Oxide superconductors, discovered in the late 1980s, have critical temperatures (Tc) higher than that of liquid nitrogen (77 K) and much higher than that of liquid helium 4.2 K, as former superconductors. It is expected that many types of applications would be realized such as compact motors, generators, transformers, and so on with considerably low cooling cost. Among the oxide superconductors, research efforts worldwide are now concentrated on Y-Ba-Cu-O superconducting wires because they have Tc higher than 90 K and the most excellent superconducting properties in magnetic fields. Usually, Y-Ba-Cu-O superconducting wires are composed of substrates using mechanically strong Ni alloys, anti-diffusion intermediate layers, superconducting layers, and stabilizing layers on the top for chemical and electrical protection. Fujikura, which concentrated its R&D resources on Y-Ba-Cu-O since early years, invented a key manufacturing technology. By this technology, called the Ion Beam Assisted Deposition (IBAD) method, the company succeeded in forming an interface structure ideal for high-quality Y-Ba-Cu-O-coated conductors. A high-performance 100-m class Y-Ba-Cu-O tape was first produced in Fujikura using this technique. Cover picture is based on this tape.
We demonstrate the fast response and high directivity of microcavity organic light-emitting diodes (MOLEDs) for optical interconnect applications. A MOLED can be fabricated onto a flexible substrate with printing or low-temperature evaporation processes. Therefore, we have developed a novel flexible optical interconnect with a MOLED light source. This optical interconnect is expected to be a useful device because this device can be assembled in a small area due to its thickness and flexibility. In the case of light source for transmission, though an OLED has several characteristics, they are not enough for practical applications. In this paper, we show the improvement on current efficiency, directional property and transmission speed by utilizing a microcavity structure. The maximum cutoff frequency and the coupling efficiency are 7 MHz and 83 % with an optical waveguide having a 0.5 numerical aperture, respectively.
Fiber lasers are promising candidates for next-generation laser sources for laser machining systems as they are superior to Nd-YAG solid-state lasers in most characteristics such as space and energy-efficiency and beam finesse required for micro-machining. In particular, there exists an obvious demand for fine marking, so that laser marking is a befitting application for fiber lasers in making effective use of the characteristics of fiber lasers. In this paper, a newly developed fiber laser for laser marking application is reported. The fiber laser employs a master oscillator power amplifier (MOPA) configuration with a Q-switch and a unique pump combiner consisting of a multi-hole silica capillary and achieves an average output power of 14.4 W and a fine beam quality of M2 = 1.1. The fiber laser also employs a direct analog control of pumping LDs and various fail-safe functions. Consequently, the developed fiber laser is proved to be a useful laser source for laser marking application, from a practical standpoint.
A novel micro-Bidirectional Optical Sub-Assembly (BOSA) has been developed in which optical transmitting and receiving functions are incorporated in a single TO-CAN package . A new compact and cost-effective Passive Optical Network (PON) Optical Network Unit (ONU) transceiver using the micro-BOSA has also been developed. Low-cost feature is achieved with a passive alignment technology and a simplified integrated structure of the micro-BOSA. Both electrical and optical characteristics are sufficient to comply with Gigabit Ethernet (GE)-PON ONU transceiver specification. In this paper, the structure and characteristics of the transceiver are reported.A novel micro-Bidirectional Optical Sub-Assembly (BOSA) has been developed in which optical transmitting and receiving functions are incorporated in a single TO-CAN package . A new compact and cost-effective Passive Optical Network (PON) Optical Network Unit (ONU) transceiver using the micro-BOSA has also been developed. Low-cost feature is achieved with a passive alignment technology and a simplified integrated structure of the micro-BOSA. Both electrical and optical characteristics are sufficient to comply with Gigabit Ethernet (GE)-PON ONU transceiver specification. In this paper, the structure and characteristics of the transceiver are reported.
To expand our range of field installable optical connectors, we have successfully developed a field installable LC connector to meet the exponential rise in demand for high space utilization in the Enterprise and Data Center markets. These connectors have similar structure to that of existing field installable SC and ST connectors and exhibit good optical performance and reliable environmental and mechanical characteristics. To improve on the current field installation process we have also refined the existing wedge unit and developed a fiber insertion tool. These changes not only simplified the field termination process and shorten the time required, they also reduced production costs.
A membrane circuit board is manufactured by screenprinting the conductive paste on the polyethylene terephthalate (PET) film. A demand for this type of circuit board is growing because of its features, such as the simple manufacturing process and low cost. With the recent downsizing and weight saving of electronic component equipment, the membrane circuit board is required to cope with narrow-pitch connectors. In order to meet these market needs, we have developed, by applying the new conductive paste, the membrane circuit board compatible with 0.3 mm pitch connectors, which is superior in its features of migration resistance, low electric resistance, and plugging/unplugging performance.
We are developing coaxial cables used in cellular phone base stations. To obtain cables with demanded electric properties, fine and uniform foaming is critically important. We used a perfluorocarbon polymer appropriate for this application to compare foaming techniques. Although technology to make fine and uniform foams is very important, there are few scientific works on foam processing. We analyzed it using an original method for representing the state of foaming under various conditions and investigated the foaming mechanism during extruding process. Using these analyzed data, we made foam with more than 70% degree of foaming.
Connectors and anisotropic conductive film (ACF) method have been already applied to the interconnection between flexible printed circuit (FPC) and rigid printed circuit (RPC). Apart from them, the authors have developed FPC-to-RPC or FPC-to-FPC interconnection with solder welding. First, straight terminals in FPC are plated by solder; secondly, they are aligned to straight terminals in RPC; and finally, all of them are connected by thermal compression. We have made prototypes and found that they have good precision, enough strength, and reliability.
For downsizing and enhancing the performance of electronic devices higher density and thinner printed wiring boards are required. Thus, we developed two-layer build-up six-layer flexible printed circuit (FPC) boards that are very thin, have soft flexible parts, and are capable of making high-density circuit. We got good results in all reliability tests such as thermal cycling test and migration test. The developed thinness of multilayer boards and high-density circuits enable us to meet demand of the market.
A further miniaturization of various electronic devices has been actively examined to make the mobile equipments device more efficient. The wafer level packaging of semiconductor ICs was one of the packaging technologies to realize smallest package. Fujikura enabled new wafer level Micro Electro Mechanical Systems (MEMS) packaging for electronic devices that had some special functions such as image sensors and MEMS devices by combining through-hole Vias in a silicon substrate formed by the MEMS processing. In this paper, bearing actual devices in mind we have made the package sample with a cavity height of 20 µm that imagers or MEMS devices needed, by bonding a glass on an 8 in. Si wafer. The glass thickness of this sample is 500 µm and that of the Si wafer is 200 µm, and the diameter of through-hole Vias is 80 µm. By optimizing all processes, we have successfully attained the process temperature of 150 º C or less in all processes except the solder reflow process.
In recent years, cellular phones and other mobile electronic devices have been miniaturized rapidly. In line with the technical tendency, internal wiring material must also be miniaturized and should have a high-speed transmission characteristics. We have developed and produced a microcoaxial cable with the high-speed transmission characteristics. In this report, the high-speed transmission characteristics of the microcoaxial cable for cellular phones and, further, the wiring material for the high-speed transmission as a step toward the next generation are discussed.
The purpose of this paper is to provide an overview of various practical cooling solutions including the use of heat pipes and vapor chambers for cooling high power processors in a confined space of personal computers (PCs). This paper discusses how to extend the air cooling capability and maximize its performance. Included in this paper are the design, data, photos, and discussion of various fan sink air cooling designs showing how the design changes can push the limit of the air cooling capability. In the main section of this paper, we present various innovative ideas of cooling solution that we are under the process developing for the cooling of next generation of high power processors. Finally, we would suggest what and which way we are going to develop next generation of high power cooling chips.
This paper describes the overview of revolution on air cooling solutions that have been combined with various heat sink for cooling high power processors in a confined space of PCs., and discusses how to extend the air cooling capability and optimum heat sink performance to against competition of cost in the retail desk top PC market. According to the cost impact, it will influence in the limitation of fan heat sink design. To keep the competition of cost in the market, it will be one of factor to limit the design of air cooling to utilize high cooling technologies at this moment. Included in this paper are the design, data, photos of various fan heat sink air cooling designs showing how the design changes can push the limit of the air cooling capability.