1. Functional partitioning, signal does not fight!

For a well-layout PCB board, first look at the partitioning.

✅ Separate analog, digital, RF, and power supply to avoid signal "group fighting".

✅ High-frequency/clock/ADC and other sensitive signals should be physically isolated.

✅ High-voltage power modules and low-voltage signals should maintain social distance.

2. Key components, first on the C position!

With the protagonist, then around the supporting role!

✅ MCU, FPGA, power chip layout first
✅ Interface devices stand aside: USB/HDMI/buttons, etc. are close to the edge
✅ Heat-generating components reserve "breathing space", close to the heat dissipation hole for more peace of mind

3. The routing should be short and the angle should be rounded

Signals are express delivery, the straighter the route, the better.

✅ High-speed lines (DDR/PCIe/LVDS) go straight and make fewer turns
✅ Avoid sharp-angle routing, use 45° or arcs, so that the signal does not "turn over"
✅ The smaller the key loop area, the better, and the stronger the anti-interference

4. The power & ground wires are well laid out, and the interference is reduced by half!

✅ Power wiring: short and thick path, from input → filtering → voltage regulation → load
✅ Decoupling capacitor: 0.1uF close to the chip foot, 10uF at the entrance
✅ Keep the ground plane continuous, analog ground/digital ground connected with a single point of magnetic beads
✅ Directly ground the heat dissipation pad, EMC performance up↑

5. Heat dissipation depends on design, not Feng Shui

✅ Electrolytic capacitors should not be close to heat sources to avoid high temperature
✅ Add vias, copper foil, and heat sinks to heat the components for all-round cooling
✅ Symmetrical layout of BGA packaged devices to prevent PCB thermal warping and deformation

6. The structure should match, don't "top the shell" or "squeeze crooked"

✅ Reserve mounting holes, 3~5mm forbidden area on the edge of the board
✅ Avoid components in the height-restricted area and make sure they don't hit the shell
✅ Don't stick ceramic capacitors near the mounting holes, which are earthquake-resistant and stress-resistant

7. EMC starts from the layout, don't let your board become an "antenna"

✅ High-frequency clock lines go on the inner layer + add Guard Ring ground hole surround
✅ Place the filter component close to the interference source (relay/motor)
✅ USB/HDMI differential line pairs are equal in length and symmetrical, with an error of <5mil
✅ There must be a continuous reference surface under the high-speed line, be careful when crossing layers!

8. Have you thought about soldering? Don't ignore these DFM details!

✅ Don't squeeze the component spacing too much, at least 0.2mm for 0402
✅ The direction of polar components is unified, and welding is efficient
✅ Don't press the pad when printing, and don't block the assembly number
✅ Line width>4mil, drilling>0.2mm, solder mask is 0.1mm larger than the pad and does not stick to tin!

9. Don't forget to check the list at the end!

✅ Power/ground connection, decoupling capacitor, reference surface check
✅ Component spacing, hole avoidance, silk screen overlap check
✅ Don't ignore the heat dissipation path, thermal symmetry, and heat concentration
✅ Check for high-frequency signals, EMC shielding, and routing antenna effects!

10. Tool Recommendation Tips (Taking Allegro as an example)

✅ Use Room to divide the area for more efficient layout

✅ Load 3D models to avoid shell interference in advance

✅ Set DRC rules to automatically detect unqualified designs

Summary

PCB layout is not as difficult as you think! Master the core logic + repeated practice + watch the boards of experts + simulation verification, and you can go from "components are placed at random" to "exquisite and elegant layout" design experts.