|Title :Laser Processing of Printed Copper Interconnects On Polymer Substrates.|
|Invited Presentation: David A. Hutt
|Affiliation: Senior Lecturer
Wolfson School of Mechanical and Manufacturing Engineering
LE11 3TU, UK
With the increasing demand for integration and embedding of electronics into a variety of devices there has been a consequent increase in the demand for novel materials and methods for the deposition of electrically conductive tracks on non-traditional substrate materials and/or complex 3D shapes. Current and future manufacturing methods of such devices may include high volume reel-to-reel processing on temperature sensitive polymer substrates, e.g. for low cost RFID tags or IoT applications, or incorporation of circuits onto or within 3D printed plastic parts. Circuit deposition techniques must therefore be compatible with these applications and ideally be additive in nature. Materials development has largely focused on silver inks and pastes due to their high conductivity and reliability; however, they are limited in their uptake by the relatively high material cost and, in many cases, the requirement for non-localised thermal processes to obtain the required electrical properties.
This presentation will describe recent research investigating methods for the deposition of micron scale copper powder based materials and their selective laser processing to form interconnects on polymer substrates. The approach uses copper powder that is chemically treated to modify its surface condition and then patterned onto the substrate either as a dry powder, or combined with a binder to be printed as a paste. A low cost CO2 laser is then used as a highly controllable heat source to deliver the required power selectively to the copper powder, leading to tracks that show good electrical conductivity and with microstructures that are dependent on the process parameters. This controlled laser treatment method has enabled the formation of conductive tracks on low melting temperature polymer substrates, thereby enabling the capabilities of the technology to be explored in the creation of 3D printed circuits.
Dr David Hutt is a Senior Lecturer at Loughborough University, UK and a Senior Member of the IEEE. He received his BSc in Chemistry and PhD in Surface Science from Imperial College, London and studied surface chemistry / physics as a Research Associate at a number of UK universities. In 1997, he joined the Interconnection Group at Loughborough University, applying this background to the field of electronics manufacture and was appointed to a lectureship in 1999. He has led numerous research projects in the area of electronics packaging and published over fifty journal papers with particular emphasis on self-assembled monolayers for surface modification and preservation, metallisation using electroless plating, flip-chip assembly, copper filled electrically conductive adhesives, polymer and glass substrate manufacture.