Innovation in TPU: Turning Challenges
into Scalable Solutions

An electrical circuit printed on a TPU substrate can be used for many diverse applications for
wearable and flexible electronics, it is usually, but not exclusively, applied to a textile woven or
nonwoven and it can carry signals, monitor the level of stretch, transfer heat etc., but it is usually difficult to print. In fact, screen printing works best with flat and stable substrates. During the printing process, the typical difficulties in the use of TPU materials are caused first by the printed sheet sticking to the mesh and lifting off the platen after being printed and second by the exposure to the curing temperature of the ink that affects the flatness and the dimensional accuracy of the TPU and the printed circuit on it. These issues are difficult to address and result in a great amount of scrap and, at times, in the total inability to produce a workable circuit. Once (or if) the printed circuit is finally produced there is a need for a dielectric layer to be applied over the tracks, usually a liquid varnish that polymerizes and becomes a stiff and rigid film. This type of dielectric layer does not match the elasticity of TPUs and breaks when Stretched. During the final step, the transfer of the printed circuit on the textile material, the heat necessary to obtain a good bond between the TPU printed circuit and the textile will soften the TPU and damage the integrity of the tracks thus reducing the level of conductivity. We have developed a product line and an application process to eliminate all these issues and allow the production of multiple layer circuits. The base product is called ELECROM STRECH TS, available as CLEAR or WHITE version, and it is used effectively in combination with ELECROM STETCH ENCAPSULATE that replaces the dielectric layer but also can work as a base for multiple based circuits. We will show a short video that explains the printing and assembly procedures for the
ELECROM STRECH product line. The sample project chosen for this video is a circuit to be
applied to a glove and furnish pressure sensors to the fingers of a hand to monitor the amount
of force applied to hold an object. Next is a 2 min video showing the various steps of the process. The fin We have compared the conductivity of ELECROM STRETCH TS which is a TPU supported by a heat stabilized and surface treated PET vs a STD PET substrate used for the production of membrane switches. The table shows a very similar behavior in terms of conductivity. The conclusion will list a number of application sectors, previously unthinkable, that can be now approached with this new material and process.