Tomoaki Shibata

Flexible opto-electronic circuit board for in-device interconnection

We propose a flexible opto-electronic circuit board (FOECB) for in-device interconnection, which is combined with a flexible printed circuit (FPC) with flexible optical waveguides having 45deg mirrors for 90deg beam turning using adhesive film. The fabricated prototype shows total optical loss of 3.7 dB, and the prototype, which mounted a 4-ch vertical-cavity surface-emitting laser (VCSEL) array and a 4-ch photodiode (PD) array, successfully demonstrated optical signal transmission at a data rate of 10 Gbps/ch. These results show that the proposed prototype has considerable potential to realize practical FOECB for in-device interconnection.

A High-Coupling-Efficiency Multilayer Optical Printed Wiring Board with a Cube-Core Structure for High-Density Optical Interconnections

A multilayer optical printed wiring board with a cube-core structure was developed for high-density optical interconnections. A fabricated multilayer optical printed wiring board with this cube-core structure has optical-coupling efficiency 2.7 dB higher than one without this structure. A fabricated optical interconnection model successfully demonstrated 10-Gbit/s/channel operation. These results show that the advantage of this cube-core structure is that it provides high optical-coupling efficiency in a high-density multilayer optical printed wiring board.

20-Gb/s/ch High-Speed Low-Power 1-Tb/s Multilayer Optical Printed Circuit Board With Lens-Integrated Optical Devices and CMOS IC

A high-speed large-capacity optical printed circuit board (OPCB) for next-generation high-capacity routers and servers was developed. This OPCB is composed of a multilayer polymer optical waveguide, a receiver optical input/output (I/O) module (with a lens-integrated photodiode and a SiGe transimpedance amplifier), and a low-power (7.1 mW/Gb/s) transmitter optical I/O module consisting of a lens-integrated surface-emitting laser and complementary metal-oxide-semiconductor (CMOS) driver IC. A 1-Tb/s (20 Gb/s/ch × 48 ch per transmitter or receiver) large-capacity OPCB prototype was fabricated and demonstrated 20-Gb/s/ch operation.

Optical waveguide materials with high thermal reliability and their applications for high-density optical interconnections

This paper describes newly-developed optical waveguide materials and their future applications in optoelectronic circuit boards. The materials achieved low optical loss and high thermal reliability, as well as good flexibility. We fabricated both flexible and rigid optoelectronic circuit board prototypes using these newly-developed materials, and successfully demonstrated light signal transmission faster than 10 Gbps/ch.

Stretchable insulating material for IoT devices

This paper reports a newly developed UV-curable and film-shaped insulating material for IoT devices that require stretchability. The material features large stretch ability, high transparency, low moisture permeability and good embedding property. An availability of the material for the stretchable devices was demonstrated through prototyping a test model and its evaluation. The good result of stretching and bending test showed that the developed material has large potential for the stretchable circuits and devices application.

Introducing novel film type adhesives into thin wafer handling technology for 3D TSV packaging applications

In this paper, the authors focus on the evaluation of novel film type thermo-plastic adhesives in thin wafer handling technology for temporary bonding purposes. The main advantages of the film type adhesives over spin coat adhesives are better uniformity of film, TTV control and high thermal stability of the film. Film type-A material has been developed and evaluated for thermal slide-off thin wafer handling applications. For temporary bonding evaluation, extensive DOE matrix has been generated and executed to identify the optimum bonding conditions. Initially adhesive films are vacuum laminated on silicon carriers and eventually bonded using thermal bonding process. Total six different bonding conditions have been considered and bonding loads have been chosen from 3kN to 9.5kN and temperatures are in the range of 150 to 210°C. Preliminary evaluation results are supposed to be feasible, but ideal thin wafer handling demands 0% voids in bonded pairs at any stage. To meet this requirement, the authors were extensively focused on the improvement of film materials and optimization of lamination and bonding parameters. 3D IC process simulation tests are also required to ensure that the adhesives layers are reliable enough for further process. For this purpose, temporary bonded pairs have been thoroughly tested through various 3D IC processes like back grinding, dielectric curing, vacuum stability and chemical stability tests. Finally de-bonding evaluation of the films is carried out at temperature ranges of 200 to 250°C. Based on the results achieved, the authors were able to identify the characteristics of the currently developed film type temporary bonding and de-bonding adhesive and direction for the further optimization.