Tomonori Ogawa

VCSEL Module With Polymer Optical Output Rods to Enable High Efficiency Coupling for Optical Interconnection

New vertical-cavity surface-emitting laser (VCSEL) modules-designed with a optical output rod surrounded by cladding-have been proposed to realize high-efficiency low-cost optical interconnection. Prototypes have been fabricated using a photomask transfer method employing two kinds of ultraviolet curable resin. Observation of the near-field pattern and eye pattern for signal transmission shows that output rods with a diameter of 50-mum efficiently confine the laser beam as an optical waveguide. In addition, ray tracing simulation indicates that this new VCSEL offers greater positional tolerance-as much as +18/ -22 mum-for coupling to optical wiring in 90deg light path conversion.

Design, Demonstration and Characterization of Ultra-Thin Low-Warpage Glass BGA Packages for Smart Mobile Application Processor

This paper presents the design, fabrication, assembly, and characterization of a fully-integrated single-chip glass BGA package at 40/80 μm off-chip I/O pitch with multilayered wiring and through-package-vias (TPVs) at 160 μm pitch. The designed test vehicle emulates an application processor package for smart mobile applications, and enables for the first time measurements of DC signal transmission from the die to the board, through the package, at this density and pitch. A daisy chain test die, 10 mm × 10 mm in size, was designed to emulate a logic processor chip comprising 5448 I/Os distributed in four peripheral rows at 40/80 μm pitch and a central area array at 150 μm pitch. The test dies were fabricated and bumped with standard Cu pillars by ASE. The glass package design included four routing layers, with blind vias (BVs) and TPVs both at 150 μm pitch, to connect 176 I/Os to the board, with BGAs at 400μm pitch. Independent multi-level test structures were added for evaluation of TPV and BV yield during fabrication, as well as partial chip-and board-level interconnection yield and reliability. The TPVs in glass were achieved by a via-first process with a high-throughput plasma etching and primer drilling method. Semi-additive processes (SAP), combined with wet chemical surface treatment methods were applied for patterning of the multi-layer wiring with a minimum of 20 μm Cu trace width at 40 μm pitch. A fan-in fan-out finger design was implemented on the top layer for bump-on-trace chip-level interconnections. Chip assembly on glass panels was carried out by high-speed thermocompression bonding with non-conductive paste (TC-NCP) with the new high-performance APAMA chip-to-substrate (C2S) bonder by Kulicke and Soffa. Yield of each process step was evaluated through fabrication and assembly by DC electrical characterization of TPV, BV and chip-level interconnection daisy chains. Die-to-substrate interconnections were characterized, demonstrating signal transmission through the fully-integrated glass package for the first time at this I/O pitch.

Fluorine-doped silica fiber with high transparency and resitivity to deep ultra violet light

Transmittance exceeding 92 %m-1 at 266 nm and its permanence after 4 G pulses of laser irradiation are realized in fluorine-doped silica fiber due to the optimized fiber-manufacturing processes such as perform-fabrication and fiber-drawing.

High Frequency Electrical Performance and Thermo-Mechanical Reliability of Fine-Pitch, Copper-Metallized Through-Package-Vias (TPVs) in Ultra-Thin Glass Interposers

This paper demonstrates the high frequency performance and thermo-mechanical reliability of through vias with 25 µm diameter at 50 µm pitch in 100 µm thin glass substrates. Scaling of through via interconnect diameter and pitch has several electrical performance advantages for high bandwidth 2.5D interposers as well as mm-wave components for 5G modules. This paper focuses on the assessment of thermo-mechanical reliability, of high aspect ratio TPVs at ultra-fine pitch, metallized using a via–first approach, and the accurate electrical modelling of TPVs and transmission lines with TPVs up to 40 GHz, using ANSYS HFSSTM. Test vehicles consisting of through via daisy chain structures were designed and fabricated on 100 µm thick glass, laminated with a 5 µm epoxy dry film polymer on both sides. Fine pitch TPV arrays were subjected to Thermal Cycle Testing (TCT) between -55 °C and 125 °C, and the majority of TPV chains passed 1000 cycles with less than 15% change in DC resistance. The impact of pitch scaling on the reliability was studied by varying the spacing of neighboring TPVs using 3D quarter-symmetric finite element models. A novel approach based on wave dimensional analysis was investigated to accurately capture the electrical parasitics of the vias in mm wave frequency bands. The resistance and inductance of a single signal TPV at 28 GHz were estimated to be 93 m and 60 pH respectively. Using Voltage Standing Wave Ratio (VSWR) calculations, it was shown that smaller via diameters are preferable for transitions from a 50 impedance matched planar to vertical interconnection.

First Demonstration of 28 GHz and 39 GHz Transmission Lines and Antennas on Glass Substrates for 5G Modules

High-performance and ultra-miniaturized mm-wave building block structures were demonstrated on panel-scale processed 3D glass packages for high-speed 5G communication standards at 28 and 39 GHz bands. To demonstrate the benefits of glass for 5G communications, various topologies of microstrip-fed patch antennas for different resonant frequencies and compact conductor-backed co-planar waveguides were modeled and designed for high bandwidth and efficiency in the mm-wave bands. The simulation results for insertion loss, antenna gain, and bandwidth are consistent with the measured values on the glass substrates. The fabricated conductor-backed coplanar waveguides show insertion losses of 0.2 –0.3 dB/mm with a channel length of 1.86 mm, and the fabricated antennas have more than around 6% bandwidth in the frequency range of 35 to 39 GHz.

New chip device with built-in optical outlet rod for easy assembly and high optical coupling in optical interconnection

New chip devices - designed with an optical outlet rod surrounded by cladding - have been proposed to realize easy assembly, high-efficiency optical interconnection. Prototypes have been fabricated using a photomask transfer method employing a VCSEL (vertical cavity emitting laser) and two kinds of UV (ultraviolet) curable resin. Observation of the NFP (near-field pattern), I-L (current vs. light output power) characteristics, the eye pattern for signal transmission and positional tolerance shows that outlet rods with a diameter of 30 µm efficiently confine the laser beam as an optical waveguide. In addition, the ray tracing simulation indicates that transmission loss and crosstalk can be substantially reduced by choosing suitable resins.

Proposal and Fabrication ofNew Chip VCSEL with a Built-in Polymer Outlet

A new chip VCSEL with a built-in polymer outlet is proposed and a prototype is fabricated. The outlet stands just on an emitting spot and is covered by polymer material. A high optical coupling efficiency and easy handling are expected.