TABLE OF CONTENTS There is a strong global market trend toward handheld devices such as cellular phones and digital personal assistants. While the first challenge was miniaturization and weight reduction, the focus now is on additional features or customer value. Highly prized models combine more and more functions, increasing the complexity of the devices. Examples are integrated cell phones, Internet browsers, global positioning systems, and so forth. This trend coincides with ever shorter product lifetimes and decreasing prices. Hot products used this year will be either obsolete next year, or at best offered at much lower prices.
Microvia technology can be successfully applied to achieve higher density and smaller feature sizes. Mechanical drilling covers a wide diameter range while pushing the limits toward smaller via sizes. Conventional mechanical drilling for non-microvias can drill all kinds of PCB materials, such as FR-4, Mitsubishi Gas and Chemical s BT, General Electric s GETEK, Hitachi Chemical s MegTran (FR-4.5), and Matsushita s MCL-679. There are many equipment vendors supplying various mechanical drilling systems, such as Advanced Controls, ATI, Ching Huei, Datron, Electro Scientific Industries, Inc., Excellon, Hitachi, OZO, Panasonic, Pluritec, Posalux, Sieb & Meyer, Technic, and Yaskawa.1
In general, mechanical drilling is not suitable for forming microvias. However, with innovative technologies of high-speed spindle and numerical control, it is still possible to make small holes at the scale of microvias by mechanical drilling. For instance, Excellon Automation has been developing an NC drilling machine that may form microvias down to 100 m (4 mil).1
