Inkjet used to make Multi Layer PCB

Multilayer circuit boards are normally produced by using a photolithography process to pattern a copper foil bonded to a base board. However, the industry has struggled to produce thin, lightweight, high-density multilayer circuit boards cheaply because the traditional process requires (1) thick copper layers; (2) the creation of a different photomask for each layer; (3) a complex step for forming through-holes to electrically connect different layers; and (4) a large volume of photoresist, developer, etchants, stripping agents and other chemicals. Against this backdrop, Epson received a grant from the New Energy and Industrial Technology Development Organization (NEDO), an independent Japanese governmental agency, to develop technology for fabricating circuit boards using inkjet technology. The goal of the three-year project, which was launched in June 2003, is two-fold: dramatically reduce the energy consumed in the manufacture of circuit boards; and fabricate small, lightweight, high-performance circuit boards used in end-products such as information and communications equipment, thus helping to bring about the realization of a ubiquitous computing society. Epson recently succeeded in producing a 20-layer circuit board sample by using an inkjet system to alternately "draw" patterns and form layers on the board using two types of ink: a conductive ink containing a dispersion of silver micro-particles measuring from several nanometers to several tens of nanometers in diameter, and a newly developed insulator ink. An inkjet-based manufacturing process has many advantages over a traditional photolithography process: (1) it uses a far lower volume of materials, since patterns are formed only in areas where they are needed, not over the entire substrate; (2) it is a dry process, so virtually no liquid waste is created; (3) it involves fewer steps, and thus consumes comparatively little energy; (4) it is readily adapted to high mix, low volume production, since no masks are used; and (5) it is well suited to multilayer structures, since interlayers can also be patterned directly onto the board. An inkjet-based process thus enables low-cost, high-density multilayer circuit boards to be produced via a green manufacturing process with a light environmental load.