Wafer Packaging
Integrated circuit packaging technology connects silicon dies directly to printed circuit boards using a six-bump ball grid array. Wafer-level chip-scale packages eliminate intermediate lead frames and plastic mold enclosures, minimizing physical package dimensions. Solder balls attached directly to die bond pads provide electrical and mechanical connections to circuit board substrates.
A wlcsp-6 package houses ultra-compact analog integrated circuits while offering minimal footprint and short interconnect lengths.
Package Integration
Microscopic solder bumps are formed on the top passivation layer of the silicon wafer during final fabrication steps. Flipping the die and reflowing solder bumps directly onto circuit board pads eliminates bond wire parasitic inductances. Small package masses reduce mechanical inertia and improve resistance to high-frequency shock loads.
Direct silicon exposure requires protective back-side coatings to prevent light-induced photoelectric current leakage.
Joint Inspection
X-ray imaging systems inspect solder bump alignment and void formation beneath chip-scale packages after reflow assembly. Automated optical inspection verifies package coplanarities and checks for solder bridging between adjacent bumps. Cross-sectional electron microscopy verifies metallic intermetallic compound formation at solder interfaces.
Reliability Boundary
Thermal expansion mismatch limits govern solder joint fatigue life during repeated temperature cycling. Silicon dies exhibit lower thermal expansion coefficients than standard epoxy circuit boards, creating mechanical stress at solder joints. Board design standards mandate specific pad dimensions and underfill application to meet thermal cycling lifetime requirements.
