Organic Conductive Ink Eliminates Sintering Step from Printed Electronics Manufacturing

­The REFORM project, a Horizon Europe-funded research and innovation consortium, has developed a proof-of-concept fully organic, sintering-free conductive ink for printed electronics, with development led by CIDETEC Surface Engineering and KTH Royal Institute of Technology.

The demonstrator shows the potential for a conductive ink that works within existing manufacturing processes, screen printing onto paper and polymeric film substrates, curing at room temperature, and assembling with standard pick-and-place equipment, with no special infrastructure needed at any stage.

The challenge for manufacturers

Conventional conductive inks require high-temperature sintering, typically between 120 and 300°C, to achieve adequate electrical conductivity. This creates a dependency on thermal processing infrastructure, limits substrate compatibility, and adds cost and complexity to the manufacturing process. For manufacturers working with heat-sensitive substrates or looking to simplify their production lines, the sintering step represents a significant constraint.

What the demonstrator shows

The proof-of-concept ink is screen printed onto a substrate in a single pass, with no special equipment required. It then cures at room temperature, approximately 20°C, with no oven or heat source. Once cured, the ink exhibits good electrical conductivity, as demonstrated by resistance measurements taken across different points on the printed circuit.

The demonstrator also shows the ink's compatibility with standard electronics assembly processes. The printed circuit is loaded into a pick-and-place machine, with LED components picked and bonded directly onto the ink. The assembled circuit is then connected to a battery, with the LEDs illuminating as proof of end-to-end conductivity on a flexible substrate.

Yolanda Alesanco, REFORM project coordinator and Senior Researcher at CIDETEC Surface Engineering, who contributed to the development of the ink and led its implementation in the printed electronics prototypes developed in the project, said:

“The sintering step has long been a limiting factor in printed electronics manufacturing; it constrains which substrates you can use, adds thermal processing requirements, and creates barriers to scaling”.

“Developing an ink that performs well at room temperature and integrates with standard equipment is a meaningful step towards making printed electronics more accessible and more sustainable. We're pleased to have led this work as part of the REFORM consortium”.

Proof-of-concept demonstrator

A proof-of-concept demonstrator has been produced showing the ink screen printed onto a substrate, cured at room temperature, and assembled with standard pick-and-place equipment. The demonstrator covers electrical conductivity measurement after curing and end-to-end circuit operation with LED components on a flexible substrate, illustrating the ink's compatibility with existing printed electronics manufacturing processes.