Toshio Hatada

A CPU chip-on-board module

A CPU chip-on-board module for low and midrange computers is described. The module consists of a CPU bare chip, 24 SRAMs packaged in SOJ packages, and some decoupling capacitors. The module substrate is a printed circuit board (PCB) made of bismaleimide-triazine resin. The module (156 mm/spl times/58 mm) consists of four signal metal layers and four power/ground metal layers. A square clearance hole (17 mm/spl times/17 mm) for the CPU is formed in the central part of the PCB. A thermal spreading metal is glued to the PCB from the rear side, covering the square hole, and the CPU chip is die-bonded onto the metal plate. The thermal resistance can be made smaller than 2/spl deg/C/W with 0.4 m/s of wind velocity. Numerical analysis of electrical characteristics of the module shows that it can reduce signal delay time from the CPU to cache memories by 10% compared with that of a daughter board type module with the CPU packaged in a pin-grid array package. It is estimated that simultaneously switched noise can be reduced by 60% from that of the daughter board type module. >

Package design for high-speed low-cost ASIC LSIs

Cofired alumina ceramic, alumina-based Cu/polyimide thin films, and plastic PGAs (pin-grid-arrays) are compared in terms of electrical and thermal characteristics and cost. Plastic PGA with the cavity down and a three-layer structure is shown to be the best way to meet the requirement of over 50-MHz signal transmission, thermal resistance and cost. The best results on the 592-pin plastic PGA package and its simulation results are described.<<ETX>>

Air-flow through high-performance louvered fins for air-conditioners

It is necessary to know the air-flow pattern through fins, in order to improve the performance of heat exchangers for air-conditioners. This report presents some visualized examples of high performance fins, that is, convex louvered fin and inclined louvered fin. Aluminum powder method and dye injection method are used where air is replaced with water. In that case Reynolas number for visualized models is adjusted so as to agree with that for real heat exchangers. The visualized results of air flow utilized for deciding the louver arrangement of high performance louvered fins.