die crack during attach

**Die crack during attach** is the **mechanical damage event where die fractures during placement, bonding, cure, or subsequent handling in attach operations** - it is a severe defect mode with immediate yield and latent reliability consequences. **What Is Die crack during attach?** - **Definition**: Visible or subsurface fracture originating from excessive stress during assembly. - **Trigger Conditions**: Excess force, warpage, particles, thermal shock, and thin-die fragility. - **Crack Forms**: Includes edge chipping, corner cracks, and internal fractures propagating from weak points. - **Detection Methods**: Optical inspection, acoustic microscopy, and electrical-screen correlation. **Why Die crack during attach Matters** - **Immediate Scrap**: Many cracked dies fail test and are unrecoverable. - **Latent Risk**: Small cracks can pass initial test but fail in thermal or mechanical stress. - **Process Signal**: Crack rates expose placement-force and handling-control deficiencies. - **Cost Impact**: Damage occurs late enough to incur significant value-loss per unit. - **Reliability Exposure**: Cracks can accelerate moisture ingress and interconnect failures. **How It Is Used in Practice** - **Force Optimization**: Set placement force windows by die thickness and substrate compliance. - **Particle Control**: Strengthen cleanliness to avoid local pressure points under die. - **Fragile-Die Handling**: Apply carrier support and low-shock motion profiles for thin dies. Die crack during attach is **a high-severity assembly failure mode requiring strict prevention controls** - crack mitigation is critical for both yield recovery and field reliability.