Improving Reliability One Component at a Time

Stephanie Steward

Altering the layout of a printed circuit board (PCB), reducing the number of electronic components in a device, or choosing a capacitor with a different base material are all methods of tackling the critical issue of improving medical product reliability. With patients’ lives—not to mention their quality of life—at stake, demonstrating high reliability in medical devices is crucial to both the patient and the success of the product.

“Reliability is a big issue,” says Mark Skoog, president of Novacap (Valencia, CA; www.novacap.com), a Dover company, which supplies multilayer ceramic capacitor products and assemblies. “When we know [a capacitor] is for implantable devices, we design it differently.” The company also subjects its components, some of which are used in implantable medical devices, to rigorous stress testing.

Skoog says that a capacitor’s design determines its reliability. The company designs its capacitors exclusively using precious metal electrodes—versus the base metals that some companies use—because precious metals are inherently more reliable, he says. Novacap’s multilayer ceramic components, such as its Cap-Rack chip capacitors that are bonded with high-temperature epoxy, are interleaved with palladium and silver. The capacitors enable the assembly of dissimilar capacitance values or dielectrics into a single component. Because the capacitors behave as individual components and not as a single ceramic mass, they do not succumb to harmful thermal stress during assembly. “The type and thickness of the ceramic can determine the reliability [as well],” Skoog adds.

Dyconex Inc. (Mesa, AZ; www.dyconex.com) also aims to help OEMs improve product reliability from a component design standpoint. The contract manufacturer specializes in high-reliability PCBs and multichip modules for a range of applications, including such implantable medical devices as defibrillators and pacemakers. From base material selection to board layout and build-up, the company focuses on performance and reliability.

“There is a strong trend to simplify the product on the board level by ever-higher integration of functions into the silicon level,” says Thomas Jacob, business development manager of advanced circuit technology for Dyconex. “The reduction of interconnects between the individual components is the driving factor to increase reliability.”

Jacob also notes a trend called the platform concept that he says is somewhat new to medical device manufacturing. The goal behind the idea is to produce a greater variety of medical electronics components while reducing manufacturing requirements. “[For example,] a very small, high-density assembled circuit board with standardized components is mounted on a bigger, but much simpler, motherboard that is tailored to match the individual product [requirements],” he explains.

A more-standardized approach to medical electronic component manufacturing like this platform concept could improve the overall reliability of devices. Jacob suggests that such a platform could be suited for fast product facelifts considering the sometimes-slow innovation cycles for implantable cardiac rhythm management devices.

With electronic components such as multilayer ceramic capacitor arrays and a variety of established and emerging design strategies, medical OEMs can take steps to improve the reliability of their products. The only option they don’t have is ignoring the issue of product reliability.

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