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<\/p>\nElectromagnetic interference (EMI) has long been a challenge in the field of electrical engineering. This article will explore methods for addressing EMI issues, with a particular focus on PCB layer stacking and electromagnetic shielding techniques.<\/p>\n
<\/p>\n
PCB design plays a critical role in addressing EMI issues. First, let\u2019s take a closer look at some basic concepts.<\/p>\n
On a circuit board, placing a capacitor of appropriate capacitance near the IC\u2019s power supply pins can improve the rise and fall times of the IC\u2019s output voltage. However, capacitors have limitations in their frequency response, which means they cannot generate the required harmonic power. Furthermore, transient voltage drops on the power bus are a major source of common-mode EMI interference.<\/p>\n
To address these issues, we can treat the power plane surrounding the IC as a high-frequency capacitor that captures the high-frequency energy leaked from discrete capacitors. In addition, the inductance of the power plane should be kept low to reduce common-mode EMI.<\/p>\n
To control common-mode EMI, the power plane must aid in decoupling and have sufficiently low inductance. The design of the power plane depends primarily on the power plane stacking, the interlayer material, and the operating frequency. Typically, the spacing between power planes is 6 mil, and the interlayer material is FR4. In this case, the equivalent capacitance of the power plane is approximately 75 pF per square inch.<\/p>\n
For devices with rise times ranging from 100 to 300 ps, a 3-mil layer spacing may no longer be suitable.<\/p>\n
For these devices, we need to use smaller layer spacing and materials with higher dielectric constants, such as ceramics and ceramic-reinforced plastics. These materials can meet the design requirements for circuits with rise times ranging from 100 to 300 ps.<\/p>\n
A good layering strategy involves placing all signal traces on one or more layers and positioning them as close as possible to the power or ground layers. For power, a good layering strategy involves placing the power layer adjacent to the ground layer, with the distance between them as small as possible. This is what is known as a \u201clayering strategy.\u201d<\/p>\n
What kind of stacking strategies help shield and suppress EMI? Here are some common stacking schemes.<\/p>\n
In a traditional four-layer board with a thickness of 62 mil, even when the signal layers are on the outer layers and the power and ground layers are on the inner layers, the spacing between the power and ground layers is still too large. To improve EMI suppression performance, two alternative solutions can be considered.<\/p>\n
The first option is to use the outer layer as the ground plane, with the two middle layers serving as signal\/power layers.<\/p>\n
The second approach involves routing both power and ground on the outer layer, with the two middle layers dedicated to signals. Both of these approaches can improve EMI suppression performance.<\/p>\n
If the component density on the circuit board is high, it is best to use a 6-layer board. There are two examples to consider. In the first example, the power and ground planes are placed on layers 2 and 5, but this results in high impedance in the power plane, which is detrimental to EMI control. In the second example, the power and ground planes are placed on layers 3 and 4, which resolves the issue of high impedance in the power plane.<\/p>\n
For two power planes with the same voltage source that require high current output, the circuit board should be laid out in two sets of power planes and ground planes. An insulating layer is placed between each pair of power planes and ground planes to create two pairs of power buses with equal impedance that divide the current equally.<\/p>\n
When addressing EMI issues, PCB layer stacking and electromagnetic shielding techniques are crucial. Different PCB designs require different strategies, but the fundamental principle is to ensure that the PCB can effectively control common-mode EMI, maintain signal integrity, and minimize transient voltages as much as possible.<\/p>\n
As the time-to-market for electronic devices continues to shrink, these technologies will become increasingly indispensable for ensuring the performance and reliability of these devices.<\/p>\n
How important is the distance between the power plane and the ground plane?<\/strong><\/p>\n The distance between the power plane and the ground plane is critical for controlling common-mode EMI. The smaller the distance, the less EMI interference there is.<\/p>\n What is a power busbar?<\/strong><\/p>\n The power bus is the power supply layer surrounding the IC; it helps with decoupling and delivers high-frequency power.<\/p>\n Why is it important to consider the layer layout of a circuit board?<\/strong><\/p>\n Layered design helps control EMI, maintain signal integrity, and reduce transient voltages.<\/p>\n What is the difference between a 6-layer board and a 10-layer board?<\/strong><\/p>\n 6-layer boards are suitable for medium component density, while 10-layer boards are suitable for applications requiring more layers of power and ground planes.<\/p>\n How Do EMI Issues Affect the Performance of Electronic Devices?<\/strong><\/p>\n EMI issues can lead to reduced performance in electronic devices, including signal interference, decreased reliability, and increased power consumption.<\/p>\n By employing appropriate PCB design and stacking strategies, EMI issues can be significantly reduced, thereby improving the performance and reliability of electronic devices.<\/p>","protected":false},"excerpt":{"rendered":" \u7535\u78c1\u5e72\u6270\uff08EMI\uff09\u95ee\u9898\u4e00\u76f4\u662f\u7535\u5b50\u5de5\u7a0b\u9886\u57df\u4e2d\u7684\u4e00\u4e2a\u6311\u6218\uff0c\u672c\u6587\u5c06\u63a2\u8ba8\u89e3\u51b3EMI\u95ee\u9898\u7684\u65b9\u6cd5\uff0c\u7279\u522b\u5173\u6ce8PCB\u5206\u5c42\u5806\u53e0\u548c […]<\/p>\n","protected":false},"author":1,"featured_media":8868,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"slim_seo":{"title":"The Role of PCB Layer Stacking Design in Suppressing EMI","description":"How does a layered stack structure suppress EMI? Explain the roles of the power bus, power planes, ground planes, and electromagnetic shielding, and provide recommendations for a reasonable PCB stack-up and layer sequence."},"_slim_seo_primary_term_category":0,"_slim_seo_primary_term_post_tag":0,"footnotes":""},"categories":[26],"tags":[255,254],"class_list":["post-2462","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog","tag-emi","tag-254"],"_links":{"self":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/2462","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=2462"}],"version-history":[{"count":1,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/2462\/revisions"}],"predecessor-version":[{"id":19256,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/posts\/2462\/revisions\/19256"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/media\/8868"}],"wp:attachment":[{"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/media?parent=2462"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/categories?post=2462"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.jingpengpcb.com\/en\/wp-json\/wp\/v2\/tags?post=2462"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}