Solderable conductive paste for electronic textiles

Abstract

Background: In recent years, electronic textiles (e-textiles) have attracted widespread attention due to their versatility, but still lack a good packaging technique. Soldering, one of the electronic packaging technologies, has been widely used to provide electronic joints with good electrical and mechanical properties. However, direct soldering on e-textiles has to overcome several problems, such as melting at high soldering temperature and non-solderability of printed conductive patterns.Methods: The thermal stability and wettability of the resin were enhanced by adjusting the formulation to provide a base polymeric adhesive material. The formulated polymeric resin was then mixed with 85 wt% metal fillers to reach good conductivity after curing. A surfactant was also added to enhance particle dispersion and lowered the paste viscosity to screen print complicated conductive patterns on textile materials.Significant findings: The printed thin film showed good solderability with a low wetting angle for solder melt. A layer of intermetallic compound (Cu6Sn5) was found between solder and solderable patterns, which provided a great adhesion strength and peel strength on fabrics. Solder joints on the printed conductive adhesive also showed great shear strength. The solderable paste was printed into a heating grid on textiles to show good electrical interconnectivity with solder joints. In summary, this study provides a general guideline for the preparation of solderable paste and can be extended for other packaging applications in electronic textiles.