Akihiro Dohya

Polyimide-Ceramic Substrate for Supercomputer Packaging

This paper introduces the Polylmide-Ceramic substrate for NEC SX Supercomputers. In case of high performance system such as supercomputers and top end machines in general purpose computer, sophisticated packaging technologies are essential to achieve fastest operations as well as to use highestspeed, highly integrated LSIs. Wiring substrate which mounts and interconnects LSIs is the key to back up LSIs higher logical-operations. The high speed interconnection wirings and high density LSI mounting are requested for substrate. The Polyimide-Ceramic substrate had been developed to meet these demands and have many features of high density thin film wiring, high power supply, high thermal conductivity and huge number of I/Os, in addition to high speed wiring. 25μm wide 75μm center-to-center spacing, two signal layers, 6ns/m signal transmissions, 2.5W/cm 2 high power density, 2177 I/Os on a 100mm square substrate have been achieved by using this super substrate technology. The packaging hierarchy, the first level packaging of TAB LSI, the second level of multi-chip packaging by using Polyimide-Ceramic substrate and liquid cooling module, and the third level of board assemblies are introduced.

An approach to the low cost flip-chip technology development with punched-out solder disks by micro-press punching method

A new low cost bare-chip LSI inter-connection lead-less-chip technology was installed by Au ball-bump (1976) and Ag-Sn solder on the printed wiring board under none flux condition. Au ball-bumps were made on the LSI Al pads directly by conventional wire bonding method and Ag-Sn bumps on the leads of the build-up processed PWB by the solder micro-press punching technology less than 120 microns pads-pitch. This micro-press punching technology has reached the higher stability of 500,000 times continuously at nearly 0.1 sec/piece speed with 50 /spl mu/m thickness soft solder tape. And the diameter of punched-out solder disk was realized at 50 /spl mu/m level on the tips of the PWB pads directly. This lead-less-chip technology of the flip-chip assembly on MCM-L, has the high reliability and the low cost possibility.

Mcm Development Using Fine Pitch Ball Bump

A fine-pitch ( less than 100 micro-meter pads pitch ) aluminum pad flip chip assembly technology for use with the built-up Printed Wiring Boards (PWB) has been developed and named “Lead-Less-Chip Assembly (LLC Assembly)” technology. Our newly developed technology consists of three points: Forming gold-ball-bumps on the aluminum pads of the bare LSI chip by a wire ball bonding method. Solder-coating on the copper pads of the built-up PWB using Micro Punching technology or the Super-Juffit technology. Flux-less solder bonding the bare chip onto the PWB with a nitrogen atmosphere. A reliability evaluation performed on a single chip and multi chip modules assembled using this LLC Assembly technology with test chips and real C-MOS devices showed a high level of endurance. We have applied this technology to Multichip modules (MCMs) for Note Personal Computers and portable terminals.