In this tutorial we are going to learn about WHAT IS GUIDELINE FOR COMPONENTS PLACEMENT IN PCB DESIGN ?
Component placement due to main reason of the amount of EMI generated. In this tutorial of The guidelines are general approaches to minimize EMI.
• Keep leads on TH components short. Place the components as close to the PCB as possible and trim leads if necessary.
• Place all components associated with one clk trace closely together. This reduces the trace length & reduces radiation.
• Place high-current components as closely as possible to the power sources.
• Minimize the use of sockets in HF portions of the board. Sockets introduce higher inductance & mis-matched impedance.
• Keep crystal, oscillators, & clk generators away from I/O ports & board edges. EMI from these devices can be coupled onto the I/O ports.
• Place the crystals so that they lie flat against the PC board. This minimizes the distance to the GND plane & provides better coupling of EM fields to the board.
• Connect the crystal retaining straps to the GND plane. These straps, if ungrounded, can behave as an antenna and radiate.
• Provide a GND pad equal/larger than footprint under crystals & oscrs on the component side of the board. This GND pad should be tied to the GND planes with multiple vias.