Study of low-temperature interconnection techniques for instant assembly of electronics on stretchable e-textile ribbons

Abstract

This article addresses the research and development of a reliable interconnection technique for mounting surface mounted device components onto newly developed conductive stretchable textile ribbons. The alternative nonconductive adhesive bonding in which electrical contact is realized only by mechanical pressure and fixed by an adhesive and the conventional soldering technique were selected for examination. Assessment of the performance of these techniques and their usability for interconnecting components on conductive textile ribbons was also our research goal. Reliability tests of the electrical and mechanical properties of realized interconnections (dry heat, damp heat, washing, electrical current load, jerk, and stretch tests) were realized. The results show that the nonconductive adhesive technique results in good mechanical properties and acceptable median electrical resistance of less than 2 Ω even after 90 washing cycles. It is also very gentle and fully compatible with textile production due to the maximal processing temperature lower than 70°C, without the risk of short circuit occurrence. This technique is suitable for sensors, illumination or data transfer applications. While soldering results in excellent median electrical resistance of less than 20 mΩ, it is more complex and costly. Moreover, there is a risk of short circuits as well as of textile damage by the high thermal load over 150°C. Soldering is more suitable for power supply applications or heating. The above-mentioned results were also confirmed in a decision analysis with pairwise comparisons, involving company representatives considering introducing the above-mentioned interconnection techniques into their production. The nonconductive adhesive technique was evaluated as 15% better in overall decision analysis than the low-temperature soldering.

Porous Conductive Textiles for Wearable Electronics

“…Sn- and In-based alloys are commonly used solders with low melting point ( T m ). For example, Sn 42 Bi 58 is a representative low-temperature solder for textiles owing to its low melting point of 138–139 °C and low cost. , However, the brittleness and poor wettability of the Sn–Bi solder hinders its application. In contrast, In-based alloys have lower melting point ( T m of In 52 Sn 48 is 118 °C), higher ductility, and wettability .…”

Reliability Testing of Recycled SMD Components Reused in E-Textiles after Ageing by Washing Cycles

“…The method for the electrical connection of SMD components, specifically resistors with 0 ohm resistance and a case size of 1206, to conductive lines on ribbons is realized by our special contacting technique [10] utilizing a UVcurable, non-conductive acrylic adhesive (NCA)specifically Loctite AA 3926 by Henkel Company. The procedure (see Figure 2) begins with dispensing the adhesive onto the space between the conductive lines on the ribbon.…”

“…Our long experience in this field (e.g. [10]) shows that e-textile product (in our case the conductive ribbon) or electrical connection itself are usually degraded, but the component remains intact. The important parameter to consider in the case of e-textiles is that the sweat from any activity is absorbed by the e-textile, and it has to be washed periodically for hygienic reasons.…”

Experimental Analyses and Predictive Modelling of Ultrasonic Welding Parameters for Enhancing Smart Textile Fabrication

“…Smart textiles are intended to conform to the body or textile structure while retaining functionality. Balancing the demands of strong, conductive bonds with the need for textile flexibility and comfort presents a challenge and material optimisation problem [ 22 , 23 ].…”