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60 The PCB Magazine • June 2015 Stretchable circuits are an evolving branch of electronics interconnection technology and the subject of growing interest to product de- velopers seeking to provide novel wearable electronic solutions for consumer and medical markets. Such circuits are designed and manu- factured using resilient materials which allow them to expand and contract with the move- ments of the user or to conform to nonplanar surfaces making possible a wide range of inno- vative and fanciful electronic interconnection devices. Obviously, the material used is a key element in making a stretchable circuit. There are a range of different types of thermoplastic polymers available in film form that can be ef- fectively stretched; however, once stretched be- by Shingo Yoshioka, Tomoaki Sawada and Takatoshi Abe PanaSOnIc cOrPOraTIOn Novel High-Performance Substrate for Stretchable Electronics yond their elastic limit the material deforms to a new length greater than that which was de- signed. There are as well elastomeric materials, such as urethanes, which have seen use in the manufacture of circuits which can be stretched and return to their original length. These mate- rials tend to be opaque, which limits the scope of possibility for their use. A new transparent, high-performance thermal setting stretchable material could open doors to a range of new and innovative products. New Stretchable Material Characteristics The new material is capable of stretching to 150% of the original length without hysteresis. Figure 1 provides a comparison of stress-strain plots of the new material compared with ther- moplastic PEN. Another key attribute of the material is its ability to reliably return to the original length FeAtuRe