Ground Layer Question...

[Leslie West]

Hello,
is it possible to use the Top Layer of a PCB as a Ground Layer?

I want to make a PCB with eagle and want only use the Layer 16 for Signal and Layer 2 for a Ground plane. No Layer 1! Is this then a dual Layer PCB, when I want to order it? Any Problems when I order it?

Thanks in advance

Leslie

 

[Svart]

you can make just about any layer ground layer, usually top or bottom depending on what you are doing exactly. layer 2 and 16? not exactly sure what you mean by those numbers..they don't mean much without reference because you can give any layer a number. Do you mean top and bottom layers? yes it would be two layer no matter where they are in the sandwich.

ground planes: remember to try not to make loops of ground areas, break any loops that you make surrounding components or else you'll simply be left with a bunch of little loop antennas!

 

[Infernal_Death]

And don't forget when stuffing the board that the components don't touch your ground plane when they shouldn't.

Flo

 

[Leslie West]

[quote author="Svart"]layer 2 and 16? not exactly sure what you mean by those numbers..[/quote]

These are the numbers in Eagle, so it doesnt matter.... Thanks for your answer. Now I know...

[quote author="Svart"]ground planes: remember to try not to make loops of ground areas, break any loops that you make surrounding components or else you'll simply be left with a bunch of little loop antennas![/quote]

Ok, some help at this point would be nice. What exactly do you mean? When I make the hole Layer as a ground Layer, where is the loop?

In the past i made the ground areas on the normal signal layer, and there you are right with these loops. But is this also a problem with a hole Layer as Ground? Are there also other problems i have to think of?

Thanks in advance and I hope you all understand my bad english...

 

[Svart]

I was just mentioning that if you put ground planes on the side where the through hole parts are mounted(not the side their legs are soldered to) you might be inclined to make a larger opening in the ground layer. All i'm saying is IF you do it don't make it too big, or at least keep one side of the loop open or you might get noise. the larger the loop, the lower frequency the noise, generally.

are you working with SMD parts or through hole?

some other hints are:

keep signal traces AWAY from power traces, it's best if they only cross at right angles.

avoid running long thin traces too close to each other, you might get crosstalk.

digital and analog ground planes need to be separate but joined through a ferrite bead, usually under an ADC/DAC or under a MCU(which usually has analog/digital i/o)

oh and there is much much more!

if you need help just let us know!

:guinness:

 

[Leslie West]

[quote author="Svart"]

are you working with SMD parts or through hole?:[/quote]

I am working through hole. No SMD.

Ok, as a summery: When I build a ground Layer I have to take a look, that all Parts in the circuit (Power suply, Input Stage, Output stage etc...) Have its own Ground Part in my Ground Layer. Is it correct or can i make a big ground Layer where all Grounds go to...?

So I have to make for example 3 different areas on my ground Layer (for Power suply/inputstage/outputstage) and route these 3 areas like star ground to on Point (XLR Input for example).

But where is the Problem with the loop. When the ground areas are in the signal Layer i have to take a look, but when I make a ground Layer, where is the Loop?

Thanks in advance... Its cool, that you help me...

Leslie