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Choosing wisely is critical for PCB quality and performance, but it can be tricky depending on size constraints, functional requirements, and environmental factors. While we sometimes have a general idea about assembly requirements or how the board will be used, there can still be a lot of unanswered questions as we begin the manufacturing process. After all, there’s a big difference between a PCB going into a drone and a PCB that will be part of a submersible drone and needs to be the size of a tennis ball, withstand intense heat or cold, and function forty fathoms below the surface.
When we receive a design, there’s a lot we can evaluate before production to ensure its manufacturability and functionality. However, we are limited in our ability to judge whether a board is too thick or too thin as designed. In general, you might think thicker is better because the board will be less brittle and won’t break as easily. But thicker is also heavier, hotter, and not appropriate for many applications or assemblies.
As you design your PCB, you should ask yourself:
- How thick does it need to be to work?
- How thin must it be to fit?
- What will it have to do?
To avoid producing boards that don’t fit into the assembly or fail to perform reliably, choose your thickness carefully. Here are some tips, guidelines, and checklists for ensuring proper fit and function.
Test Your Design Assumptions
Keep in mind, PCB design is often as much an art form as it is a science. It’s not as straightforward as plugging a bunch of numbers into an equation and receiving an answer.
To read this entire column, which appeared in the January 2019 issue of Design007 Magazine, click here.
Anaya Vardya, American Standard Circuits
One of the biggest challenges facing PCB designers is not understanding the cost drivers in the PCB manufacturing process. The next final finishes to discuss in this series is OSP. As with all surface finishes there are pros and cons with the decision of which to use. It is a combination of application, cost, and the properties of the finish. OSP is RoHS-compliant as there is zero lead content in the finish.
Happy Holden, I-Connect007
Gerry Partida, vice president of technology at Summit Interconnect, authored a technical paper, “Next Progression in Microvia Reliability Validation—Reflow Simulation of a PCB Design Attributes and Material Structural Properties During the PCB Design Process,” at IPC APEX EXPO 2022, and it’s worth revisiting. This significant paper on microvia reliability validation provides a summary of what’s been happening in the microvia fabrication arena, especially regarding the issue of latent defects in stacked microvias.
Scott Miller, FreedomCAD Services
There is a new acronym bubbling up in the design world: DWM, which stands for “design with manufacturing.” Why is this different than design for manufacturing, or DFM? With DWM, the emphasis is on integration between the design team and the manufacturers during the design process. DWM is much more than that. We are tasked with producing designs that meet various technical requirements, yet are cost-effective and manufacturable. We provide this service to hundreds of customers who have varying degrees of processes, tools, and manufacturing partners. Given this diversity, we have recognized the importance of designing with manufacturing to achieve the product development goals of manufacturability and technical excellence.