Stud Bumping Technology

Stud bumping technology is a wafer-level interconnect process that creates high-density gold bumps for advanced semiconductor packaging, enabling reliable fine-pitch connections for next-generation devices. This process transforms traditional wire bonding into a precise method suitable for applications demanding high performance and compact designs.

Using an Electronic Flame Off (EFO) spark, a gold ball is formed at the end of a bonding wire and thermo-sonically bonded to the device pad with heat, pressure, and ultrasonic energy—creating a strong metallurgical connection. The wire is then cleanly broken, leaving a solid gold stud or “bump” on the pad surface.

These precision bumps provide reliable attachment points for flip-chip and wafer-level assembly, enabling fine-pitch interconnects for advanced applications such as CMOS image sensors, RF modules, and other high-performance semiconductor devices.

K&S delivers industry-leading wafer-level stud bumping solutions backed by decades of wire bonding expertise. Our ATP Lite™, ATPremier™ PLUS, and ATPremier™ MEM PLUS platforms integrate advanced thermo-sonic control, precision mechanics, and smart automation to achieve consistent, fine-pitch bump quality on 200 mm and 300 mm wafers. Widely adopted in the SAW filter market, these solutions also feature automation options like the Auto Wafer Handler System. With unmatched throughput, lowest cost of ownership, and the fastest performance in the industry, K&S wafer-level platforms set the standard for efficiency and reliability.

We support both Standard Stud Bump and AccuBump™ processes. In each method, an EFO-formed ball is bonded to the pad using heat, force, and ultrasonic energy, followed by a clean wire break that leaves a solid gold stud. For standard stud bumping, capillary motions are programmed to tear the wire just above the bonded ball in the heat-affected zone, ensuring uniform termination. In the AccuBump™ process, after forming the bond, advanced z-axis motions create a flat surface and weaken the wire for more precise termination. This flat landing area is critical for later bonding steps such as Standoff Stitch Bump (SSB) or stacked bump bonding. Enhanced control of z-axis profile, wire clamp timing, and ultrasonic energy perfects bond integrity and repeatability, while AccuBump™ further tightens bump geometry for complex pad layouts.

Internal benchmarking and customer deployments show high UPH, compact footprint for superior productivity per square meter, and tight bump height control (~±3 µm)—all critical for wafer-level economics. These platforms are engineered for sustained throughput, long MTBA, and fast recipe swaps between stud bumping and wire bonding configurations where needed.