Using Grids for PCB Design

Before you ever place your first component you need to familiarize yourself with how to manipulate the grids using your pcb design software. Grids are critical to good pcb design and the largest mistake made by beginners. Using a grid of 100mil is usually adequate for most designs. If you’re space constrained moving down to 50mil is acceptable.

Once your grid is setup and you begin placing your components on the circuit board they’ll snap to the grid which keeps your components neatly arranged and symmetrical. This will also leave adequate room for running your traces. Another often overlooked advantage is it allows you to move groups of components easily making your growing design easier to work with.

After you component placement is finished you’ll want to reduce your grid to something finer. If you went with a 50mil coarse grid for your components then going to a 25mil grid for routing will allow you to place a trace exactly between pads. As the design becomes more and more complex you’ll need finer and finer grids. Just be sure you keep your grid size as a multiple of coarse grid (5, 10, 20, 25). Picking something in between will just cause you headaches down the road, so don’t do it!

Lastly, know your pcb design software. Any respectable package will have macros setup for easily changing grid sizes to save you precious time. You’ll end up changing grid sizes 1000’s of times so read up on your software in the beginning and get used to using macros. you’ll probably find there are 2-3 different types of grids. Thus far we’ve only discussed the snap grid. A visible grid, which may be different size or units, is used to line up components as you’re placing them on the circuit board. Often time an electrical grid is available which will snap the cursor to the center of electrical objects like pads or traces. Lastly the component grid will allow you to align components to a different grid size, just be absolutely certain it’s a multiple of the snap grid otherwise routing your design will be a nightmare.

Becoming a pcb design master will take some time, but mastering the grids will make your designs neat and professional. Not only that it will save your hours and hours of design time.