Stacking optics into the chip in 3D wins electrically but pays across the board in thermal management. imec's paper quantifies 2.5D vs 3D CPO thermal crosstalk one number at a time: 8 K vs 60 K, a 13x spatial gradient, a 60x temporal gradient. All 18 figures explained.

imec pushed 3D-stacking hybrid bonding to a 200 nm pitch, but the real message is that the deciding factor has moved from bonding to overlay, CMP and pad design. Why is 200 nm a yield cliff, why are overlay accuracy and electrical yield locked in a linear relationship, and where is the next bottleneck for AI 3D integration?

For glass to work as an advanced packaging interposer, the first hurdle is filling deep, straight TGVs with good copper. Tohoku University combines an electroless nickel seed, chemically tailored electroplating and HIP annealing to fill straight vias in 1 mm-thick glass void-free and grow >45 µm grains — a foundational breakthrough for glass TGVs.

W2W Cu-Cu hybrid bonding pushed to 450 nm pitch for the first time while holding high yield (98%/100% across 20 million interconnects). Applied Materials traced the yield killer to residual BTA carbon at the bond interface and engineered the interface chemistry, barrier and anneal — groundwork for 3D DRAM and HBM.