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42 The PCB Magazine • January 2016 • Surgery tools: These include electronic saws, screwdrivers and cauterizing scissors for clamping and closing blood vessels while per- forming surgery. • Single-use devices (SUDs): Applications include ultrasonic scalpels, electrode recording catheters, biopsy instruments, electric biopsy forceps and other applications where sterile re- quirements dictate one time use. The variety of uses and applications is con- tinually expanding with innovative new designs or redesigns of existing equipment. During the past several years the medical industry has cer- tainly become one of the fastest growing seg- ments for flexible circuit applications. A num- ber of important factors make flexible circuitry ideal for the medical industry: Reliability: As early as the 1950s, flexible circuitry was used in the military and avionics industry, with both applications demanding extraordinary reliability. Years of proven per- formance in these demanding applications pro- vided the medical industry with confidence in flex circuitry's reliability and robustness. Flex- ible circuitry has inherent advantages because it eliminates connection points. This can be accomplished by designing out the need for connectors, soldered wires, and/or rigid circuit boards. Integrating these components into a single flex circuit assembly is a common adop- tion of the technology. This often helps sim- plify the assembly and can reduce the chance of human error. Space and Weight: Electronic applica- tions within the medical market drive demand to make devices smaller and lighter. This feature is typical of why flexible circuits are often ad- opted when weight and space are a premium. Flexible circuitry is very thin, can be easily bent for assembly, and connects components across multiple planes. While implantable devices may be fully sealed to eliminate contamination, non- implantable devices are frequently used in ap- plications requiring contact with human skin. Feature Density: Flexible circuits can be built with narrow lines and spaces (conductor trace and space widths less than .005» are quite common) and are often constructed with multi- ple conductive layers. Resistive metals are some- times added as a layer that can be designed as a heater element. This becomes increasingly im- portant as designers continue to reduce volume while increasing functionality. Dynamic Flexing: Flexible circuitry has often been employed for dynamic bending or movement. This includes applications to pro- vide interconnection through a hinged device or for maintaining connection through devices that expand, contract or telescope during use. Material construction and circuit layout are particularly important in dynamic flex applica- tions. Consulting with a flex vendor or other industry expert is recommended when moving parts need to be connected. Supply Chain: Materials used to make flex are widely available. A good supply chain in- frastructure exists as the market growth has at- tracted the attention of multiple vendors. This helps create a foundation of technical resources available for application and design support in the USA, including capable and experienced applications engineering talent. Organizations such as IPC have helped support the cross fer- tilization of technology and knowledge. The variety of applications has created a wealth of experience and has spawned innovation within the industry. The demand for flexible circuitry in the medical industry will remain robust as electron- ic medical equipment continues as one of the hottest growth areas for the electronics industry. The aging population, longer life expectancy, demands for more affordable and less invasive health care, and the continued advancement in technology are some of the factors driving growth in this market segment. Increasing pos - sibilities for the use of flexible circuitry in medi- cal electronics will grow rapidly as designers identify additional ways to take advantage of the utility offered by this three-dimensional in- terconnection technology. PCB FLEx: JUST WHAT THE DOCTOR ORDERED FOR MEDICAL DEVICES all about Flex Dave Becker is vice president of sales and marketing at all Flex Flexible circuits llc. to read past columns, or to contact the author, click here.