Custom pad shapes

cosborne2000 wrote:

Is there a "correct" way to create a through hole pad with different

diameters on the top and bottom (same drill size of course)?

I've created a part that attaches with a small screw with a spacer on

the opposite side. The bottom pad needs to be large (0.3inches) to

cover the area under the bolt head. The top pad just needs to be

large enough for the plated through hole. Using a standard pad (large

diameter on both sides) makes routing very difficult in that area.

 

I created a circle around the pad in the bottom copper and solder

stop layers for now. This works but always generates a DRC error

which I have to ignore.

In Orcad and Altium I simply make the correct padstack -- is there

some type of equivalent in Eagle?

 

Eagle does not currently have pad stacks. They are on the wish list.

For the large pad, draw a polygon circle (0.3inches) over that bottom pad

and give it the same 'name' as the signal to the pad you are covering.

In this way you will not get a DRC error.

In the library part to remind you of the need for the large pad, create the

polygon/circle on  a custom layer or doc layer. In this way it can be used

as a template for the size of the polygon when you draw it in the board

editor.

Warren

"Warren Brayshaw" <warrenbrayshaw@paradise.net.nz> wrote:

cosborne2000 wrote:

>> Is there a "correct" way to create a through hole pad with different

>> diameters on the top and bottom (same drill size of course)?

>> I've created a part that attaches with a small screw with a spacer on

>> the opposite side. The bottom pad needs to be large (0.3inches) to

>> cover the area under the bolt head. The top pad just needs to be

>> large enough for the plated through hole. Using a standard pad (large

>> diameter on both sides) makes routing very difficult in that area.

>>

>> I created a circle around the pad in the bottom copper and solder

>> stop layers for now. This works but always generates a DRC error

>> which I have to ignore.

>> In Orcad and Altium I simply make the correct padstack -- is there

>> some type of equivalent in Eagle?

>>

 

Eagle does not currently have pad stacks. They are on the wish list.

For the large pad, draw a polygon circle (0.3inches) over that bottom pad

and give it the same 'name' as the signal to the pad you are covering.

In this way you will not get a DRC error.

In the library part to remind you of the need for the large pad, create the

polygon/circle on  a custom layer or doc layer. In this way it can be used

as a template for the size of the polygon when you draw it in the board

editor.

Alternatively I guess you can just use keepout/restrict in library. The

spacer side doesnt need to be fully filled, but you want to avoid shorts

and components.

On 07/07/2011 01:13 AM, Morten Leikvoll wrote:

"Warren Brayshaw" <warrenbrayshaw@paradise.net.nz> wrote:

>> cosborne2000 wrote:

>>> Is there a "correct" way to create a through hole pad with different

>>> diameters on the top and bottom (same drill size of course)?

>>> I've created a part that attaches with a small screw with a spacer on

>>> the opposite side. The bottom pad needs to be large (0.3inches) to

>>> cover the area under the bolt head. The top pad just needs to be

>>> large enough for the plated through hole. Using a standard pad (large

>>> diameter on both sides) makes routing very difficult in that area.

>>>

>>> I created a circle around the pad in the bottom copper and solder

>>> stop layers for now. This works but always generates a DRC error

>>> which I have to ignore.

>>> In Orcad and Altium I simply make the correct padstack -- is there

>>> some type of equivalent in Eagle?

>>>

>> Eagle does not currently have pad stacks. They are on the wish list.

>> For the large pad, draw a polygon circle (0.3inches) over that bottom pad

>> and give it the same 'name' as the signal to the pad you are covering.

>> In this way you will not get a DRC error.

>> In the library part to remind you of the need for the large pad, create the

>> polygon/circle on  a custom layer or doc layer. In this way it can be used

>> as a template for the size of the polygon when you draw it in the board

>> editor.

Alternatively I guess you can just use keepout/restrict in library. The

spacer side doesnt need to be fully filled, but you want to avoid shorts

and components.

In addition to the keepout/restrict layers, you could draw the circle in

the library on a layer that is included with your copper layer in your

cam job.  You'd have to keep the keepout and restrict layers since DRC

doesn't understand that the additional layer is destined to be copper.