The Use of Inkjet to Create Direct Write Conductive Features
Abstract:The process of inkjet dispensing metal particulate dispersions to obtain conductive features is an intriguing prospect and reflects an interesting dichotomy for inkjet technology. The ink must be reliable to the extreme, whilst at the same time, contain the maximum possible solids loading of metal particles to create high conductivity, typically less than 10 milliohms per square. It is not straightforward to jet metal dispersions as most conductive materials have densities of up to10g/cm, leading to rapid settling rates in low viscosity fluids for anything other than nano-sized particles. In addition, such high densities create problems in depositing sufficient active materials. For example, an ink with a 35% w/w solids loading ink can contain only 3.5% of active material by volume, significantly reducing the ability to deposit thick metallic layers. Finally, in order to achieve high inkjet reliability and conductivity, the metal particles require a highly effective dispersant which needs to be volatilised during a post heating treatment process.
In contrast, this paper describes an alternative novel approach to allow the direct inkjet dispensing of a range of metals onto non porous materials. The technology uses UV cure based inks and relies on creating a cured “honeycomb” open structure and depositing metal in bulk around strands of a three dimensional UV polymeric network. The process is flexible and capable of being used in many different industrial configurations, including as an inline high speed digital web. This approach achieves high inkjet reliability, high conductivity and the flexibility of tuning a wide range of metal layer and line thicknesses without the need for any post treatment process. Examples of the use of inkjet to create a range of metal tracks using both piezo and thermal inkjet printheads will be presented. The electronic functional performance and properties will be illustrated using a range of different key features such as printing directly to chips or components, printing small features down to less than ten microns and creating highly conductive tracks.
Document Type: Research Article
Publication date: 2005-01-01
For more than 25 years, NIP has been the leading forum for discussion of advances and new directions in non-impact and digital printing technologies. A comprehensive, industry-wide conference, this meeting includes all aspects of the hardware, materials, software, images, and applications associated with digital printing systems, including drop-on-demand ink jet, wide format ink jet, desktop and continuous ink jet, toner-based electrophotographic printers, production digital printing systems, and thermal printing systems, as well as the engineering capability, optimization, and science involved in these fields.
Since 2005, NIP has been held in conjunction with the Digital Fabrication Conference.
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