Bridge Rectifiers use four diodes that are arranged cleverly to convert the AC supply voltage to a DC supply voltage.
The output signal of such a circuit is always of the same polarity regardless of the polarities of the input AC signal.
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Plastic film capacitor
In film capacitors, plastic film is used to construct the dielectric and aluminum or zinc is used to construct the electrodes of the capacitor. Film capacitors are also known as plastic film capacitors or film dielectric capacitors. Plastic film capacitors are mainly used in circuits where low loss and high insulation resistance is required.
Plastic film capacitor definition
Plastic film capacitor is a capacitor that uses plastic film as the dielectric and aluminum or zinc as the electrodes to store electric charge.
What is dielectric?
Dielectric is the insulating material placed between the electrodes of a capacitor. Dielectric materials are chosen based on their ability to allow electrostatic attraction and repulsion. Good dielectric materials are poor conductors of electricity. However, they allow the electrostatic field.
In plastic film capacitors, polyester, polypropylene, polyethylene terephthalate, and polyphenylene sulfide are commonly used as dielectrics.
Types of plastic film capacitors
Film capacitors are classified into two types:
Film-foil capacitors
Metallized film capacitors
Film-foil capacitors
The film-foil capacitor is made of two plastic films or sheets; each is layered with thin aluminum metal foil or sheet. The plastic sheets and aluminum sheets are then rolled in the form of a cylinder and wire leads are attached to the both ends of aluminum sheets. Polyester, polypropylene, polyethylene terephthalate, and polyphenylene sulfide are commonly used as dielectric in film capacitors. In plastic film capacitors, aluminum sheets acts as electrodes and plastic sheets acts as dielectric.
The film-foil capacitor is made of two plastic films; each is layered with thin aluminum metal foil.
Metallized film capacitors
In metallized film capacitors, the aluminum sheet or foil is replaced by a layer of metal vacuum deposited on the film layer. The most commonly used metal layer is aluminum or zinc that is extremely thin.
In metallized film capacitors, the aluminum foil is replaced by a layer of metal vacuum deposited on the film layer. The most commonly used metal layer is aluminum or zinc that is extremely thin.The plastic film layers made of synthetic material act as dielectric and the aluminum layers act as electrodes. The major advantage of film dielectric capacitors over natural dielectric capacitors is that the plastic film is synthetic or artificial. Therefore, we can able to increase thickness and heat resistance of the dielectric. In other words, we can change the thickness and heat resistance of the plastic film capacitor.
Applications of film capacitors
The various applications of film capacitors include:
A/D converters
Filters
Motor run
Peak voltage detectors
Advantages of film capacitors
High stability
Low cost
Low losses even at high frequencies
Semiconductor chips shortage will extend to 2022
By Jack Li 2021.12.23
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A few days ago, the annual China Integrated Circuit Design Industry 2021 Conference (ICCAD 2021) was grandly opened in Wuxi, Jiangsu.
At the summit forum held at the same time, Mr. Peng Jin, senior vice president of Semiconductor Manufacturing International Co., Ltd. （SMIC, the biggest Semiconductors’ factory in China）, delivered a speech titled "Docking the Whole Machine Enterprise, Coordinating Industry Supply". In this speech, he mentioned that in his It seems that throughout 2022, the capacity of wafer and chips is still tight, and there is an overbooking situation in the industry. However, SMIC will continue to invest firmly and continuously to help the global chip industry chain overcome difficulties and join hands to move towards a new future for the chip industry.
Peng Jin said that the continuous shortage of chip production capacity is caused by the combined influence of multiple factors such as the epidemic, geopolitics and demand.
According to him, the emergence of the above-mentioned factors has prompted Chinese complete machine companies, including mobile phones, automobiles, home appliances and screen manufacturers, to increase their stocks in the past year or so, making chips a reserve material; at the same time, they are still working hard. Seek localized chip design and manufacturing. Especially in terms of manufacturing, even if there are some chips that China cannot design at present, they also hope that overseas companies can switch to Chinese manufacturing in a planned way, which brings huge demand to the design and manufacturing of domestic integrated circuits.
Peng Jin took the development of domestic screen factories as an example to explain why chips have become the bottleneck of industrial development. According to him, if only the production capacity of domestic AMOLED is counted, it can fully meet the needs of domestic mobile phone manufacturers, but because of the capacity limitation of the driver chip, it affects the power of the terminal.
In addition to the limited capacity of existing chips, new demand brought about by new applications has become another key factor affecting supply.
Peng Jin mentioned in his speech that in 2021, the domestic sales of new energy vehicles will reach 3.2 million, and the production and sales far exceed expectations at the beginning of the year. At the same time, new energy vehicles themselves have more demand for chips, and the resulting production capacity tension is obvious. "Each new energy vehicle needs an 8-inch silicon chip. Among them, discrete devices IGBT account for 0.4, DMOS account for 0.1, and the other 0.5 belong to integrated circuits such as MCU, power management and high-performance computing." Peng Jin said for example. "According to relevant forecasts, the national sales of new energy vehicles will reach 6 million next year. If calculated in this way, 2.8 million new energy vehicles will be added next year, which means that at least 1.4 million 8-inch silicon wafers will be needed to meet this requirement. Demand." Peng Jin continued.
In addition, in Peng Jin's view, carbon neutrality promotes analog semiconductor opportunities in the industrial equipment and automotive markets, and AIoT also brings more demand for wireless chips and microcontrollers.
"At present, the focus of the industry will shift from products that used to be digital IC-based products such as mobile phones, computers, and televisions, to areas that are dominated by analog IC demand. These analog chips, including power management and CIS, will bring huge benefits in the future. Opportunity." Peng Jin emphasized. From the data he provided, we can see that, driven by chips such as automobiles, power management, and communications, the growth rate of analog ICs will be about 10% from now to 2025, and the demand for analog ICs in China will reach 28.5 billion next year. US dollars. Although many domestic companies in this field have already gone public, there are still many companies that are rapidly establishing and growing. "Peng Jin concluded that this can also explain the important reasons for the shortage of certain products during this period.
"The repeated construction of the global semiconductor market that does not follow the market demand has pushed up the equipment delivery cycle, which has slowed the expansion of the fab, and further affected the supply of chips. From his introduction, we learned that the delivery of equipment The period has been extended from only half a year before to one year or even one and a half years now. According to a recent report by the well-known analyst firm Omdia, China’s fabless fabs are actively entering the AMOLED-driven market, but because there are only a limited number of crystals. OEMs can provide production capacity for high-voltage (HV) 40nm and 28nm AMOLED driver chips. However, first-tier brands or fabless fabs will occupy most of the foundry capacity in 2022. Therefore, only a small amount is left. Production capacity is left to Chinese panel makers. "In the third quarter of last year, smartphone-related businesses accounted for 46% of the company's total revenue, but this year this figure is only 32%. But the Internet of Things, computer and automotive businesses, which accounted for 16% last year, doubled to 32% this year. "Peng Jin said for example.
Finally, Peng Jin also introduced SMIC's future technology layout. He pointed out that SMIC will continue to consolidate its original special storage and CIS advantages, and will also invest in display, MCU, analog, automotive and radio frequency fields. "In the key development areas mentioned above, SMIC will continue to invest in research and development and will also expand its production capacity."
How to correctly determine the positive and negative poles of chip tantalum capacitors?
One end of the chip tantalum capacitor is marked with a horizontal line, which is the positive electrode of the chip tantalum capacitor, and the other end is the negative electrode. The long end of the lead tantalum capacitor is the positive electrode, and the short end is the negative electrode.
SMD tantalum capacitors are polar capacitors. The positive and negative poles cannot be reversed. In case of reverse connection, the tantalum capacitor will not work or fail.
The positive and negative poles of SMD tantalum capacitors are distinguished and measured. The black block with the mark on the tantalum capacitor is the negative pole. There are two semicircles on the capacitor position on the PCB, and the pin corresponding to the colored semicircle is the negative pole. The length of the pins is also used to distinguish the positive and negative poles as positive and short pins as negative.
When we don’t know the positive and negative poles of SMD tantalum capacitors, we can use a multimeter to measure them. The medium between the two poles of the capacitor is not an absolute insulator, and its resistance is not infinite, but a finite value, generally above 1000 megohms. The resistance between the two poles of the capacitor is called insulation resistance or leakage resistance, and only electrolytic capacitors When the positive pole of the electrolytic capacitor is connected to the positive power supply (the black test lead when the electricity is blocked), and the negative terminal is connected to the negative power supply (the red test lead when the electricity is blocked), the leakage current of the electrolytic capacitor is small (the leakage resistance is large).
