Kenichi Kasai

Hardware technology for the Hitachi MP5800 series (HDS Skyline Series)

The Hitachi MP5800 series (HDS Skyline Series/sup TM/) has been developed as the top-of-the-line member of the M Parallel Series general computer family. Its highlights include the highest processor performance, dramatically reduced installation requirements (footprint and power consumption), and enhanced reliability and availability. To achieve these goals, innovative technologies have been developed: semiconductor technology called Advanced CMOS-ECL (ACE), which combines high speed emitter coupled logic (ECL) and high density complementary metal oxide semiconductor (CMOS) circuits, one-module processor, which employs a glass ceramic substrate, a high density packaging scheme whereby up to four instruction processors (IPs) are mounted on a single printed wiring board, a cooling technology for large scale integration (LSI) chips with a power consumption as high as 140 W/chip, and a compact high-efficiency power supply system.

A powerful yet ecological parallel processing system using execution-based adaptive power-down control and compact quadruple-precision assist FPUs

This paper reports the first trial in which spatially and temporally fine-grained power-down control has been implemented in a high-performance processor in the sense that the FPUs are controlled spatially and dynamically based on the execution sequence.

Improvement of the reliability of the C4 for ultrahigh thermal conduction module with the direct solder-attached cooling system (DiSAC)

In the HITACHI MP6000 (HDS Skyline Trinium TM), the bipolar-CMOS processor dissipates about 600 W, and the new direct solder-attached cooling (named DiSAC) method has been developed for use with it. In this cooling method, the HDM is supported by the 97Sn/Ag C4 (or CCB; controlled collapse bonding) bumps, which are affected by almost all the deformation that occurs in the power on/off cycle. Hence, the fatigue life of the C4 bumps is most important in the application of this cooling method. In this paper, the causes of C4 bump strain are analyzed by the finite element method, and several techniques for reducing strain are simulated. A new method of estimating the fatigue life of the C4 connections, pseudo-elastic plastic creep analysis (EPC), is developed in order to improve the accuracy of fatigue life calculations, and is used to evaluate the creep strain in a 3D model. Using EPC and experimental C4 power cycle damage data, a new strain-fatigue life curve is defined. Process defects in the direct solder attachment are found to markedly shorten the fatigue life of the C4 connections, and the effects are estimated. All the technological developments presented are implemented in the DiSAC model, and the improvement in reliability is verified by experiment.

Construction of a fatigue-crack-growth database for nuclear-component ferritic steels in Japan and its statistical analysis

Abstract A database of the fatique-crack growth for nuclear-component ferritic steels was constructed. Data collected are for the low-alloy steels (A533B-1, A508-2, A508-3) and a carbon steel (STS42), tested in air from room temperature up to 371°C. Characterization of the fatigue-crack-growth data and improvement of the conventional design curve were attempted. A proposed design curve is given as follows: d a/ d N = 3·57 × 10 −9 [(1 + 0·30R)(E 0 /E) 0·51 ΔK] 3·02 ( d a/ d N:mm/cycle, ΔK:MPa√m) where da/dN is the fatigue-crack-growth rate, R is the stress ratio, E0 is the Youngs modulus at room temperature, E is the Youngs modulus at the temperature concerned, and ΔK is the stress-intensity-factor range. This equation proved more applicable than the one proposed for the revision of Section XI of the ASME Boiler and Pressure Vessel Code.

Corrosion Behavior of Copper in Liquid Perfluorocarbon.

Liquid perfluorocarbon coolant Fluorinert® FC-72 for electronic devices has high thermal stability and low chemical reactivity. However, the presence of water in FC-72 at less than 10wt ppm has been shown to appreciably increase copper corrosion. In the present study, the corrosion mechanism under low solubility of water in FC-72 was investigated by chemical analysis, water volume measurement, and corrosion testing. It was found that FC-72 liberates no decomposition products in temperatures below 100°C and copper corrosion depends on liquid temperature, dissolved water, and oxygen. In FC-72, copper specimens were corroded by wet oxidation at temperatures of 50, 70, and 85°C and by both wet and dry oxidation at 100°C. Copper corrosion was induced when dissolved water in FC-72 was increased to more than 8wt ppm. However it was reduced when oxygen in FC-72 was decreased to less than 25ml/L. Dissolved water in FC-72, as in air, equilibrates with adsorped water on copper surface. Therefore, the mechanism of copper corrosion in FC-72 is the same as that in air. It is considered that the mechanism for FC-72 can be extended to explain corrosion behavior in almost all inert coolants.

Study of rotational bending stress in multi-stage centrifugal pump shafting.

多段遠心ポンプ軸系を模擬した装置により, 環状シールの偏心や傾きのミスアラインメントが軸の回転曲げ応力に及ぼす影響を実験的に検討し, 計算結果と比較した. その結果, 下記の事項が明らかになった. バランスブッシュが軸に対して下方に偏心していたり, 軸のたわみ角と逆方向に傾いていると回転曲げ応力が大きくなる. ブッシュのラビリンス状のみぞを大きくすると回転曲げ応力が減少する. 計算値は実験値とほぼよく一致する.