Single Layer vs Multilayer PCBs

[Jason Keel]

Is there any specific way to differentiate the single layer and Multilayer PCBs? Can anyone give me an example please?

[robert-hh]

@Jason-Keel Identifying a single layer PCB is easy. It has copper connections only on one side. The other side may be colored, but you will always be able to see traces, because they stand out from the surface my typically 35 to 70 µm. Double layer PCBs have traces on the top and bottom side. Beyond that it is hard to determine just by looking at it how many layer a board has. Usually there are even numbers of layers > 1, so 2, 4, 6, 8. For manufacturing costs 1 or 2 layer boards are not very different. Even one layer boards are typically made in the 2 layer process. Beyond 2 layers it gets more expensive, because these are sandwiched by a pack of thinner 2 layer boards. Boards with high thermal load may also have an additional thicker aluminum or copper core to spread the heat.

[livius]

In addition to @robert-hh

Some pcb are quite transparent. If you place them in a strong light source, you can see traces at different levels.
I have one pcb from Samsung which have 16 layers and all are visible in this way. Even there are numbers on particular levels :)

[Jason Keel]

Thanks @robert-hh for such a nice explanation. During my research, I came across this article https://www.derf.com/printed-circuit-boards-overview-and-explanation/ where they have depicted two diagrams. One, printed circuit boards with components and other one is blank. Do you know any place or diagram depicting single layer and Multilayer pcbs.

[Jason Keel]

@livius Thank you for the additional information.