Impedance, measured in ohms, extends the concept of “opposition” to alternating current (AC) applications. It accounts for resistance, the opposition of current flow, and reactance, the measure of opposing alternating current – an effect of inductance and/or capacitance. In direct current (DC) applications, we talk in terms of resistance, not reactance. Chances are: This isn’t new information. But there’s a reason we wanted to cover this topic – impedance values play an important role in capacitor selection.
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.
Topics: High Reliability
Capacitors are essential passive components for designing any electrical circuit. But there are so many options to choose from with a wide range of specifications that it can be overwhelming to determine what capacitor may be the best fit for your application. One early decision that circuit designers must make is to determine if a single-layer capacitor (SLC) or multi-layer ceramic capacitor (MLCC) is the right fit for their application needs.
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.
If you are a medical device engineer working to improve the longevity for implantable devices such as pacemakers, defibrillators, insulin pumps, cochlear devices, or bladder stimulators, be sure to checkout our latest on-demand webinar – The Importance of High Reliability for Medical Implantable Devices.
When designing a ceramic capacitor, the type of dielectric used will influence the characteristics of the capacitor and define its electrical behavior. At a high level, there are two types of dielectrics made with ceramics – paraelectric and ferroelectric. Dielectrics containing paraelectric (or non-ferroelectric) ceramics are known as Class I dielectrics. These dielectrics show a linear relationship of polarization to voltage and are formulated to have a linear temperature coefficient. Capacitors using a Class I dielectric have high stability across various temperatures, but have low permittivity, which means the capacitor will offer low capacitance.
If you’re struggling with the challenges of ensuring high-reliability with your medical device electronics, you won’t want to miss our upcoming webinar sponsored by GlobalSpec, Using High-Reliability MLCCs for Medical Implantable Applications, on Thursday, November 4 at 11:00 am EDT.
Standards are a form of technical infrastructure, and their influence is felt throughout the electronics industry. For example, formed in 1924, the Electronic Industries Alliance (EIA) was an American standards organization that established an alliance of trade associations in the United States electronics manufacturing industry. Their collaboration ensured that electronic equipment produced by different manufacturers was compatible and interchangeable. The EIA formally dissolved in February 2011, dividing by sector.
As complex electronic systems become more prevalent in our daily lives, the demand for high-temperature, high-reliability components continues to increase. Standard electronic components have an operating temperature of -55 °C to 125 °C, but the number of applications requiring functionality above 125 °C is growing. Components in these applications, like capacitors, must maintain their functionality and take the heat (literally and figuratively) while powered. To meet the brief, material and design of these high-temperature components must deviate from today’s standard.