Medical implantable devices require High Reliability Components to perform all the time, every time!

Knowles has built a legacy of testing and screening military-grade reliability specifications (MIL-SPECS) for defense and military applications, and we've adopted that same rigor for medical applications. The MD Series, a range of medical-grade capacitors for implantable designs, encompasses C0G, X7R and X5R monolithic ceramic chips and can be screened using two long-standing MIL-SPECs: MIL-PRF-55681 (Group A) and MIL-PRF-123 (Group A).

We wanted it to be easy for design teams to identify which components are medical-grade and what screening they’ve undergone. It saves time in ordering and sourcing, and expedites the overall production process. 

Putting parts through our testing and screening processes means you can be confident that our components will produce the level of reliability and safety necessary for being on the circuit boards of your life-critical implantable medical devices.

MD Series Brochure


There are devices for Neurostimulation, Pacemakers, Pain Management Devices, Cardiac Assist & Insulin Pumps, devices to treat and monitor hypertension, sleep apnea, brain/spinal cord problems, devices for heart monitoring, loop recorders, cochlear implants and the range continues to expand.

As devices get smaller, making implant surgery simpler for the physician, the one constant that must remain if the device is to deliver its lifesaving or enhancing function, is its reliability.

The manufacture of medical implantable devices are highly regulated by regulatory bodies such as the International Standards Organization (ISO) and the US Food and Drug Administration (FDA) to maintain the highest level of reliability. The tight controls placed on the design, development and manufacture of these devices must be met by the suppliers of the component parts.

In alignment with these exacting regulatory requirements the operational processes, testing and quality assurance provided by Knowles Precision Devices is tightly controlled. We work closely with medical device innovators to create source control drawings (SCD) governing every aspect of the capacitors we supply. SCD’s provide an engineering description, qualifications and acceptance criteria for the delivery of specialized components for critical applications.

The two main SCD specifications for medical components are MIL-PRF-55681 and MIL-PRF-123.

MIL-PRF-55681 is the one most widely used in the field of medical implantable devices. It defines a mid-K stable dielectric designated as BX.

The MIL-PRF-123 specification covers the general requirements for high reliability, general purpose (BX and BR) and temperature stable (BP and BG) ceramic dielectric fixed capacitors, through-hole and SMD and affords an increased reliability level over MIL-PRF-55681.

You can learn more about Knowles Precision Devices High Reliability Capacitors for Medical Implantable Devices through our High Reliability Products Brochure.