Designing medical implantable devices for high reliability is crucial for a variety of reasons. First, given the life-critical functions performed by many medial implantable devices, and the invasive procedure required to implant medical equipment properly in the human body, it is imperative that all medical devices are designed to function reliably throughout their entire lifetime. Furthermore, since patient safety is paramount, any precautions to reduce the possibility of potentially life-threatening malfunctions, recalls, and replacement surgeries are necessary. And, beyond preventing patient safety issues, there may also be severe economic and legal implications for device manufacturers if an implantable device fails.

Today, millions of people around the world rely on pacemakers to help regulate their heart’s rhythm. A traditional pacemaker usually consists of a pulse generator that is about the size of a tea bag and implanted under the skin near the collarbone, and a wire, or lead, that runs through a blood vessel to the heart. The end of the lead has an electrode on it that touches the heart wall to deliver electrical impulses. However, in the last decade, innovations in pacemaker technology have led to the introduction of a new style of pacemaker, known as the leadless pacemaker, that is about 1/10th the size of a traditional pacemaker, or about the size of a vitamin (Figure 1).

When launching expensive mission-critical equipment and people into space, there is absolutely no room for failure of any component. Therefore, if you are an RF system designer working on an aerospace application, you must be sure you are selecting high-quality, high-reliability electronic components for all your designs. But do you have a process in place for this type of component selection? At Knowles Precision Devices, we know it can be a challenging to navigate component selection for aerospace applications as there are many combinations of standards and tests that can be performed to space-qualify parts.

In an ideal world, capacitors could be designed in a way where they would exhibit no resistance. However, this is physically impossible to achieve as there will always be some type of internal resistance in a capacitor that appears in series with the capacitance of the device. Known as equivalent series resistance (ESR), the level of this resistance will vary across capacitors depending on a variety of factors including the dielectric materials used, frequency of the application, leakage, and quality and reliability of the capacitor. The two graphs in Figure 1 show an example of how ESR can change as frequency increases across various capacitances on two different classes of ceramic dielectrics.

Space missions present a unique set of environmental challenges that demand high reliability down to the smallest electronic components. Mission failures could cost human lives. From in-flight systems to power supplies, every single system contributes to the success of a space project, so they must maintain high quality and safety standards for long durations.

There are two main mounting schemes for placing components on a printed circuit board (PCB): through-hole technology (THT) and surface-mount technology (SMT). Given its popularity over the last few decades, it’s no surprise that designers default to SMT, but there are advantages to both schemes that are worth exploring, especially for high-reliability application designs.

When an electrical device fails, oftentimes, the root cause can be traced to a field failure of a capacitor. While it is rare for the failure to be caused by a capacitor defect that was introduced during manufacturing, it can happen. This is especially true when multi-layer ceramic capacitors (MLCCs) are used versus other more simplistic capacitor types such as single-layer capacitors (SLCs) since the manufacturing process involves stacking many layers of dielectric and electrodes on top one another.

Many power electronics today are being designed for use in high-temperature, high-voltage environments, such as inside electric vehicles (EVs). However, size, weight, and power (SWaP) are also key factors driving electronic product development. These conflicting design criteria are an issue for many electrical engineers because space is not available to simply add a cooling system, as this will add weight and increase the product’s overall footprint. Therefore, many of these electronic components are susceptible to “running hot” at the high temperatures and high voltages used in these tiny spaces.

From systems that diagnose, like a magnetic resonance imaging (MRI) machine, to implantable devices that treat patients, like pacemakers and implantable cardioverter-defibrillator (ICDs), highly reliable electronic components are necessary. While the functionality of these devices is quite different, the challenges associated with designing these devices, such as selecting failsafe electronic components designed for lifetime reliability and ensuring supplier partners can meet industry-specific standards, are shared. Let’s look more closely at some of the industry-wide challenges associated with electronic component selection for medical devices as well as some of the application-specific decisions medical device designers need to make to ensure these devices function consistently and reliably for the long term.

Achieving high capacitance means going big. But how do you do that while still maximizing board space? At Knowles Precision Devices, we’ve developed a new method for building customizable large capacitor assemblies that capitalize on the vertical space above the circuit board. While stacked capacitor assemblies have been around for many years, these parts do not have very good bump and vibration withstand due to the thin leads used in their construction. These new assemblies from Knowles Precision Devices offer a ruggedized construction capable of withstanding high levels of shock and vibration. This offers a unique combination of capability, durability, high capacitance, and very high voltage in a smaller area, making these capacitors ideal for automotive, military, and aerospace applications.