Hitachi Cable, Ltd., is pleased to announce that it has begun the world 's first mass production of a double-sided Chip On Film (COF) module tape for use in mobile phones. The increasing sophistication of mobile phones means that they require an increasing number of IC chips and digital components. Because of this, the Company expects that demand for a double-sided COF module tape will grow dramatically, as it represents an efficient and space-saving solution for mounting the increasing number of IC chips and digital components.

Until now, the main current in mobile phone LCD panel wiring has been separate mounting of IC chips and digital components. Specifically, IC chips are mounted directly on the LCD panel glass (a process called Chip On Glass, or COG), while digital components are mounted on a printed circuit board. The wiring is laid on a film that connects the LCD panel glass and the printed circuit board.

However, the trend toward more sophisticated, color LCD screens requires the use of a more and more IC chips and digital components. Therefore, manufacturers are quickly turning to COF modules as a space-saving design that can accommodate both IC chips and digital components, as this method allows all parts to be mounted on a film. Because the increased number of components has caused an increase in patterns that cannot be wired on one side alone, it was necessary to quickly develop a double-sided COF module tape that could mount IC chips with a wiring pitch under 50 µm.

Hitachi Cable has long manufactured TAB tapes for the IC chips used in LCDs. Leveraging its microscopic wiring technology, the Company was able to begin the manufacture of a single-sided COF module tape last year. In addition, in 1996 Hitachi Cable became the world 's first producer of double-sided tape for Ball Grid Arrays (BGAs). Using the technology amassed in these areas, the Company was able to develop a double-sided COF module tape that is fine-pitch compatible. Hitachi Cable is pleased to announce that it has begun production of this product.

Hitachi Cable 's double-sided COF module tape has the following advantages:

1) Fine pitch compatible

The double-sided tape includes a copper-coated through hole to allow conduction between the top and bottom patterns. Because copper foil on the wiring surface is attached to the surface plating, the copper foil gets thicker. This makes it difficult to realize a narrower wiring pitch. Hitachi Cable has solved this problem using the fine pitch etching and via plating technology garnered from the manufacture of TAB tapes, allowing for a pitch of 45 µm.

2) Optimal Bendability

In order to insert this product into the tight spaces mobile products provide, it is very important that the product be bendable. By using a highly bendable polymide substrate that is 25 µm thick combined with flexible film, the Company has been able to realize optimal bendability.

3) Using Press Via, a Method Excellent for Mass Production

In the past, via holes for conductivity were formed using a laser. Using the more economical press method represents a new direction in via hole creation technology. Through combining this method with the reel-to-reel TAB tape mass production process, it is possible to realize faster mass production and shorter delivery times, making it the optimal technology for the demanding mobile phone components market.

In the future, Hitachi Cable will continue to develop single- and double-sided COF module tapes that meet all diverse mobile device needs. The fiscal 2003 COF module tape for mobile phones sales target is set at 2.0 billion yen.

This product is produced at:

Densen Works
1-1 Sukegawa-cho 3-chome, Hitachi City, Ibaraki