If you scroll down below you will see my projects where I have used a custom board .Today i will share how i made that .first of all you need to have Eagle PCB designing software then you need to the STM32F4 user manual that briefly describes the scales of the board .since I am using LCD of a phone i will have to design the LED Driver circuits .I have chosen the TPS61040 for this purpose. It has a option to control the brightness of the LCD using a PWM signal. below are two images of the circuit.
Scroll below to see these boards in action ..