Advancements in electronics technology are bridging the gap from consumer products to medical devices in the form of medical electronic equipment designed for faster diagnosis, improved patient quality of life, and new drug-based therapies.
One trend is the movement toward compact and portable patient monitoring, display, and testing equipment that is more accurate and versatile for improved bedside treatment. Such equipment includes blood glucose monitoring systems, insulin pumps, defibrillators, and neurological stimulators. Implantable devices are also incorporating the latest technological advancements for sophisticated and targeted therapies ranging from drug delivery and pain management to the treatment of neurological disorders.
As electronic devices become smaller, more portable, and more complex, reducing the size of component real estate to enhance product design and functionality is becoming more important. To meet the demand, device manufacturers have readily embraced pressure-sensitive adhesives (PSAs) for their functionality and ease of use in both medical and electronic device assembly. PSAs feature an adhesive coated on to a continuous web of a substrate material -- in either single-faced, double-faced, or transfer adhesive constructions -- wound into large rolls that are then converted to the exact specifications required for the end application.
Advancements in PSA technologies are enabling smaller electronic designs through thin, reliable bonds with highly desirable functional benefits. The PSA's roll format provides device manufacturers ease of handling and application; precise thickness control; a thin, consistent bond line conforming to irregular surfaces; and the capability to be precisely die cut into custom shapes and narrow widths for improving manufacturing efficiency with mess-free processing.
As device manufacturers face the pressures of faster prototyping, quick changeovers, and the increased use of automation, the advantages of PSAs as an alternative material choice for interconnects, grounding, and shielding applications traditionally dominated by labor-intensive soldering operations are becoming more evident. Combining the traditional benefits of the PSA format with additional desirable functional capabilities, such as an electrically conductive adhesive, makes simplification of electronic device design and manufacturing possible.
Designing electrically conductive PSAs
Achieving electrical conductivity in a traditionally insulative polymer matrix is accomplished by adding conductive particles to the adhesive. A number of conductive particles are available for loading into an adhesive, including gold, silver, nickel, copper, and tin. These conductive particles may be prepared in solid metal formats, metal-coated polymer, or metal-coated glass particles. The application and the level of conductive reliability required will determine the type of conductive particle best suited for the matrix. Similarly, the level of conductive reliability required also dictates the polymer matrix. With the advent of conductive carbon materials such as graphene and other nano materials, a new level of formulation flexibility is available for achieving the desired conductive properties.
The process of designing an electrically conductive PSA begins with the polymer backbone of the adhesive. The polymer can be designed using silicones, acrylics, or synthetic rubbers. While acrylic polymers offer the most formulation flexibility, the end application will determine the adhesive's chemistry.