The traditional PCB fabrication process—involving thick copper layers, the creation of different photomasks for each layer and complex steps for forming plated through-holes—struggles to produce thin, lightweight, high-density multi-layer circuit boards cheaply.
Now Epson, the Japanese inkjet printer maker, says it can offer an alternative: a 20-layer PCB fabricated by inkjets.
The company 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 to reduce energy consumption in PCB manufacture and to make small, lightweight, high-performance PCBs to “help bring about the realisation of a ubiquitous computing society”.
The company’s 20-layer circuit board sample was made 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 of nanometre dimensions and a newly developed insulator ink. The board measured 20 by 20 mm and was 200 μm thick (excluding the baseboard); it features line pitches down to 110 μm.
Epson claims that the inkjetprocess has many advantages over a traditional photolithography process, including: Reduced material usage, since patterns are formed only in areas where they are needed, not over the entire substrate; virtually no liquid waste is created; fewer steps, consuming less energy for manufacture, and being well suited to multi-layer structures, since interlayers can also be patterned directly onto the board.