Ultra‐thin narrow bezel of 5G mobile phone is very attractive, but obviously when the thickness of LGP is constant, the optical homogeneity is better when the distance from LED to visual area is bigger, so establish an optical analysis model to analyze the optical homogeneity in light emitting side in vertical direction by the relations between the distance from LED to visual area and the thickness of LGP. When the thickness of LGP is above 0.34 millimeter and the distance from LED to visual area of BLU is above 1.75 millimeters, the optical homogeneity can meet mass production by normal design. if the thickness of LGP compress from 0.34 millimeters to 0.26 millimeters and distance from LED to visual area of backlight units compress from 1.75 millimeters to 1.57 millimeters, the optical homogeneity in light‐emitting side can be above 75% by the angle of LGP wedge surface is below 5 degree and the length of LGP wedge surface is between 0.35 and 0.55 millimeters, so the border of backlight units can be compressed to 2.8 millimeters based on the LED under the FPC and the thickness of liquid crystal display module can reach 0.95 millimeters. The optical effect and structural reliability of liquid crystal display module is both OK under the value of G is above 0.55 millimeters by using linear silver paste or the value of G is between 0.4 millimeters and 0.55 millimeters by using L shape silver paste based on DOE experiment.