ACWWong
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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.
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