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22 DESIGN007 MAGAZINE I JULY 2025 E L E M E N TA RY, M R . WATS O N the board and someone else is working on another, constraints make sure they both follow the same rules. That keeps the design neat, clear, and easy to understand. It also makes the fin- ished board more likely to work correctly the first time. Design constraints also help you save time. Since you don't have to stop and fix as many mistakes at the end, your work gets done faster. You can com- plete the design more quickly and proceed to the next step, such as building or testing. This is particularly helpful when work- ing on a large project or when you're nearing a deadline. Finally, using constraints makes it easier to reuse parts of your design in future projects. Once you know that these con- straints are effective, you can reuse them in the future. This will save time and help maintain high quality in your next designs. EDA Software Outpaces Fab Capabilities Over the past decade, our won- derful ECAD software plat- forms have made giant leaps forward. Today's ECAD tools offer advanced features, includ- ing high-speed simulation, auto- mated routing, AI-driven opti- mization, and real-time collabo- ration on cloud platforms. With today's software, designers can now create highly complex PCB layouts with a level of precision and efficiency that was unimagi- nable just a few years ago. For example, one popular ECAD software (which I won't name here) can operate at a precision of 0.001 mil (one thousandth of a mil) for a PCB trace, which is 2,000 to 4,000 times smaller than the thick- ness of a human hair. As a result, EDA software has been outpacing the capabilities of the fabrication processes for some time now. Fabricators face challenges such as minimum trace widths, layer alignment tolerances, and material limitations that don't always match the extreme design possibilities ECAD tools offer. Manufacturers are limited by phys- ics. For example, while ECAD soft- ware can generate those ultra- fine trace routes and very dense component placement, many fab- rication shops may not have the equipment or processes to reli- ably produce boards at the level of complexity or precision that the ECAD programs can achieve. This gap means designers must balance pushing the limits of software with realistic expec- tations of what fabricators can achieve. It also encourages closer communication between design and fabrication teams to ensure manufacturability. In some cases, fabrication plants are working hard to upgrade their technology, adopting finer lithography and inspection tools; however, these investments require time and money. Just Because You Can, Doesn't Mean You Should Can the PCB designer use high levels of precision in the design process? Yes, they could, theoret- ically. But in this case, it's not just about whether you can—it's about whether you should. Not every design demands tight constraints. For those fabricators who dare to take on complex PCB designs, there are quite a few challenges. First, complicated designs usu- ally cost more because special- ized machines and additional work are required. They can also take longer to finish because the process is more careful and slower. Because the design is complex, more boards may con- tain errors, resulting in a lower yield. If the boards don't work well after they are made, it can make customers unhappy and hurt the fabricator's reputation. Additionally, working on intricate designs can consume a signifi- cant amount of the factory's time and space, making it more chal- lenging to perform other tasks. The bottom line on the design side, as everywhere else, is profit. When a PCB design is too com- plex to implement, it can be costly for the designer. Higher production costs and delays can eat into profits. Fixing mistakes or redesigning also adds extra expenses. If the product is late or has problems, it might lose sales. All of this means less money earned and more money spent. So, here's the $64,000 ques- tion: Why do designers even try to push these limits? (For you younger folks, "The $64,000 Question" was a TV show in the " " Using constraints makes it easier to reuse parts of your design in future projects.