Abstracts of Magazine FUJITSU 2000-9 (VOL.51, NO.5)

Special Issue : Simulation for Design

• Fujitsu Virtual Product Simulator (FJVPS)

Fujitsu Virtual Product Simulator (FJVPS) is a powerful simulation software that has verification and display functions for using three-dimensional (3D) digital computer-aided design (CAD) models in various stages of product development. This software operates on Microsoft Windows NT V4.0. With its advanced features for verifying product operability and operation and for evaluating environmental loads, FJVPS significantly expands the range of verification using 3D digital CAD models, reduces product designers' workloads, and improves design efficiency. FJVPS also provides persons other than product designers with functions for using FJVPS output data or proprietary 3D digital CAD models. This paper outlines FJVPS and describes its function modules, some application examples, the effects of using FJVPS, and Fujitsu's plans for upgrading FJVPS.

• Computer-Aided Optimization System (CAOS) for Optimal Designing of Electronic Equipment

As more and more parts are integrated into smaller and lighter bodies, thermal stress and heat generation in electronic packages are becoming serious problems. This has prompted many designers to use computer simulation to quantitatively estimate thermal stress and temperatures early in the design process. Computer simulation is an effective method of evaluation that is quicker and less costly than conventional evaluation methods based on experiments. However, it has been difficult to use computer simulation to optimize the combination of a large number of design ideas because such an optimization requires an extremely large amount of calculation. Therefore, computer simulation has mostly been applied to one or a few design ideas. Fujitsu has developed a new statistical optimization system called “Computer-Aided Optimization System (CAOS)” which incorporates an experimental evaluation method into numerical simulation and efficiently performs optimization by computer simulation. This paper describes the technical background and principle of CAOS and an example application of CAOS to electronic-package cooling design.

• Numerical Analysis of Developer Behavior in Electrophotographic Printers

Electrophotographic devices, for example, laser printers and copying machines, now need to be faster than ever. In conventional cases, these devices have been designed on a trial-and-error basis using measurments and experiments. However, for the efficient improvement in operation speed and image quality, we must clarify the principles of electrophotographic processes and take a theoretical approach to design. In this study, we aimed to numerically analyze the physical behavior of developer in the developing process by using the basic equations of motion. We focused on the dual-component developing method (which is a popular developing process), devised a new method for analyzing fine particles, and developed a technique for numerically analyzing developer behavior. This study made it possible to quickly perform a numerical analysis of developer behavior, developing capacity, and image quality in the developing process. This paper describes the technique used for numerically analyzing developer behavior and a development analysis based on calculations of the distribution and amount of toner electrodeposition.

• Simulation Techniques for Magnetic Recording Media of Hard Disk Drives

The growth of multimedia applications and information technology (IT) has explosively increased the amounts of digital information being processed by computers. Hard disk drives (HDDs) have been the main storage devices, and their areal recording densities have been increasing at an annual rate of 60 percent or more. However, development of the magnetic recording media for HDDs is becoming very difficult and the development period needs to be shortened. Under these circumstances, simulation techniques are regarded as important tools for designing magnetic recording media. This paper describes some simulation techniques that can be used for a magnetic recording medium, which is one of the main parts of an HDD. One technique described here is the simulation of medium noise, which is used to set a medium development guideline for improving the areal recording density. Another technique is the simulation of magnetic fluctuation due to thermal energy, which is used to ensure the long-term stability of information recorded on magnetic recording media.

• GMR Head Simulation System “3D-GMRSIM”

The areal recording density of hard disks has been increasing at an annual rate of 60 percent or more. Therefore, it has become important to heighten the development efficiency for the giant magnetoresistive (GMR) heads of HDDs. This paper describes a new simulation system called “3D-GMRSIM” for simulating the properties of GMR heads. After the 3D-GMRSIM system has been given the three-dimensional geometry of a GMR element, it calculates the magnetic response of the GMR element by three-dimensional micromagnetics modeling and outputs the GMR head's properties. The 3D-GMRSIM system therefore enables us to calculate GMR head properties and make the development of GMR heads efficient. This paper also describes two applications of the 3D-GMRSIM system: 1) the simulation of a new GMR structure with a bias compensation layer to improve head output properties and 2) the analysis of the mechanism of magnetization reversal due to electrostatic discharge.

• Line Noise Analysis System “SIGAL” for Gigahertz Transmission

For accurate transmission of high-frequency signals, various effects of noise must be analyzed precisely and the analysis results must be reflected in the design of transmission equipment and systems. Also, bi-directional simultaneous communication has been introduced as a new bus system to transmit a large amount of data at high speed. Accordingly, there is a need to verify transmission circuits by simulating transmission in the circuit design stage. Fujitsu's existing noise analysis system “SIGAL” can perform highly accurate analysis of noise levels and timing and has already been widely applied to many transmission devices and systems. Fujitsu has developed a new function for SIGAL that supports analysis of bi-directional simultaneous communication circuits as well as highly accurate analysis of noise in high-frequency transmission. The new function enables the user to analyze the following: the skin effect, which is a major factor of waveform distortion during high-frequency signal transmission in the gigahertz band; differential signal transmission circuits with eye pattern analysis incorporated; and bi-directional simultaneous communication signals based on ternary logic. This paper describes the analysis features of the new function, for example, the large reduction of analysis time, eye pattern analysis covering jitter and skew analysis, and transmission signal analysis based on ternary logic.

• Neutron-Induced Soft Error Simulator (NISES) for Improvement of LSI Reliability

Soft errors are temporary malfunctions of LSIs in electronic equipment that are believed to be caused by neutrons in secondary cosmic rays. To analyze neutron-induced soft errors, Fujitsu has developed the Neutron-Induced Soft Error Simulator (NISES). NISES has a nuclear reaction database based on the latest nuclear reaction theory and analyzes soft errors using Monte Carlo simulation. NISES has already been applied to the analysis of soft errors in CMOS circuits and DRAMs and has proved the significance of neutron-induced soft errors. It has also been used to evaluate soft error rates in LSI design processes and has contributed to the improvement of LSI reliability. This paper describes the configuration and functions of NISES and some examples of its application.

• Integrated Injection Molding Support System “MOLDEST”

Fujitsu, FANUC, and TORAY have jointly developed and marketed an injection molding support system called “MOLDSET” which integrates computer-aided design (CAD), computer-aided engineering (CAE), and computer-aided manufacturing (CAM) for resin molding processes into a single system. MOLDSET is an innovative software system that can provide the optimum injection molding conditions for mass production of products from the three-dimensional CAD data of molded parts. This system enables the user to not only reduce the trial molding operation at the beginning of mass production but also to determine whether the selected molding conditions are appropriate before producing metal molds. This paper describes the joint development of MOLDSET and gives an outline of MOLDSET. This paper also describes the design quality feedback system that Fujitsu plans to develop as the final goal of MOLDEST by linking it with the metal mold design system “MOLDWARE.”

• RS-Station -Software for Simulating Heat Transfer in Lead-free Reflow Soldering-

Reflow ovens using infrared radiation or hot blasts have been widely used to solder components onto the printed-circuit (PC) boards of electronic equipment. Increasing environmental awareness is making tin-silver (Sn-Ag) solders promising alternatives to solders that contain lead (Pb). However, because components have a wide range of heat capacities and tin-silver solders have high melting points, it is difficult to use these solders without overheating components. To solve this problem, Fujitsu has developed software called “RS-Station” to simulate heat transfer during reflow soldering of PC boards. This paper gives an outline of RS-Station and describes an example of its application to PC board design. In this example, during reflow soldering, the maximum component temperature minus the minimum solder temperature was kept to below 10℃, which an important achievement for lead-free soldering.

• Computational Modelling of Solidification for Electronic Packaging

In electronic packaging, solidification is commonly associated with solder materials used to bond components together such as microchips onto a printed circuit board. A number of defects may occur during the bonding process such as flux entrapment, void formation, and cracking of the joints. The consideration for a cleaner environment may also mean solder materials with high lead content are to be replaced by ones that are low or lead free. Finding substitute materials with similar characteristics that minimize changes to existing manufacturing processes creates added challenges for the engineers. Computer simulation provides an effective design and testing tool to reduce defects and to assess solder and board integrity and reliability. As electronic devices become smaller and more compact, new technical challenges will be more multidisciplinary and require analysis commonly referred to as Multiphysics simulation. For example, suppressing electromagnetic emissions by encasing the packaged electronics in sealed compartments provides good shielding but it restricts air movements. This in turn influences cooling that affects both thermal and mechanical reliability and performance of the packaged components. Solving and optimizing the tradeoffs for such problems involves electrical, thermal and mechanical processes that are interdependent and interrelated. This paper describes our modelling of solidification and solving electronic packaging problems that are Multiphysics.

• Use of Simulations to Develop Mobile Personal Computers

For efficient development of mobile personal computers, Fujitsu has applied thermal fluid, thermal stress, and drop test simulations to the development processes starting from the product planning stage. Fujitsu has applied these simulations to reduce the number of prototypes that need to be made and to reduce development costs and development periods. To be useful in product development, simulations must be fast and highly accurately. To meet these needs, Fujitsu has improved the accuracy of analysis (including experiment verification), simplified the models used for simulation, and reduced the time needed for simulation. This paper describes the use of simulation in the design of a mobile personal computer and the effects of the application.

• Simulation Technologies for the Development of Magneto-Optic Disk Drives

Magneto-optic (MO) disk drives record information using magnetic recording and optical technologies. Engineers who develop MO disk drives not only need a knowledge of electromagnetism and optics but must also be familiar with a wide range of other technologies such as mechanics, control, and signal processing. These technologies are interrelated, and their applications to an MO disk drive determine its performance. Developing an MO disk drive, which is a complex system covering various fields of technologies, requires an evaluation of the drive's characteristics using simulations to enhance its performance (mainly its recording density). Use of simulations also leads to a reduced number of prototypes, more efficient development, and shorter development periods. This paper describes the simulation technologies for analyzing the vibrations of mechanical parts, electromagnetic fields, and optical systems which have been used for developing MO disk drives and the outcomes of their applications.

• Use of Simulations to Develop Portable Telephones

Portable telephones must not only have enhanced functionally but must also be compact, lightweight, and durable. To realize such conflicting features in a portable telephone within a short development period, simulations must be performed in the development process. BGA packages have recently been used in portable telephones to reduce the size of the circuit boards of portable telephones. Because BGA packages have relatively weak solder joints, the casings and parts layout of a portable telephone must be carefully designed to prevent the joints from receiving excessive loads. However, the loads that will be applied to each joint cannot be evaluated by conventional modeling methods because the dimensions of the component leads, solder joints, and circuit board conductors are very small. Also, an optimum design can only be obtained through an understanding of the loads applied to a portable telephone's body during normal use. This paper describes a technology for evaluating the durability of a portable telephone in a general environment and other simulation technologies used for developing portable telephones.

• Development of Lead-free Tin-Silver-Copper (Sn-Ag-Cu) Solder

Fujitsu has developed a new lead-free solder consisting of tin (Sn), silver (Ag), and copper (Cu) which has a high joint reliability. The new solder has a higher melting point than tin-lead eutectic solder. However, it also has a high joint reliability and is suitable for soldering both the currently used type of component pins and the lead-free component pins which will be widely used in the future. Thus, the new solder will promote lead-free soldering. Fujitsu has already applied the new solder to the printed-circuit boards of certain Fujitsu products and is planning to extend its application to other products. This paper describes the basic characteristics of this lead-free Sn-Ag-Cu solder and the results of a study on its practical uses.

• Virtual Channel on Open Electronic Commerce Service “SupplyMART”

Fujitsu's network service “SupplyMART” is an open marketplace for trading auxiliary materials such as stationery and office equipment on the Internet on a business-to-business basis (networking between companies). Fujitsu has recently added a virtual channel feature in SupplyMART. The virtual channel feature allows many buyers and sellers participating in SupplyMART to make individual trade transactions with each other in an open marketplace by using an electronic catalog function. The virtual channel feature enables trading based on estimates and a simple trade procedure using the electronic catalog. With the virtual channel feature, SupplyMART advantageously gives the buyers and sellers participating in the electronic commerce a way to make real transactions and create a proper degree of competitiveness.