Investigating Test Methods for Electrochemical Consistency in PCB Assembly Processes

BackgroundPromoting consistent HIV testing is critical among young, Black Men Who Have Sex With Men (MSM) and transgender women who are overrepresented among new HIV cases in the United States. New HIV test options are available, including mobile unit testing, one-minute testing, at home or self-testing and couples HIV testing and counseling (CHTC). In the context of these newer options, the objective of this study was to explore whether and how preferences for specific characteristics of the tests acted as barriers to and/or facilitators of testing in general and consistent testing specifically among young Black MSM and transgender women aged 16 to 29.MethodsWe conducted 30 qualitative, semi-structured, in-depth interviews with young, Black, gay, bisexual or MSM and transgender women in the New York City metropolitan area to identify preferences for specific HIV tests and aspects of HIV testing options. Participants were primarily recruited from online and mobile sites, followed by community-based, face-to-face recruitment strategies to specifically reach younger participants. Thematic coding was utilized to analyze the qualitative data based on a grounded theoretical approach.ResultsWe identified how past experiences, perceived test characteristics (e.g., accuracy, cost, etc.) and beliefs about the “fit” between the individual, and the test relate to preferred testing methods and consistent testing. Three major themes emerged as important to preferences for HIV testing methods: the perceived accuracy of the test method, venue characteristics, and lack of knowledge or experience with the newer testing options, including self-testing and CHTC.ConclusionsThese findings suggest that increasing awareness of and access to newer HIV testing options (e.g., free or reduced price on home or self-tests or CHTC available at all testing venues) is critical if these new options are to facilitate increased levels of consistent testing among young, Black MSM and transgender women. Addressing perceptions of test accuracy and supporting front line staff in creating welcoming and safe testing environments may be key intervention targets. Connecting young Black MSM and transgender women to the best test option, given preferences for specific characteristics, may support more and more consistent HIV testing.

With lead-free legislation impacting printed circuit board (PCB) manufacturing, immersion silver (ImAg) finish is adapted as the top finish of copper trace on PCB due to its many advantages. However, it is easy for silver to form electrochemical migration (ECM) in high humid environment, so that the potential bias and spacing between adjacent circuits are limited. In addition, since the thickness of ImAg finish is usually less than 0.15µm restrained by the electroless plating process, the copper trace under the silver finish cannot be fully covered, which causes the complexity of corrosion and electrochemical migration. In this paper, water drop test was used to induce the electrochemical migration on ImAg finished “Y” pattern circuits on PCB. The surface insulation resistance was detected by a picoammeter and the growth of dendrite deposit between two electrodes was monitored by a video system. The electrolytic reaction and galvanic reaction on the electrodes formed by bimetal couples was analyzed theoretically. The mechanism of electrochemical migration of copper driven by immersion silver finish was discussed. The effects of potential bias, spacing and electric field intensity between adjacent circuits on electrochemical migration were discussed.

Multilayer ceramic capacitors (MLCCs) are increasingly used in harsh environments. For example, battery electric vehicles typically employ up to five times more MLCCs than an equivalent internal combustion engine vehicle. However, with exposure to humid or condensing environments, failure by electrochemical migration is an increasing issue as electronic feature sizes diminish, and voltages and environmental stresses increase. Contamination and bias in the presence of moisture facilitate electrochemical corrosion that results in lower surface insulation resistance (SIR) and this can be greatly accelerated in the presence of condensation. Therefore, it is crucial to develop rapid and dependable tests to predict the reliability of electronic components, in condensing environments. Nevertheless, reproducing repeatable levels of condensation during testing can be challenging, as most humidity chambers are designed to achieve stable, well controlled humidity and temperature conditions, but they do not offer controlled condensing options. This study employs a rapid condensation test that enables the creation of various levels of controlled condensation environments. This method uses the approach in which the test board is mounted on a platen whose temperature can be controlled independently of the humidity chamber. By reducing the test vehicle to a set temperature below the dew-point of the environment, controlled levels of condensation can be produced. This method significantly improves the repeatability and accuracy of electronic component reliability testing under such conditions. For the test, multiple test vehicles were assembled using 0603 sized MLCCs from different manufacturers, no-clean solder paste and reflow soldering. The obtained SIR result for each type of MLCCs at different condensation levels enabled a comparison of their relative performance. The results of this study confirmed that this condensation test, in combination with SIR measurements, can successfully evaluate the reliability of different types of MLCCs under identical conditions. This approach can predict potential failure mechanisms in condensing environments, helping to identify the most reliable options by observing how and when failures occur. These insights can provide a basis for design and manufacturing improvements, as well as component selection for specific applications.

With the miniaturization of the electronic devices, the spacing among the circuit traces on printed circuit boards (PCB) keeps reducing, which increases the risk of insulation failure based on electrochemical migration (ECM), especially for immersion silver (ImAg) plated PCB. Meanwhile, due to the severe air pollution in developing countries, airborne dust can deposit on the PCBs in electronic devices. The soluble salts in the dust can decrease critical humidity and increase the ion concentration in the moisture condensed on the PCB surfaces, so that the failure mechanism based on ECM may be changed and the time to failure (TTF) can be shorten. In this paper, the effect of the soluble salt with various concentrations on the ECM failure on PCB was investigated. The life model of ECM was built up based on the electrochemical reactions on electrodes. Then the ECM of PCB under sodium chloride (NaCl) solution with various concentrations was simulated on Y- pattern PCB by water drop (WD) test method. The failure characteristics of ECM during various stages of migration and under various concentrations of salt solution were analyzed by the morphology and element compositions of dendrite products, as well as real time monitoring of surface insulation resistance (SIR). The TTF of ECM was extracted to fit the life model. Finally, the mechanism and performance of ECM of PCB under salt solution was analyzed. And the application of the life model of the ECM failure of PCB contaminated by soluble salts was discussed.

Dendrites, Electrochemical Migration (ECM) and parasitic leakage, are usually caused by process related contamination. For example, excess flux, poor handling, extraneous solder, fibers, to name a few. One does not normally relate these fails with environmental causes. However, creep corrosion is a mechanism by which electronic products fail in application, primarily related to sulfur pollution present in the air. 1 The sulfur reacts with exposed silver, and to a lesser extent, exposed copper. This paper will explore various aspects of the creep corrosion chemical reaction What is driving the creep corrosion reaction? Why is drying the product a necessary precursor to obtaining creep corrosion in tests? 2, 3 Test methods with Flowers of Sulfur, FoS, and sulfur rich clay. Discussion of creep corrosion related field fails. When does creep corrosion become ECM. Sources of sulfur containing pollution. Methods to take to avoid creep corrosion. While there are places with sulfur containing pollution, creep corrosion will be a factor which will impact reliability. Creep corrosion will need to be understood and handled.

Electrical interconnection, mechanical support and electrical insulation are basic function requirements for printed circuit boards (PCB) in all of electronic products. The current trend toward miniaturization in electronics industry has forced a continuous reduction on conductor spacing. This fact has brought a greater reliability challenge to insulating properties of PCB. Short failure had become one of the most common PCB problems in field. In the present study, the various short failures had been summarized and classified into four typical categories: (1) quality defects of PCB; (2) foreign conductive metal residues on PCB; (3) electrochemical migration (ECM, conductive anodic filament (CAF) is regarded as one type of ECM) (4) ionic residues. The fault features, analysis methods, failure mechanisms and preventive measures were discussed through comprehensive analysis on the real short failure cases of each type. It is suggested identifying fault features first, which is helpful to choose proper analysis methods, then find out root failure causes accurately, and put preventive measures specifically from electronic auxiliary materials controlling, PCB quality controlling, PCB layout design or electronic assembly management.

Miniaturization and increasing voltage for e-mobility solutions both are a big challenge for the design of robust electronic devices in the automotive industry considering the harsh environmental conditions that they work in. The operation of electronic control units (ECU) in humid environments can lead to electrochemical migration (ECM) that can cause unpredictable electrical failures in cases where unsuitable materials, processes, or housing concepts are used. Due to the variety of components, materials, and assembly steps, following the common no-clean approach in the automotive industry, a complex mixture of materials with a specific ionic load and hygroscopic behavior is combined on a printed circuit board assembly (PCBA) in a way that the electrochemical reliability is not easily predictable. The simple measurement of ionic contaminants on PCBAs, as widely assumed, does not predict the reliability of the unit in the end-use-environment. Therefore, reliability testing by measurement of the surface insulation resistance (SIR) of the combination of materials that are used and processed on high volume electronic assembly lines is a fundamental task for the automotive industry. Robert Bosch GmbH has established the B52 test board (IPC-9202) and developed it further in a way that it can be used as a base for material and process release on an ECU-platform level. SIR-results from long-term testing (constant climate conditions) and from damp heat testing (environmental testing following IEC60068-3-4) with B52 test boards are presented. The results show that even under high humidity load reliable electronic devices can be achieved with the benefit of no-clean fluxes, if suitable materials and processes are chosen and controlled. The approach and results confirm that the B52 test board and content of the IPC-9202 can be successfully transferred and applied to the requirements of the automotive industry if improvements are considered. These should become part of further international standardization.

Pb-free solders incorporated with nano-sized particles have been identified, as potential Pb-free nanocomposite solders that could provide higher microstructure stability and better mechanical properties than the conventional solders. Nowadays, the miniaturizations of electronic devices increase in their usage have increased the risk of failure due to ion migration and corrosion phenomena. This research investigates the effects the electrochemical migration (ECM) and corrosion behaviour of Sn- 3.0Ag-0.5Cu (SAC305) reinforced by NiO, Fe2O3 and TiO2 nanoparticles in 0.1M NaCl solution. The SAC305 solder alloys were doped with different percentages of NiO, Fe2O3 and TiO2 at nominal percentages of 0.01, 0.05 and 0.15 wt% in producing nanocomposite solder paste. Then, the solder paste has flowed in the reflow oven at the temperature of 240°C. After that, the Water Drop Test (WDT) was performed using 0.1 M NaCl solution to investigate the ion migration behaviour and Potentiodyamic Tafel Polarization technique to determine the corrosion behaviour on the solder alloys. In general, the results showed the mean-time-to-failure (MTTF) of SAC305 solder alloy increased when added of the nanoparticles of NiO, Fe2O3 and TiO2. Besides, SAC305-TiO2 has the longest MTTF in 0.1 M NaCl solution followed by SAC305-Fe2O3 and SAC305-NiO nanoparticles. This results is believed due to the presence of nanoparticles as the alloying element in the solder that hinder the process of ECM to suppress the growth of the dendrites accelerating for the short circuit occurs and causes the failure of the IPC-24 test board. The potentiodynamic polarization curve results exhibit the SAC305 with nanoparticles decreased the corrosion rate compared with SAC305 solder alloy only. SAC305 with NiO and TiO2 have slightly lower corrosion rates compared with Fe2O3 nanoparticles. Therefore, SAC305 reinforced by TiO2, Fe2O3 and NiO nanoparticles exhibited excellent ECM and corrosion resistance behaviours in the 0.1 M NaCl solution.

Reliability is the primary concern of electronic assemblies in many applications today. The risk of electrochemical migration (ECM) is growing with new component packages and the exposition of assemblies to harsh environments. Experience shows that cleaning is the best option to enhance robustness against ECM. Also, it is often proven that cleaning must be thorough, including under components and any spaces between poles of the assembly. Such perfect cleaning requires not only dissolving and removing the flux residues to get the assembly visually clean but also removing the active ionic compounds and non-ionic or weak ionic compounds, which are invisible. Precise control of the rinsing steps is, therefore, inevitable. A previous study [3] showed that the current rinse monitoring by only conductivity is insufficient. Cleaning chemistry and flux contain different non-polar compounds, which cannot be adequately seen by conductivity change. Finally, a growing concentration of these low polar compounds causes not only a lowering of surface tension but also a dropping in surface insulation resistance values. In this study, we would like to show a new method to monitor the (so far not measured) proper function of active carbon filter in the close-looped rinsing system. We introduced the principle of such measuring at the SMTA Harsh conference in 2022. Also, we introduce the engineering method, how to simulate the practical loading of a cleaning machine by pollution of dissolved flux residues in the field, how to shorten and capture such process, and what possible reality distortions can occur.

This paper is in English and Chinese languages. Conformal coatings have been used for many years in markets requiring high reliability like automotive, military, aerospace and energy, to protect Printed Circuit Board Assemblies (PCBAs) operating under harsh environmental conditions such as high humidity, vibrations, presence of solvents, corrosive atmosphere... Use of conformal coating will increase in the coming years due to the demand to improve performance and lifetime of electronics, also to increase reliability of circuits due to miniaturization, and the growth of some markets including inverters, electronics in automotive, etc To ensure an optimal performance of a coating over a PCBA, cleaning the flux residues as well as all the contaminants before coating is a must. However, due to the additional costs of this cleaning step, sometimes it is not considered as an option in several markets (i.e, Automotive, Energy) using today no clean materials. This paper describes the performance of several kinds of conformal coatings (acrylics, polyurethanes, UV cured) over no-clean lead free solder paste residues. The physical and chemical compatibility will be assessed using several techniques. After a description of the coatings and pastes chemistries used in the study, the compatibility before curing will be investigated (influence of viscosity, surface tension, thickness … ) Second, the adhesion properties of the coatings after curing on different surfaces including lead free solder paste residues will be evaluated. Finally, Surface Insulation Resistance (SIR), Electrochemical Migration (ECM) tests and Bono corrosion test - which has been proven to better differentiate the nature of solder pastes residues- will be used for the chemical compatibility. It will be shown that several tools are necessary and complementary to anticipate the performance of conformal coatings with no-clean pastes residues due to the different kinds of coatings and pastes chemistries.

The spread of the Covid-19 virus which is still increasing requires the Indonesian government to issue a policy to limit mobility for the sake of the nation's recovery. In the end, community activity in public places decreased and community activity in the house increased. This causes an increase in internet usage traffic, including digital transactions. Banking is one of the industries that also plays a major role in digital transactions, one of which is Bank BCA which has been the largest and most trusted private bank in Indonesia since 1957. The study will use six variables, namely product quality, service quality, environment quality, product assortment, customer satisfaction, and customer loyalty on the BCA Mobile application. This study uses a quantitative approach with Structural Equation Model (SEM) analysis techniques and AMOS 22.0 software. Collecting data in this study using an online questionnaire to 100 respondents with the characteristics of men and women who live in Surabaya and aged 18-60 years who have used the BCA Mobile application at least three times in the last six month. The results of this study indicate that product quality has a significant effect on customer satisfaction with a regression coefficient of 0.354 but product quality has no significant effect on customer loyalty with a regression coefficient of 0.059, service quality has a significant effect on customer satisfaction with a regression coefficient of 0.520 and service quality also has a significant effect. on customer loyalty with a regression coefficient of 0.283, environment quality has a significant effect on customer satisfaction with a regression coefficient of 0.480 and environment quality also has a significant effect on customer loyalty with a regression coefficient of 0.287, product assortment has no significant effect on customer satisfaction with a regression coefficient of 0.060 and product assortment also has no significant effect on customer loyalty with a regression coefficient of 0.097, and customer satisfaction has an effect significant to customer loyalty with a regression coefficient of 0.312.

Field programmable gate arrays (FPGAs) have drawn wide attention from nuclear power industry for digital instrument and control applications (DI&C), because it’s much easier and simpler than microprocessor-based applications, which makes it more reliable. FPGAs can also enhance safety margins of the plant with potential possibility for power upgrading at normal operation. For these reasons, more and more nuclear power corporations and research institutes are treating FPGA-based protection system as a technical alternative. As nuclear power industry requires high reliability and safety for DI&C Systems, the development method and process should be fully verified and validated. For this reason, to improve the application of FPGA in NPP I&C system, the specific test methods are critical for the developers and regulators. However, current international standards and research reports, like IEC 62566 and NUREG/CR-7006, which have demonstrated the life circle of the development of FPGA-based safety critical DI&C in NPPs, but the specific test requirements and methods which are significant to the developers are not provided. In this paper, the whole test process of a pressurized water reactor (PWR) protection sub-system (Primary Coolant Flow Low Protection, Over Temperature Delta T Protection, Over Power Delta T Protection) is described, including detail component and integration tests. The Universal Verification Methodology (UVM) based on System Verilog class libraries is applied to establish the verification test platform. All these tests are conducted in a simulation environment. The test process is driven by the test coverage which includes code coverages (i.e., Statement, Branch, Condition and Expression, Toggle, Finite State Machine) and function coverage. Specifically, Register Transaction Level (RTL) simulation is conducted for Component tests, while RTL simulation, Gate Level simulation, Timing simulation and Static timing analysis are conducted for the integration test. The issues (e.g., the floating point calculation, FPGA resource allocation and optimization) arose in the test process are also analyzed and discussed, which can be references for the developers in this area. The component and integration tests are part of the Verification and Validation (V&V) work, which should be done by the V&V team separated from the development team. The testing method could assure the test results reliable and authentic. It is practical and useful for the development and V&V of FPGA-based safety DI&C systems.

Since 1993, many BGA board level manufacturability and reliability related papers have been published. Many of them were based on simple and non-product-oriented test boards. It is believed that a product-oriented BGA test vehicle design, assembled in a production environment, will provide more direct applicable information to BGA package users, and thus improve manufacturability and reliability of products utilizing BGA technology.

The New England Lead-free Electronics Consortium is a collaborative effort of New England companies spanning the electronics supply chain, created by the University of Massachusetts Lowell in 1999 and sponsored by the Toxics Use Reduction Institute and the U.S. EPA. The consortium has completed and published the results of three phases of manufacturing and testing of lead-free Printed Wiring Boards (PWBs) with the goal of achieving zero-defect leadfree soldering processes with comparable or superior reliability to that of leaded solder processes. In this fourth phase of testing, which began in 2007, several simulated conditions of assembly and rework processes were evaluated in a matrix of multiple levels of components, PWB lead free surface finishes and solders, and compared to a baseline of leaded equivalent materials and processes. Both Through Hole (THT) and Surface Mount (SMT) Technologies were evaluated. The assembly portion of the testing and rework is completed and the long term reliability and vibration is ongoing. All quality and reliability testing was performed with industry standard methodologies, using specially trained production inspectors for the quality evaluation, and extreme thermal cycling for reliability testing. Our results indicate that with proper selection of currently available (2008) materials and finishes and careful control of the assembly processes, successful lead free assembly and rework can be achieved. Comparison of different strategies for rework, and recommendations for least copper dissolution for THT technology processes are discussed in the published book by the paper authors. Reliability testing to date showed interesting inflection points for leaded versus lead free reliability that has to be resolved by additional thermal cycling, to be published when completed in 2009, together with vibration testing.

Gallium oxide power devices (GaO power devices) have attracted significant attention in the field of power electronics due to their excellent wide bandgap characteristics. This paper analyzes their operating principles, including device structure and operational characteristics, and discusses the key factors affecting reliability as well as the current state of research. Particular emphasis is placed on the physicochemical mechanisms of thermal failure and electrical breakdown failure, revealing the complexity of failure behaviors. Reliability testing methods, such as mechanical stress testing and accelerated lifetime testing, are also introduced. Finally, strategies for improving reliability through material enhancements (such as doping techniques) and process optimization are proposed, providing guidance for the research, development, and application of gallium oxide power devices.