Panasonic

It is not only since the widespread introduction of 5G...

...that the demand for Multilayer Ceramic Chip Capacitors (MLCCs) is growing: Applications in the field of consumer electronics, data processing, telecommunications and many others have not only significantly intensified MLCC market growth – they even led to an industry-wide shortage for the recent years.
All those parameters contributed to more and more OEMs started looking for alternatives to eventually replace MLCCs with different capacitors – also in anticipation of an increasing demand due to 5G.  
Some relevant MLCC alternative can be found within Panasonic Industry’s portfolio: As leading manufacturer of Polymer Capacitors with a long design-in expertise, the SP-Caps and OS-CON are as well worth a closer look as POS-CAP Tantalum Polymer Capacitors or the manufacturer’s Polymer Hybrid Aluminum Electrolytic Capacitor technologies.
For conductive Polymer capacitors, the fields of application have remarkably broadened. The Polymer capacitor (as well as conventional aluminum electrolytic capacitors) stands out with large capacitance figures and excellent bias characteristics that are clearly outperforming multilayer ceramic capacitors.
Panasonic Industry Polymer capacitors already have been proven as a highly relevant alternative for customers seeking to save PCB space and money.
Those Polymer-based capacitors offer a performance edge over conventional electrolytic and ceramic capacitors when it comes to: 
    
•    Electrical characteristics
•    Stability
•    Longevity 
•    Reliability 
•    Safety
•    Life cycle cost 

The various Polymer and hybrid capacitors have very specific advantages and benefits in terms of their ideal voltages, Low ESR, operational conditions and other application requirements.

Polymer capacitors - and what Panasonic Industry has to offer

Including the hybrid ones, there are basically four main varieties of Polymer capacitors. Each of them comprises different construction, electrolytic and electrode materials, packag¬ing and application targets. Let us have a brief overview:

SP-CAPs – the new flagship of Ultra-low ESR

Using a conductive Polymer as the electrolyte and an aluminum cathode, the distinguishing electrical characteristic of these Polymer capacitors is their extremely low equivalent series resis¬tance (down to 3mΩ), which is among the lowest in the industry. SP-caps cover a voltage range from 2–6.3V and offer capacitances between 2.2–820μF. Packaged in a molded resin as compact SMD, these layered Polymer capacitors come in a low pro¬file. As a result of the electrical and form factor characteristics, they suit a variety of handheld electronic devices or other applications that require a low-profile capacitor that will not interfere with a nearby heat sink. 

Large capacitance – long lifetime: OS-CON

OS-CON caps are also based on conductive Polymers and aluminum, but they have a wound foil structure. The wound Polymer capacitors cover a wider range of voltages and capacitance values than other types of Polymer capacitors. Voltages extend from 2.5 to 100V, while capacitances run from 3.3 to 2,700μF. In addition, their long life time span is one of the factors that they are preferred to be used for servers and base stations. For example, SVPT series with 20,000 hours of life time at 105°C is a unique solution for such applications.

POSCAPs - the chip capacitors of choice for compact devices

These types employ a conductive Polymer as the electrolyte and have a tantalum cathode. They span voltages from 2 to 35V and capacitances from 3.9 to 1,500μF. They also convince with a low ESR, with some of our POSCAP capacitors exhibiting ESR values as low as 5mΩ. Packaged in a molded resin case, the tantalum Polymer capacitors are among the most compact options available on the market. Though compact, a wide range of sizes is available for this capacitor type. 

Best of both worlds: Hybrid capacitors

Hybrid capacitors consist of a combination of a liquid and conductive Polymer to serve as the electrolyte and aluminum as the cathode. The Polymer offers high conductivity – and a correspond¬ingly low ESR. The liquid portion of the electrolyte, meanwhile, can withstand high voltages and provide higher capacitance rat¬ings due to its large effective surface area. The hybrid capacitors offer a voltage range from 25 to 80V and capacitances between 10 and 1000μF. At 8 to 120mΩ, ESR values for hybrids are higher than other types of Polymer capacitors, but still very low considering the higher power applications they address. 

Polymer capacitors - and what makes them outperform MLCCs and other technologies

It's not only the industry-wide MLCC shortage: Panasonic Industry Polymer caps stand out with excellent specs and characteristics that makes them outperform conventional MLCCs ion several regards.

Capacitance density and stability vs. DC bias

The MLCC exhibits strong capacitance dependence on DC bias due to ferroelectric dielectric materials used for MLCCs. Polymer ca¬pacitors have no such problem and remain stable over time. This specific advantage allows a significantly lower part count using Polymer instead of MLCCs – apparently saving precious PCB space, costs and steps during production process.

Stability vs. temperature

This figure illustrates typical temperature characteristics. The curve changes for MLCCs in various ways within the tolerance range of each product. For Polymer capacitors the capacitance is growing in parallel to the increase of temperature. The temperature characteristics of MLCCs differ according to the dielectric type, but all of them suffer aging failure by exhibiting temperature dependency and require lower operating temperature. Ceramic capacitors are brittle and sensitive to thermal shock, so precautions need to be taken to avoid cracking during mounting, especially for high-capacitance large MLCCs. Typically, ceramic capacitors reveal a temperature range from -40°C to 85°C, respectively 125°C, while the capacitance varies about from +5% to -40%, being in the optimal range around a low temperature of 5 to 25°C. Also in terms of density, field stress and temperature – which is currently still limited to 125°C – Polymer capacitors have great development potential to achieve higher ratings on density, field stress and temperature (yet currently limited to 125°C) due to their working mechanism and dielectric materials advancement, yet higher dielectric constant Polymers enable a higher energy density.

Piezoelectric effects

A MLCC deforms – meaning contraction or expansion - when exposed to voltage. This MLCC's characteristic is called inverse piezoelectric effect - the reverse of a piezoelectric effect. A DC voltage output from an AC adaptor or switching power supply causes a ripple voltage in some cases. If the frequency of the ripple voltage is within the audible frequency range, it may result in emission of a screeching noise. A conductive Polymer capacitor has no inverse piezoelectric effect and therefore does not cause any noise emission or micro-vibrations.

Stability vs. frequency

Stable Capacitance: The figure on the left shows the change in capacitance over a wide frequency range for different technologies. It clearly shows that Polymer capacitors exhibit very similar performance to multi-layer ceramic capacitors.

Robustness

Cracks in ceramic surface mount technology (SMT) components limit assembly reliability and yields. These cracks manifest themselves as electrical defects: intermittent contact, variable resistance, loss of capacitance and excessive leakage currents. That is why MLCCs are exposed to different reliability tests including thermal shock, board flex (bending), and biased humidity tests, etc., depending on the targeted applications. Among the reliability tests, the board flex test evaluates the mechanical resistance to cracking when MLCCs are subjected to bending stress on the printed circuit board (PCB) that the MLCC is soldered on. The bending of PCB can occur frequently during/between manufacturing steps and during operation under temperature variations. Flex cracking is due to excessive circuit board flexure. Ceramics are strong in compression but weak in tension. Thus, when a soldered MLCC experiences excessive board flex, a crack is easily generated in the element. A flex crack can cause an electrical conduction between opposing internal electrodes. It is also possible that a fail open can progress to a fail short with continued product usage. If a crack on a capacitor element progresses to a short circuit failure, it may cause problems such as heat generation, smoking, or ignition; therefore, it is indispensable to take measures against them, particularly in equipment where reliability is essential.

Safety

Most ceramic capacitors have a fairly high voltage rating. If the capacitor experiences a voltage between its terminals higher than its rated voltage, the dielectric may break down and electrons will flow between the thin metal layers inside of the capacitor, creating a short. Luckily, most ceramic capacitors are built with a hefty safety margin and do not experience any sort of catastrophic failure (such as exploding). However, the rule of thumb dictates that you should derate ceramic capacitors by 50% to 90% depending upon series, voltage and temperature, which means that if you are expecting to have a maximum of 5V between the capacitor’s leads, then you should use a capacitor rated for 10V or more. On the other hand, no derating needs to be considered for Polymer capacitors and normally they can withstand 15-25% surge voltage as well.

Conclusion

The range of Polymer caps as MLCC alternatives is various and comprehensive – there are specific types for specific requirements. What they all have in common, however, is that they are a contemporary choice in terms of electrical performance, reliability, durability and safety - and not least when looking at the overall lifetime cost.

Or to put it even more simply: Polymer caps are not only a good alternative in case of supply shortages of other products, but are actually the first choice for the design process of modern applications.  

 

Admittedly, Wi-Fi technology is not the latest thing – but it’s still state of the art when it comes to processing higher data rates, especially in personal area networks.

Now, Panasonic Industry is breaking new ground with its new PAN9520 wireless module. Containing the ESP32-S2 chip, it can be considered as the first Espressif-based module that enables standalone Wi-Fi applications.

The PAN9520 is part of a new generation of Panasonic Industry’s evolution boards coming with the Arduino form factor, serving the trend for mass-market available shields with the mere purpose of rapid prototyping.

Surveillance cameras, for instance, still are a domain of Wi-Fi networks, so let’s look exemplarily at the Arduino PAN9520 evaluation board and its interaction with the OV2640 camera – from the required hardware and toolchain to finally running the demo. So join us for this step by step instruction:

1. Some specs at first

2. Required Hardware

Figure 1. The Panasonic Industry PAN9520 is a 2.4 GHz 802.11 b/g/n embedded Wi‑Fi module based on Espressif ESP32-S2 that includes the powerful Xtensa 32-bit LX7 CPU.

Figure 2. OV2640 Camera Module with flexible PCB connector (like this one)

3. Installing Toolchain

The project has been developed in Visual Studio Code (VS Code). Thanks to its cross-platform compatibility, the code can be built and adapted on all operating systems.
You are required to take two simple steps:

1. Install Visual Studio Code (here)

2. Install PlatformIO Extension over the VS-Code extension menu and wait for the installation to finish, this might take a while.

3. Restart Visual Studio Code and clone the project either by typing in the Terminal:

git clone –recursive https://github.com/panasonic-industry-europe/pan9520-etu-camera-stream-web-server.git

Or by going directly to the GitHub repository https://github.com/panasonic-industry-europe/pan9520-etu-camera-stream-web-server.git and download the Code directly from there.

4. Go to "File" -> "Open Folder" and select the project folder containing this application. Wait for all the dependencies to be downloaded and installed automatically.

4. Editing the Code

Basically, the code works out of the box. However, it is important to know where to change the settings for the softAP, e.g. to change the password or the SSID.

main.c

In the main.c file, the initialize_cam function is used to configure and initialize the hardware to ensure that the camera works properly (lines 38-61). These settings were made for the OV2640. In principle, it is possible to connect other cameras if the pinout is similar. In the main function app_main, the previously mentioned initialization of the camera is started alongside the WiFi access point and the webserver.

httpd.c

In the httpd.c file the settings are configured for the webserver. The setup for the webserver is done in the app_httpd_main function, where two URI handlers are being registered: the index_handler for the static Html output and the stream_handler which streams the camera image continuously.

What you end up seeing in the browser is set in the index_handler (line 45-73). A simple static text "PAN9520 ETU Cam live stream" (line 60) alongside the continuous camera stream in a small box below the text (line 61) which is being delivered by the stream_handler (line 76-139). If you analyze the code more closely, it becomes clear that the image is loaded from the framebuffer (line95-100) continuously and sent in fragments so-called chunks (line 101-127). A calculation of the framerate is displayed in the logging (line 128-137).

Wifi.c

The settings of the WiFi connection are made in the wifi.c file. The Access Point configuration like the SSID name or maximum numbers of connections is set in lines 30-34. The event handling for Wifi is handled in the wifi_event_handler function (line 39-58), for the sake of simplicity, this function will not be discussed further in detail. It is only important to know that there are basically two states from the handler's point of view: that of a connected and disconnected client.

The most important settings and initializations of the access point are made in the wifi_init_softap function (line 61-83). The SoftAp is assigned a static IP address (line 66, in this case 192.168.4.1) and a password in line 75. WPA2 is being used as a security certification program (line 78), but it’s also possible to change this. However, this requires changing the security features in menuconfig. (see here)

5. Get things connected

The PAN9520 ETU contains a 24-pin FPC connector for operating a camera module via an 8-bit parallel camera interface and SCCB (Serial Camera Control Bus). Connect the camera like shown in the picture. Please make sure that the lens is turned towards you so that the pinning is the right way round. As soon as the camera and Evaluation Board are connected, plug in a micro USB cable in the “USB Module” Interface.

6. Flashing and Running the Demo

1. Open VS Code
2. Click on the project task menu (Alien Head) and choose: esp32-s2-kaluga-1
3. Click on General and then Build.
4. Press reset while holding pressed down the SW1 Button. This will activate the download mode.
5. Click on General and then Upload.

After the upload, you will see an error message in the terminal. This is because the task can’t reset the Board itself. You have to reset the board by pressing the reset button.

1. 1. A Wi-Fi Access Point will occur with the SSID you named above
   2. Connect to that AP with the password you set
   3. After the connection has been established open a browser and type 192.168.4.1 into the URL field
   4. Enjoy the livestream!

Far more than constructive or material differences, it is the principle – or more specifically: the pattern – of laser trimming that makes the difference for a SMD chip resistor’s reliability and performance. Let us investigate, why:

Resistors - seemingly the most accessible of components in almost any application. However, the process of manufacturing surface mount chip resistors is rather complex. In a typical construction of a surface mount chip resistor, there is a block of alumina substrate, which could be manufactured from several kinds of ceramics. Then, there are the electrodes which conventionally have several layers including nickel and tin. The resistive element is printed on the ceramic substrate - and then trimmed using a laser. It is the laser trimming that ultimately defines the resistance value of the final chip resistor.

The laser trimming is a deciding factor in the quality and performance of the end product. There are several factors that play a decisive role here: The laser trimming must be stable in the long run and should not deteriorate. Taking almost any application into account, resistors go through thousands of cycles in their lifetime and the resistance value is expected to remain constant. Additionally, the laser trimming should be of utmost accuracy, so that the desired resistance value can be achieved within the range of the defined tolerance. Furthermore, the trimming speed itself is important while not “sacrificing” the performance of the resistor. In component manufacturing, there is usually a trade-off between speed and accuracy. Panasonic Industry factories pursue the highest efficiency and speed in manufacturing; however, it is always made sure that the quality of the products does not drop because of this. Last but not least, trimming geometry is the most crucial aspect of all. This geometry defines other characteristics of the resistor like power range and pulse withstanding capabilities.

The trimming pattern can have several shapes and geometries – in the following overview we’ll have a deeper look at two (important ones!) of them:

L-pattern:

The L-pattern is a fast and well-known trimming pattern. This pattern includes two parts: the first part marked with 1 in image 1 defines the resistance value slightly below the targeted resistance value, while the second part marked with 2 accurately corrects and adjusts the resistance value within the allowed tolerance range. Analyses in the Panasonic Industry technical laboratories illustrate, however, for certain features like pulse-withstanding characteristics, this trimming method is not ideal, because, with the occurrence of pulse, certain areas around the trimming are exposed to higher temperatures and hot spots, see image 3. This is why this laser pattern is mostly used in the more conventional resistors, in which pulse withstanding characteristics are not that essential. The L-pattern is otherwise very fast and easier to apply.

Figure 1. The L pattern

Symmetrical C-pattern:

Panasonic Industry’s solution for producing premium resistors with pulse withstanding capabilities is the symmetrical C pattern. As opposed to the L- pattern, where the pulse load and heat would concentrate on the corner and edge of the pattern and, in this pattern, the trimming shape is changed to an arc, similar to the letter C. The current pathway here is bi-directional, so two symmetrical trimming patterns are used, see image 2. Based on the Panasonic load and heat simulation study, the heat concentration is reduced by 64% using our unique technology. This enables the resistor to have a higher power range and better pulse characteristics.

Figure 2. The symmetrical C pattern

However, the C geometry is far more complex to realize with the laser, because it is much slower and has to be monitored meticulously to maintain the desired resistance value. But for applications requiring pulse-resisting chip resistors, the Symmetrical C-pattern would be a perfect solution.

Figure 3. Comparison of hot spot buildup using L pattern and symmetrical C pattern

Panasonic Industry is constantly seeking state-of-the-art solutions to further improve its resistor portfolio. The highly-trained engineering team at the Morita factory in Fukui, Japan, is continuously researching and testing new materials and methods to enhance the quality and reliability of the resistors.

The relevance of smart metering has increased globally during the last couple of years for different applications such as water, gas and electricity – on both the supplier and the consumer side.

Additionally, the global shipment of smart meters has reached approximately 136.45 million units in 2020, according to the Global Smart Meters Market report - and is even assumed to reach 198.53 million units by 2026, forecasting a CAGR of 6.6% from 2021 to 2026.

In most countries, it has become common sense to tackle the environmental effects caused by pollution and to strive for adopting emission control regulations. Smart grids are a promising approach in this regard – and essential in the course of this: smart meters.

Some basics: Smart meters are digital meters representing a transformative technology for the utility industry and its customers. They enable two-way communication between the meter and the supplier.

Typically, their circuit diagram is as displayed below:

There are three main areas of a smart meter design, namely the power system, the microcontroller, and the communications interface. The power system has a switched-mode power supply and battery backup to ensure that the metering electronics remain powered even when the mainline is disabled. A Microcontroller Unit (MCU) includes an Analog-to-Digital Converter (ADC) and Digital-to-Analog Converter (DAC) to provide intelligence. And the communication interface allows the meter to interact with the rest of the grid - and in some cases the end user’s network.

Given this brief overview of basic smart meter technology, let’s take a brief trip through the world of passive components and investigate which capacitors, resistors and inductors optimally suit the needs of smart metering applications and why.

Capacitors

At the input side of the power supply circuit, film capacitors are commonly placed in EMI filters for EMI suppression purposes. In order to protect users from harm due to electric shock, X/Y classified EMI suppression film capacitors are normally required with high voltage impulse handling ability.

Taking these requirements into consideration, Panasonic Industry provides an excellent metallized PP film capacitor solution with ECQUA (safety class X2) and ECQUB (safety class X1/Y2) series for high safety and high reliability.

Thanks to Panasonic’s in-house patterned metallization technology (also known as “fuse function”), ECQUA series and ECQUB series (fuse function applies to class X1 only) offer overvoltage impact reduction and therefore guarantee high safety with open failure mode.

To ensure smart meter reliability also for outdoor metering products - especially under humidity exposure - Panasonic Industry developed its enclosure sealing technology and aluminium vapor deposition to achieve a high humidity resistance.

For smoothing in the input side, typically Tantalum capacitors are employed in parallel since they have a high capacitance level. But they suffer from derating, so for a 12V line, usually 25V caps are used.

To overcome that voltage derating, Panasonic Industry offers Polymer capacitor technology to efficiently replace those tantalums. Polymer caps provide high capacitance values at a very low ESR – in this case, for a 12V line, one 16V POSCAP or OSCON would be the product of choice, combined with reliable performance in a miniaturized housing.

Replacing two Tantalums in parallel with one Polymer capacitor – have a look at the following overview.

1.xV dc/dc Input (Smoothing)

Coming to the 3rd main area of a smart meter, the communications interface, amplifier (DSL) circuit is especially important for amplifying the small signals from sensors which are later converted into digital signals that MCU can process. Panasonic Industry provides its stacked metallized film chip-type capacitors to improve the filtering ability in the amplifier circuit.

The stacked metallized PPS film capacitor ECHU(X) series feature stable capacitance characteristics against temperature, frequency and DC bias – next to a very compact size (down to 0603). And there is no need for concerns about piezoelectric effects as known from MLCCs. With its high preciseness for high-speed data transmission, ECHU(X) series is the ideal solution to optimize the design for DSL circuits.

Simplified DSL circuit for smart meter

Resistors

Similar to capacitors, resistors can also be used for different purposes in smart meters.

For the motor control of the valve system, it is essential to use resistors with high precision, high reliability, and high stability specs over the entire lifetime of the meter - which is of course meant to be a long one.

Additionally, in the current-voltage sensor, the output signal is highly dependent on the level of accuracy of the resistors employed. Meeting those requirements, Panasonic Industry offers a wide range of high precision resistors in thin-film (ERA* series) and thick film (ERJPB series) technology.

Looking at the DC-DC converter, it is common to use resistors with a higher voltage range and pulse-withstanding capabilities. The wide variety of Panasonic anti-pulse resistors (ERJP/T series) makes it easy to find the perfect component for each and every design.

Occasionally, smart meters are exposed to areas or conditions with tougher environments. Standard resistors sulfurize when getting in contact with above-average concentrations of oil in the air. For this, anti-sulfur resistors come into play, coming with silver or gold layers in the inner terminals to avoid sulfurization.

Panasonic’s anti-sulfur portfolio offers two major product categories, one using silver and one using gold, each in a variety of sizes and resistance values.

Circuit protection

In the power supply line, it is crucial to protect the IC from an overcurrent that might even cause a fire. Panasonic Industry chip fuses render an appropriate solution for making sure that the IC - and in the end the entire smart meter - remains safe. Furthermore, for the communication line, no matter if it is cellular RF or Wi-Fi, the signal has to be protected against ESD and noise. The signal processing, however, has to happen with the minimum of signal degrading. Panasonic ESD suppressors can withstand a high amount of ESD with minimum degrading of the signal and minimum insertion loss (S21) of 0.4 pF.

Inductors

Next to capacitors, the DC/DC input requires also an inductance for current smoothing.

An established technology would be THT wire-wound inductors with a ferrite core. They, however, require considerable space as well as two reflow processes for mounting on the PCB.

Here, Panasonic Industry offers a more elegant solution with the ETQP_L and ETQP_M series, which both provide a much higher energy density that leads to a remarkably higher efficiency due to their innovative metal composite technology.

Therefore, both series only require half the space on the PCB compared to the conventional THT wire-wound inductor. Thanks to SMD mounting, only one reflow process is needed – which of course saves further production time and costs. The images below show an example of the possible differences on a PCB.

1.xV dc/dc Input (Smoothing)

Summary

The high expectations regarding compact housings, high performance and lifetime: Next-gen smart metering applications meet them, if the used components are the right ones. Manufacturers like Panasonic Industry offer the entire range of passive components, dedicated to the reliability and functionality of tomorrows smart metering innovations.

Undoubtedly, downsizing is a trend in the electronics industry - watch this latest and comprehensive short video and learn what Panasonic Industry has to offer for resistor downsizing - while ensuring the highest power range in smallest case sizes and avoiding the risk of solder joint cracks.

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Find more information on resistors by Panasonic Industry Europe here.

In plastic materials that are flame retardant with red phosphorous, outgassing can occur.

This has an impact on electronic components – in relays, for example, it can cause increased contact resistance, and some corrosion phenomena of components on printed circuit board assemblies (PCBAs) can also be traced back to red phosphorous.

In both the outgassing itself and the corrosion process, humidity plays a crucial role. In certain environmental conditions, it leads to the formation of different phosphorous acids and gaseous phosphine.

Now, there is a whitepaper available, comprehensively addressing the phenomenon and discussing ways to tackle it.

On the occcasion of its presentation during the latest International Conference on Electrical Contacts (ICEC), Panasonic Industry's most specialized experts spoke about the influence of plastics containing red phosphorous on electronic components and relays and shared their research of the influence of three differently flame-retarded polyamide (PA) choke coil bobbins on the contact resistances of a nearby unsealed relay.

This illustrated fundamental component design-in insights to overcome contact failures and increase the reliability and lifetime of applications using relays.

For anyone interested in learning more details about this topic, a comprehensive whitepaper from Panasonic's researchers is available free of charge here.

Did you know that not all film capacitors are big fellows with two or four legs as you would commonly guess? And also, that besides the well-known PP and PET dielectric there are

film capacitors using PPS or PEN as a dielectric material?

"The bigger, the better" is no longer necessarily true - and all the more so since

electronics design is evolving continuously. Also miniaturized housings can conceal great amounts of power. 

High precision, high performance – and contemporarily miniaturized: An ideal choice for

optimizing countless electronic circuit designs.

A higher level of power in smaller parts – this is undoubtedly the overriding direction where the electronic component market is currently heading.

That also applies for resistors, being the smallest and most accessible components in any electronic design. When looking, for instance, at a standard resistor in 1206 case size with a power range of 0.25W, there is a constant demand from the market to achieve this range in a case size not larger than 0603.

Pure tantalum capacitors – also in modern electronics design they stand for extremely high capacitance values for any given volume. But as beneficial as their constructive principle appears - it also reveals pitfalls that make engineers investigate suitable alternatives. Learn why Polymer capacitors could be an appropriate substitute.

We remember: Regularly, pure tantalum capacitors consist of a tantalum anode and a liquid or solid electrolyte as a cathode. This constitutes a certain behaviour that can be eventually outperformed by Polymer-based caps, that use conductive polymers to form the entire electrolyte – or conjunction with a liquid electrolyte, which is known as a hybrid capacitor. Let’s have a look at some key performance aspects:

Ripple current ratings and ESR:

Although pure tantalum capacitors are being offered in many different sizes, they do not come with a very high ripple current which disqualifies them for being employed in applications requiring different levels of current to be passed.

Additionally - albeit they do not suffer from any DC-Bias ageing – the relatively high ESR makes it hard for designers to use those types as smoothing capacitors. By contrast, Polymer caps achieve a very low ESR (e.g. 3mΩ for SP-CAP) with ripple currents up to 10.2A.

In recent years, there has been an increase in the use of low ESR capacitors including POSCAP. The ability to reduce the ripple voltage is introduced here as one advantage of low ESR capacitors.

The following figure below illustrates an example circuit of a general step-down DC-DC converter:

When a capacitor is used for the output smoothing capacitor “Cout”, there is some residual ripple voltage. The graphs above compare residual ripple voltage of different ESR POSCAP capacitors (Fig.1-2 and Fig.1-3) to that of conventional tantalum capacitors (Fig.1-4 and Fig.1-5).

That means, the smaller the capacitor’s ESR, the smaller the ripple voltage becomes.

Miniaturization:

Keeping that in mind will help designers to reduce part counts on the PCB where many tantalum capacitors are connected in parallel to deliver a specific output ripple. Consequently, this saves precious PCB space.

Safety:

Important: tantalum capacitors cannot resist excess voltages - and a very small spike might destroy them and even cause ignition which might affect the surrounding area on the PCB.
That’s why those types are not recommended for applications that are likely to be suffering from higher spikes.

Moreover, as conductive polymer – an organic material - is used as an electrolyte in POSCAPs, it acts non-conductive and as an insulator against leakage current at a temperature of approximately 300℃.

The conductive polymer used for the electrolyte of the POSCAP contains no oxygen molecules. In the unlikely event of a crack forming on the conductive oxide layer, a significant oxide reaction will not occur between sintered tantalum and electrolyte because there are no oxygen molecules. That means POSCAP won’t be exposed to ignition in case of overvoltage.

Frequency:

Polymer capacitors are ideal as decoupling capacitors to remove noises because their impedance shows ideal frequency characteristics. Using a high conductive polymer for the electrolyte greatly improves the ESR characteristics and enables the POSCAP to clearly outperform pure tantalum capacitors at higher frequency levels.

Conclusion:

To sum it up briefly: There is more than one rather clear reason for replacing the pure tantalum types with their polymer alternative in some cases: The specs in terms of ESR, ripple current and frequency characteristics are convincingly better while the overall level of circuit safety is undoubtedly higher.

And last but not least: The polymer caps are the first choice when it comes to saving space on the board – a true ace up the sleeve when acknowledging the unstoppable trend of keeping things safe in ever-smaller designs.