The trend in medical devices, as in all electronics, is for increased mobility, smaller size and increases functionality. Among other design requirements, a powerful battery is required. In a device such as a pacemaker, medical device manufacturers require the electrical insulation of the battery from other components to ensure safe operation.

This critical requirement is where high performance films have found new uses. These films include the fluoropolymers FEP and ETFE along with other high performance films like polysulfone, PEEK, PET(G), PEI and PI. The dielectric properties of these films offer electrical insulation for the most extreme voltages. FEP, for example, has a high dielectric strength of over 6500 V.mil for 1 mil film (260 kV/mm for 0.025 mm film).

As many of today's medical device manufacturers produce smaller and smaller units, the space available for a powerful battery is extremely tight. In this environment, the advantage of thin film battery sleeves over thicker traditional injection molded plastic sleeves becomes significant. Leading energy storage companies drive innovations for multiple battery chemistries, including advanced lithium technologies for implantable medical devices. Minimizing battery size while maintaining power and performance is the essence of their business. The aggressive chemical nature of these lithium-based batteries and their high voltage potential makes a thin, durable battery sleeve a critical component.

When thermoforming thin gauge materials, maintaining control of process parameters becomes even more critical in producing a quality part. Fluoropolymers like FEP are thermoplastics that must be processed at extremely high temperatures, upwards of 550ºF. Having a complete understanding of the thermoforming process and how these films react in the melt is key to continuously meeting the extreme tolerances required from leading edge device manufacturers. Taking advantage of fluoropolymer film characteristics provides manufacturers with added protection from electrical arcing. The high melt points of these materials allow them to be placed near weld rings used to close the exterior shells of implantable devices.

Even though the first implantable medical devices appeared in the 1960s, conformal fluoropolymer insulators were not used until the early 1980s. Even today, engineers designing today's implantable devices typically do not have a thermoforming background, especially one based in thin, high-performance films. One of the first applications of high performance films in an implantable device was the use of Kapton® polyimide adhesive tape. However, use of tapes is labor intensive and is impractical when the tape is required to go around corners, where it becomes failure-prone. Having relationships with materials and thermoforming experts allows a company's design team to expand their design solutions palette to include benefits of thin, high-performance films and create three-dimensional electrical insulation solutions within very tight parameters.

The key to forming a successful collaborative design team integrating outside expertise is to make sure that the materials expertise is coupled with hands-on manufacturing experience and capabilities. Many innovative and compelling project designs fail when they reach the critical point of manufacturing feasibility evaluation. It is important to bring materials, manufacturing and design expertise together in the earliest stages of the design cycle. Then the resulting product design meets marketing requirements, as well as volume manufacturing and quality benchmarks.

In today's competitive markets, medial companies are introducing new products at a staggering pace. Their ability to design, prototype, tool, and manufacture critical components in a short amount of time is essential to remaining competitive. Thermoformed parts can go from initial concept to finished product in a matter of weeks as opposed to the months that are typical of injection-molded designs. In addition to their performance as electrical insulators, thermoformed parts outperform injection-molded parts in their ability to produce very thin wall thicknesses over a large surface area. This becomes even more of an advantage as there is less real estate available inside the device. WIth all of the advantages that thermoforming has over other processes, thin high-performance films have moved to the forefront as a key component in the next generation of medical devices.