Commercialization of high-capacity DDR2 DIMM*1 using µBGA®*2/sFBGA
In the field of development of advanced computers such as high-end servers, there is always a need for higher DRAM speed and capacity as well as for higher microprocessor speed. FBGA (Fine-pitch Ball Grid Array) is now receiving attention as an ideal package structure for such advanced DRAM. In collaboration with Hitachi, Ltd., we put µBGA®, a type of FBGA, into practical use ahead of the competition. In addition to typical features of FBGA, i.e., a high packaging density and an outstanding transfer rate, µBGA® ensures further increased reliability and transfer speed due to the inclusion of a unique cushioning material structure between the chip and TAB tape.
In collaboration with Elpida Memory, Inc., we commercialized a µBGA® package product that accords to DDR2 SDRAM, the fastest DRAM standard at present. This achievement has received much acclaim within the industry. For example, for this product, we were awarded the Nikkan Kogyo Shimbun’s 2nd Monozukuri Component Grand Prize in its electric/electronic component category in March 2005. Our collaboration has also resulted in successful practical use of sFBGA (stacked FBGA), a technology for packaging µBGA® in two layers, the highest capacity available in the industry within the bounds of the current module standards.
*1 DIMM stands for Dual In-line Memory Module, a memory module standard.
*2 µBGA® (micro Ball Grid Array) is a registered trademark of Tessera, Inc. in the United States.
Cross sectional view of sFBGA |
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Roles of main memory
“Memory” used in PCs and electronics is broadly divided into two: main memory, such as DRAM, and external memory, such as an HDD and removable memory. Main memory temporarily holds programs or data needed for calculations and processing performed by the CPU; the data is transferred at high speed between main memory and the CPU. Main memory temporarily stores the calculation results, which will be displayed by output devices or stored in external memory. To maximize performance of the CPU, it is necessary to make sure that main memory has adequate capacity and transfer rate.
