Advanced Circuit Routing Techniques for Innovative PCB Designs

September 20, 2019 Cadence PCB Solutions

Screenshot of OrCAD PCB Designer showing complex internal layer routing

 

At the core of most electronic devices is a printed circuit board. Whether they are controlling the activities of the device, regulating power, or providing computing power, these boards are typically the heart of the system that they are installed in. They come in a variety of shapes and sizes, and their complexity will vary depending on the needs of the device. No matter what they look like and what they do though, they typically all share some common attributes. Electronic components are soldered in place on the board, and metal traces electrically connect these components together within the different layers of the circuit board.

For years PCB designers have used a variety of tools to create the trace routing needed on the circuit boards that they are designing. Some have used automated routers that are either part of their tools or have come from third party software, while others have used automated assisted routers that work together with the regular interactive routing tools built into the design system. Most designers however, if not all, are very accustomed to manually routing the connections on the printed circuit board designs using the interactive routing tools in their PCB design systems. This is a tried and true process that has been in place for a very long time, and has done the job admirably through the years.

Like everything else in life though, there is always change on the horizon. Circuit board technology is evolving in order to meet the challenges presented by new emerging technologies, and PCB designers need to be ready to face those challenges as their board designs grow in complexity. Especially in the area of routing traces, designers need to be ready to respond to these new design requirements. How will PCB designers work with these new PCB routers and routing methods? Fortunately there are advanced circuit routing techniques already available to help, and we will take a look at some of those here.

Advanced Circuit Routing Techniques for Emerging Technologies

Just because a new product isn’t being obviously introduced to the public on a regular basis doesn’t mean that electronic development is standing still. On the contrary, electronic innovations are always pushing ahead in leaps and bounds. There are advancements being made everyday in how electronics are being used in different fields such as computing, telecommunications, aerospace, and medical. Each of these advancements require new levels of electronics technology, which in turn requires new and more complex PCB designs.

As an example, the medical electronics field is making enormous advancements in its technology. Wearable devices to monitor the health of the user is just the beginning of what is being created, and more and more we are seeing the use of IoT in these devices to interconnect them together. Devices that sense, monitor, and stimulate your health such as blood pressure detectors and pacemakers all need to be interconnected through the internet in order to operate together and report their results back to health care professionals.

The question is, how do designers create the electronics needed for these requirements? The answer is through the use of smaller components, precise manufacturing processes, and the use of advanced circuit routing techniques. Here is where the new advancements in PCB technology are really needed.

 

 Screenshot of 3D OrCAD layout showing BGA escape routing

Escape routing for BGA pads using advanced PCB design tools

 

Printed Circuit Board Trace Routing for Modern Technologies

To design printed circuit boards that will do the job that medical IoT devices require will demand a lot from both the designer and the PCB design tools. Medical devices are often constricted in their size and power, and yet require as much if not more attention to detail in their trace routing to maintain signal integrity. 

With wireless communication and sensitive data signals both being processed in such a small area, the design of these circuit boards can be quite the challenge for any designer. There are also many other electronic devices that require advanced circuit routing techniques to effectively deal with these same type of constraints as well.

In addition to the routing architectures required by medical IoT devices, there are also other electronics in development that require these same advanced routing skills. Devices such as computing and telecom all rely on continually evolving processor and memory technologies which will need more advanced PCB routing.

Larger processor components with pin counts that continue to grow such as ball grid arrays (BGA packages), will demand precise routing skills to successfully route traces from all of the BGA pins. Advancements in memory components will require new methodologies of trace routing to accommodate their double-data rate connectivity.

The key to success here for PCB designers that are developing boards that will require the use of these new routing strategies and techniques, is to become more familiar with them. You will want to learn more about routing architectures with medical IoT circuits to see what they require and what some of the considerations are. 

You will also want to find out more about trace routing BGA packages in order to have a better understanding of what you will be up against with the newer larger BGAs. It would also be a good idea to find out as much as possible about DDR routing techniques so that there aren’t any surprises when you start laying out your memory circuits. Thankfully there is a lot of information on these topics, some of which we will direct you to here.

 

Screenshot of 3D OrCAD layout showing tuned routing

Trace tuning to control the length of PCB routing are essential for DDR routing

 

PCB Trace Routing Tips and Recommendations

The best way to be prepared for the complex PCB trace routing that new design technologies will require is to find out as much as you can about them. Here are some resources that will give you a good start on the subject:

Routing Architecture with Medical IoT Circuits

We have all become familiar with how the internet of things (IoT) has connected our everyday appliances together so that we can re-order groceries through our refrigerator, or turn the living room lights on at home while we are away on vacation. Medical devices are also connected together through the IoT in order to monitor and maintain our health through a variety of devices that are either worn or implanted. 

The challenges for PCB designers are much greater as are the responsibilities to create robust and reliable circuit boards for these devices. Being unable to toggle your lights on or off doesn’t have nearly the consequences of having an implanted sensor report an incorrect heartbeat, and designers need all the help that they can get to create flawless medical devices.

If you’d like to learn more about this subject, read about some of the medical IoT connection considerations here.

Routing Traces Out of BGA Packages

As the need for increased computing power grows, fine-pitched parts such as ball grid array (BGA) packages will continue to get larger with more and more pins. Component vendors routinely decrease the pin-pitch of these parts while increasing the number of pins on them to accommodate the added functionality of the parts. 

There are a lot of different resources available to the designer for how to best route out of these increasingly complex parts. Some of the basic routing tips for BGAs include ideas such as organizing your signal paths, and using diagonally routed escape patterns for larger devices.

If you would like additional information on routing BGA packages, read about it here.

Considerations for DDR Routing Techniques

One of the most exacting PCB trace routing that you will do will be connecting the memory circuitry. Double-data rate (DDR) memory requires specific routing patterns on your circuit board in order to work correctly. This involves matching the lengths of the traces so that the data can be captured on the rising and falling edge of the associated clock signal. 

To do this requires precise component placement of the memory chips while allowing yourself enough room to route all the connections in. When routing DDR memory, the PCB designer will usually need to add length to the traces in order to get them all to match using a practice known as trace tuning. The designer will also have to plan ahead to incorporate specific routing patterns depending on the needs of the memory circuits.

There’s a lot for the designer to understand in memory routing, and you can read more about DDR routing techniques here.

 

Screenshot of OrCAD 3D layout showing trace necking

PCB design tools with advanced functionality can help to create routing like this

 

Precise Routing Techniques Results in a Superior PCB Design

Maintaining the constraints of exacting routing architectures such as what you would find in medical IoT devices, or routing out of fine-pitch high-pin count BGA packages, or routing dense and complex DDR memory circuitry will take great skill on the part of the PCB designer. Fortunately, you are not alone in this as PCB design tools have added an enormous amount of functionality over the years to help. 

You will find features in the best tools that will allow you to assign design rules to nets, components, and classes, as well as specific high-speed design rules as needed for the design. There are also helpful features such as designating specific areas where the trace width will automatically reduce temporarily so that you can route traces out of high-density BGA areas. DDR memory routing can also be done much more efficiently now with automated trace tuning length matching functionality in your PCB design tools.

To put it simply; in order to create the best printed circuit board trace routing, you need the best design tools that you can get. The PCB design systems from Cadence have the features and functionality within them to make sure that you can create the type of advanced circuit routing techniques that we’ve been talking about. With its advanced capabilities, OrCAD PCB Designer is the PCB design tool that you need for success on every printed circuit board that you design.

If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts

About the Author

Cadence PCB solutions is a complete front to back design tool to enable fast and efficient product creation. Cadence enables users accurately shorten design cycles to hand off to manufacturing through modern, IPC-2581 industry standard.

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