PCB design best practices: design reuse

Welcome back to the PCB Design Best Practices newsletter! The next best practice that I’m going to dive into is design reuse.  

PCB design reuse is the reuse of approved, validated, or known-good circuitry or Intellectual Property (IP) across multiple designs and throughout an organization. Implementing reuse eliminates unnecessary and/or repeated efforts, saves time, and reduces project risk. 

What’s not working? 

If you don’t utilize design reuse, you’re reinventing the wheel over and over every time you start a new project. More than likely, you’re redoing the same tasks of creating similar design content every time.

If you’re designing similar electrical circuits, design constraints and PCB layouts to what you've done in the past — whether it’s a power supply circuit, or any kind of driver circuit, DDR circuitry, an FPGA or a microprocessor circuit — you can use the same design information that is already proven and in the market to speed up your process.

We have been able to achieve a certain level of success within the legacy process to date, but the process is not optimized and comes at a cost and with a level of risk.

What are the roadblocks? 

One of the roadblocks you’ll have when implementing design reuse is inefficient processes for managing and sharing data. Ideally, good design content should be saved, tracked, and version controlled in your library for future implementation on multiple projects throughout the enterprise. 

Reuse content is basically managed like an individual component in the library, such as a cap, resistor or integrated circuit (IC), even though it's more than just a symbol tied to a land pattern which makes up a component within the library. A reuse circuitry block or module could potentially contain a multi-sheet schematic with its own proven and validated PCB layout of that specific circuitry already completed, versus just one component that now must undergo all the manual repeated steps to achieve your result. 

Another roadblock might be that you don’t trust using another person’s design or an unknown author’s circuit or PCB layout. Often, you’ll hear engineers say, “Well, I have my own circuit or set of circuits I’m going to use. I know John in that other division used this circuit instead, but I don’t trust that design content. So, I’m going to use my design content instead.” In this example, the engineer or designer could have saved time if he/she would just reuse the design content that was already known to be good, validated, and completed. It comes down to either an individual and or company that simply does not buy into, or see the true value of, implementing reuse. 

And the biggest roadblock, I’d say, is that there’s no pressure to change processes or methodologies. Companies may feel that the return on investment is not at an acceptable level for them to change their current formula of success. They’ll continue to use the same methodology that they’ve been implementing over and over, because the level of success they’ve had to date is acceptable. They feel it’s good enough, but good enough could potentially be only like 65%, at best. 

Best practices: design reuse 

The key best practice is to utilize existing known-good circuitry, and proven layouts, so you’re not reinventing the wheel. You want to be able to manage the reuse modules no differently than you would manage a single component in your library. And then you want to be able to share that hardware IP, not just from design to design within your business unit or within your local division, but if you’re part of a huge enterprise that’s global, you want to be able to share that IP globally. So that you could take advantage of designing whole systems a lot faster, and with already known-good, validated, and proven design content. 

The value and ROI you’re going to get from implementing design reuse is you’re using and leveraging known-good parts, circuitry, and layouts, and you’re going to reduce your design cycle time, which will ultimately reduce costs and lower risk. You’re going to be able to share IP at the enterprise level while being able to reuse these modules and manage them within your library. Reuse is a game changer and has a significant positive ROI.  

How it works: design reuse 

In the case of Xpedition, reuse modules can be created and managed similarly to single components in a library. This means that not only are reuse modules shared easily, but with this comes the ability to track which reuse modules have been used where, in case the need to modify, or update/revise the reuse modules presents itself, which may happen if a part used in the module is out of stock or has been recently made obsolete. Reuse is also easily done on the fly locally in a design, by simply copying and pasting circuitry and layouts. 

To learn more, tune in to this episode of the Printed Circuit Podcast. where I discuss this topic with Carlos Gazca. Any questions? Please feel free to leave them in the comments here, and I'll respond with my thoughts!