Yuji Iseki

MCM-D/L using copper/photosensitive-BCB multilayer for upper microwave band systems

This paper describes an MCM-D/L technology for upper microwave band systems. The substrate of this MCM is constructed of copper/photosensitive-benzocyclobutene (P-BCB) multilayer formatted onto a print wiring board (PWB). Features of the developed MCM are (1) a novel microstrip structure for improvement of high-frequency characteristics and (2) a low-cost simple copper/P-BCB process using polishing technology. As BCB has good thermal and electric characteristics compared with polyimide or epoxy, BCB is expected to be applied to high frequency systems. We have developed a low-cost copper/P-BCB multilayer process with a new microstrip structure, and measured the high-frequency characteristics (10 GHz/spl sim/40 GHz). In the process technology, we took note of the adhesion of the metal film/BCB interface. As a result of a study of the adhesive metal and chemical/thermal treatment before and after fabrication of the film, we found that the necessary adhesion force was obtained by N/sub 2/ plasma treatment of the BCB surface before metal evaporation and annealing (250/spl deg/C:BCB cure temperature) after evaporation. Also, Cr was found to be the best material for adhesion. The high-frequency characteristics (10 GHz/spl sim/40 GHz) were estimated by a ring resonator and microstrip transmission line of copper/P-BCB multilayer fabricated on a PWB. Also, the S-parameters showed good characteristics. The developed MCM-D/L substrate has been proved to be suitable for high-frequency systems.

Multichip module technology using AlN substrate for 2-Gbit/s high-speed switching module

The authors describe a multichip module (MCM) technology for making broadband digital switching modules. A copper/polyimide thin-film multilayer substrate is developed to achieve high-speed digital transmission. The substrate is formed on an aluminum nitride ceramic (AlN) wafer with good thermal characteristics. The meshed strip-line structure is used to control the characteristic impedance for 50- Omega signal lines, and the thin-film termination resistors are made of NiCr to prevent reflections. With this technology, the authors experimentally fabricated a broadband digital switching module, which is constructed from switching ICs in bare dies, clock distributing ICs in flat lead packages, and chip/micro-chip capacitors. In this module, differential digital transmission lines are adopted for high-speed signals to reduce the crosstalk noise effect. Heat generated from the module, which has a total of 25 W of power dissipation, is efficiently conducted through the AlN wafer. This module can operate many 2-Gbit/s high-speed channels. A novel multichip module technology for high-performance systems was successfully developed.<<ETX>>

2.5 GHz Wide Band Linear Amplifier with Feedforward Lineariser on a Board

A wide band feedforward lineariser amplifier we have developed is described. In particular, we report the IM3 improvement obtained without automatic adaptive control circuits, indicating the possibility of realizing small, low-cost products. We designed a lineariser amplifier for 2.5 GHz band to demonstrate the effectiveness of our approach and measurement revealed the wide band linearising capability of over 100 MHz.