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The purpose of this paper is to attempt to study the failure mechanism of BGA (ball grid array) Cu wire bond ball lift and specifically focused on substrate outgassing’s impact on Cu wire bonding quality and reliability.

The Galvanic corrosion theory has been widely adopted in explaining the failure mechanism of Cu ball bond lift issue during reliability test or field application in the presence of moisture. In this study, ion chromatography was performed on BGA substrate halogen analysis. EDX (energy-dispersive X-ray spectroscopy) was also used to detect the contaminant’s element at the bottom surface of a window clamp. Further FTIR (Fourier transform infrared spectroscopy) analysis verified that the contamination is from substrate outgassing during wire bonding. A new window clamp design proved effective in reducing the negative impact from substrate outgassing during wire bonding.

The solder mask in a fresh substrate contains a chlorine element. The chlorine can be detected in the BGA substrate outgassing during wire bonding by FTIR and EDX analyses, which have a negative impact on the Cu wire bonding. The window clamp with a larger opening can reduce the negative impact of the Cu wire bonding from the BGA substrate outgassing.

Because of the limitation of time and resources, bonding pad surface contamination from substrate outgassing and its correlation with Cu bonding ball lift failure after reliability test will be studied in depth later.

The BGA substrate outgassing has negative impacts on Cu wire bondability. A window clamp with a larger opening can reduce the negative impact from substrate outgassing.

The purpose of this paper is to investigate the reliability of wire bonds with three varying ball bond diameters, which are ball bonded with three different sizes of gold wires in light-emitting diode (LED) package under high-temperature environment. In automotive applications, “lifted ball bond” issue is a potential critical point for LED device reliability, as the wire bonds are usually stressed under high operating temperature during their lifetime. Moreover, the reliability of wire bonds in recent LED production has fallen under scrutiny due to the practice of reducing wire diameters to cut down production costs.

Three gold wires with sizes of 2, 1.5 and 1 mm were ball bonded on the LED chip bond pad via thermosonic wire bonding method to produce three different ball bond diameters, that is, 140, 120 and 100 μm, respectively. The reliability of these wire bond samples was then studied by performing isothermal aging at 200°C for the time interval of 30, 100 and 500 hours. To validate hypotheses based on the experimental data, COMSOL Multiphysics simulation was also applied to study the thermal stress distribution of wire bond under an elevated temperature.

Experimental results show that the interfacial adhesion of wire bond degrades significantly after aging at 200°C for 500 hours, and the rate of interfacial degradation was found to be more rapid in the wire bond with smaller ball bond diameter. Experimental results also show that ball bonds randomly elongate along an axis and deforms into elliptical shapes after isothermal aging, and ball bonds with smaller diameters develop more obvious elongations. This observation has not been reported in any previous studies. Simulation results show that higher thermal stress is induced in the wire bond with the decrease of ball bond diameter.

The reliability study of this paper provides measurements and explanation on the effects of wire diameter downsizing in wire bonds for automotive application. This is applicable as a reliability reference for industries who intend to reduce their production costs. Other than that, the analysis method of thermal stresses using COMSOL Multiphysics simulations can be extended by other COMSOL Multiphysics users in the future.

To resolve “lifted ball bond” issue, optimization of the bond pad surface quality and the wire bond parameter has been studied and reported in many studies, but the influence of ball bond diameter on wire bond reliability is rarely focused. Moreover, the observation of ball bonds randomly elongate and deform more into elliptical shape, and ball bond with smaller diameter has the highest elongation after isothermal aging also still has not been reported in any previous studies.

The purpose of this paper is to investigate the efficiencies of argon (Ar), oxygen (O₂) and O₂ followed by Ar (O₂→Ar) plasma treatments in terms of contaminant removal and wire bond interfacial adhesion improvement. The aim of this study is to resolve the “lifted ball bond” issue, which is one of the critical reliability checkpoints for light emitting diodes (LEDs) in automotive applications.

Ar, O₂ and O₂→Ar plasma treatments were applied to LED chip bond pad prior to wire bonding process with different treatment durations. Various surface characterization methods and contact angle measurement were then used to characterize the surface properties of these chip bond pads. To validate the improvements of Ar, O₂ and O₂→Ar plasma treatments to the wire bond interfacial adhesion, the chip bond pads were wire bonded and examined with a ball shear test. Moreover, the contact resistance of the wire bond interfaces was also measured by using four-point probe electrical measurements to complement the interfacial adhesion validation.

Surface characterization results show that O₂→Ar plasma treatment was able to remove the contaminant while maintaining relatively low oxygen impurity content on the bond pad surface after the treatment and was more effective as compared with the O₂ and Ar plasma treatments. However, O₂→Ar plasma treatment also simultaneously reduced high-polarity bonds on the chip bond pad, leading to a lower surface free energy than that with the O₂ plasma treatment. Ball shear test and contact resistance results showed that wire bond interfacial adhesion improvement after the O₂→Ar plasma treatment is lower than that with the O₂ plasma treatment, although it has the highest efficiency in surface contaminant removal.

To resolve “lifted ball bond” issue, optimization of plasma gas composition ratios and parameters for respective Ar and O₂ plasma treatments has been widely reported in many literatures; however, the O₂→Ar plasma treatment is still rarely focused. Moreover, the observation that wire bond interfacial adhesion improvement after O₂→Ar plasma treatment is lower than that with the O₂ plasma treatment although it has the highest efficiency in surface contaminant removal also has not been reported on similar studies elsewhere.

November 28, 1967 Factory — Lifting tackle — Hook — Steelworks — Removal of scab — Hook placed under it — Hook suspended from chain of crane — Strain taken up by crane to enable brick to be placed under scab — Whether “raising” operation — Factories Act, 1961 (9 & 10 Eliz. II. c.34), s. 26(1).

MANY who realise the implications of White's book on The Organisation Man have probably closed it with the self‐satisfied reflection that ‘it can't happen here.’ That is the anodyne we generally swallow to protect us from disagreeable fears.

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.

THE Fourth European Work Study Congress, held in Paris during the third week of May, was a well‐organized affair. A tribute is due to M. Loubert and his colleagues for the way in which they devised such well‐lubricated machinery for the convenience of their guests and for the imaginative touch of holding the official dinner aboard a bateau‐mouche as it sailed for two hours up and down the Seine.

The purpose of this paper is to review recent advances in fine and ultra‐fine pitch wire bonding.

Dozens of journal and conference articles published recently are reviewed.

The problems/challenges such as possible wire sweep and decreased bonding strength due to small wire sizes, non‐sticking, metal pad peeling, narrow process windows, wire open and short tail defects are analysed. The solutions to the problems and recent findings/developments in fine and ultra‐fine pitch wire bonding are discussed.

Because of the page limitation, only brief discussions are given in this paper. Further reading is needed for more details.

This paper attempts to provide an introduction to recent developments and the trends in fine and ultra‐fine pitch wire bonding. With the references provided, readers may explore more deeply by reading the original articles.

The purpose of this case study is to identify and develop maintenance performance indicators (MPIs) for a mineral processing plant producing high quality iron ore pellets, as well as studying and analyzing the short plant stops and planned maintenance stops.

An action research approach was adopted for this study, with interactive process of interviews. The existing MPIs are analyzed and a set of MPIs are developed to measure the performance of balling area of the pelletization plant, where the effect of shorter stops in the process have been studied, analyzed and measured, and linked to the management's objectives. The utility of the MPIs are tested and validated within the framework of a multi‐criterion and hierarchical maintenance performance measurement (MPM) framework. The plant stop data of the plant were collected and analyzed for MPIs and for maintenance decision making. Some other criteria were also considered from a holistic, integrated and balanced viewpoint in the model.

This study resulted in identifying a set of MPIs for the operational level of the pelletization plant of LKAB, after analyzing the short plant stops and planned maintenance stops data, and the stakeholders' requirements. This study has identified nine MPIs at operational level or shop floor level that describe the status of plant and at the same time facilitates linking of plant performance with corporate strategy.

The approach used in the paper to study, analyze and develop MPIs, can be useful for plant managers and asset owners to select and develop MPIs that can describe the health status of their plant and asset and that also can be linked to the corporate strategy. The framework used to verify the multi‐criteria hierarchical framework can also be used by similar asset managers and infrastructure owners. This study has also lifted the impact of short duration stoppages, thus highlighting the total influence in terms of reduced life length, quality and productivity. This approach can be used by plant engineers, asset managers and infrastructure owners to assess the performance of maintenance process.

This paper presents an approach for identifying MPIs relevant to the plant status and facilitating measuring maintenance performance at corporate level in a structured way.

In this article, a detailed design of a novel power line inspection robot is studied. This robot can be used to move on ground wires for special purposes such as inspection and fault detection of electric power lines. The paper aims to discuss these issues.

Designed active and passive mechanisms in the proposed robot enable it to move over various obstacles on ground wires, such as clamps, warning balls and mast tips. Indeed, this robot is the first designed robot with the capability of moving over all ground wire obstacles. The active mechanisms contain seven rubber-coated rollers (i.e. four vertical rollers and three horizontal rollers) as well as three mechanisms in order to make horizontal rollers move vertically. The passive mechanisms also include a set of spring-dampers installed in each joint of robot arms.

The simulation results in the ADAMS software revealed a desirable stability of performance when moving on the ground wires with a maximum slope of 30-degree. Also, the robot showed a suitable performance when passing over the warning balls (with a maximum diameter of 700 mm), rectangular mast tips (170×170 mm) and mast tips with a 30-degree twist in the horizontal plane.

The feasibility of these maneuvers is proved with a prototype implementation and successful test results. This robot is approximately 60 kg weight and can move in ground wires with maximum speed of 20 m/min.

The proposed robot is able to move on ground cable and pass over different kinds of obstacles like warning balls and mast tips (straight and angular) with maximum speed of 20 m/min.