  Stringent physical requirements need to be met for the high performing
surface-electrode ion traps used in quantum computing, sensing, and
timekeeping. In particular, these traps must survive a high temperature
environment for vacuum chamber preparation and support high voltage rf on
closely spaced electrodes. Due to the use of gold wire bonds on aluminum pads,
intermetallic growth can lead to wire bond failure via breakage or high
resistance, limiting the lifetime of a trap assembly to a single multi-day bake
at 200$^{\circ}$C. Using traditional thick metal stacks to prevent
intermetallic growth, however, can result in trap failure due to rf breakdown
events. Through high temperature experiments we conclude that an ideal metal
stack for ion traps is Ti20nm/Pt100nm/Au250nm which allows for a bakeable time
of roughly 86 days without compromising the trap voltage performance. This
increase in the bakable lifetime of ion traps will remove the need to discard
otherwise functional ion traps when vacuum hardware is upgraded, which will
greatly benefit ion trap experiments.
