are flipchip using "6.9.1 Solder Bump Rules" from the SG13G2 Layout Rules Rev. 0.3 supported in the opensource runs? or is this an other process? and how is it accessible from commercial MPW?

Solder Balls and Cu pillars are part of the PDK although the access to it via open source MPW is under discussion.

my idea is: it should be accessible, it will allows wirebond-free connecting of the chips. i would like try a flipchip LNA to extend the range of commercial 77GHz MiMO-radar chips. as example the Ti.COM chips have typical noise-figures of 15dB...

If you are from academia the easiest and fastest way to do so could be to get access via Europractice

@Krzysztof Herman: I didn't see anything in the open source PDK that specifically identifies a solder ball other than the drawn copper pillar itself. Is that sufficient to define the solder bump? Normally I expect to see via and under-bump material (UBM), but the layer could be automatically generated.

@Tim Edwards I do not have ad hoc answer right now. Let me ask tomorrow.

Thanks, I appreciate the feedback.