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The purpose of this paper is to provide a systematic method to perform long‐term reliability assessment of gold (Au) and copper (Cu) ball bonds in fineline ball grid array package. Also with the aim to study the apparent activation energies (E_aa) and its associated wearout mechanisms of both Au and Cu wire in semiconductor device packaging. This paper discusses the influence of wire type on the long‐term reliability and mechanical performance after several component reliability stress tests.

A fineline ball grid array (FBGA) package with Cu and Au wire bonds was assembled with green molding compound and substrate. Samples are subjected for long‐term high temperature storage bake test at elevated temperatures of 150°C, 175°C and 200°C. Long‐term reliability plots (lognormal plots) are established and E_aa of both ball bonds are determined from Arrhenius plots. Detailed failure analysis has been conducted on failed sample and HTSL failure mechanisms have been proposed.

Reliability results show Au ball bond in FBGA package is observed with higher hour‐to‐failure compared to Cu ball bonds. The E_aa value of high temperature storage life (HTSL) reliability for Au ball bond is lower than Cu ball bond. Typical HTSL failure mechanism of Au ball bond is induced by micro‐voiding and AuAl intermetallic compound (IMC) micro‐cracks while CuAl IMC micro‐cracking (induced by Cl⁻ corrosion attack and micro‐cracking) caused wearout opens in Cu ball bond. These test results affirm the test‐to‐failure data collected is a useful method for lifetime prediction and E_aa calculation.

The paper reveals higher reliability performance of Cu ball bond in FBGA flash memory package which can be deployed in flash memory FBGA packaging with optimised package bill of materials.

The test‐to‐failure methodology is a useful technique for wearout reliability prediction and E_aa calculation.

Solder joint failure history has generally been assumed to follow a straight line when plotted as a lognormal or 2‐parameter Weibull distribution. Test results presented here show that a deviation from straight‐line behaviour occurs at low percentage failure probabilities. This indicates that solder joint failure history is more correctly characterised as a 3‐parameter Weibull distribution with a failure‐free period of life for true wearout failures. The solder joint failure distribution characteristic is also affected by applied strain. Lower strain, in addition to increasing median life, also improves the distribution such that the number of cycles‐to‐first‐failure is increased compared with the median cycles‐to‐failure. The ratio of cycles‐to‐first‐failure/median cycles‐to‐failure and apparent Weibull slope increases as strain decreases in a predictable manner. The effects of part elevation, part size, solder joint volume and shape, conformal coating, temperature differential, and alternative board materials are also presented with test data showing the effect of variation of these parameters.

The objectives of this article are: 1 to give an overview of some basic ideas that were outlined in an earlier review paper by the author; 2 to bring it up to date by outlining the more important theoretical developments that have been reported since then; 3 to mention briefly some speculations arising from work in progress which has not yet been published.

The purpose of this paper is to propose a framework of decision making to aid practitioners in modeling and optimization experimental data for improvement quality of industrial processes, reinforcing idea that planning and conducting data modeling are as important as formal analysis.

The paper presents an application was carried out about the modeling of experimental data at mining company, with support at Catholic University from partnership projects. The literature seems to be more focussed on the data analysis than on providing a sequence of operational steps or decision support which would lead to the best regression model given for the problem that researcher is confronted with. The authors use the concept of statistical regression technique called generalized linear models.

The authors analyze the relevant case study in mining company, based on best statistical regression models. Starting from this analysis, the results of the industrial case study illustrates the strong relationship of the improvement process with the presented framework approach into practice. Moreover, the case study consolidating a fundamental advantage of regression models: modeling guided provides more knowledge about products, processes and technologies, even in unsuccessful case studies.

The study advances in regression model for data modeling are applicable in several types of industrial processes and phenomena random. It is possible to find unsuccessful data modeling due to lack of knowledge of statistical technique.

An essential point is that the study is based on the feedback from practitioners and industrial managers, which makes the analyses and conclusions from practical points of view, without relevant theoretical knowledge of relationship among the process variables. Regression model has its own characteristics related to response variable and factors, and misspecification of the regression model or their components can yield inappropriate inferences and erroneous experimental results.

The behaviours of the electric and magnetic fields inside a conducting cylinder with a single axial aperture are not as well understood as is commonly believed. The experimental measurements and computer simulations described in this paper comprise a work in progress. The intention of the work is to use the conducting cylinder with a single axial aperture as a standard test object, in order to demonstrate present capabilities in measuring field strengths inside such a test object and to demonstrate the level of agreement attainable with commonly used computer codes. As the following experimental data will show, current free‐field B‐dot sensors cannot be used for measurements inside cavities, as they significantly perturb the fields they are trying to measure. There is indeed a pressing need to develop such nonperturbing sensors for use inside cavities.

To assess and improve the reliability of computerized numerical control (CNC) lathes, it is essential to collect field failure information throughout the products’ life and perform analysis on these data. This paper describes the collection of field failure data, codification of data and establishment of the field failure database for CNC lathes and gives some examples of the kind of analysis possible when sufficient data have been collected and the database has been accrued.

Aims to explain the main requirements for printed circuit boards (PCBs) and to determine the survival rate of boards in lead‐free assembly.

The first two main requirements are the survival of 5‐6 cycles lead free reflow with peak temperatures of up to 260°C and an identical or even better board reliability of such boards compared to todays eutectic soldered ones. In a first series of tests the influence of base materials, reflow temperature gradient and peak temperature on PCB survival rate are investigated. Thermo‐mechanical data of different epoxy‐based materials are compared to survival rate investigations using repeated reflow tests. The impact of PCB manufacturing and design on the lead free performance is discussed. A second series of investigations is air‐to‐air life cycle tests of daisy chain boards out of different epoxy‐based materials with varying preconditioning were done.

The tests showed that dicy cured epoxy base materials are not able to withstand the thermal stress of the mentioned soldering steps. Board design and the heating gradient in reflow also influence the assembly performance. Thermal cycling tests (air‐to‐air), showed clearly the effect of reflow temperature and number of reflow cycles on through‐hole reliability. There was no significant impact of z‐axis‐expansion on the through‐hole failure rate in air‐to‐air cycling.

Provides further information on the lead‐free assembly of PCBs.

This paper focuses on the comparative study on reliability performance of various surface coatings. Only brief descriptions of coating processes, material physical properties, costs, and their applications are given.

Aims to investigate the causative factors and clinical applicability of spontaneous regression of malignant tumours without treatment, a really paradoxical phenomenon with many therapeutic potentialities. Analyses past cases to find that the commonest cause is a preceding episode of high fever‐induced thermal fluctuation which produces fluctuation of biochemical/immunological parameters. Using Prigogine‐Glansdorff‐Langevin stability theory and biocybernetic principles, develops the theoretical foundation of a tumour’s self‐control, homeostasis and regression induced by thermal, radiation or oxygenation fluctuations. Derives a threshold condition of perturbations for producing regression. Presents some striking confirmation of such fluctuation‐induced regression in Ewing tumour, Clear cell cancer and Lewis lung carcinoma. Using experimental data on patients, elucidates a novel therapeutic approach of multi‐modal hyper‐fluctuation utilizing radiotherapeutic hyper‐fractionation, temperature and immune‐status.

The potential advantage of extreme value theory in modeling management phenomena is the central theme of this paper. The statistics of extremes have played only a very limited role in management studies despite the disproportionate emphasis on unusual events in the world of managers. An overview of this theory and related statistical models is presented, and illustrative empirical examples provided.