How to apply net class to unconnected pad?

On 2/02/2015 9:06 p.m., Tomas Bergh wrote:

Hi all,

 

I would be glad to have some input on an issue I ran into recently:

 

Assume I added a diode in a sot23 package. The diode symbol only have

two (anode and cathode) connecting pins but the package has three pads.

To the two connecting pins I assign netclasses with different clearance

and creepage restrictions but then there will be no netclass assigned to

the third pad of the package. This generates tons of errors when running

drc and I dont have full control of the clearance and creepage

distances.

 

For the devices I create myself I can add a connecting pin for each pad

in the device and then add a short unconnected net to the unconnected

pads so that I can apply a netclass. This is not the correct way to do

it, does anyone know if is there any other way to do this?

You say you get "tons of errors" to this unconnected pad so I assume it

is a polygon pour that is getting too close to this unused pad. If this

is the case keep the polygon away by surrounding the pad with a fence

wires on the tRestrict layer.The width of the wire is at least the

clearance you require and should be close to but not touch the pad.

HTH

Warren

On 2/02/2015 9:06 p.m., Tomas Bergh wrote:

Hi all,

 

I would be glad to have some input on an issue I ran into recently:

 

Assume I added a diode in a sot23 package. The diode symbol only have

two (anode and cathode) connecting pins but the package has three pads.

To the two connecting pins I assign netclasses with different clearance

and creepage restrictions but then there will be no netclass assigned to

the third pad of the package. This generates tons of errors when running

drc and I dont have full control of the clearance and creepage

distances.

 

For the devices I create myself I can add a connecting pin for each pad

in the device and then add a short unconnected net to the unconnected

pads so that I can apply a netclass. This is not the correct way to do

it, does anyone know if is there any other way to do this?

You say you get "tons of errors" to this unconnected pad so I assume it

is a polygon pour that is getting too close to this unused pad. If this

is the case keep the polygon away by surrounding the pad with a fence

wires on the tRestrict layer.The width of the wire is at least the

clearance you require and should be close to but not touch the pad.

HTH

Warren

Hi,

No, I do not use a fill in the top layer here. The clearance issues of importance are between the unconnected pad (top right pad of D9) and the other two pads on the same sot23 package. (D9)

There are also clearance errors to other components in this example. (between T1, D7 and D9)

Any ideas?

Regards,

Tomas