Semiconductor packaging is changing due to inkjet technology
Unlike with traditional dispense technologies, inkjet deposits a large number of very small droplets (picoliter volume) of functional liquid materials on a substrate. Thousands of individually addressable nozzles are utilised to dispense these materials in a non-contact way. The technology enables digitally patterned layers as well as homogeneous layers, even on 3D surfaces and 3D structures. Besides, in advanced semiconductor packaging, these benefits are recognised in many other industries such as printed circuit board (PCB), photovoltaics (PV), display, 3D printing and even pharmaceutics where inkjet technology finds its way into industrial manufacturing. The feature size of inkjet printing is not compatible with semiconductor front-end processes because sub-micron patterning is required. However, many wafer based back-end-of-line and strip based packaging process steps need features of tens of microns up to millimetres, and can benefit from inkjet. Therefore inkjet printing is being adopted by some of the largest semiconductor producers in the world. This paper will review the advantages of inkjet in comparison to traditional technologies, give an overview of inkjet compatible materials and highlight two application examples of the technology.