Setting Design Constraints Effectively

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PCB design requires controlling energy within the medium of a PCB. The manner in which we control the chaos of energy is by implementing and utilizing physical and electrical rules, known as constraints, along with a specific structure and material(s) that make up what is known as the foundation of the design. These rules govern everything within the PCB structure and generally fall into two camps: performance and manufacturability. Setting this foundation correctly is extremely important and the key to success.

At times, especially with very complex designs, it’s no easy task to make sense of these rules while creating and implementing these design constraints. It can be daunting and time-consuming. How many times during the initial phase of the design process have we heard project management ask, “What is taking so long? Why haven’t you started placing components and routing? Why do you even need constraints?”

I’m sure many can relate to such questions. The goal for any PCB design is to be “correct by construction,” where you have the highest potential for first-pass success. This means that revision 1 works with no respins required, and there are no interruptions in the process of getting the product to market as fast as possible. This is accomplished by implementing and utilizing design constraints along with industry best practices, which are vital toward achieving PCB design success.

Design constraints are typically derived from customer requirements. Depending on the intended function of the end product, how it needs to function and under what conditions it needs to operate are the keys to deriving the specific details of the actual constraints to be implemented in your design. Make sure you work closely with your manufacturers (both fabrication and assembly) from the very beginning of the project and throughout the design process. I cannot stress enough that close collaboration with your manufacturers, also known as your external stakeholders, is key to downstream success.

To continue reading this article, which originally appeared in the July 2025 issue of Design007 Magazine, click here.