High speed multichip modules using flip chip mount technology for 10 Gbps optical transmission systems

Abstract

This Paper describes small-sized multichip modules (MCMs) for 10Gbps optical transmission systems. We have developed three kinds of MCMs. MCMs include LSIs we have newly developed by employing SiGe bipolar process. Each kind of MCM is composed of an alumina substrate with flat lead frames, LSIs mounted by flip chip mount technology, passive SMT components, and a heat spreader. To achieve wide-band characteristics of MCMs, the grounded coplanar waveguide design is adopted for the transmission lines on MCMs. The heat spreader is attached to the backside of each LSI through thermally conductive silicone compound for highly effective cooling. These MCMs have been applied for our 10Gbps optical transmitter and receiver modules in the wavelength division multiplexing (WDM) system, and achieved 1.6Tbps (10Gbps x 160 channels) of transmission capacity. IntroductionRapidly increasing demand for lightwave transmission capacity drives wider bandwidth-use of optical fiber cables and higher line rate per channel for spectral efficiency improvement in WDM optical transmission. In the large capacity WDM system, high line rate as 10Gbps and small footprint are required for a transponder.The block diagram of WDM system is shown in Fig.1. WDM system provides the ability of multiplexing the multiple light wavelengths on a single fiber and increase the carrying capacity. This WDM system includes pairs of a transmitterside transponder (TxPND) and a receiver-side transponder (RxPND). The 10Gbps transponder in our WDM system has a forward-error-correction (FEC) function in order to realize the long span optical transmission. The 10Gbps TxPND consists of an optical receiver module (indicated as O/E) for 9.95Gbps (OC-192), a forward error correction encoder (FEC COD) LSI, and an optical transmitter module (indicated as E/O) operating at 10.66Gbps (optical channel for 10Gbps). The RxPND consists of another optical receiver module for 10.66Gbps, a forward error correction decoder (FEC DCOD) LSI, and another optical transmitter module (indicated as E/O) for 9.95Gbps.A large amount of the optical transmitter and receiver modules are applied in the WDM system, so that small-sizing of these optical modules is indispensable for small footprint of the whole systems.To realize the small-sized optical transmitter and receiver modules, we adopted the following approaches for packaging of LSIs.

A comparative analysis of short- and long-wavelength multi-chip optical transmitter modules for optical PCBs applications

“…For the multichip packaging, the flip-chip bonding technology has widely accepted. 4,5 In this paper, multichip transmitter modules prepared by the flip-chip packaging are examined to apply in the optical interconnection based on the optical printed-circuit board (OPCB). Dynamic characteristics and optical crosstalk are compared for the 850 nm short-wavelength VCSEL and 1310 nm long-wavelength VCSEL.…”