Modeling and characterization of an industrial inkjet head for micro-patterning on printed circuit boards

A conceptual design using computational fluid dynamics (CFD) and micro-electro-mechanical systems (MEMS) fabrication has been performed to develop an industrial inkjet head for micro-patterning on printed circuit boards. The printhead has been fabricated with silicon and silicon on insulator (SOI) wafers by MEMS process and silicon to silicon bonding method. The measured displacement waveform from a piezoelectric actuator by laser doppler vibrometer (LDV) was used as input data for the three-dimensional flow solver to simulate the droplet formation. The mechanism of droplet ejection from piezoelectric-type inkjet heads was investigated by simulating two-phase flows of the air and metal inks. As a preliminary approach, liquid metal jetting phenomena are identified by simulating droplet ejection and droplet formation in a consequent manner. Parametric studies are followed by the design optimization process to deduce key factors to inkjet head performance: nozzle geometry, droplet size, ejecting speed, pulse amplitude, and ink viscosity. The present design tool, based on a two-phase flow solver and experimental measurements, has shown its promising applicability to various concept designs of industrial inkjet system for micro-patterning on electronic chips and boards.