Jun 7 2005
Hitachi Chemical Co., Ltd. has developed a new base material for multi-layer printed wiring boards. The new base material, named "Cute®," is flexible and extremely thin (50 microns or thinner), and will be marketed in earnest from FY 2005. Cute® is manufactured by applying the company's epoxy-based, low elastic modulus thermosetting resin to coat and impregnate 20-micron or thinner glass cloth and then overlaying it with copper foil. The new product should play an effective role in efforts to further miniaturize and slim down portable digital products such as digital camcorders, camera phones, etc.
Electronic devices continue to be further miniaturized and sophisticated. To this end, the printed wiring boards used to electrically control such devices require not only a high-density and multi-layer structure, but also a structure that allows flexibility in space-constrained installation. Conventional solutions for use in such small spaces where boards must be bent to fit have been primarily flexible PWBs and/or rigid-flexible PWBs that combine both rigid and flexible PWBs.
The newly developed "Cute®" utilizes extremely thin (20 microns or thinner) glass cloth as the core material, although it had not been actively employed for reliability reasons. Hitachi Chemical, however, has succeeded in manufacturing an ultrathin and multi-layer PWB base material that not only provides high strength and dimensional stability, but that can also be freely deformed as needed. Hitachi Chemical accomplished this by applying an epoxy resin of its own development, which has excellent properties in such as flexibility, heat resistance, adhesiveness, low coefficient of thermal expansion, etc., to coat and impregnate the core material.
The base material is primarily composed of (1) glass cloth as the core material (TC-C-100), (2) prepreg (TC-P-100), and (3) copper foil integrated with resin which works for the coverlay and interlayer bonding (TC-F-100). PWBs structures with any number of layers can be manufactured by a combination of these components.
A Cute®-based four-layer PWB can be manufactured with a thickness less than a half that of the prevailing four-layer PWBs. It can also eliminate the connectors that were otherwise necessary for connection between the rigid and flexible boards as in the case of flexible PWBs. These advantages, plus the fact that they are foldable, should make the CuteR-based PWBs suitable for use in even smaller spaces and help provide more freedom and new possibilities in designing portable digital products.
The new base material also allows easy via connection to flexible layers, which has been technically difficult with the currently available rigid-flexible PWBs, and makes it possible to produce PWBs with high density in all 3D planes. Also of note is that the Cute® material, which uses low elastic modulus thermosetting resin, can improve the material yield rate because the resin does not produce much plastic dust in the cutting process.
Hitachi Chemical plans to begin successive commercial production of halogen-free Cute® and highly heat-resistant Cute® within this year, both of which are designed to be environmentally friendly materials. The company intends to actively promote the marketing of the new material by focusing on the multi-layer PWB market for portable digital products, and hopes to achieve annual sales of 4 billion yen by FY 2008.
http://www.hitachi-chem.co.jp