World's Fastest PCB Manufacturing
My Message
Suggestions
Account

Get started now

Log In

or

Sign Up

My ALLPCB

My Orders Shipping Address Balance Account Settings My SNS Profile
0
  • Home
  • Instant Online Quote Alternate Text
    • PCB Instant Quote
    • PCB Assembly Quote
    • SMD-Stencil Quote
  • PCB Assembly
  • PCB Capabilities
  • Feedback
  • Resources
    • Sponsorship
    • PCB Softwares
    • Units Conversion
    • FAQ
  • About Us
    • About Us
    • Why Us
    • Contact Us
    • News
Log In Sign Up
  • Home
  • Instant Online Quote
    • PCB Instant Quote
    • PCB Assembly Quote
    • SMD-Stencil Quote
  • PCB Assembly
  • PCB Capabilities
  • Feedback
  • Resources
    • Sponsorship
    • PCB Softwares
    • Units Conversion
    • FAQ
  • About Us
    • About Us
    • Why Us
    • Contact Us
    • News
service@ALLPCB.com
Thank you very much for your valuable suggestion!
We will solve it as soon as possible!

The EMC improvement of in 8 layer PCB design

2017/1/19 8:25:17

8 Layer PCB Stackup Guidelines
How to improve EMC performance on 8 layer PCB design?

An eight-layer board can be used to add two more routing layers or to improve EMC performance by adding two more planes. Although we see examples of both cases, I would say that the majority of eight layer board stack-ups are used to improve EMC performance rather than add additional routing layers. The percentage increase in cost of an eight-layer board over a six-layer board is less than the percentage increase in going from four to six layers, hence making it easier to justify the cost increase for improved EMC performance. Therefore, most eight-layer boards consist of four wiring layers and four planes.


An eight-layer board provides us, for the first time, the opportunity to easily satisfy all of the five originally stated objectives. Although there are many stack-ups possible, we will only discuss a few of them that have proven themselves by providing excellent EMC performance. As stated above, eight layers is usually used to improve the EMC performance of the board, not to increase the number of routing layers.
An eight-layer board with six routing layers is definitely not recommended, no matter how you decide to stack-up the layers. If you need six routing layers you should be using a ten-layer board. Therefore, an eight-layer board can be thought of as a six-layer board with optimum EMC performance.
The basic stack-up of an eight-layer board with excellent EMC performance is shown in Fig 9.
This configuration satisfies all the objectives listed in my previous post. All signal layers are adjacent to planes, and all the layers are closely coupled together. The high-speed signals are buried between planes, therefore the planes provide shielding to reduce the emissions from these signals. In addition the board uses multiple ground planes, thus decreasing the ground impedance.
For best EMC performance and Signal Integrity, when high frequency signals change layers (e.g., from layer 4 to 5) you should add a ground-to-ground via between the two ground planes, near the signal via, in order to provide an adjacent return path for the current.
The stack-up in Fig. 9 can be further improved by using some form of embedded PCB capacitance technology (e.g. Zycon Buried Capacitanceú) for layers 2-3 and 6-7. This approach provides a significant improvement in the high frequency decoupling and may allow the use of significantly fewer discrete decoupling capacitors.
Another excellent configuration, and one of my favorite, is shown in Figure 10. This configuration includes two outer layer ground planes. With this arrangement all routing layers are buried between planes and are therefore shielded.
H1 indicates the horizontal routing layer for signal 1, and V1 indicates the vertical routing layer for signal 1. H2 and V2 represent the same for signal 2. Although not commonly used this configuration also satisfies all the five objectives presented previously, and has the added advantage of routing orthogonal signals adjacent to the same plane. Typical layer spacing for this configuration might be 0.010"/0.005"/0.005"/0.20"/0.005"/0.005"/0.010"
Another possibility for an eight-layer board is to modify Fig. 10 by moving the planes to the center as shown in Fig. 11. This has the advantage of having a tightly coupled power-ground plane pair at the expense of not being able to shield the traces.
One of the many advantages of this layer stackup is the tightly coupled power-ground plane pair in the center. Typical layer spacing for this configuration might be 0.006"/0.006"/0.015"/0.006"/0.015"/0.006"/0.006." This configuration satisfies objectives 1 and 2, 3, and 5, but not 4. This is an excellent performing configuration with good signal intergity and is often preferred over the stack-up of Figure 10 because of the tightly coupled power/ground planes.
There is very little EMC advantage to use a board with more than eight layers. More that eight layers is usually used only when additional layers are required for signal trace routing. If six routing layers are needed, a ten-layer board should be used.


  • 4066
  • 1
  • 350
Post Comment

    babinyecz

    2017/1/21 8:25:17

    Great article! Keep up the great writing.

    You might like

    Blair

    • Threads

      8

    • Following

      0

    • Followers

      0

    PCB Prototype

    PCB Instant Quote

    x mm

    Quantity

    Quote Now

    PCB Assembly

    SMT-Stencil

    • 12
    Products & Service
    PCB Capabilities
    Aluminum PCB Service
    PCB Assembly Service
    SMT-Stencil
    Quotation & Feedback
    Online Auto-Quotation
    PCB Assembly Quote
    Quote by Salesperson
    Customer Reviews
    Customer Support
    FAQ
    Community
    Sponsorship
    Referral Program
    About Us
    About Us
    Why Us
    Contact Us
    News
    Resource Details
    PCB Software
    Units Conversion
    service@allpcb.com central_support@allpcb.com
    Follow Us:
    Facebook Youtube Twitter Tumblr Youtube
    Certification: Certification
    Our Preferred Partners: Our Preferred Partners

    Please send Gerbers to service@ALLPCB.com for quotation © ALLPCB.com,All Rights Reserved Privacy PolicySitemap

    Secure Site by GoDaddy.com This site has earned the McAfee SECURE certification.