<@U016EM8L91B> what is the top metalisation compo...
# caravel
s
@Tim Edwards what is the top metalisation composition of the chips pads, is it Au?
t
No, it's all aluminum, as shown in the metal stackup diagram.
s
Can efabless help to put solder bumps on the aluminium pads ? I need for flip chip applications
t
No, we do not do that kind of service. For MPW-1 (and, I think, MPW-2), we outsourced the bump bonding to Micross (where it was done on a full wafer). I do not think it is possible to put solder bumps on a wirebond pad; they are not designed for it. The Micross process involved multiple layers of polyimide and copper prior to adding the bump bonds.
s
How can I go about it then? Any suggestion pls
t
I suggest that if you have a chip that is designed with wirebond pads, then you wirebond it.
s
I am planning for my September tapeout, so I can chnage still if there is a way
t
Is there are reason that you must have bump bonds?
s
I am doing flipchip of caraval with other chip, so vendor needs bumps, solder bumps r must for it
t
Then you would need to find a 3rd party vendor to add the solder bumps. I do not know of any that do solder bumping on a single die, just whole wafers.
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s
I will look for solutions accordingly. Thanks for feedback 😊
a
Samarth, It is both common and feasible to bond between die (Or you have a tall stack of multiple die where you must bump them.) This service can be done on individual die during assembly and does not require any wafer level processing. This is a well proven technology offered by many vendors. Google "stacked wirebonde dice" images https://ewh.ieee.org/soc/cpmt/presentations/cpmt0210b.pdf