Layers of a motherboard?

Gundog48

Gundog48

Gundog48

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I am doing an essay type thing on how PCB is made, and I decided to talk about motherboards.

From what I understand, there is an insulated layer on top which is the bit that you see, then underneath is a routing layer, which routes the power to the components via copper wire in the layer. Underneath that is an insulative prepreg layer this insulates the power layer from the routing layer, exept that the points where the power is supposed to go. Then is the power layer, the big ol' copper layer where all the power travels through to give power to the routing layer (which is taken to the right place thanks to the prepreg layer).

Then you get another few insulating layers and you find the ground power layer, this is self-explanatory. Then you get some more insulating layers towards the bottom.

Have I got this right? The main area which I think I made mistakes is the bit about the prepreg allowing power from the power layer to be taken to the correct points on the routing layer. It's a bit technical, but if you know this, please let me know!
 
You can have multiple layers of traces if needs be.

What you have described is a very simple design, probably something the likes of boards from the mid-late 90's.
 
Well, as long as the principle is right. Everyone else will be doing standard 2 layer PCBs and the teacher doesn't know much about computers anyway!
 
It is very hard to find information on the internet about this, so the only way to find out is by asking people who know, or making it up while looking at one of Gigabyte's ads for their 2oz copper layers. Fortunately, I guessed right.

I think motherboards have a lot more that 4 layers now, but I wouldn't like to say as I have no real expertise on the matter!
 
Someone posted this on my question on Yahoo Answers which is pretty interesting. This is just general PCB it is relevant to motherboards:

There is a good description of multi-layered pcb's here

http://en.wikipedia.org/wiki/Printed_circuit_board

The number of layers is even because you effectively take double sided boards and sandwich them with an insulating layer

Assuming that you are not making a flexible pcb, then somewhere in the construction there will be a rigid board e.g. fibreglass

you can have as many plane or signal (routing) layers as you need - but each layer adds expense to the board.

the 'plane' layers can have signals routed in them (but then you have an incomplete plane)

You can also have split plane layers - e.g. an area of analogue ground and an area of digital ground.

Ultimately, each layer is just a thin sheet of copper with none, some or most of it 'cut' away
 
If you'd like and if you feel it would add weight to your essay, I'd be happy to give you some information on how ASUS PCB's are constructed - I may even be able to get someone from ASUS Motherboard RD department to help out :)

Ping me a message in trust if you're interested, you're more than welcome to.
 
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