Fraunhofer Institute for Reliability and Microintegration IZM
As part of the Cornet project ENAMEL, we have worked with the Research Institute for Textile and Clothing from the Hochschule Niederrhein (DE), the Research and Innovation Centre for Electrical Engineering from the University of West Bohemia (CZ), and the industry partner VÚB Co.Ltd. (CZ) to tackle one of the key challenges for textile-integrated electronics. The project focused on two promising ideas: Encapsulating conductive textile structures and assessing PCB embedding as a technology option for e-textiles.
Simpler processes with embedded electronics
PCB embedding makes it possible to completely embed electronic components, such as chips, into the material of the circuit board itself. This removes the need for additional process steps in conventional encapsulation technologies, such as applying casting compounds, mounting casings, or adding additional coating layers. With these steps removed, the entire production process becomes streamlined and more commercially attractive.
Improved bonding performance with planar module surfaces
The planar chip-embedded modules studied in the project offer other advantages beyond the simplified processes: With their flat surface topography, they are exceptionally well-suited for the electrical and mechanical integration into conductive textiles by non-conductive adhesive bonding technologyCompared to more conventional modules with assembled components on the top layer, there is no need for complex frame bonding solutions. The planar surface of the PCB-embedded modules ensures that pressure is spread evenly during bondingand ensures even heat distribution, in turn making the process more reliable and the connections more reliably reproducible. Standardized flat bonding tools can be used for a different module types, offering a more flexible and faster, less tooling-intensive process.
A thorough study of the protection for e-textiles
As one of its key areas of focus, the project also looked at the effectiveness of combining PCB-embedded moduleswith an additional barrier film laminated over the top of the module. The over-laminated modules were subjected to laundry, moisture, and sweat exposure. Additional innovative avenues opened up in the form of the rigid-to-soft gradient created by the films between the rigid electronics and the flexible fabrics. This gradient serves to reduce the incidence of broken conductors, which can occur when the e-textiles are bent, crumpled, and spun during laundry. The follow-up Cornet WET project will pursue this aspect of the protection / transition layer further.