**PCB EMI Design Specification Steps**
1. **IC Power Processing**
1.1) Ensure that each IC power PIN is equipped with a 0.1μF decoupling capacitor. For BGA chips, place eight capacitors (0.1μF and 0.01μF) at the four corners. Special attention should be given to adding filter capacitors, such as VTT, for power supply traces. This not only influences stability but also significantly impacts EMI.
2. **Handling of the Clock Line**
2.1) It is advisable to route the clock line first.
2.2) For clock lines with frequencies of 66M or higher, limit the number of vias per line to 2, with an average not exceeding 1.5.
2.3) For clock lines with frequencies below 66M, restrict the number of vias per line to 3, with an average not exceeding 2.5.
2.4) For clock lines longer than 12 inches, if the frequency exceeds 20M, the number of vias should not surpass 2.
