BPN969: Joule Bonding: Localized Solder Bonding for Heterogenous Integration of MEMS

We are developing a new MEMS bonding process in which we use extremely carefully controlled resistive heating to make a solder bond with negligible substrate temperature rise and tighter temperature control than in laser bonding; we do this by using the temperature change of the heater resistivity as a temperature sensor for closed-loop control. Previously, we analyzed transient heat flow and showed initial progress toward heater control. Now, we have completed our theoretical analysis with a description of temperature fluctuations due to local inhomogeneities on the chip and how to control them (or exaggerate them to create a fuse), and have more thoroughly demonstrated robust heater control. We are currently attempting to use this to hermetically package an air- and temperature-sensitive liquid electrolyte lithium-ion battery on chip.