2D / 2.5D / 3D packaging comparison
How 2D, 2.5D, and 3D packaging differ in arrangement, interconnect, thermal behaviour, integration challenge, and typical use. Terminology varies by architecture; treat this as a conceptual guide.
| Dimension | 2D | 2.5D | 3D |
|---|---|---|---|
| Arrangement | Dies side by side on the package substrate | Dies side by side on a shared interposer or over an embedded bridge | Dies stacked vertically |
| Interconnect | Through the package substrate (longer, lower density) | Through a dense interposer/bridge (short, high density) | Through the stack, e.g. TSVs and hybrid bonding (shortest) |
| Thermal | Heat spreads across the footprint; easiest to cool | Similar to 2D, with added interposer layers | Hardest — inner dies have no direct path to a heatsink |
| Integration challenge | Lowest; mature and inexpensive | Moderate; interposer/bridge adds cost and complexity | Highest; stacking, TSVs, and bonding are demanding |
| Typical use | Cost-sensitive and simpler multi-die products | High-bandwidth compute + memory (e.g. accelerators with HBM) | Maximum density and bandwidth in a small footprint (e.g. stacked memory, 3D cache) |
No universal ranking
These are conceptual families, and industry usage of the labels varies by architecture. No approach is universally best — the right choice depends on bandwidth, footprint, thermal limits, and cost.