PCB (Printed Circuit Board) is crucially important and can decide an led display's quality, efficiency, reliability and durability, especially when led displays are used for outdoor led electronic signs and digital billboards.

But how to verify the quality? Here is an easy way:

First you need a light source. If you have a flashlight, it would be perfect. If not, don't worry, just turn on your mobile phone's.

Next you will shine the flashlight under the PCB you are inspecting, and check from the other side.

Here is the result:

1. If the PCB transmit light - you would know it's a 2 - layer PCB which doesn't meet the tech requirement for outdoor led signs' and digital billboards' application.

2. If the PCB doesn't transmit light - congratulations, you get multi-layer PCB which should be good for led displays under outdoor environments & conditions.

PCB's quality is decided by other factors for example of copper foil thickness. But when a led display manufacturer adopt multi-layer PCBs to their products (considering especially it's a point very "commonly ignored" for most customers), it can greatly indicate they are not "cutting corner". And their led displays tend to be good quality.

Conversely, you have to be aware of possible failures (and sometimes very terrible) in future, even when the led displays' you are inspecting show perfectly at the beginning.