Based on the development example of SOM (System on Module) equipped with NXP i.MX 8M Mini application processor and LPDDR4-SDRAM, we will introduce the pattern design method of the printed circuit board equipped with LPDDR4 and our original verification result. The following three types of boards were manufactured with reference to the NXP evaluation board board (8-layer board). (1) A board in which the timing between multiple signals is not ideal, (2) A board in which the power supply / GND solid plane layer is partially rationalized to 6 layers, (3) A board in which the signal wiring arrangement layer is changed and the distance between signal vias is shortened. .. We have confirmed whether these redesigned products operate normally. In addition, we will introduce the results of actually measuring the signal waveform and power supply noise and examining the effects of design changes.