Wafer Stud Bumping

Stud Bumping Technology

Stud bump bonding is ideal for flip chip bonding for LCD drivers, SAW filters, CMOS, memory and image sensors. Customer products include hearing aids, smart cards, personal digital assistants, and many more...wherever a low cost, small footprint or high performance interconnect is needed!

"The gold stud bump flip chip assembly process creates conductive gold bumps on the die bond pads, and connects the die to the circuit board or substrate with adhesive or ultrasonic assembly. Stud bumping requires no under-bump metallization (UBM) and thus does not require wafer processing, so that individual die can be stud bumped as easily they can be wire bonded."
(quoted from www.flipchips.com).

Stud bump types include standard stud bump, coined bump, AccuBump™ and Stacked AccuBump. The interconnect may consist of gold, gold/palladium, copper or solder. Wafer Stud bumping is recommended for applications with low and medium pin count devices, with 400,000 or fewer bumps per wafer.

Advantages of stud bumping with Au (Gold)* wire
Au bumping is significantly less expensive than solder bumping
Au bumping supports finer pitches than solder bumping: 65µm Au vs. 160µm (leading edge for solder)
Au bumping uses existing peripheral pad infrastructure (IC design, test, and manufacturing)
Au bumping is lead-free
Au bumping is more reliable, with less fatigue than solder
Variety of techniques exist to attach Au bumps to the next level of interconnect, depending on application and requirements
Au stud bumping does not require UBM (under bump metallization)
Au stud bumping enables rapid prototyping

* Cu, Au/Pd and solder bump options available

Typical Packages

Package size reductions will continue to be an important driver for flip chip manufacturing.

Today: Surface Acoustical Wafer (SAW) Filters, Digital Signal Processors, Power Amplifiers

Future: Memory, high-end ASICs, high-end graphics.