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EPTE Newsletter: Exotic Materials— A Prerequisite for Next-generation Flexible Circuits

More than 20,000 results populate on an Amazon search for wearable technology. There is no question that wearable electronic devices have created a new electronics market, especially those earmarked for medical and healthcare. Wearable devices demand 3D flexible wiring, so flexible circuits are an appropriate solution for these devices.

Wearable electronics require different performances from their circuit makeup compared with traditional flexible circuits. Previously, we advised customers to design flexible circuits according to the standard design guide to optimize performance and manufacturing yields. Wearable electronics changed our way of thinking relative to these new performance prerequisites.

3D wiring is one of the major features of typical flexible circuits because of the flexibility from the base materials. However, you are limited to the number of material choices for traditional flexible circuits. Designers create circuits with only a small selection of materials available. Polyimide film is one of the limited choices for high-temperature processes such as soldering and wire bonding. It has a good balance as the dielectric material for traditional flexible circuits; however, it is not comfortable to wear polyimide films when used in clothing.

Comfort is everything in wearable technology, but the low moisture permeability from plastic films does not provide this comfort when the films are attached directly to the skin. Film color is also a deterrent where artistic value is compromised from the eyes of the consumer. The base materials require higher dimensional stabilities to increase process yields in high-density circuits, but healthcare devices need elasticity when attached to the body. Thus, a conflict exists with base materials.

Exotic materials have been developed to satisfy these new requirements for traditional flexible circuit technologies. The materials are not necessarily new products but rather modified to generate some unique performances. A  few examples are listed here.

This article originally appeared in the January 2019 issue of FLEX007 Magazine, click here.