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<\/p>\nIn the 21st century, household appliances and consumer electronics are products that almost everyone uses and comes into contact with, but very few people know much about surface-mount capacitors on circuit boards. Today, our editorial team at a Shenzhen PCB prototyping manufacturer will provide a detailed introduction to surface-mount capacitors on PCBs, including their types, functions, and how to distinguish between their positive and negative terminals.<\/p>\n
<\/p>\n
Surface-mount capacitors, also known as SMD capacitors or surface-mount ceramic capacitors, are a type of multilayer ceramic capacitor. They typically have a rectangular shape and a yellow, black, or light blue surface. Surface-mount capacitors can be classified into two types: non-polar and polar.<\/p>\n
Their primary function in a circuit is to eliminate crosstalk caused by various high-frequency signals generated by the chip itself, thereby ensuring that each chip module can operate normally without interference. In addition, surface-mount capacitors are used in high-frequency electronic oscillator circuits, along with components such as crystal oscillators, to form oscillator circuits that provide the required clock frequencies for various circuits.<\/p>\n
Surface-mount ceramic capacitors are the most common type and are frequently used in small-signal circuits with supply voltages generally below 15 V. On the surface of the circuit board, they are typically yellow, light blue, or light gray.<\/p>\n
Surface-mount tantalum capacitors are suitable for applications that require high performance and stability. They typically feature high capacitance and low tolerance. On a circuit board, they look similar to surface-mount ceramic capacitors.<\/p>\n
Surface-mount aluminum electrolytic capacitors are typically used in circuits that require high capacitance, such as power supply circuits. Their appearance differs slightly from that of other surface-mount capacitors.<\/p>\n
The primary functions of surface-mount capacitors in a circuit are to stabilize voltage, filter signals, reduce noise, and provide clock frequencies. They are capable of storing electrical charge and releasing it when needed to maintain the stability and performance of the circuit.<\/p>\n
Generally, the negative terminal of a surface-mount aluminum electrolytic capacitor is identified by a black mark on the capacitor itself. On the PCB, there are two semicircles at the capacitor\u2019s location; the pin corresponding to the colored semicircle is the negative terminal.<\/p>\n
Sometimes, the positive and negative terminals of a chip capacitor can be distinguished by the length of their leads. The longer lead usually indicates the positive terminal, while the shorter lead indicates the negative terminal. This is the standard method for mounting chip capacitors on a circuit board.<\/p>\n
If you encounter a situation where you cannot accurately distinguish between the positive and negative terminals, you can use a multimeter to measure them. The insulation resistance between the positive and negative terminals of a capacitor is typically 1,000 megohms or higher. By connecting the positive terminal to the positive terminal of the power source and the negative terminal to the negative terminal of the power source, the leakage current through the capacitor should be very small, allowing you to determine the positive and negative terminals.<\/p>\n
Surface-mount capacitors on circuit boards are typically identified by a serial number starting with the letter C (e.g., C1, C47, etc.). Because components are mounted closely together on the circuit board, only the serial number is marked, not the capacitance value. Low-capacitance capacitors are usually unmarked, while only miniature capacitors are labeled.<\/p>\n
A capacitor consists of two plates at either end and an insulating dielectric in the middle. When an electric current is applied, the plates become charged, creating a voltage; however, because of the insulating material in the middle, the capacitor as a whole does not conduct electricity. However, when the voltage exceeds the capacitor\u2019s breakdown voltage, the capacitor breaks down and ceases to be an insulator.<\/p>\n
In a DC circuit, a capacitor acts as an open circuit. Capacitors can store electric charge and release it when needed to stabilize the circuit's voltage. They also play an important role in AC circuits.<\/p>\n
The capacitance of a capacitor refers to its ability to store electric charge. Tolerance indicates the deviation between the actual capacitance and the rated capacitance. Capacitor tolerances are classified into several grades, such as \u00b15%, \u00b110%, and \u00b120%.<\/p>\n
The rated operating voltage is the maximum DC voltage at which a capacitor can operate stably over the long term.<\/p>\n
The temperature coefficient represents the relative change in capacitance within a given temperature range. The lower the temperature coefficient, the better.<\/p>\n
Insulation resistance is a parameter used to measure the insulation performance of a capacitor. The higher the insulation resistance, the lower the leakage current.<\/p>\n
Loss is the energy consumed by a capacitor as it generates heat under the influence of an electric field per unit of time. It is typically expressed as the tangent of the loss angle.<\/p>\n
By understanding these parameters, you can better select surface-mount capacitors that meet your circuit's requirements.<\/p>\n
This article aims to help you better understand the applications and characteristics of surface-mount capacitors on circuit boards. Although surface-mount capacitors may not be very noticeable in electronic devices, they play a crucial role in the performance and stability of those devices.<\/p>\n
Visit the following links for more information about PCBs and surface-mount capacitors:<\/strong><\/p>\n Surface-mount capacitors are an indispensable component of modern electronic circuits; they come in a variety of types and serve important functions. By correctly identifying their positive and negative terminals and understanding their parameters and characteristics, you can better incorporate them into your circuit designs to ensure the performance and stability of your devices.<\/p>\n Surface-mount capacitors can store electrical charge and release it when needed to stabilize the voltage in a circuit. They play an important role in both DC and AC circuits.<\/p>\n You can use the black mark method, the lead length method, or the multimeter method to distinguish between the positive and negative terminals of a surface-mount capacitor.<\/p>\n Electrolytic capacitors and surface-mount capacitors are two different types of capacitors with distinct characteristics and applications. Electrolytic capacitors are typically used in circuits that require high capacitance, while surface-mount capacitors are suitable for small-signal circuits.<\/p>\n The temperature coefficient indicates the extent to which capacitance varies with temperature. For certain precision applications, capacitors with a lower temperature coefficient are more suitable because they maintain stability across a range of temperatures.<\/p>\n Insulation resistance is an indicator of a capacitor\u2019s insulation performance; it reflects how well the capacitor is insulated. The higher the insulation resistance, the lower the leakage current, and the better the capacitor\u2019s performance.<\/p>\n Related Reading<\/strong>\uff1aHow to Tell if the Solder Joints on a PCBA Board Are Leaded or Lead-Free<\/a> \u00b7 Applications of 0-Ohm Resistors in Circuit Design<\/a><\/p>","protected":false},"excerpt":{"rendered":" \u572821\u4e16\u7eaa\u7684\u4eca\u5929\uff0c\u751f\u6d3b\u7535\u5668\u3001\u65e5\u7528\u7535\u5b50\u7b49\u51e0\u4e4e\u662f\u6bcf\u4e2a\u4eba\u90fd\u4f1a\u4f7f\u7528\u63a5\u89e6\u5230\u7684\u4ea7\u54c1\uff0c\u4f46\u662f\u5173\u4e8e\u7535\u8def\u677f\u4e0a\u7684\u8d34\u7247\u7535\u5bb9\u5374\u5f88\u5c11\u6709\u4eba\u77e5 […]<\/p>\n","protected":false},"author":1,"featured_media":19464,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"slim_seo":{"title":"An Introduction to Surface-Mount Capacitors on PCBs","description":"What types of surface-mount capacitors are used on PCBs? Explain the structure and function of ceramic, tantalum, and aluminum electrolytic capacitors, and describe the \"black dot method,\" \"lead method,\" and \"multimeter method\" for determining their polarity."},"_slim_seo_primary_term_category":0,"_slim_seo_primary_term_post_tag":0,"footnotes":""},"categories":[413,26],"tags":[],"class_list":["post-1520","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-pcb-basics","category-blog"],"_links":{"self":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/1520","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/comments?post=1520"}],"version-history":[{"count":4,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/1520\/revisions"}],"predecessor-version":[{"id":19466,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/1520\/revisions\/19466"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/media\/19464"}],"wp:attachment":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/media?parent=1520"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/categories?post=1520"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/tags?post=1520"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nConclusion<\/h2>\n
Frequently Asked Questions (FAQs)<\/h2>\n
1. How do surface-mount capacitors work?<\/h3>\n
2. How do you distinguish between the positive and negative terminals of a surface-mount capacitor?<\/h3>\n
3. What is the difference between electrolytic capacitors and surface-mount capacitors?<\/h3>\n
4. Why is the temperature coefficient of a capacitor important?<\/h3>\n
5. What is the insulation resistance of a capacitor?<\/h3>\n