions still use static strategies. To determine the dynamic distribution influence on the data flow domain, this article proposes a new deep ensemble learning method with domain fluctuation adaptation. Specifically, a new distribution discrepancy identifier based on estimation of the data set distribution and data characteristic is proposed. It utilizes advantages of both the deep convolutional neural network (CNN) and the shallow feature-based learning method to achieve higher robustness and fine-grained detection in streaming data scenes. In order to validate the proposed method, an inspection bench test system, as a part of a real industrial surface mount technology production line, is designed and fabricated. The proposed inference model is successfully applied to an embedded terminal with a hybrid and heterogeneous computing architecture. At last, the method is validated on the data collected from the manufacturer. The result suggests that the proposed method possesses a competitive mean average precision (mAP) rate with good adaptation and robustness in industrial streaming data scenes.

Large-scalable fabrication of improved Bi–Te-based flexible thermoelectric modules using a semiconductor manufacturing process

Among the several flexible thermoelectric modules in existence, sintered Bi–Te-based modules represent a viable option because of their high output power density and flexibility, which enables the use of arbitrary heat sources. We have fabricated Bi–Te-based modules with a large-scalable fabrication process and improved their output performance. The reduction in the interconnection resistance, using thick electrodes of the flexible printed circuit, significantly improves the module’s output power to 87 mW cm−2 at ΔT = 70 K, which is 1.3-fold higher than a previous prototype module. Furthermore, the establishment of the fabrication for the top electrodes by using the surface mount technology makes it possible to realize a high-throughput manufacturing of the module. Our durability tests reveal that there is no significant change in the internal resistance of the module during 10 000 cycles of mechanical bending test and 1000 cycles of thermal stress test.

Compact Silica-based 16 × 16 Multicast Switch with Surface Mount Technology for PLCs

Compact Silica-based 16 × 16 Multicast Switch with Surface Mount Technology for PLCs

Development and Testing of the FDM Read-Out of the TES Arrays Aboard the LSPE/SWIPE Balloon-Borne Experiment

The design and experimental demonstration of a 16-channel frequency-domain multiplexing (FDM) read-out for transition-edge sensor bolometers is presented. This MUX electronics is intended to read out the 326 spiderweb bolometers of the LSPE/SWIPE balloon-borne experiment, which aims at the detection of the B mode polarization of the cosmic microwave background at large angular scales. The cryogenic part of our 16-channel FDM read-out chain features LC resonators composed of custom Nb superconducting inductors and surface mount device ceramic capacitors mounted on boards next to the detector wafers, at 300 mK, while the superconducting quantum interference device board is at 1.6 K. The warm section is based on a modular solution, with mezzanine plug-ins for digital-to-analog converters, analog-to-digital converters and a system-on-chip (based on the Altera Cyclone V field programmable gate array). The warm electronics handles the generation of the FDM tones, the de-multiplexing and the digital signal analysis including, e.g. cosmic ray glitches removal. Here, we recall its specifications, we address noise considerations, and finally we present the latest results obtained using flight models of our custom-designed boards.

Current-Voltage Response of Cold White LED Strip to Radiotherapeutic Electron and Photon Beams: A Preliminary Study

Photonic devices such as photodiodes, phototransistors, solar cells, and charge-coupled devices (CCDs) have been associated with clinical radiation detection in recent studies. Light Emitting Diodes (LEDs) are of low-cost in comparison to photodiodes and available in various flexible designs, including surface mount devices (SMDs). LEDs are purposely designed to emit light, but they can also be implemented for detecting light in a photovoltaic mode. Despite the LED-related merits, a few studies, compared to other photonic devices, especially photodiodes, have adopted them as medical radiation detectors. This research hence exploits the LED’s dual applicability by investigating a cold/cool white LED strip current-voltage (C-V) signal response to photon and electron beams. Radiation parameters such as beam energy, angle of incidence, field size, surface source distance (SSD), and monitor units (prescribed dose) were varied. According to the obtained results, the electron beams induced a 10% higher C-V signal compared to photon beams. An angular dependence was also observed, i.e., the C-V signal fluctuated due to a variation in the irradiation angles; -45°, -25°, 0°, 25°, 45°, and radiation type – photon and electron beams. The C-V signal response to SSD alterations additionally produced bimodal signal graphs, skewed towards shorter SSDs, for all the beams used in this study. Finally, the C-V signal was generally linear to the prescribed dose for both the photon and electron beams. Overall, the response of LEDs to photon and electron beams separately exhibited a similar signal trend for the beam energy, field size, angular dependence, and SSD parameter variations. On the other hand, dose linearity produced contrasting signal trends across the photon and electron beams.

Weighted Smallest Deformation Similarity for NN-Based Template Matching

This article deals with the template matching problem, and a weighted smallest deformation similarity measure, which is robust to occlusions, background outliers, and complex deformations. The appearance-based nearest neighbor (NN) matching of points is constructed and the smallest location distance between each point in the template and its matching points is employed to penalize the deformation explicitly. Then, the weights are added to points in the template relied on their likelihood of belonging to the background through NN matching with the points around the target window. Experiments show that the proposed method improves the state-of-the-art performance on real-world scenario benchmarks and can be applied in rough positioning of surface mount technology components.

SMT assembly effects on organic substrate lifetime reduction

PurposeThe purpose of this study is that the effects of surface mount technology (SMT) assembly process on the product lifetime of fine-pitch printed circuit boards (PCBs) were investigated under biased highly accelerated stress testing (HAST).Design/methodology/approachSMT assembly from a semiconductor SMT assembly process was replicated to test PCBs under the same conditions as SMT-assembled PCBs. The median lives µ and standard deviation s of the test PCBs were calculated from the log-normal distribution. The failure analysis of current leakages was conducted by the focused ion beam, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Using the inverse power law and modified Peck-H’s relationship, the PCB lives at accelerated (by SMT assembly stress) and user conditions were calculated.FindingsThe failure analysis demonstrated that SiO2 and BaSO4 fillers added for stiffening organic materials promote current leakage failure. Therefore, the hydrophobicity of these fillers is believed to be necessary to suppress the current leakage failure under biased HAST. The inverse power law model indicates that the acceleration life model with SMT assembly stress can be given as follows: L(V) = 271.9(S)−0.5031. From modified Peck-H’s relationship, after the third SMT assembly, the time required to attain 0.96 per cent failures at 35°C/60 per cent RH/1.9 V and 130°C/85 per cent RH/3.5 V are 129 y and 69.5 h, respectively. The biased HAST at 130°C/85 per cent/3.5 V after the third SMT assembly for 69.5 h on 238 samples could be recommended as an early quality-monitoring procedure.Research limitations/implicationsIn the future, the failure modes in an early stage of a bathtub should be analyzed and the life prediction model should be studied accordingly.Originality/valueThrough this study, the lifetime prediction model and early quality-monitoring procedure for organic substrates because of SMT assembly stress were obtained.

Printed Smart Devices on Cellulose-Based Materials by means of Aerosol-Jet Printing and Photonic Curing.

Printed electronics is an expanding research field that can reach the goal of reducing the environmental impact on electronics exploiting renewable and biodegradable materials, like paper. In our work, we designed and tested a new method for fabricating hybrid smart devices on cellulose substrates by aerosol jet printing (AJP) and photonic curing, also known as flash lamp annealing (FLA), capable to cure low temperature materials without any damage. Three different cellulose-based materials (chromatographic paper, photopaper, cardboard) were tested. Multilayer capability and SMDs (surface mount devices) interconnections are possible permitting high flexibility in the fabrication process. Electrical and geometrical tests were performed to analyze the behavior of printed samples. Resulted resistivities are 26.3 × 10−8 Ω⋅m on chromatographic paper, 22.3 × 10−8 Ω⋅m on photopaper and 13.1 × 10−8 Ω⋅m on cardboard. Profilometer and optical microscope evaluations were performed to state deposition quality and penetration of the ink in cellulose materials (thicknesses equal to 24.9, 28.5, and 51 μm respectively for chromatographic paper, photopaper, and cardboard). Furthermore, bending (only chromatographic paper did not reach the break-up) and damp environment tests (no significant variations in resistance) where performed. A final prototype of a complete functioning multilayer smart devices on cellulose 3D-substrate is shown, characterized by multilayers, capacitive sensors, SMDs interconnections.

Contactless pick-and-place of millimetric objects using inverted near-field acoustic levitation

We model and realize an ultrasonic contactless pick-and-place device capable of picking, self-centering, self-orienting, translating, and releasing flat millimetric objects. The device is an ultrasonic Langevin transducer operating at 21 kHz that radiates into air through a tapered tip. Objects are trapped few micrometers below the tip due to the near-field acoustic levitation phenomenon. We first investigate the conditions to achieve an attractive force on the object depending on its size and the device operating frequency. Second, we use a 3D acoustic model that describes the converging forces and torque that provide the self-centering and self-orienting capabilities. Third, a more advanced Computational Fluid Dynamics model based on the Navier–Stokes equations explains the small gap between the tip and the trapped object. The contactless manipulation capabilities of the device are demonstrated by picking, transporting, and releasing a Surface Mount Device in air. The presented manipulation concept can be an interesting alternative for manipulating delicate objects such as microelectromechanical devices, silicon dies, or micro-optical devices.

Improvement of Field Effect Capacity Type Gas Sensor Thermo Inertial Parameters by Using Laser Micromilling Technique

This paper presents a verification of technology aspects for improvement of field effect capacity type gas sensor parameters by using laser micromilling technique for fabrication ceramic surface mounting device (SMD) package and microheater for sustentation working temperature of metal-insulator-semiconductor structure (MIS structure). Innovative claims include: demonstration of flexible opportunities for new digital fabrication process flows based on laser micromilling tech: fast design of SMD sensor 3-D model, flexible changing topology of microheater, thick and thin film technology combination for reducing of power consumption. The results show possibility to fast fabrication functional sensor in customer ceramic SMD package with base 9x9 mm with twice reduced power consumption and improving mechanical properties compare with classical metal-glass microelectronic packages using before for such type sensors.

Parameter Studies of Ceramic MEMS Microhotplates Fabricated by Laser Micromilling Technology

This paper presents a modeling of technology aspects for fabrication ceramic microelectromechanical systems (MEMS) microhotplate and surface mounting device (SMD) packaging for (MOX) gas sensors applications. Innovative claims include: demonstration of flexible opportunities for new fabrication process flows based on laser micromilling tech; modeling of power consumption MEMS microhotplate depending on the thickness and topology; demonstration of necessity changing thick film technology of metallization to vacuum sputtering by reducing of power consumption. The results show possibility to fast fabrication of different topologies for ceramic MEMS microhotplate in form-factor of SOT-23 type SMD package.