11 Rules for PCB Components Placement

PCB components placement is a major part during the board design. In this article, we concluded 11 rules for your reference, but please note that we will not take any responsibility for anything that results from this article.

1.Start by placing big/ major /critical components (such as MCU, DSP, FPGA, DDR, clocking devices), and then placing support components like resistors, capacitors, etc., around them.  

2.Use 50 or 100mil as a component grid to place these large components (like QFP, BGA, SOP, SOIC or through-hole connectors). Use 25mil as component gird for these SMT resistors/ capacitors or other small passive components.

3.Isolate analog, digital and power sections.

4.The clock driver/ synchronizer should be placed as close as possible to the clock oscillator.

5.Arrange components in rows and columns with the same orientation for easy installation, inspection and rework. If possible, all polarization components like tantrum capacitors and diodes are placed in the same direction. The polarity of these components should be marked on the silkscreen.

6.Keep at least 40mil space between components, and 100mil space from component to board edge is at least. Locate connectors on one edge or one corner of the board.

7.Try to place all components on the top side only. If not possible, small size and low thermal dissipation components (such as SMD passive components) can be on the bottom side.

8.Placing the decoupling capacitor as close as possible to the VCC pin on the active component.

9.Maintain a gap of at least 200 mils from transformer to electrolytic capacitor.

10.Placement for indication LEDs, test points, switcher, jumpers and adjustable components should be easy access.

11.Carefully check signals about analog, high frequency, RF, high voltage, high profile, high heat signals or heavy components before starting to trace routing.