1. Basic process knowledge, such as substrate three processes, tenting, msap and ets; Packaging process, flip chip or Wire bond or Wafer fanout
2. According to the design rule set under the process conditions
3. The electrical performance requirements of each module of the chip, such as differential pair routing, sheilding routing, and minimum ground impedance of the power supply
4. The improved version can see the complete analysis of the signal, and will have a little emotional understanding of the design
5. Other knowledge, such as PCB design, to facilitate ballmap adjustment; IOpad adjustment, floorplan adjustment, use of package design software, etc.
Knowledge is not very difficult, you can learn while doing, good luck