Hitachi Cable, Ltd. has begun mass production of a proprietary µBGA*1 package - the Mx µBGA*2 - which achieves low cost without changing the basic structure of previous µBGA packages. By doing so, Hitachi Cable hopes to expand use of µBGA technology into DRAM memory for high-volume, general-purpose personal computing, in addition to its traditional roles in high-end applications.

µBGA is employed primarily as a semiconductor package for DRAM*3 use. By positioning a cushioning material (an elastomer) between the semiconductor chip and TAB*4 tape, µBGA technology achieves high on-board reliability, easing thermal stress in response to dramatic changes in temperature on the chip, TAB tape, or circuit board. Since it uses a polyimide with low permittivity as a base material and enables direct bonding to the chip through the inner lead formed on the TAB tape, it also improves high-speed transmission characteristics by minimizing signal waveform distortions.

Highly regarded for this reliability and transmission characteristics, the technology is used primarily for high-end applications, including servers and digital consumer products. It is also used in semiconductor packages for DDR3 DRAM,*5 which is expected to enter mainstream use for its ability to maximize the performance of high-speed devices.

In cost, however, the technology has suffered when compared to competing BOC*6 packages. It has seen limited use in general-purpose personal computing, which represents the high-volume zone of the DRAM market, with BOC to date capturing the bulk of this market. For this reason, µBGA's share of the DRAM market remains small, and current sales are limited.

To boost sales of µBGA, Hitachi Cable has developed Mx µBGA, achieving attractive pricing levels suitable for general-purpose personal computing while retaining the advantages of µBGA technology, including high reliability and high-speed transmission characteristics. By incorporating into the production of TAB tape (the substrate of the semiconductor package) the 158-mm line large-width tape manufacturing technology developed for COF*7 tape and improving production efficiency by revising the TAB-tape layout, Hitachi Cable has achieved Mx µBGA costs equivalent to or less than those for BOC technology.

By constructing an in-house sheet-based assembly line, Hitachi Cable has also established package assembly technologies suitable for equipment used by many assembly manufacturers.

While BOC technology employs sheet-based assembly, traditional µBGA technology employs reel-to-reel assembly. For this reason, to adopt µBGA technology, assembly manufacturers needed to install specialized equipment. The successful development of sheet-based assembly technology allows assembly manufacturer clients to use existing assembly infrastructures with Mx µBGA, thereby minimizing capital expenditures.

Due to these advances, Mx µBGA is highly cost competitive with respect to both TAB tape and assembly and is expected to see use among expanding numbers of clients for applications in general-purpose personal computing. Hitachi Cable intends to begin full mass production of the newly developed Mx µBGA (TAB tape and assembly) in May 2009.

In the future, Hitachi Cable plans to expand the µBGA share of the market for DRAM package substrates by improving cost competitiveness and by developing package technologies that meet the needs of its clients.

*1	µBGA is a registered trademark of Tessera Inc. of the United States.
*2	Mx µBGA is an abbreviation for Matrix µBGA, a semiconductor package suited to sheet-based assembly by arranging IC packages in a matrix and employing TAB tape with increased production efficiency.
*3	DRAM is an abbreviation for Dynamic Random Access Memory.
*4	TAB is an abbreviation for Tape Automated Bonding, a semiconductor packaging material based on film technology.
*5	DDR3 DRAM is an abbreviation for Double-Data-Rate 3 Dynamic Random Access Memory. Theoretically, it realizes a data transmission speed which is twice as fast as DDR2 DRAM.
*6	BOC is an abbreviation for Board On Chip, a type of semiconductor packaging used primarily in DRAM memory. It commonly uses glass epoxy as a base material, bonded to the chip using bonding wire.
*7	COF is an abbreviation for Chip On Film, a packaging material using two substrate layers with an LCD driver IC chip installed.