App note from Alpha & Omega Semiconductor about current limitations on MOSFETs with exposed pads. Link here (PDF)
Power MOSFET datasheets will usually show maximum values for continuous drain current Id, on the first page of datasheets.
For bottom exposed part such as DPAK, TO220, D2PAK, there is always a note besides Id rating saying that Id is limited by bonding wires. Is this true? The answer is no for most of the cases.
The reason would be shown in this article and more studies will be present to show, how low the silicon resistance should be to lead to a bonding wire limitation issue.