CMK makes Ultra-Level boards

CMK Corp. has developed a way to fabricate boards that are so smooth that surface irregularities are kept below 0.1 micron, according to the Nikkei Business Daily.

The company has already begun shipping samples of the boards to producers of electronic paper, sensors and chip packages, products for which boards with extremely flat surfaces are most in demand.

Using existing manufacturing equipment, CMK has the capacity to make around 500 sq. meters of the material a month.

Printed wiring boards are usually made by fabricating the circuit wiring on a flat surface of insulator material, resulting in a finished surface with irregularities ranging from 10-20 microns before polishing.

In CMK's new technique, the circuit wiring is fabricated on a base of film or metal foil and then covered by the insulator. Additional layers can be stacked, but in the end, the base is peeled off and the board flipped over so the wiring on the bottom is now on the top. When this is done, the surface irregularities can be limited to around 1.2 microns. With polishing, the irregularities can be smoothed out to less than 0.1 micron.

CMK said the procedure can be used for boards with copper wiring as narrow as 20 microns and spaced as close together as 18 microns. It can also be used for multilayer and flexible boards.

(Source: The Nikkei Business Daily Tuesday edition and www.circuitree.com)