Is there a maximum force that the bare die pads can withstand? Is there any worry with crushing the metal stack underneath the pads and shorting connections?

Flip-chip is not a problem. For these pads, the only issue would be if you intended to use a wedge bonder. Ball bonding and flip-chip both work fine with these pads.

@Tim Edwards would be nice to see which documentation you are referring to; I can't seem to find anything in here https://skywater-pdk.readthedocs.io/en/main/ & IO docs re wedge bonding. Thanks!

This pad has not yet been qualified by us but was qualified previously by the developing company for very high quality mass production devices. (Literally trillions of these pads {hundreds for every man, woman and child on earth} have shipped), It is good to assume that they knew what they were doing. I'm not aware of anybody ever doing ribbon bonding but there was definitely both ball and wedge bonding on the original pads in lab and development environments and no expected fallout. I think all of the qual work was done via ball bonding. Many of the devices were qualified with gold and copper bond wires at different times. For Flip Chip package discussions we should get more detail on what you are trying to do so that we can enable you as quickly as possible.

re: wedgebonding, we attempted to wedge bond our devices with a survival success rate of 1 out of the 3 chips... The problems we found were shorts between VDDIO and our GND, which we think is due to the fact that our wire bonder misses the pads slightly and crushes the metal stack under the passivation around the pad

@Xiaochen Ni: Since the VDDIO and VSSIO buses run very close to the pad, then that is certainly a possible scenario; although they also pass under the pad on metal 3, so shorting to a point below the pad is also possible. Either way, I hope that 33% yield gets you enough working parts.

Yes, thank you! our testing has been going very well with the parts we have been able to use so far