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Reliable, impermanent connectors are a significant challenge in the development of e-textile devices, needed to increase their modularity, a key factor in their ability to be repaired or recycled. The combination of spring loaded contacts and magnetic fastenings is a promising option, as these components exhibit the small size and mechanical compliance necessary for use in flexible devices. This letter details the evaluation of a five-pin, spring finger connector held in place by two pairs of 1-mm-thick NdFeB button magnets. The connector is subjected to bending and straightening around a 9-cm diameter to analyze its suitability for use in an e-textile device. The results show that with 1.3-mm high springs and a backing with a flexural rigidity of $1.16\,\, {}\times {}10^{-4}$ Nm2, 100% reliability can be achieved on that test. These results indicate a necessity to use small springs that can easily be flattened. However, their small working range means that they may not be as reliable when connecting to uneven surfaces. [ABSTRACT FROM AUTHOR]

A novel packaging method that enables the reliable mounting and protection of bare die within a textile yarn has been investigated. The reliability of electronic textiles is highly challenging given the flexibility of the fabric and the rigors of typical applications. Achieving reliable operation requires novel packaging approaches. In order to maximize the reliability and to minimize stresses in the electronic package, the die should be located as close as possible to the central axis of the overall assembly. The die is bonded to a bottom Kapton substrate that contains patterned conductive interconnects and bond pads forming the functional circuit. The circuit is protected by a molded Kapton film that has recesses formed where the die is located. This approach has been compared with three other traditional packaging technologies during washing, twisting, and cyclical bending tests. The novel electronic packaging method shows the best performance in all tests surviving up to 45 wash cycles. [ABSTRACT FROM AUTHOR]

A method for packaging integrated circuit silicon die in thin flexible circuits has been investigated that enables circuits to be subsequently integrated within textile yarns. This paper presents an investigation into the required materials and component dimensions in order to maximize the reliability of the packaging method. Two die sizes of 3.5 \,\,\text mm \times 8 \,\,\text mm \times 0.53\,\, \text mm and 2 \,\,\text mm \times 2\,\,\text mm \times 0.1 \,\,\text mm have been simulated and evaluated experimentally under shear load and during bending. The shear and bending experimental results show good agreement with the simulation results and verify the simulated optimal thickness of the adhesive layer. Three underfill adhesives (EP30AO, EP37-3FLF, and Epo-Tek 301 2fl), three highly flexible adhesives (Loctite 4860, Loctite 480, and Loctite 4902), and three substrates (Kapton, Mylar, and PEEK) have been evaluated, and the optimal thickness of each is found. The Kapton substrate, together with the EP37-3FLF adhesive, was identified as the best materials combination with the optimum underfill and substrate thickness identified as 0.05 mm. [ABSTRACT FROM AUTHOR]