Hitachi Cable has recently succeeded in developing semiconductor packaging materials capable of high-density packaging for portable electronics and other applications, and has developed a mass-production system for this purpose. These semiconductor packaging materials are an enhanced version of µBGA*, the patents on which are held by Tesera Corporation, U.S.A(headquartered in San Jose, California, U.S.A). These materials achieve higher reliability and dramatically greater mass-production efficiency.

Recently the demand has been growing even faster than before for downsized semiconductor packages, together with lager-capacity, faster, and higher-function semiconductors, in response to demand for higher performance and downsizing of cellular phones and other portable electronics.

Spotlighted accordingly is a package structure called the ball grid array(BGA). BGA is not an arrangement of pins along the sides of a lead frame as in conventional quad flat package structures. Rather, it is an equal arrangement of solder balls on the bottom of the package and therefor adaptable to downsized, multi-pin packages. Out of all the BGAs with such advantages, only µBGA is adaptable to solder ball Pitches of less than 0.75mm. So compared to both conventional BGAs with a pitch of 1.27mm and fine-pitch BGAs with a pitch of 0.8mm, µBGA has a smaller solder ball pitch, and thus is advantageous in realizing downsized, high-density packages. The semiconductor packaging materials developed by Hitachi Cable are enhanced version of this µBGA. These materials comprise of the following two types:

1.µBGA tape

This high-density patterning tape for manufacturing µBGA has a wire tip that can be bonded directly to the aluminum wiring bonding pad on semiconductor chips by thermo-compression. The terminals of the wiring, on the other hand, connect to solder ball.

Therefore the role of the µBGA tape is to connect solder balls to semiconductor chips and this is the key to making chip scale packages(CSP) a reality. Using its original technology, Hitachi Cable has established a reliable bonding method. We enhanced the copper foils for leads that connect semiconductor chips to solder balls and produced a plating method for surface-treating the copper foils.

While the width and pitch of printed wiring used in conventional BGAs are 100micrometers, the µBGA tape which Hitachi Cable has developed has a wiring width and pitch of 25 micrometers, thus enabling hyperfine patterning, and consequently allowing the company to successfully make high-density wiring a reality.

2. Hitachi Cable Chip Mounting Tape(HCMT)

HCMT is high-density patterning tape for making µBGA. It combines µBGA tape with an elastomer (a cushioning material) enhanced by Hitachi Cable's innovative technology, whereas conventional µBGAs require printing for installing an elastomer. The attachment method of this highly functional film developed by Hitachi Cable can now be used to greatly increase dimensional stability and mass-production efficiency. Also the elastomer can be made of different materials depending on the operating environment of the semiconductor packages.

The aforementioned materials developed by Hitachi Cable are characterized by the following features:

(1)	The attachment method of the highly functional film developed by the company not only absorbs strains due to differences in the expansion coefficients of different film layers, but also produces highly reliable semiconductor packages.
(2)	The elastomer is applied to the tape in advance, thus increasing the productivity of chip assembly.
(3)	The present µBGA tape involve the thin gold plating of connecting leads, so that the copper foil can be connected directly to the chip, thus making our tape cheaper than the traditional tape automated bonding(TAB) and gold wire bonding.

µBGA is expected to be used for semiconductor packages for flash memory and for multi-chip mounting. We product that the µBGA tape and HCMT developed by Hitachi Cable will increase both quality and mass-production efficiency resulting in accelerating the spread of BGA.

Hitachi Cable is planning to set up facilities capable of supplying new materials, such as µBGA tape with a double-layer structure based on the technology of TAB tape, face-down µBGA tape, and materials for semiconductor packages adaptable to CSP age.

*	µBGA is a registered trademark of Tessera Corporation, U.S.A