Modern Electronic Industry Research Articles

Nanoindentation Experiments at Elevated Temperatures for the Determination of Mechanical Solder Material Properties

AbstractThe continuous effort of modern electronic industry is the miniaturization of microelectronic components. In order to guarantee the reliability of the joining process, the quantitative knowledge of the solder material properties is very important, especially the values of Young's modulus, Nanoindentation hardness and yield stress. However, small‐sized microelectronic devices require the fabrication of small sized specimens and the use of corresponding miniature material tests. At the Technische Universität Berlin nanoindentation tests are applied. Moreover the material properties at elevated temperature are of particular interest in order to characterize the solder materials more detailed. This work describes the setup and the elevation of high‐temperature nanoindentation tests in context with first results for selected materials. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Profile of the wafer level ECD gold bumps under variable parameters

The uniformity and deformation of electrochemical deposition (ECD) bumps get more and more important with the pitch shrinking and density increasing according to the requirement of modern electronic industry. In this paper, wafer level diameter and thickness distribution, surface roughness and hardness of Au bumps were characterized under different electroplating current densities and bath temperatures. Some valuable results were obtained. First, the diameter of ECD Au bumps was enlarged for 5–30 μm at all positions on the wafer for both the bumps of 10–100 μm diameters. Electroplated at 40 °C, the diameter distribution of Au bumps was similar to that of photoresist. While electroplated at 60 °C, its distribution was more symmetric. Second, more uniform thickness distribution of Au bumps was obtained when the bath temperature increased from 40 to 60 °C or the electroplating current density decreased from 8 to 3 mA/cm2. Third, the Au bumps electroplated at 60 °C exhibited the surface roughness of 105–125 nm independent of electroplating current densities. The Au bumps electroplated at 40 °C exhibited the surface roughness of 40–45 nm for 3 mA/cm2 and 5 mA/cm2 and 923.45 nm for 8 mA/cm2. Fourth, the hardness of Au bumps decreased with electroplating temperature increasing from 40 to 60 °C. The difference of hardness got at between 40 and 60 °C can be vanished by the following anneal process at 60 °C. In addition, the big differences among different current densities electroplated at 40 °C can also be vanished by the anneal process. Finally, possible reasons leading to above results were discussed.

Comparison between two processes using oxygen in the Cu/AlN bonding

The modern electronics industry uses, at the present time, increasingly high intensities of current which produce large quantities of heat which can be dissipated by using a ceramic substrate, having a high thermal conductivity associated with a high electrical resistivity. Aluminium nitride with a good electrical resistivity and thermal conductivity (between 170 and 220 W m −1 K −1) closed to copper, can fulfil this role on condition that its interface with the metal, generally copper, allows an acceptable thermal conduction. On ordinary conditions, it is not possible to get a direct good junction between Cu and AlN. An eutectic phase is necessary to ensure both thermal continuity and good mechanical resistance. This eutectic phase can be seen on the thermodynamic copper-oxygen phase diagram, and is easily formed at 1065 °C. In all cases, oxygen is brought to the interface by copper oxide Cu 2O and by alumina systematically formed by oxidation at the surface of AlN. Two processes have been investigated: - the layer of Cu 2O is formed by oxidation of Cu by oxygen before the contact; - the copper oxide is formed in situ at the interface during contact. These processes require the control of the contact parameters of copper on aluminium nitride: thickness of Cu 2O formed, partial pressure of oxygen, temperature, contact time, are important parameters of the both processes. Good connections between copper and ceramic have been obtained by these methods. The analysis of the interfaces by electron microscope, highlight in all cases the role of residual oxygen. Ceramic metal adherence, has been evaluated by mechanical tests and the heat transfer through the interface, has been measured by the flash-laser technique. The results lead to values of thermal resistance of contact (1.7 × 10 −6 m 2 W −1 K −1) largely improved compared to commercial assemblies by direct bonding copper (7 × 10 −6 m 2 W −1 K −1).

Thermal analysis and optimization for a ball grid array package

In this study, a computational fluid dynamics (CFD) approach is employed for heat transfer analysis of a ball grid array (BGA) package that is widely used in the modern electronics industry. Owing to the complicated geometric configuration of the BGA package, the submodel approach is used to investigate in detail the temperature distributions of thermal vias and solder balls. The effective thermal resistance of a BGA package has been successfully obtained from numerical simulations. An artificial neural network (ANN) is trained to establish the relationship between the geometry input and the thermal resistance output. The well-trained network is then coupled with the complex optimization method to search for the optimum design of the BGA package to achieve the lowest thermal resistance. The results of this study provide the electronic packaging industry with a reliable and rapid method for heat dissipation design of BGA packages.

The origins and evolution of the PCB: a review

Many people believe that Eisler invented the printed circuit board (PCB) in the mid‐1930s, but the origins actually lie nearly before 50 years this. If this is true then who invented the PCB? This review offers an alternative view of the history of the PCB including early developments and contributions from the world of art and printing, through innovations in science and engineering to the key developments of the modern electronics industry.

Handling plastics containing brominated flame retardants — part 2

Brominated flame retardants are known for their very efficient role in saving lives and goods due to their optimal combination of properties. They are found in many places in our daily lives and they are vital to the modern electronics industry. Large quantities of styrenic copolymers are used in the electronic industry to produce housings for television sets, PC monitors and printing machines. These applications are very demanding in terms of weight reduction, impact strength, in some case color stability and above all cost reduction. New flame retardant systems developed by the Dead Sea Bromine Group to cope with this challenge will be discussed in this paper. Moreover these new flame retardants are not related to diphenyl oxide chemistry in order to satisfy users who may be sensitive to this.

New flame retardant systems for styrenic plastics and method of preparation

Brominated flame retardants are known for their very efficient role in saving lives and goods due to their optimal combination of properties. They are found in many places in our daily lives and they are vital to the modern electronics industry. Large quantities of styrenic copolymers are used in the electronic industry to produce housings for television sets, PC monitors and printing machines. These applications are very demanding in terms of weight reduction, impact strength, in some case color stability and above all cost reduction. New flame retardant systems developed by the Dead Sea Bromine Group to cope with this challenge will be discussed in this paper. Moreover these new flame retardants are not related to diphenyl oxide chemistry in order to satisfy users who may be sensitive to this.

Modeling Solder Joint Fatigue Life for Gullwing Leaded Packages: Part I—Elastic Plastic Stress Model

It is a challenge to assess solder joint fatigue life in the modern electronics industry because of complex geometries, complex non-linear viscoplastic material properties, and the frequently changing environmental conditions. The first step in the fatigue life assessment process is to find the stress distribution in the solder. Traditionally, this has been done using numerical tools like finite element methods. The finite element approach requires a highly trained and experienced analyst and huge computing resources, while the accuracy is always questioned. This study aims to develop a more accurate analytical-cum-empirical model to predict critical stresses in the solder joint so as to avoid the necessity of finite element simulation. This paper presents a generic elastic-plastic stress model that is obtained based on theoretical stress analysis solutions that is tweaked by using a design of experiments technique with FEA simulations.

Porous-Core Electrode for Emission Spectroscopy

A core was made of porous graphite to fit a preformed electrode. This porous-core electrode replaces old popular methods using graphite powder as an absorbent to accomplish concentration of liquid samples, but without causing contamination problems of Teflon® ware. When the amount of sample solution is not limited, a concentration of several thousand times is possible, to extend detection limits required by the modern electronics industry. High-purity water, solvents, volatile acids, and alkali were concentrated, and ultra trace impurities were determined. Some organic material can be ashed at 400°C on the electrode for arcing. Boron in trichlorosilane was separated with an addition of mannitol and routinely determined in low ppba range. The cost of this operation is a small fraction of that for new instrumentation required for achieving these sensitivities. The old spectrograph with a dc arc source unit and photographic detection has found some applications to meet new stringent requirements. The technique should be able to be easily applied to the determination of metallic impurities in trichlorosilane, dichlorosilane, hydrogen chloride, and others.

Application of neutron activation analysis in the field of silicon technology for the modern electronic industry

The specific application of neutron activation analysis in the research on the preparation of silicon integrated circuits is discussed. The high flux irradiation facility for large silicon wafers (up to 15 cm diameter) was used, the analytical procedure, and some typical results will be described.

光学的観察方法による電子デバイス用結晶評価

Modern electronics industry requires very many crystals. And the crystals must be characterized not only before using device process but also before their research and development. The first approach to crystal characterization starts with optical observation. The observation is originated from natural history including mineralogy and crystallography. The first step of optical observation is seeing outlook, and the second is sampling. If the sampling is not suitable, the following observation will be a waste of time.

Ion Implantation of Semiconductor Devices

The technology of doping semiconductors is of central importance to the modern electronics industry: it influences both the technical performance of devices and the economics of their production. Until comparatively recently dopant impurities have been introduced by thermal techniques, either homogeneously during the growth of a crystal from the melt, or over a limited thickness during epitaxial growth or by diffusion.

Magnetic Ater-effect investigated from a Chemical Stand point

Industrialization of ferrite core had been attained 25 years ago in this country. The ferrite industry already developed to higher level, both in economical and technical fields, has been a vital element to modern electronics industry. This rapidly growing industry requires ferromagnetic oxide substance of high performance characteristics but it has been very difficult to satisfy such requirement on the initial phase. The material available at that time was those having on magnetic. changes in characteristics ; it is called non-magnetic after-effect substance. This research consists of a part of the experiment report describing the results of a study to resolve the above-mentioned problem. In our research the subject is resolved from a chemical standpoint, therefore, a relation to theory of vacancy in the physical term shall be adjusted in the future in connection with the aforesaid standpoint.