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Design >> RF Design >> pad layers
https://designers-guide.org/forum/YaBB.pl?num=1212126794

Message started by aaron_do on May 29^th, 2008, 10:53pm

Title: pad layers
Post by aaron_do on May 29^th, 2008, 10:53pm

Hi all,

just wondering, how many metal layers do we normally have under the pad layer for an RF or digital pad?

thanks,
Aaron

Title: Re: pad layers
Post by vivarf on May 30^th, 2008, 3:55am

I get the pad from the seniors' design which contain all the metal from bottom to the top.
However I did not get any explanation so I also need some advices.

Thanks

Title: Re: pad layers
Post by bernd on May 30^th, 2008, 4:58am

We have

- RF pad top metal to top metal -2
- Digital pad top metal to bottom metal

Bernd

Title: Re: pad layers
Post by ACWWong on May 30^th, 2008, 6:25am

As bernd indicates, the details depends on your foundry.

But RF pads benefit from being top metal only if it is mechanically robust enough for the bonding process. I have used technology where this was allowed... others where it is not.

I have also seen a trend for circuitry (mostly ESD or IO drivers) to be incorporated beneath pads, in which case the metal layers which constitute the pads are the higher levels only.