Waves of Microelectronics are sweeping the every accessible device and electronic equipment. Amid rapid technological innovation, the lead time from development to commercialization is becoming drastically shortened and high technology is put to use one after another as palm-sized products. Fujikura has a long history of developing a wide variety of wiring materials from their development and prototype production to mass-production. We intend to supply high-tech electronic components as system products that satisfy user needs.
This is our policy for electronic component development at Fujikura as a comprehensive wiring system creator.
The packaging technology to embed electronic components into printed circuit board attracts the large attention as the next generation high density packaging technology because it enables significant improvement in packaging density and downsizing.
Our laboratory is developing a Wafer And Board level device Embedding Technology (WABE TechnologiesTM) to embed a thin IC into a multi-layer FPC, combining a Wafer-Level Chip-Scale Package (WL-CSP) technology of copper-rewiring on an IC wafer and a polyimide multilayer printed circuit board technology.
We developed the world thinnest level IC embedded board by embedding a low-profile WL-CSP into a thin polyimide multilayer printed circuit board. That feature is being utilized in commercializing next-generation system-in-package (SIP) and various module substrates for mobile phones.
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| Cross sectional view of the structure of an IC chip-embedded board |
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Together with advancing miniaturization and weight reduction of mobile electronic devices, there are needs for realizing lower-profile, higher-density circuit boards in devices. All-polyimide interstitial via hole co-laminated (APIC) boards are multi-layered circuit boards compatible with high-density assembling, manufactured using processing methods developed uniquely by Fujikura. Since they employ a structure having all-polyimide-film lamination, not only are the boards kept thin even when multi-layered but they also make it possible to draw a flexible cable from any layer. Layers are connected by interstitial via holes (IVHs), realizing both high design flexibility and high-density wiring. In addition, since semi-additive circuitry can be applied to all layers, they can realize higher precision in line width along with narrower pitches, compatible with next-generation high-speed transmission technologies. In terms of reliability, they have passed both JEDEC level 1 moisture-absorption reflow testing and PCT testing, so that they are optimal for use as substrates in automotive electronics and semiconductor packages. APIC boards are made of RoHS-compliant halogen-free materials. At the same time, their manufacturing process reflects consideration for the environment as well. Together with reducing the wastewater treatment load by employing inter-layer connection technologies using no plating, their co-lamination process that creates multiple layers in a single press regardless of number of layers also keeps down energy consumption. Through simplification of processing, the batch lamination processing reduces the volume of defective products produced while at the same time contributing, by shortening lead times, to increased competitive strength in the electronics industry, which is characterized by short product cycles. |
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The flexible printed circuit (FPC) boards used for DVD pickups, HDD heads and the surrounding area of a lens of a digital camera are required to have excellent characteristics of low spring-back and bendability, with the aim of lowering the spring-back and saving power consumption. To provide such FPCs, Fujikura attempts to reduce the spring-back by thinning Copper-Clad Laminates (CCLs), Cover Lay (CL), and Solder Resist (SR) that are components of the FPC using materials with low elasticity. The current, mass-produced, thinnest FPC has a thickness of 80 μm, and we are ready to mass-produce FPCs with a thickness of 45 μm. We have been successful in reducing the repulsive force to approximately a half of that of the current mass-produced products. We are now in the process of developing FPCs with a thickness of 40 μm or lower by using thinner materials. |
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A thin FPC that can be bent into any form is used for the hinge area connecting the display and key switch section of a cell phone. As demand for lightweight and thin types of cell phones is accelerating, the FPC in the hinge area must be able to be installed in a thin and lean space and have a long lifetime for repetitive bending. We build prototypes of such FPC and begin the mass-production after designing patterns and selecting materials that are appropriate for complicated bending modes such as crank bending, α shape bending and sliding to respond to smaller and thinner shapes of new cell phones. In addition, we propose optimal solutions by combining various options such as mounting electronic components like connectors and materials to shield electromagnetic noise whenever the necessity arises. |
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As cell phones nowadays has come to be equipped with a wide variety of functions such as high-pixel cameras and IC cards, FPCs as internal wiring materials also need to increase the number of signal lines and the speed of response. As the hinge area, however, has only limited wiring space, more than one-sided FPCs have to be piled up to save space. For this reason, Fujikura has commercialized multilayer boards with a hollow structure by not bonding layers in the bending area each other so as to maintain both of multilayer and flexibility of the FPC at one time. These products have an extremely long life-time to endure 100,000 bendings or higher although they are a multilayer board consisted of two to four single-sided FPCs. In addition, we are ready to provide optimal proposals for actual product design based on the accumulated data on FPCs made of different materials and pattern designs through durability tests that simulate the operations of actual cell phones. |
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With the recent sophistication of hand-held devices such as smartphones, there are growing needs for multilayer flexible printed circuits (FPCs) that have both reliability and implementability. Multilayer FPCs have three or more copper conductor layers. It is an advanced form of FPC that integrates different designs: a multilayer structure on which components are mounted and a single- or double-sided structure that serves as a connector or bending part. The manufacturing process laminates single- and double-sided FPCs on which circuits are formed, prepares adhesion layers using bonding sheets, and creates a multilayer FPC by thermo-compression. A single FPC can provide three-dimensional wiring that runs along the interior, small-footprint (space-saving) wiring, and wiring at folding parts within the limited space of a small electronic device such as a smartphone. Recent designs use high-density wiring that contains impedance-control circuits, which cannot be implemented with double-sided boards due to space limitations. Multilayer FPCs find many applications in such areas. |
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With the miniaturization and sophistication of electronic devices such as mobile phones, flexible printed circuits (FPCs) with enhanced density, transmission speed, and flexibility are required. To meet these demands, we have been developing semi-additive process FPCs. The semi-additive process forms a circuit by electrolytic copper plating with resist shaped in a photo-process with high accuracy. It can create high-precision and high-density circuits. In addition, circuits produced in this process are thinner compared to the conventional FPCs, which increases flexibility. We are also working on the development of high-density circuit multilayer board technology using the semi-additive process. |
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Seat occupant detection sensors for automobiles are sheet-style sensors with a membrane switch embedded in the lower section of a seat and detect whether passengers are sitting on their seats. Actual applications are so-called seat belt reminder (SBR) sensors and repair cost reduction sensors. The SBR is a system that prompts passengers to wear their seat belts by detecting whether a passenger is sitting on their seats and issuing an alarm when the passengers do not use their seat belts working together with a seat belt wearing detection sensor. A repair cost reduction sensor not only detects whether passengers are sitting on their seats, but also differentiates whether a person or baggage is on the seat, according to the weight. It works as a system that controls the operation of each air bag with this function, eliminating the unnecessary inflation of air bags, resulting in no repair costs for an inflated air bag. Particularly, the safety functions for cars such as SBR are often regulated overseas, and we are developing sensors abiding by such regulations. |
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We are producing membrane printed circuits that are formed by screen-printing conductive ink on a polyester film substrate. Recently, there are growing needs for finer circuit patterns that exceed the limits of conventional screen-printing. To cope with this trend, we have developed membrane printed circuit board technology that can create finer circuits using intaglio offset printing, in which ink in the hollows on the original plate is transferred to the blanket roll and printed on the substrate. As the plate is created by etching, it is possible to generate very high-definition patterns. We have succeeded in producing a 10 µm-pitch circuit at a prototype level. We are now preparing a volume production line to meet the demands for finer membrane printed circuits for capacitive touchpads of input devices and wiring boards of digital appliances. |
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Demands for HDD have been increasing mainly in the PC market, and HDD is now becoming widespread as the devices are employed for new applications, such as HDD recorders and music players, in the digital household appliance market. The constant demand for the larger capacity has led to increase in the surface recording density of HDD year after year. The recording method has shifted from longitudinal magnetic recording to perpendicular magnetic recording and several techniques such as "discreet track media," "patterned media" and "heat-assisted magnetic recording" have been proposed, which have served to technological innovations related to HDD. We manufacture and sell the carriages to support and drive the read/write head comprising HDD. Also we develop technology for securing high levels of clean environment and precise resonance control for mechanical vibration of a carriage required with increase in recording density while improving our production technology to efficiently supply products with high performance and reliability. |
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As our micro coaxial cables are thin and flexible and have noise immunity, good transmission characteristics in GHz frequency bands as well as high flexing characteristics, they are used widely as wiring materials in the opening/closing or rotating structures of small electronic instruments such as cell phones. We have developed flat-type micro coaxial cable assemblies to meet the needs for sliding-type opening/closing equipment. We have developed ribbon cables made of 3 to 5 micro coaxial cables covered with resin excellent in abrasion resistance and processability, achieving the height of the wiring assembly of 1 to 1.5 mm by arranging the ribbon cables vertically and assembling them using components such as connectors. It has endured sliding of more than 200,000 times due to larger radius of bending section. Existing sheet type wiring materials need heights of 2 to 3 mm for assembling while our product need only 1 to 1.5mm, and thus our flat micro coaxial cable assemblies will become the best solution to slimmer equipment in the future. |
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We were ahead of others in developing a cable assembly that conforms to USB 3.0, which is the next-generation standard enabling 5 Gbps transmission, 10 times faster than USB 2.0. It was the world's first genuine cable assembly USB 3.0-certified by USB-IF in 2011. In these days where information terminals and cloud-computing environments are widespread, we have achieved the world's thinnest 3.6 mm-diameter cable for greater compactness. Using a proprietary low-loss shielded differential pair cable as the signal line, and introducing transmission analysis technology and tuning based on impedance matching processing techniques for the terminal assembly, the product has low loss in wide bandwidth in spite of its small diameter. The signal line is a shielded pair cable with silver-plated annealed copper wires, using low-density/low-loss olefin resin and metallic foil. It has achieved a low loss of 3 dB/m at 2.5 GHz (5 Gbps) and 6.25 dB/m even at the third harmonic of 7.5 GHz.Z The product lineup consists of an up to 2 meters long type and an up to 1 meter long and thin (3.6 mm-diameter) type. Both types support the Standard A-Plug, Standard B-Plug, and Micro B-Plug assemblies. |
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With the evolution of information terminals and the spread of wireless connection, there are growing demands for high value-added solutions for antennas embedded in devices. We have reviewed the construction and manufacturing method of the FPC to achieve a thinner antenna that can be stuck on the curved surface inside the housing. Proprietary antenna design technology has enabled us to build an embedded film antenna with high radiation efficiency in a small size, which has made it attractive to many customers. There is a rich lineup of products with original device designs, including WWAN, LTE, WiMAX, WLAN, Bluetooth, GPS, UWB, terrestrial digital TV film antenna devices, a single multi-band antenna device with multiple resonant frequencies, and an integral antenna that is resistant to mutual interference. According to the type of feed specified by the customer, we design and select materials to support a range of assemblies that include RF coaxial cable connection, metallic feed pad construction, feed point plating, and resin mold components. The material composition is worry-free. It is compatible with the UL and RoHS directives and non-halogen requirements. The full service provides device design, product design, prototyping, evaluation, real device tuning, and mass-production under one roof. In the prototyping stage, following evaluation and design improvements in an anechoic chamber, a product form is created in three days, which provides products customized to the customer's equipment. |
