Reliability aspects of electronic devices for advanced requirements

Purpose – This paper aims to detail the qualification of alternative substrate materials and reliability aspects for quad flat no lead (QFN) packages for highly stressed electronic devices, e.g. for use in automotive applications. Design/methodology/approach – Detailed information is given on the advanced climatic and mechanical requirements that electronic devices have to withstand during life cycle testing to qualify for the automotive industry. Studies on the suitability of high-temperature thermoplastics as substrate materials for printed circuit boards and the qualification of QFN packages for advanced requirements are described. In addition, information on cause-effect relationships between thermal and vibration testing are given. Findings – With respect to adhesion of metallization on high-temperature thermoplastics and the long-term stability of the solder joints, these substrate materials offer potential for use in electronic devices for advanced requirements. In addition, the long-term stability of the solder joints of QFN packages depends on the design of the landings on the PCB and the separation process of the components during manufacturing. Research limitations/implications – The paper covers only a selection of possible high-temperature thermoplastic materials that can be used in electronics production. Also, this paper has a focus on the new packaging type, QFN, in the context of qualification and automotive standards. Originality/value – The paper details the requirements electronic devices have to meet to be qualified for the automotive industry. Therefore, this contribution has its value in giving information on possible substrate alternatives and the suitability for the usage of QFN components for highly stressed electronic devices

Advances in pulmonary monitoring and thoracic imaging

The high incidence of pulmonary disease in critically ill patients necessitates new and improved techniques for pulmonary monitoring and thoracic imaging. To investigate pulmonary monitoring techniques using pressure and flow signals, I developed a comprehensive computational model of subjects breathing spontaneously or with the support of an assist-ventilator. The model was used to quantitatively assess measurement techniques for dynamic intrinsic positive end-expiratory pressure (PEEP$rm sb{i})$ and inspiratory work of breathing. The results demonstrate that some means of correction for both expiratory muscle activity and cardiogenic oscillations on esophageal pressure is necessary if dynamic PEEP$rm sb{i}$ and work of breathing are to be measured accurately on-line. I also conclude that the discrepancies between static and dynamic PEEP$rm sb{i}$ are caused by heterogeneity of the expiratory flow limitation. An adaptive filter to reduce the cardiogenic oscillations on esophageal pressure was developed and validated in a computer simulation. In four intensive care patients, the adaptive filter markedly attenuated the apparent cardiogenic oscillations and reduced the standard deviation of the measured PEEP$rm sb{i}$ by 57%. Investigation of the interactions between patients and a pressure support ventilator using the computer model confirmed our present understanding of patient-ventilator asynchrony and indicated that patient and ventilator form a highly nonlinear dynamic system, so that the optimal ventilator settings most likely vary between patients and with time. In the second part of this thesis, I investigated the importance of inaccuracies in conventional Finite Elements for thoracic Electrical Impedance Tomography (EIT) imaging. Augmenting the number of first-order Finite Elements did not efficiently reduce these inaccuracies. A computer simulation suggested that the accuracy of the forward solution needs to be improved by at least 30 dB before usefu

Influences on the reflow soldering process by components with specific thermal properties

Purpose – The purpose of the paper is to focus on the research into components with specific thermal properties and their influences on the reflow soldering process. Design/methodology/approach – After a brief introduction, the paper gives an overview of the necessity of thermal management on printed circuit boards (PCBs) and the possible effects on the manufacturing of electronic devices. In the next sections, different test boards are presented for investigations into different thermal effects during soldering. The last section deals with the influences of molded interconnected devices (MIDs) on the reflow soldering process. Findings – The investigations show that components from the thermal management influence the reflow soldering process more or less. The highest impacts on the soldering process are from components with a thermal connection to the electrical component and its solder joint. All results from the investigations have in common that the thermal influence can only be compensated by increasing the temperature during soldering. However, this significantly increases the risk of overheating the electrical components or the PCB itself. Research limitations/implications – This paper shows only the influence of some of the effects caused by thermal management on the reflow soldering process. Furthermore, vapour phase soldering is not considered, but actual investigations are carried out on vapour phase soldering ovens as well. Originality/value – Thermal management becomes more and more important with the increasing functionality of electrical components and electronic devices. This topic has been the subject of a large number of articles. However, this paper deals with influences that thermal management has on the soldering process during the manufacturing of the electronic device

Selection and qualification of polymers for rigid and flexible interconnect applications

Purpose – This paper seeks to give an overview on the benefits and challenges of moulded interconnect devices-technology and the use of flexible printed circuits (FPC) in electronics production. Design/methodology/approach – Each process step was adapted to the boundary conditions of manufacturing three-dimensional substrates and FPC. The substrate materials were examined under the specific requirements of electronics production with a special focus on the thermal stability of the materials and the adhesiveness of the metallization. Findings – The use of thermoplastics as substrate materials for electronic devices offers high potential but new challenges, e.g. the higher coefficient of thermal expansion of thermoplastics, have to be taken into consideration as well. In most cases, standard machines for surface mount technology can be used with few modifications. Research has shown that even components with very fine pitches can be used successfully on alternative substrate materials. Research limitations/implications – The paper covers a selection of possible thermoplastic materials that can be used in electronics production. Depending on the requirements of the application and the operating environment other substrate materials open up a large variety of possible solutions. Originality/value – The paper details the most promising thermoplastic materials for use in electronics production as rigid and FPC. Furthermore, it gives information about manufacturing guidelines for the production of three-dimensional circuit carriers

The effect of iron deficiency on cardiac resynchronization therapy: results from the RIDE‐CRT Study

Aims Cardiac resynchronization therapy (CRT) improves functional status, induces reverse left ventricular remodelling, and reduces hospitalization and mortality in patients with symptomatic heart failure, left ventricular systolic dysfunction, and QRS prolongation. However, the impact of iron deficiency on CRT response remains largely unclear. The purpose of the study was to assess the effect of functional and absolute iron deficiency on reverse cardiac remodelling, clinical response, and outcome after CRT implantation. Methods and results The relation of iron deficiency and cardiac resynchronization therapy response (RIDE-CRT) study is a prospective observational study. We enrolled 77 consecutive CRT recipients (mean age 71.3 ± 10.2 years) with short-term follow-up of 3.3 ± 1.9 months and long-term follow-up of 13.0 ± 3.2 months. Primary endpoints were reverse cardiac remodelling on echocardiography and clinical CRT response, assessed by change in New York Heart Association classification. Echocardiographic CRT response was defined as relative improvement of left ventricular ejection fraction ≥ 20% or left ventricular global longitudinal strain ≥ 20%. Secondary endpoints were hospitalization for heart failure and all-cause mortality (mean follow-up of 29.0 ± 8.4 months). At multivariate analysis, iron deficiency was identified as independent predictor of echocardiographic (hazard ratio 4.97; 95% confidence interval 1.15–21.51; P = 0.03) and clinical non-response to CRT (hazard ratio 4.79; 95% confidence interval 1.30–17.72, P = 0.02). We found a significant linear-by-linear association between CRT response and type of iron deficiency (P = 0.004 for left ventricular ejection fraction improvement, P = 0.02 for left ventricular global longitudinal strain improvement, and P = 0.003 for New York Heart Association response). Iron deficiency was also significantly associated with an increase in all-cause mortality (P = 0.045) but not with heart failure hospitalization. Conclusions Iron deficiency is a negative predictor of effective CRT therapy as assessed by reverse cardiac remodelling and clinical response. Assessment of iron substitution might be a relevant treatment target to increase CRT response and outcome in chronic heart failure patients