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Flexible Thinking: PCB Designers Still Wanted

From their relatively simple beginnings, PCBs were largely structured using through-components, including axial leaded resistors, capacitors and diodes, and the iconic dual inline bug-like IC packages. They were often assembled using breadboard and wire-wrapped connections that enabled the electronics hobbyists to prototype their imaginative circuit designs. Current generation PCBs rival their integrated circuit siblings in complexity as they have become even more closely associated with creating today’s mind-numbing products.

As you can see, designing printed circuits requires a diverse combination of skills that cover basic electronics, fundamentals of circuit design, and an appreciation for the various common components mentioned earlier (as well as how they behave in circuit function). Along with some basic problem-solving skills, one should have proficiency with one or more electronic design automation/EDA (PCB design automation) software tools such as those offered by Altium, Cadence, Mentor, and others. Another good skill is using a good PCB simulation tool such as that offered by Ansys. Designers should limit themselves to a single design spin to prevent wasting time; simulation will go a long way toward preventing such a wasted effort.

Mastery of any PCB design software normally requires a working knowledge of PCB layout rules, including component placement, routing, and layer stackup guidelines codified in IPC design standards. These include:

• IPC-2221, Generic Standard on Printed Board Design, which provides guidelines for the design of PCBs, including requirements for copper thickness, minimum annular ring, conductor spacing, and other design considerations.
• IPC-2222, Sectional Design Standard for Rigid Organic Printed Boards, covers specific design considerations for rigid PCBs and includes topics like thermal stress, thermal conductivity, and mechanical considerations.
• IPC-2223, Sectional Design Standard for Flexible/Rigid-Flexible Printed Boards, reviews the unique design challenges associated with flexible and rigid-flex PCBs, including bend radius, material selection, and dynamic flexing considerations.
• IPC-6012, Qualification and Performance Specification for Rigid Printed Boards, covers qualification and performance requirements for rigid PCBs, including criteria for base materials, conductor thickness, hole plating, and other fabrication processes.
• IPC-6013, Qualification and Performance Specification for Flexible Printed Boards, which is like IPC-6012 but is specific to flexible PCBs, covering material properties, design considerations, and fabrication requirements.
• IPC-6018, Microwave End Product Board Inspection and Test, focuses on requirements for microwave PCBs, addressing high-frequency design considerations and inspection/test requirements.
• IPC-2226, Sectional Design Standard for High Density Interconnect (HDI) Printed Boards, provides guidelines for the design of HDI PCBs, and involves advanced technologies like microvias, fine-line traces, and high-density component placement.
• IPC-7351, Generic Requirements for Surface Mount Design and Land Pattern Standard, gives guidelines for the design of surface mount components, including recommended land patterns and component dimensions.

Another highly valuable skill is related to actual board manufacturing and assembly. The designer should invest as much time as possible in learning about the actual manufacturing process used in PCB fabrication and assembly, the many materials used in manufacturing, and the circuit features, including line and space, and via dimensions. The decisions made by the designer have far-reaching consequences. Making informed decisions is vital.

As signal speeds continue to climb, a designer should have a solid understanding of signal integrity principles, including impedance matching, trace length matching, and noise reduction techniques, along with electromagnetic interference (EMI) regulatory requirements and standards. This includes paying attention to ESD, which can destroy a board if not well managed.

In the realm of the actual product, there is an increasing need to understand and apply thermal management techniques to prevent overheating of components on the PCB. It’s a growing problem as the industry moves toward ever-higher performance and physically hotter products.

I would be remiss not to mention the elephant standing in the corner getting ready to take the stage: PCB design enabled or assisted by artificial intelligence (AI). This will likely be here quicker than most folks can imagine. I’m very intrigued, for example, by Benchmark's recent investment in Quilter, which intends to do just that. However, as Quilter CEO Sergiy Nesterenko said in an interview with Reuters1, "Just because (software) got to 90% completion doesn't mean it did 90% of the work. That remaining 10% of the work that is left is really, really difficult." On the bright side, it’s likely PCB designers will still be needed, just as autonomous vehicles will require drivers for some time to avoid crashes along the way.

The last skill (perhaps it should have been the first) is having well-polished documentation and communication skills. The long list of technicians and engineers who will be using the design information product can produce an electronic circuit no better than the information presented will allow. Check your work and then check it again. It is critical to stay updated. Even though it is infinite, the most valuable entity on the planet is time. Unfortunately, it only runs in one direction (though physicists point out that physics works regardless of the direction of time), so don’t waste it.

References

1.       “Quilter raises $10 million for AI-powered circuit board design, led by Benchmark,” Quilter.ai.

Joe Fjelstad is founder and CEO of Verdant Electronics and an international authority and innovator in the field of electronic interconnection and packaging technologies with more than 185 patents issued or pending. To read past columns or contact Fjelstad, click here.  Download your free copy of Fjelstad’s book Flexible Circuit Technology, 4th Edition, and watch his in-depth workshop series “Flexible Circuit Technology.”

This column originally appeared in the March 2024 issue of Design007 Magazine.