Die bonding (die attach) is the assembly process of picking individual semiconductor dies from a diced wafer and placing them onto a substrate, leadframe, or another die with precise alignment and permanent attachment.

Bonding Methods

Epoxy die attach: Adhesive paste dispensed on substrate, die placed and cured at 150-175°C. Most common for standard packages. Eutectic die attach: Die bonded using a solder alloy (AuSn, AuSi) that melts and solidifies at a specific temperature. Superior thermal conductivity. Used for high-power and RF devices. Film adhesive (DAF): Die Attach Film pre-applied to wafer backside before dicing. Clean, uniform bondline. Common in memory stacking. Direct bonding: Oxide-oxide or Cu-Cu bonding for 3D integration. No adhesive—atomic-level bonding. Used in advanced 3D stacking (e.g., AMD 3D V-Cache).

Process Steps

Step 1 - Wafer Mount: Diced wafer on tape frame loaded into die bonder. Step 2 - Die Inspection: Vision system inspects each die for defects, reads ink marks or e-test maps to skip bad dies. Step 3 - Die Eject: Needles or laser push die up from tape backside. Step 4 - Pick: Vacuum collet picks the die from the tape. Step 5 - Place: Die aligned to substrate using pattern recognition and placed with controlled force. Step 6 - Cure/Reflow: Epoxy cured or solder reflowed to complete the bond.

Key Specs

• Placement accuracy: ±5-25μm (standard), ±1-2μm (advanced 3D bonding) • Throughput: 2,000-30,000 units per hour depending on accuracy requirements