When Panasonic started the development of the first metal composite power inductor nearly two decades ago, the key target was to design a product that would be able to withstand severe conditions and provide the highest reliability for automotive applications.
Nowadays, Automotive engineering witnesses almost dizzying progress in electrification. Correspondingly, the demand for passive components such as coils reliably withstanding harsh automotive conditions is higher than ever before. And it’s not only about constructive toughness and heat resistance: At the same time, there is a clear trend towards ever smaller components to save space and reduce weight.
With the introduction of the ETQP-series, those requirements were not only met, but in many cases even exceeded. In the following, we will briefly spotlight those key design elements that substantiated the PCC’s excellent reputation in many fields of applications:
Back then, when the development of the first metal composite inductors started, power inductors were basically all made of ferrite. This type of inductor consists of several sintered parts which are combined and come with an air gap inside the body. Due to its assembled structure, the resistance to vibrations of ferrite inductors is limited from <4G to a maximum of 10G.
In contrast, the Panasonic Industry metal composite power inductor has a monolithic design by pressed metal powder around the copper wire. The monolithic structure leads to a much higher vibration resistance, up to 30G - depending on the series.
Another important feature that guarantees the highest reliability is the terminal design. The gap structure between the backside of the terminal and the core minimizes solder joint crack issues caused by thermal stress. Furthermore, a unique terminal structure without an internal joint ensures superior vibration resistance. The ETQP_M___Y__ - series leads the copper wire from the inside core to the bottom of the outer terminal, enabling a direct connection to the PCB and safeguarding the highest mechanical joint solder connection stability.
As temperature requirements are getting more and more demanding in automotive and other customer applications - not least because the component density in modern vehicles is increasing more and more - it is crucial that a power inductor can withstand high temperatures over a long lifespan. Depending on the type, the ETQP series is specified for operation up to 160 °C including self-heating. This is possible because no adhesives are used in the design, which is typically a weak spot for temperature resistance. The resin material of the core itself as well as the coating of the copper wire have a heat resistance of over 200°C.
Although the standard ETQP types already offer a very high vibration resistance, there are some applications that require an even higher specification, for example, PCBs which are mounted directly on a motor or powertrain. Panasonic Industry tackled this challenge and developed the ETQP_M___YS_ series, ensuring resistance to vibrations of up to 50G. This has been made possible by lowering the centre of gravity with a change in the terminal structure – so this series is ready to use in even the most demanding environments.
In summary, with the ETQP-series, Panasonic Industry created a power inductor whose monolithic structure of the metal composite core in combination with the terminal design and thermal robustness leads to a product with the highest reliability for even the most demanding automotive, high temperature, high vibration applications, throughout the lifespan of a modern vehicle.
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:
Chip | ESP32-S2 |
|---|---|
Performance | Up to 240 MHz |
Technology | 2.4 GHz Wi-Fi 802.11 b/g/n |
Memory (internal) | 128kB ROM, 320kB SRAM, 16kB low power SRAM |
Memory (additional external ) | 4MB Flash, 2MB PSRAM or MB Flash, 0MB PSRAM |
Security features | WPA2 and WPA3 personal |
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)
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.
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.
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)
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.
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.
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:
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
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.
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.
Function | EMI Suppression | ||
|---|---|---|---|
Safety class | X2 | X1 | Y2 |
Product series | ECQUA | ECQUB | |
Voltage | 275VAC, 310VAC | 300VAC | |
Capacitance | 0.0082μF to 10μF | 0.001μF to 1.0μF | 0.001μF to 0.0068μF |
Fuse function | built-in | built-in | - |
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.
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
Function | Filtering |
|---|---|
Product series | ECHU(X) |
Category temp. range | -55℃ to 125℃ |
Voltage | 16VDC, 50VDC |
Capacitance | 0.1nF to 220nF |
Capacitance tolerance | ±2%, ±5% |
Dissipation factor （1kHz）(%) | <0.6 |
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.
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.
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.
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.
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.
For anyone seeking a capacitor coming in a small case size, with a low-to-high voltage range, high precision and stable capacitance, Panasonic Industry chip type film capacitors could be the ideal solution.
Figure 1: Panasonic Industry Chip Type Film Capacitor line up
Looking at the shape of chip type film capacitors and some of their basic features, one might easily start to wonder: they look pretty much like MLCCs. So, what’s the difference between the two technologies? What are the advantages chip type film capacitors have?
Let’s make a quick comparison to find the answer.
Figure 2: Comparison between Chip Type Film Capacitor and MLCC
Easily being recognized, compared with MLCCs, chip type film capacitors have following advantages in terms of electric characteristics:
Let’s dive into each Panasonic product type to have a better understanding of the technology.
ECHU Type
This type has ECHU(X) and ECHU(C) series available. These two series utilize stacked metallized PPS film as dielectric with simple mold-less construction. They are small in case size (down to 1.6mm x0.8mm footprint!), feature a tight capacitance tolerance of ±2% & ±5%. The capacitance in a single component can go up to 220nF.
ECHU(X) series is available in a low voltage range of 16VDC to 50VDC.
ECHU(C) series is available in a middle voltage range of 100VDC.
Figure 3: Construction of ECHU(X) type
Figure 4: Construction of ECHU(C) type
Now, let’s take a closer look at ECHU(X) series.
As mentioned earlier, ECHU(X) series is focusing on low voltage range of 16VDC to 50VDC.
It benefits from excellent electric characteristics of low ESR, low loss, stable capacitance against temperature and DC bias.
Figure 5: ECHU(X) has excellent electric characteristics
This makes ECHU(X) series the most suitable solution for filtering in xDSL circuit of class D amplifiers for speakers, smartphones and wireless communication etc., as well as for LED circuits.
Figure 6: ECHU(X) series is the ideal solution for xDSL and LED circuit
Furthermore, it guarantees a very fast lock-up time and doesn’t show a piezoelectric effect as MLCCs do, which makes it a perfect solution for PLL (phase locked loop) circuit in applications such as smart phones, wireless communication and Bluetooth devices etc.
Figure 7: ECHU(X) series is ideal solution for PLL circuit
ECPU Type
This type has ECPU(A) series available. This series utilizes stacked metallized plastic film as dielectric and inner electrode with simple mold-less construction. It features a wide capacitance range up to 1.0μF within an ultra-small case size (only 3.2mm x2.5mm footprint for 1.0μF!).
Figure 8: Construction of ECPU(A) type
ECPU(A) series benefits from excellent electric characteristics as low ESR, low loss and stable capacitance over temperature. All this enables its outstanding performance for noise reduction in measurement circuits.
Figure 9: ECPU(A) has excellent electric characteristics
And with ultra-low distortion characteristics being added, ECPU(A) is the most appropriate capacitor solution for coupling in audio circuits.
Figure 10: ECPU(A) series features ultra-low distortion
ECWU Type
Lastly, let’s check out the ECWU type. This type has ECWU(C) series available.
This series is based on stacked metallized PEN film as dielectric with simple mold-less construction. Like the other two types introduced earlier, this series also features a small case size while covering a wide voltage range up to 630VDC.
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.
For established suppliers of high quality resistors like Panasonic, this means to continuously strive for innovation in order to meet the customers’ demands for a contemporarily advanced resistor portfolio.
Image 1: Construction of Panasonic Industry wide terminal resistors
Panasonic Industry's blueprint for meeting those resistor downsizing requirements would be the wide terminal resistors.
The name is based on two innovative constructive principles:
First, the terminals on this type of resistor are found on the long side of the resistor whereas they are on the short one at conventional products (cf. image 1).
So, when having conventionally a 2010 case size, the wide terminal type would be correspondingly 1020 case size. This increases the amount of current being able to pass through the resistor which results in a significantly higher power range.
Second: Instead of using one block of resistive element, two or three blocks are used. Each of these smaller elements is trimmed by laser. This supports the heat dissipation throughout the alumina substrate elements and avoids hotspots in one area, as illustrated in image 2.
Image 2: Heat generation in Panasonic wide terminal resistors vs. conventional wide terminal resistors
As a result, the power range can be increased. Depending on the case size of the wide terminal resistor types, they contain two or three resistive elements.
Panasonic Industry wide terminal resistors with lower resistance values are particularly popular for replacing metal shunt resistors. If the replacement is technically feasible, resorting to these resistors helps saving space on the PCB.
Last but not least, wide terminal resistors are much cheaper compared to metal shunt resistors, rendering them the perfect solution for current sensing with higher power requirements.
The field of suitable applications for wide terminal resistors is wide: From automotive and industrial applications to building automation and many other applications where a higher power range is as essential as a compact case design.
In the automotive sector, wide terminal resistors can be used in electrical control units (ECU), anti-lock braking systems, headlights, EPS, motors and many other applications whereas in industrial contexts, wide terminal resistors are the perfect solution for power supplies, DC/DC converters or motor controls.
Whilst mostly focusing on low ohmic values, Panasonic Industry wide terminal resistors are available in three different categories: the conventional type with the widest range as ERJA/B series, anti-sulfur wide terminal resistors as ERJC and low TCR type as ERJD series.
Get a glimpse on the following overview on the company’s wide terminal resistor series – and keep them in mind if you are looking for a new resistor meeting your downsizing needs without any compromises in terms of power handling.
Series | Description | Resistance range | Power range |
ERJA/B | current sensing and conventional wide terminal resistors | 5 mΩto 1 MΩ |
|
ERJC | current sensing and anti-sulfur wide terminal resistors | 10 mΩ to 1 Ω | 2 W |
ERJD | current sensing and low TCR wide terminal resistors | 10 mΩ to 200 mΩ | 1-2 W |
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:
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.
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.
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.
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.
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.
Doubtlessly, there is a shift towards an entirely new and more environmental-friendly perception of individual mobility. Apparently, we are talking of electric vehicles and the corresponding charging infrastructure. The goals are set – more and more car manufacturers state their promises to discontinue the production of combustion engines.
There are plenty of visions – that, however, can only be brought to life when there are matching technologies and components available that make EVs catch up with their petrol-driven predecessors. In terms of reach, in terms of safety and in terms of voltage.
All that still causes some headache for automotive engineers, as next-gen mobility widely depends on next-gen components.
Let’s exemplarily look at capacitors and see what Panasonic Industry has to offer along the driveway to the future:
Figure 1: Main in-vehicle application for xEV
OBC & DC / DC converter
As the most essential part of an electric vehicle, batteries’ increasing capacity is the key for development nowadays. This requires design for EV chargers (on-board chargers) with higher and higher power output.
Ready to meet this need, Panasonic Industry offers its film capacitor ECQUA (AC rated), ECWFG (DC rated) and ZPV (DC rated) series featuring large current handling ability, high reliability and high safety, contributing to high-power OBC and DC/DC converter design and development.
Figure 2: OBC (on-board charger) & DC/DC converter circuit
Taking into account that reliability i.e. humidity resistance is critical for this application, Panasonic Industry has developed its proprietary enclosure sealing technology and aluminium vapour deposition to achieve humidity resistance along with compliance to AEC-Q200.
Figure 3: High humidity-resistant vapour deposition film & sealing technology
Taking ECQUA series as an example, it has the following guaranteed THB (temperature humidity bias) testing data:
・AC275V rated product : 85℃, 85%RH, AC240V, 1000h; 85℃, 85%RH, AC275V, 500h
・AC310V rated product : 85℃, 85%RH, AC275V, 1000h
Have a look at those two reliability tests to compare Panasonic’s technology with the conventional one:
Figure 4: Humidity resistance load test
Figure 5: High-frequency step-up loading test
Without an iota of doubt, the safety and security of automobiles are certainly also two of the most critical areas of automobile engineering today.
Taking it into account, Panasonic Industry has been providing its automotive-grade film capacitors with patterned metallization technology (also well known as “fuse function”), which ensures the safety of the electric circuit with open failure mode.
Figure 6: Comparison of general and patterned metallization
Demo video for fuse function
Figure 7: Safety limit AC step-up test
Thanks to this excellent impact deduction Panasonic Industry automotive-grade film capacitors are the ideal solution for high-stress application such as onboard chargers, DC/DC converter, electric compressors and inverters.
Briefly said - one less worry: In terms of capacitor reliability, the way to future mobility should be paved.
For more information on the automotive-grade film capacitor product line-up and the respective specs and advantages, please visit the Panasonic Industry website:
