Have a question about CadSoft EAGLE?  Ask our Expert, Richard! (Archive)

Richard,

Do you know of any library that contains castellations for PCB's ?      I am making a surface mount PCB that contains castellated edges for pads and wanted to check to see if they exist  before I make them myself.

Thanks,

Joe A.

Hi Joe,

I am sorry, but I am not familiar with the expression "Castellated edges". Is this something like passer marks which we have in our marks.lbr?

Regards,

Richard

Castillated edges could be two things...

- series of (unplated) drill holes closely spaced  in a row so that

the board breaks off there.

-  I/O signals and power for the entire board are routed the

equivalent of large vias (plated drill holes) cut in half right at the

edge of the board, that are then used to make the board like a

"surface mount" assembly. Sometimes found on things like a smt radio

module.

Hi Joe,

you can use two pads as well. Best would be then to use two pins and connect them both with the signal....

Currently there is no better solution. We have to wait for EAGLE version 6. There we will have the possibility to connect one pin to several pads and it will be possible to draw arbitrary pad shapes with a POLYGON or WIREs. There won't be DRC errors and polygons in the layout will be connected or isolated properly.

Best regards,

Richard

BTW: You know that "Adler" is the German word for "eagle"?  SCNR... 

Richard,

Thanks for the quick reply.

I find that when I make the library part, if I just add another square pad to cover one round end of the test point pad, I wind up with the shape I need wiithout having to draw any polygons.

The stop layer is made automatically and shows up on the PCB when I enable the layer to see it.

The only problem I still have is that when I connect the PAD to ground and pour a ground plane, the section of the PAD that is made by the square does not connect to ground.  The other part of the pad (the part with the two rounded ends) connects just fine.

I was thinking of making another PAD that would have a separate connection for both pads and I would just connect both to ground on the schematic.

I hope this makes sense.  Anyway, thanks for your help.

Hi Joe,

the way you did it is okay. You have to use an SMD and use for example a polygon to create the final shape. please think of solder stop maks and solder paste. You have to draw this in layers tStop and tCream manually. You will get an DRC error in the layout editor which you have to approve.

Be sure that the polygon does not use a too fine wire width.  So there won't be any problems with manufacturing your board.

Regards,
Richard

Thanks for your help with this.  It turns out to be an easy thing to accomplish.

I have one more question.

Is there any way to make an SMD pad that is shaped like a rectangle, but has a square end on one side and a rounded end on the other side?

What I do right now is to add a square SMD pad at the end of the SMD pad that is rounded at both ends. I dont connect it to anything when I make the device.

I used this method to make a new test pad library part.

This works fine, but I am not sure if this will cause any problems down the road.

What do you think?  Is there a better way to do this?

Thanks again,

Joe

BTW - I tried it once (Case 2) , - exactly as you mentioned (just put

plated vias at edge of board) and have mfr mill through them, and the

castellated pads seem very fragile. Of course this is dependent on the

manufacturer etc....

At the time i also was wondering if there was a "bettter way".

Ideallly the plating-up needs to happen AFTER a milling operation during

manufacturing.

Hi Iain,

thank you very much for your explanation....  

@all and @Joe: There are no such objects in our libraries. You have to create them by yourself.

But this can be done very easily: Choose a decent grid and place HOLEs. This can be done in the libara editor or in the layout dierctly.

For the second possibility Iain mentioned, you have to take vias and place them at the edge of the board. In the manufacturing process the vias will be cut into half when milling the board contour.

Regards,

Richard

Hi Iain,

thank you very much for your explanation....  

@all and @Joe: There are no such objects in our libraries. You have to create them by yourself.

But this can be done very easily: Choose a decent grid and place HOLEs. This can be done in the libara editor or in the layout dierctly.

For the second possibility Iain mentioned, you have to take vias and place them at the edge of the board. In the manufacturing process the vias will be cut into half when milling the board contour.

Regards,

Richard

Hi Joe,

you can use two pads as well. Best would be then to use two pins and connect them both with the signal....

Currently there is no better solution. We have to wait for EAGLE version 6. There we will have the possibility to connect one pin to several pads and it will be possible to draw arbitrary pad shapes with a POLYGON or WIREs. There won't be DRC errors and polygons in the layout will be connected or isolated properly.

Best regards,

Richard

BTW: You know that "Adler" is the German word for "eagle"?  SCNR... 

Richard,

Thanks for the quick reply.

I find that when I make the library part, if I just add another square pad to cover one round end of the test point pad, I wind up with the shape I need wiithout having to draw any polygons.

The stop layer is made automatically and shows up on the PCB when I enable the layer to see it.

The only problem I still have is that when I connect the PAD to ground and pour a ground plane, the section of the PAD that is made by the square does not connect to ground.  The other part of the pad (the part with the two rounded ends) connects just fine.

I was thinking of making another PAD that would have a separate connection for both pads and I would just connect both to ground on the schematic.

I hope this makes sense.  Anyway, thanks for your help.

Hi Joe,

the way you did it is okay. You have to use an SMD and use for example a polygon to create the final shape. please think of solder stop maks and solder paste. You have to draw this in layers tStop and tCream manually. You will get an DRC error in the layout editor which you have to approve.

Be sure that the polygon does not use a too fine wire width.  So there won't be any problems with manufacturing your board.

Regards,
Richard

Thanks for your help with this.  It turns out to be an easy thing to accomplish.

I have one more question.

Is there any way to make an SMD pad that is shaped like a rectangle, but has a square end on one side and a rounded end on the other side?

What I do right now is to add a square SMD pad at the end of the SMD pad that is rounded at both ends. I dont connect it to anything when I make the device.

I used this method to make a new test pad library part.

This works fine, but I am not sure if this will cause any problems down the road.

What do you think?  Is there a better way to do this?

Thanks again,

Joe

BTW - I tried it once (Case 2) , - exactly as you mentioned (just put

plated vias at edge of board) and have mfr mill through them, and the

castellated pads seem very fragile. Of course this is dependent on the

manufacturer etc....

At the time i also was wondering if there was a "bettter way".

Ideallly the plating-up needs to happen AFTER a milling operation during

manufacturing.