4 ms·

> Ordinarily WLCSP packaging costs a fortune Compared to what, a bare die? WLCSP is usually cheaper than plastic packages... Edit: Maybe that's only true in

by ohazi 6y ago

> Ordinarily WLCSP packaging costs a fortune Compared to what, a bare die? WLCSP is usually cheaper than plastic packages... Edit: Maybe that's only true in volume? I guess throwing a handful of dies on a wirebonder is easy compared with designing and fabbing the interposer, and who cares if the plastic costs a few cents more.

octoberfranklin 6y ago
WLCSP unit cost is very low, but there is a very high fixed cost. Also WLCSP packaging must be done a wafer-at-a-time. With an MPW, you don't get a whole wafer of your chips -- they cut up the wafer and send the chips with your design to you, and the chips with other peoples' design to the other people. So ordinarily on an MPW if you want WLCSP, you have to pay the fab to run a whole second "boat" of wafers just for you, so those wafers can be run through the packaging process before they are cut up. This often costs more than the MPW booking does!