Get Acquainted With The Backplane Pcb Fundamentals

By Author: Ryan
Total Articles: 75
Comment this article

Backplane


Backplane PCB is also a type of PCB in a wide sense. To achieve custom functions, a backplane is a type of motherboard carrying daughter boards or line cards specifically speaking. To distribute functions including power signals, supplies, etc, the leading function of the backplane is to carry boards to each daughterboard so that appropriate signal transmission and electrical connection can be obtained. The backplane is capable of leading the whole system to smoothly and logically run working together with carried boards.


Nowadays along with the progress in terms of the high frequency of signal transmission, electronic assembly technology, and high speed of digitalization, the I/O number rises and IC (Integrated Circuit) component integration goes up. In addition, upgrading on high-speed development is demanded by electronic devices. As a result, functions like power supply transmission, signal transmission, and functional daughterboard carrying must be carried by the backplane. Meanwhile displayed in the following aspects, the attributes of the backplane should be obvious and specific. ...
... The thickness, layer count, high-reliability demand, via count, signal transmission quality, and high frequency at a high speed, etc must be displayed.


Backplane PCB Attributes


With a nature of specialization, Backplane has been a type of product when it comes to the PCB fab industry. Therefore, more specializations are held by the backplane as compared to ordinary PCBs.


Heavier


It’s not difficult to understand that high weight will be brought up by a thicker Backplane Board. Besides the weight of the backplane, a high volume of copper is also added.


Thicker


More layers are featured by usually Backplane and it can transmit signals at a high speed. The copper layer should be thick enough to offer essential current when application cards with high consumption are inserted into the backplane. The backplane gets thicker as compared to ordinary PCBs due to all the mentioned elements.


Higher Count of Drilling Hole


The backplane has to realize more signal transmissions and electrical connections due to complex function and structure implementation. This is based on a large buried or blind/ vias number. To contribute to function achievement, the backplane has to carry more vias or drilling holes as a result.


High Heat Capacity


Backplane thereafter features higher heat capacity as backplane is heavier and thicker as compared to ordinary PCBs.


The focus of Backplane PCB Fabrication


Backplanes should be manufactured with special technology and attention owing to the higher requirements and complexity of the backplane.


Cleaning


It usually occurs that working fluid flows out as backplanes feature more vias or drilling holes as compared to ordinary circuit boards and are thicker. Therefore, with a high-pressure cleaning machine, you must clean drilling holes to prevent working fluid from staying in vias or drilling holes.


Reflow Soldering


Heat on backplanes is more difficult to be dissipated from the board as backplanes are heavier and thicker than ordinary boards. After reflow soldering, it takes backplanes more time to cool down in other words. To provide more time for backplane boards to be cooled down, the reflow soldering oven should be strengthened as a result. To make backplane boards cooled down, air cooling should be forced at the exit of the reflow soldering oven to be used In addition.


Component Assembly


Traditionally for the concern of reliability, passive components tend to be placed on backplanes. However, to lead active boards, active components like BGAs have been increasingly designed on backplanes to maintain at a fixed cost. Component assemblers must be able to place silicon-packaged components and smaller resistors and capacitors. Additionally, larger assembly platforms are demanded by the large size of backplanes.


Layer Alignment


Layer alignment is therefore very difficult to obtain as of drilling hole and higher layer count. Accordingly, with much high technology and carefulness, layer alignment should be done during the process of fabrication of the backplane board.


Backplane PCB Development Trend


Backplane should develop towards high thickness, ultra more layers, and large dimension as data transmission and network communication move toward mass-volume and high-speed transmission, playing a key node role in terms of network transmission. With more difficulties, backplanes will be fabricated as a result and to backplane board manufacturing such as backplane size, backplane thickness, backplane alignment, backplane layer count, electroplating drilling depth, back drilling stub and depth, etc, more requirement has to be laid. All in all, the above expectations will be brought forward to PCB manufacturers in the future.


Beginning with Backplane PCB Design


When getting started with backplane routing, layout, and design, there are multiple angles to take. These designs can be difficult as across a large board with layer count and limited space, you might find yourself managing thousands of connections. Furthermore, through a variety of high-speed devices, backplanes might be involved in supplying power to daughter cards. Multiple Amps of current might be pulled by each daughter card. This means 100 A of current might be needed by your backplane to support.


Everything revolves around the connectors you’ll use, and these connectors are where your design begins. Providing connections between multiple boards in a larger system is a major function of the backplane. In backplane design, here are some of the basic tasks involved:


Pinout: Determining the pinout on your connectors to support your required routing topology is the first step.


Mechanical requirements: To ensure proper structural integrity and mating, guide pins are used In addition to proper placement of daughterboard connectors. Used with backplane connectors, the image at the bottom of this list shows a typical guide pin.


Material choice: This is a critical point in the design process for high-speed backplanes. Across the entire plane could experience significant loss, any signal that needs to travel as backplanes can be quite large. To help minimize insertion loss on long interconnects, Low-loss laminates with tight glass weaves are needed.


Grounding and Power strategy: You’ll need a grounding and powerful strategy that helps keep the temperature low for backplanes that carry high power to a large number of daughter boards. For high-speed signals being routed around the board, the power plane or ground arrangement on different plane layers should also provide isolation.


Layer count: on the plane layer count, the count of signal layers you’ll require as well as the count of layers you need in your backplane will be based. To accommodate all design requirements, a Backplane PCB could be several mm thick and have up to 24 layers.

High Quality PCB Co., Limited is a leading PCB(Printed Circuit Board) Manufacturer in China since 1995. Dedicated to the technologies innovation, being engaged in IC Substrates, High-Density Interconnect PCB, Multi-layer PCB, Rigid Flexible PCB, Flexible, Radiofrequency PCB.