changing pad size in Eagle

[Alcaid]

How do you change the pad size in Eagle on just a single device and not the whole PCB?

In the updated library burr-brown.lbr that I downloaded from www.cadsoft.de the pads for the BUF634T (TO220-G5) has about 16mils spacing, but when I use the DRC, the minimum pad size must be set to 7mils to not get an error with pad-distance set to 10mils.

This is because the pad is sized as a percentage value of the drill size (25%). What I want to do is to set different design rules for the BUF634T and the rest of the PCB, or else I'll get to small pads on the rest of the design.

1) Is this possible?

2) If not, any suggestions on what to to?

Photo of the board with normal DRC settings (padsize=25% of drill, min 10mil, max 25mil):

[Alcaid]

Photo of the board with changed DRC settings (padsize=min 7mil, max 7mil):

[azira]

Sorry, I don't have an answer for you, but I am interested in how you did the jumpers for the traces that had to get run on the top layer?
I've been trying to figure that out, I ended up just deleting those nets and dropping in pads but your solution is much better.
--
Danny

[rendisha]

To change pads, you must open the library that contains the part you want to change. Then you click on IC looking icon (package) and choose the one that represents your part. Then you simply use Change tool and do what you want - change diameter, shape, drill size... Then you save the library, close it and return back to the schematics. Go to library menu and choose update library or update all...

[Alcaid]

Originally posted by azira
Sorry, I don't have an answer for you, but I am interested in how you did the jumpers for the traces that had to get run on the top layer?
I've been trying to figure that out, I ended up just deleting those nets and dropping in pads but your solution is much better.
--
Danny

Just click the Via-tool (the green circle). Edit the via to the size you want to use (I use the octagon with 32mil drillsize and 56mil diameter). Route to the first via, and continue from the second one. Then I draw the link between in the silkscreen-layer with the wire-tool. (Change the layer to 21 tPlace).
Done!

Originally posted by rendisha
To change pads, you must open the library that contains the part you want to change. Then you click on IC looking icon (package) and choose the one that represents your part. Then you simply use Change tool and do what you want - change diameter, shape, drill size... Then you save the library, close it and return back to the schematics. Go to library menu and choose update library or update all...

The padsize is narrower in the library, It's the DRC that changes the width of it. I said that in the first post.

[rendisha]

I thought that DRC affects pad size when it's set to auto, but when you do it manually, it stay's as you want it.

I haven't done some PCB recently so my memory must be fading though

[Alcaid]

The distance between the pads is 16 mils in the library, but the DRC changes it. I don't know how to keep it from doing that.

[Pjotr]

Hi Alcaid,

Although this is not an answer to your question, for simple designs like your board at hand go straight to this:

http://www.abacom-online.de/uk/html/sprint-layout.html

It is very simple to use, you are completely on the run in a few hours and it works very fast. Also you have full control on any detailed element. However no parts and netlist import, you have to do that manually. It is in fact a plain PCB drawing program. I am used to Mentor, Valid and Ultiboard, but for simple designs and most analog work I stick to Sprint-Layout. In Europe it is also available from Conrad Electronics.

Cheers

[edpgc]

Right, has anyone got an answer to this original problem because it driving me nuts!

I just want the samm TO220 pads to shrink a bit not all my pads!

Cheers
Ed

[teodorom]

I went on this thread searching for a solution for my problem. In the meanwhile I found a possible solution. So ... here it is.
If you want to have larger pads for resistors and so on, open the library rcl.lbr and then run the package change-pad-in-lbr.ulp.
It allows to change the diameters of the pads. Then save the library.
Thos changes do not immediately reflect on the actual PCB's. To apply those changes put in the circuit any component belonging to that library. Eagle warns you that it need to reload the library.
Say yes. Done !
Then you can delete the component you added.