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Connect the Dots: Selecting the Right Board Thickness—A PCB Designer’s Balancing Act

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.