Flip Chip Assembly of Thin Substrates, Fine Bump Pitch, and Small Prototype Die

Bump bond assembly of sensors and circuit chips is often a critical step for detector projects, and yet it can be expensive, time consuming, and carry high technical risk. In particular bump formation on singulated die, as obtained on multi-project wafer runs, is difficult due to the hydrodynamics of resist coating and handling of small parts. An increasing number of science applications need thin substrates for reasons such as increased speed of charge collection or reduction of mass to reduce multiple scattering, and there is always a demand for finer bump pitches. SLAC is involved in many challenging detector development efforts for particle physics, astrophysics, and the photon sciences and most of these require hybridization of small, prototype dies from multi-project wafer runs. Results on process development on bump deposition and bonding of thin substrates, small area chips, and chips with small bump-to-bump spacing will be described.