Direct copper-to-copper bonding without solder microbumps — the next-generation stacking interconnect for HBM5+ and high-end logic-on-logic 3D integration. Enables sub-1µm pitches versus 25-40µm for thermocompression bonding (TCB), allowing 20-Hi+ HBM stacks and TSMC SoIC. Wafer-to-wafer (W2W) hybrid bonding is expected to become mainstream in the HBM5 generation (~2028-2029); die-to-wafer (D2W) for higher mix. Equipment is concentrated at BE Semiconductor (BESI), ASMPT, and Applied Materials, with EV Group and SUSS Microtec on the prep side.