Exxelia Ohmcraft Resistors serve Neurodiagnostics of Newborn Patients

ROCHESTER, N.Y., January 4, 2021—Neurodiagnostic tools are used every day in neonatal critical care units to monitor, diagnose and treat impairments in newborns.


This type of equipment successfully detects disorders in the brain, nerves and muscles that have the potential to impact the child’s long-term health. To ensure the reliability of this testing, global leaders in the manufacturing of neurodiagnostic technologies leverage Exxelia Ohmcraft’s custom, high voltage surface mount resistors in their equipment.

Exxelia Ohmcraft has the ability to provide high voltage resistors in a small form factor, which is essential for the smaller multi-channel patient monitoring equipment utilized in hospitals today. Additionally, the low noise of Exxelia Ohmcraft’s resistors is critical to eliminating interference that could impact the biosignals being transmitted from the newborn patient to the monitoring equipment.

“By utilizing our resistors, leading neurodiagnostics manufacturers have been able to develop cutting-edge monitoring and testing solutions that improve outcomes and enhance the care of the youngest and most vulnerable patients,” said Eric Van Wormer, Vice President of Exxelia Ohmcraft. “We are proud to partner with many of the world’s top medical device manufacturers in the design of many products that are crucial to the diagnosis, treatment and prevention of so many diseases and conditions.”

Exxelia Ohmcraft’s technology utilizes the proprietary Micropen electronic printing system to “print” precise, narrow, serpentine lines with resistive ink on a ceramic substrate, producing higher performance resistors over a wider range of values on a smaller surface area than is possible with conventional film resistor technology.

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Published on 04 Jan 2021 by Rebecca Charles

High Voltage Resistor Selection Checklist

Introduction to High Voltage Resistor Selection Checklist The resistor is the most common and well-known passive electrical component. A resistor is a device connected into an electrical circuit to introduce a specified resistance. The resistance is measured in Ohms. As stated by Ohms Law (E=IR), the current through the resistor will be directly proportional to the voltage across it and inversely proportional to the resistance. Resistors have numerous characteristics that determine their accuracy during use. The performance indices affect the accuracy to a greater or lesser extent depending on the application. Some of these indices are: Tolerance at DC, Temperature Coefficient of Resistance (TCR), Voltage Coefficient of Resistance (VCR), Noise, Stability with respect to Time and Load, Power Rating, Physical Size, and Mounting Characteristics. Resistor networks typically require temperature and voltage tracking performance. Please refer to the application note: Glossary of Resistor Terminology for an expanded explanation of resistor terminology. Selection Requirements 1. Determine the resistance in ohms and watts. 2. Determine the proper physical case size as controlled by voltage, watts, mounting conditions, and circuit design requirements. 3. Select the resistor that meets your needs for type, termination and mounting. Step 1 : Determine the resistance in ohms and watts. Ohm’s Law: E=IR or I=E/R or R=E/I Ohm’s Law, as shown in the above formula, enables one to define the voltage (E), current (I), or resistance (R) when two of the three terms are known. When current and voltage are unknown they must be measured in the model circuit.   Power Law: W=I2R or W=EI or W=E2 /R Watts (power) can be determined from the above formulas that are derived from Ohm’s Law. R is measured in Ohms, E in volts, I in amperes, and W in watts. Watts must be accurately determined before resistor selection. Simply stated any change in voltage or current produces a much larger change in wattage (heat dissipated by the resistor). The effects of relatively small increases in voltage or current must be determined because the increase in wattage may be significant enough to influence resistor selection. As stated in the above formulas the wattage varies as the square of the current or voltage. Allowances should be made for maximum possible voltage. Step 2 : Determine the proper physical case size as controlled by voltage, watts, mounting conditions, and circuit design requirements. Power Rating and Physical Size: A resistor operated at a constant wattage will reach a steady temperature that is determined largely upon the ratio between the substrate size (surface area) and the wattage dissipated. Temperature stabilizes when the sum of the heat loss rates (by radiation, convection, and conduction) equals heat input rate (wattage). The larger the resistor surface area per watt to be dissipated, the greater the heat loss rate and therefore the lower the temperature rise. Free Air Wattage Rating (Maximum Power Rating) is defined as the wattage rating of resistors as established under specified standard conditions. The absolute temperature rise for a specific resistor is roughly related to the area of its radiating surface. It is also dependent upon a number of other factors such as thermal conductivity, ratio of length to width, heat-sink effects of mounting, and other minor factors. The precise temperature limits corresponding to 100% rated wattage are somewhat arbitrary and serve primarily as design targets. Once a wattage rating has been assigned on the basis of an empirical hot spot limit, the verification of its correctness must be established through long term load life test (see Application Note: Life Test Data – High Voltage Chip Resistors) based on performance and stability standards rather than the measurement of hot spot temperature. Step 3 : Select the resistor that meets your needs for type, termination and mounting. ✔ Resistor Selection: Select the most suitable resistor that meets the requirements of the application. OhmCraft resistors are made to your specification. Refer to the appropriate data sheet to determine part number or call OhmCraft for assistance. ✔ Wattage Rating: To allow for the differences between actual operating conditions and the Free Air Wattage Rating it is a general engineering practice to operate resistors at less than the nominal rating. ✔ Voltage Rating: Determine maximum applied (working) voltage that the resistor will be exposed to and select the appropriate package size. ✔ Pulse Operation: When a resistor is operated in a pulse application, the total power dissipated by the resistor is a function of the pulse’s duty cycle. Typically, one will define the number of joules of energy the resistor must dissipate and choose a resistor accordingly. For additional information refer to our Pulse Resistor white paper or contact OhmCraft. ✔ High Frequency: OhmCraft resistors, due to their design and construction, have very low capacitance and are inherently a non-inductive design. For additional information refer to our High Frequency Attributes Application Note. ✔ Military and Other Specification: The special physical operating and test requirements of the applicable industrial or military specification must be considered. Contact OhmCraft for additional information. Effect of the power ratings on components All the components of an electrical apparatus including resistors, capacitors, rectifiers, and semiconductors have their own limitations as to the maximum temperature at which they can reliably operate. The attained temperature in operation is the sum of the ambient temperature plus the temperature rise due to the heat dissipation in the equipment. Ambient Temperature Derating, below defines the percent of full load that power resistors can dissipate as a function of ambient temperature. Temperature Coefficient of Resistance Temperature Coefficient of Resistance (TCR) is expressed as the change in resistance in ppm (0.0001%) with each degree of change in temperature Celsius (C). MIL STD 202 Method 304 is often referenced as a standard for measuring TCR. This change is not linear with temperature. TCR is typically referenced at +25C and changes as the temperature increases or decreases. It can be either a bell or S shaped curve. It is treated as being linear unless very accurate measurements are required, then a temperature correction chart is used. A resistor with a TCR of 100 ppm will change 0.1% over a 10-degree change and 1% over a 100-degree change. An example of a TCR curve can be found in the application note: Glossary of Resistor Terminology. The following formula expresses the rate of change in resistance value per 1 C in a prescribed temperature range. TCR (ppm/°C) = (R-R0)/R0 X 1/(T-T0) X 106 - R: Measured resistance (Ω) at T °C - R0: Measured resistance (Ω) at T0 °C - T: Measured test temperature °C - T0: Measured test temperature °C In the context of a resistor network, this TCR value is called absolute TCR in that it defines the TCR of a specific resistor element. The term TCR tracking refers to the difference in TCR between each specific resistor in the network. Voltage Coefficient of Resistance The Voltage Coefficient of Resistance is the change in resistance with applied voltage. This is entirely different and in addition to the effects of self-heating when power is applied. A resistor with a VCR of 100 ppm/V will change 0.1% over a 10 Volt change and 1% over a 100 Volt change. VCR becomes very important in high Ohmic value resistor (100M Ω and above) where typical VCRs can be greater than 1000 ppm/V to specify the voltage that will be applied. Failing to do this may result in a resistor that will not meet your specification. The rate of change in resistance value per 1 volt in the prescribed voltage range is expressed by the following formula: VCR (ppm/V) = (R0-R)/ R0 X 1/(V0-V) X 106 - R: Measured resistance (Ω) at base voltage - R0: Measured resistance (Ω) at upper voltage - V: Base voltage - V0: Upper voltage In the context of a resistor network, this VCR value is called the absolute VCR in that it defines the VCR of a specific resistor element. The term VCR tracking refers to the difference in VCR between each specific resistor network. Please refer to the application note: Voltage Ratio Tracking and Voltage Coefficient of Resistance. Summary When specifying a resistor, the following parameters MAY be of interest. Please use this chart to help you define the operating characteristics for your specific application. All of them may not important for your specific application. Also, please do not hesitate to contact Ohmcraft for application help. At Exxelia Ohmcraft, our commitment transcends the creation of resistors. We are dedicated to empowering the visionary innovations that define the future of military technology. Our team is poised to collaborate and customize solutions that perfectly align with the evolving needs of military applications. In a landscape where reliability is non-negotiable and precision is imperative, Exxelia Ohmcraft stands as the beacon of unwavering support, fortifying military operations with resilient, high-performance resistors. Download our White Paper   Exxelia Ohmcraft’s sister division, Exxelia Micropen Medical is at the forefront of medical device product development, providing design engineers with unique insights on conceiving and implementing new designs and features. 

EXXELIA invests in ALCON ELECTRONICS

PARIS, France and NASHIK, India, January 18th, 2022 – Exxelia, a leading designer and manufacturer of high-performance passive components and sub-systems, announces that it has completed the majority acquisition of Alcon Electronics on December 29th, 2021. Alcon is a leading Indian designer and manufacturer of catalog and custom-designed film & aluminum electrolytic capacitors, specifically serving the renewable energy, induction heating equipment, medical imaging, power generation, and railways end markets.   Established in 1977 in Nashik, India, Alcon Electronics offers a wide range of film and screw terminal aluminum electrolytic capacitors for power electronic applications. Through continuous innovation and a focus on R&D, Alcon meets the evolving customized requirements and high-quality standards of its products, and enjoys long-standing relationships with both Indian and international clients. Since inception, Alcon has heavily invested in its state-of-the art facility in Nashik, India, becoming a niche-market leader in the country and competing with large international players. With this partnership, Exxelia will benefit from the unique engineering capabilities of Alcon centered around testing & instrumentation equipment, leveraging it extensively within the group.   Paul Maisonnier, Chief Executive Officer of Exxelia, said: “We are excited to have Alcon join the Exxelia family! Alcon is an established, niche-market leader with great technology, very talented and committed teams and deep business and technical knowledge. Thanks to Alcon, we significantly strengthen our film and electrolytic product portfolio, and we gain a foothold in India which will allow us to better seize opportunities in this booming region and support our French customers with regards to their offset obligations”.     Siddharth Sachdev, Managing Director and Chief Executive Officer of Alcon Electronics, added: “Alcon is delighted to be a part of Exxelia, a human-sized passive component group focused on high reliability products for professional markets. We found ourselves sharing common values and vision and we believe that this combination enhances the capabilities of both groups to serve our combined customer base in film & aluminum electrolytic capacitors both in India and globally.”     KPMG India acted as the exclusive financial advisor to the shareholders of Alcon Electronics, and Lincoln International acted as the exclusive financial advisor to Exxelia, for this transaction. On the Legal side, Pioneer Legal, India acted as the legal advisors to Alcon Electronics, and BTG Legal, India acted as the legal advisors to Exxelia.   About Alcon Electronics Alcon Electronics is a leading Indian designer and manufacturer of film & aluminum electrolytic capacitors, with a state-of-the art facility in Nashik, India. The company sells 3 main types of film capacitors: IGBT snubber (direct mounting with different terminals styles to suit all types of IGBT modules), DC Link and Power Film capacitors, and is developing a new product line of AC Capacitors. Alcon serves the power electronic industry globally, especially the renewable energy, induction heating equipment, medical imaging, power generation, and railways end markets. Alcon controls every step of product development in-house and is able to supply customers globally with custom-designed capacitors. For more Information, visit alconelectronics.com