Problems with Ground plane artwork

J

Jan Beck

Guest
Hello everybody, I would greatly appreciate if someone could help me
with this problem or point me at the right place to look.

I am using Cadence Allegro.
I have just had a board manufactured and in it I have one ground
plane. I called the plane GND in the stackup and the net GND in
sechematic. The design routed completely.

The problem: none of the ground pins are connected to the ground
plane, they are as isolated from the plane as the rest of the pins. I
checked in the gerber file, and sure enough the plane is negative and
present.

Anyone have an idea of what I have done wrong?

Thanks to anyone who took the time to read this,

JAn
 
When creating this plane, did you assign a signal to it? Like "GND"?
If you left out this step, you created a "Dummy" plane with no
connections. Do an "Info" on the plane...it should say "Dummy" as your
signal name. If so, edit the plane and assign the signal "GND" to that
plane.

I bet if you check your board stats or do a ratsnest, you won't have a
100% connected board and it will tell you or you will see that the
plane "GND" is the culprit.

If by a wild chance, "GND" is assigned to that plane, check your
padstacks on your various pads and pins on the board...that is where
the info for flashes/connections are taken from to make the
connections to the plane.

janbeck@gmail.com (Jan Beck) wrote in message news:<f9fbbdf3.0409151932.64527cd@posting.google.com>...
Hello everybody, I would greatly appreciate if someone could help me
with this problem or point me at the right place to look.

I am using Cadence Allegro.
I have just had a board manufactured and in it I have one ground
plane. I called the plane GND in the stackup and the net GND in
sechematic. The design routed completely.

The problem: none of the ground pins are connected to the ground
plane, they are as isolated from the plane as the rest of the pins. I
checked in the gerber file, and sure enough the plane is negative and
present.

Anyone have an idea of what I have done wrong?

Thanks to anyone who took the time to read this,

JAn
Click to expand...
 
This is going to sound silly I bet, but I dont know how to select the
plane. The only place I can find information about the plane is in the
stackup dialog and I have called the plane GND there. I have gotten
one other reply via email that states Allegro does not care what the
plane is called in the stackup and I have to assign the net name
somewhere else.

So my question is how do I assign a net to a plane? The plane does not
show up as a solid color anywhere, so how do I click on it? A quick
reply just pointing out the menu to go to would be perfect.

Thank you for taking the time to read this

JAn


gsletch@yahoo.com (Greg) wrote in message news:<1c163be7.0409181009.566b8893@posting.google.com>...
When creating this plane, did you assign a signal to it? Like "GND"?
If you left out this step, you created a "Dummy" plane with no
connections. Do an "Info" on the plane...it should say "Dummy" as your
signal name. If so, edit the plane and assign the signal "GND" to that
plane.

I bet if you check your board stats or do a ratsnest, you won't have a
100% connected board and it will tell you or you will see that the
plane "GND" is the culprit.

If by a wild chance, "GND" is assigned to that plane, check your
padstacks on your various pads and pins on the board...that is where
the info for flashes/connections are taken from to make the
connections to the plane.

janbeck@gmail.com (Jan Beck) wrote in message news:<f9fbbdf3.0409151932.64527cd@posting.google.com>...
Hello everybody, I would greatly appreciate if someone could help me
with this problem or point me at the right place to look.

I am using Cadence Allegro.
I have just had a board manufactured and in it I have one ground
plane. I called the plane GND in the stackup and the net GND in
sechematic. The design routed completely.

The problem: none of the ground pins are connected to the ground
plane, they are as isolated from the plane as the rest of the pins. I
checked in the gerber file, and sure enough the plane is negative and
present.

Anyone have an idea of what I have done wrong?

Thanks to anyone who took the time to read this,

JAn
Click to expand...
 
OK, I just solved the problem. Very much a beginner's mistake I bet.
So for the benefit of future students looking at this post, I will
make clear what was not clear to me:

My assumption was that making a plane layer in the stackup would
create a plane of solid copper by itself. This is not true. You have
to designate the layer as a plane and then fill it with copper by
yourself. You can do this by selecting the correct layer in the
options tab on the right hand side of the screen and then picking the
"etch" class and the subclass corresponding to your layer, e.g. "GND".
You then can fill this layer with copper using the shape add tool, for
example a rectangle. ON the right hand side of the screen you can then
see options for the shape, including its name, which has to be the
same name as the net that should be routed in this plane, e.g."gnd".

Thanks for everyone who took the time to help me, your comments
pointed me in the right direction. I very much appreciate it.

JAn

gsletch@yahoo.com (Greg) wrote in message
news:<1c163be7.0409181009.566b8893@posting.google.com>...
When creating this plane, did you assign a signal to it? Like "GND"?
If you left out this step, you created a "Dummy" plane with no
connections. Do an "Info" on the plane...it should say "Dummy" as your
signal name. If so, edit the plane and assign the signal "GND" to that
plane.

I bet if you check your board stats or do a ratsnest, you won't have a
100% connected board and it will tell you or you will see that the
plane "GND" is the culprit.

If by a wild chance, "GND" is assigned to that plane, check your
padstacks on your various pads and pins on the board...that is where
the info for flashes/connections are taken from to make the
connections to the plane.

janbeck@gmail.com (Jan Beck) wrote in message news:<f9fbbdf3.0409151932.64527cd@posting.google.com>...
Hello everybody, I would greatly appreciate if someone could help me
with this problem or point me at the right place to look.

I am using Cadence Allegro.
I have just had a board manufactured and in it I have one ground
plane. I called the plane GND in the stackup and the net GND in
sechematic. The design routed completely.

The problem: none of the ground pins are connected to the ground
plane, they are as isolated from the plane as the rest of the pins. I
checked in the gerber file, and sure enough the plane is negative and
present.

Anyone have an idea of what I have done wrong?

Thanks to anyone who took the time to read this,

JAn
Click to expand...
 
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