High Voltage Ceramic Capacitors
CalRamic Ceramic Capacitor
Application & Theory Notes
CERAMIC CAPACITOR APPLICATION NOTES
Soldering High Voltage Multilayer Ceramic Capacitors
Recommendations offered in this Application Note are intended to provide general guidelines for soldering multilayer ceramic capacitors. They reflect industry accepted protocols and should, if applied properly, provide the basis for a reliable soldering process.
Wave Soldering and Large Multilayer Ceramic Capacitors
Wave soldering was one of first production techniques for soldering surface mount components, including multilayer ceramic capacitors (MLCCs). This application note provides best practices to reduce thermal shock cracking.
Hand Soldering Large Radial Leaded Ceramic Capacitors
Recommendations offered in this Application Note are intended to provide general guidelines for soldering radial leaded ceramic capacitors. They reflect industry accepted protocols and should, if applied properly, provide the basis for a reliable soldering process.
Testing and Screening for High Voltage Ceramic Capacitors
This is a summary of the testing conditions that are called out in the High Voltage Ceramic Capacitor Military specification, MIL-PRF-
49467C, which are components rated at or above 500 VDC to 20,000 VDC.
Partial Discharge Testing and Long Term Reliability
High reliability life critical systems require enhanced reliability high voltage multilayer ceramic capacitors, thereby necessitating improvements in materials, design, process control, and in-process screening procedures. This paper expands on the concept that partial discharge (PD) is a technique ideally suited to detecting critical internal defects within high voltage capacitors.
Land Pattern Recommendations for HV Ceramic Capacitors
Tables I and II, in this application note, illustrate recommended land pattern / solder pad layout dimensions for surface mount MLCC capacitors and capacitor assemblies. They have been derived in part from the “Surface Mount Design and Land Pattern Standard IPC 7351.
Solder Rework Recommendations for HV Ceramic Capacitors
Recommendations offered in the Application Note are intended to provide general guidelines for reworking multilayer ceramic capacitors and capacitor assemblies. They reflect industry accepted protocols and should, if applied properly, provide a basis for a reliable result.
The Effect of Temperature and Voltage Changes on High Voltage Ceramic Capacitors
This application note reviews the basics for both Temperature and Voltage Coefficient of Capacitance as it relates to common dielectric material types used for high voltage ceramic capacitor designs. When utilizing ceramic capacitors for circuit design, engineers are generally aware of and where needed, compensate for the effect changes in temperature can have on the capacitance value for certain
dielectric types.
Ceramic Capacitor Encapsulation for High Voltage Applications – Selection Overview
Use of ceramic capacitors in the manufacture of high voltage systems rated for 800 VDC and above, mandates the use of an encapsulate to insure proper isolation and functionality of the device. Given the seemingly endless number of options available, it becomes incumbent on the designer to have a clear understanding of the characteristics of any potting material being considered and how it might impact the capacitor and / or assembly, prior to any selection being made.
Handling of Ceramic Capacitors
Recommendations offered in this Application Note are intended to provide general guidelines for handling of ceramic capacitors. It reviews the importance of basic handling techniques and provides recommendations that when followed, will help to prevent associated problems from occurring.
DC and AC Voltage Dependence of Ceramic Capacitors
This application note covers the relationship between higher K dielectric types and voltage bias and is intended to help the engineer in making a more informed decision when engaging in the ceramic capacitor selection process. Selection of a low dielectric constant Class I material or a higher K Class II dielectric, can for example, have a significant impact on how that capacitor might behave when exposed to either DC or AC bias conditions.
High Voltage Ceramic Capacitor Testing Protocols
The level of reliability associated with capacitor selection is generally dictated by the intended application in which a capacitor will be used and the associated environmental conditions to which the part will be subjected. This application note reviews the more common applications and presents testing protocols most often associated with the governing specifications that exist.
Ferroelectric Properties of Class II Ceramic Dielectrics
The selection of a capacitor manufactured with Class II dielectric materials like X5R, X7R, X5U, Z5U, etc., offer significant advantages due to their high dielectric constant (K) and their ability to offer substantial improvement in volumetric efficiency, when compared to typical Class I, lower dielectric constant materials like NPO / COG. The engineer intending to utilize these high K type of capacitors, also needs to consider the relative instability of these materials and how they might behave when subjected to actual application conditions.
Soldering Recommendations for SMPS Stacked Ceramic Capacitors
Recommendations offered in this Application Note are intended to provide general guidelines for soldering multilayer ceramic capacitors. These recommendations are limited to Case Code 3, 4 and 5 package sizes, but may not be applicable to all situations and as such should not be considered a guarantee against failure.
CERAMIC CAPACITOR THEORY NOTES
CAPACITOR BASICS I – How Capacitors Work
A capacitor is an electrical device which serves to store up electrical energy for release at a
predetermined time. In its most basic form, it is comprised of three essential components, two (2) metal plates or conductors, separated and insulated by the third part called the dielectric.
CAPACITOR BASICS II – Capacitor Types
In practice, capacitors are available in many different forms. They can vary by the type dielectric utilized, the size, shape and nature of the electrodes used and the type of packaging employed. All of these variables can strongly affect the characteristics of the capacitor and the type of application for which these devices are most suitable.
CAPACITOR BASICS III – Mechanical Configurations
The most obvious difference in construction between a single layer and a multilayer capacitor is that the electrodes are external to the device for a single layer, whereas electrodes are basically encased in ceramic for the multilayer approach. Multilayer capacitors represent a design methodology whereby several alternating layers of ceramic and electrode material are stacked, pressed and fired together to form a single monolithic structure.
CAPACITOR BASICS IV – Ceramic Material Designations
Classifications are organized into two basic groupings based on whether they exhibit either extremely stable Class I, or stable / semi-stable performance characteristics (Classes II, III and IV). Classes I and II represent the more commonly utilized dielectrics, with Class III a distant third and Class IV limited to only a few remote applications where capacitor stability is not a critical component of the system design.
CAPACITOR BASICS V – Performance Characteristics
The following Application Note defines the various characteristics that affect performance of the capacitor. Information provided here will give the reader an appreciation for how a capacitor may behave when operated within their intended operating environment.
CAPACITOR BASICS VI – Testing / Screening Requirements
So if manufacturing operations for ceramic capacitors tend to produce highly consistent results, why test at all? There are in fact several reasons, not the least of which would be to ensure that the theoretical design meets customer expectations. In addition, it is important to ensure that some unintended process variable has not inadvertently been introduced to the system, which could alter the anticipated result.
Testing also provides confirmation that the materials used to manufacture the capacitor are within specification and that the equipment will operating properly.