News
SK Hynix diversifies HBM4 TCB tool suppliers as advanced MR-MUF persists
Tuesday, January 6, 2026 at 05:17 AM
UBS reports that SK Hynix has likely split its initial HBM4 thermo-compression bonding (TCB) tool orders between Hanmi and Hanwha Semitech, with ASMPT also expected to join the supply chain by 2026. SK Hynix is expected to maintain its advanced MR-MUF process for HBM4 12Hi, utilizing flux-type TCB tools with specs similar to HBM3E. While HBM4 capacity expansion continues at the M15X fab, industry adoption of fluxless TCB and hybrid bonding is projected to shift toward HBM4E and HBM5, involving suppliers such as BESI, SEMES, and ASMPT across SK Hynix, Micron, and Samsung.
Context
SK Hynix is currently evaluating the transition to hybrid bonding technology for its upcoming HBM4 and HBM4E production lines to overcome the physical limitations of current stacking methods. While the company has maintained market leadership using its proprietary Advanced MR-MUF process, the move toward 16-layer and 20-layer stacks necessitates eliminating traditional micro-bumps. Hybrid bonding enables direct copper-to-copper connections, reducing total package height to the 775-micrometer JEDEC limit while significantly improving thermal management for AI accelerators drawing over 1,000 watts.
The company plans to commence mass production of 12-layer HBM4 in early 2026, with a high-density 16-layer rollout targeted for the fourth quarter of 2026. To accelerate this shift, SK Hynix has solidified a "One-Team" alliance with TSMC for base logic dies and established a joint research lab with Applied Materials for equipment verification. Mastering this technology is essential to support the next generation of AI hardware, which features a 2048-bit interface and bandwidth exceeding 2.0 TB/s.
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