The chokepoint fact first: in high-performance systems, the constraint has moved from making the transistors to connecting the dies, and that connection layer is advanced packaging. US10943869B2, granted March 2021 to Apple, patents high-density interconnect through a fanout interposer chiplet (CPC H01L 23/5385).
Gloss it once. An interposer is an intermediate layer that carries dense wiring between chips. A "fanout" approach spreads connections out into the packaging itself rather than relying on a separate silicon interposer, and doing it as a "chiplet" means the interposer function is modularized. The point is more, shorter, denser connections between dies — which is the whole game in multi-die systems.
Why this is a chokepoint story: packaging capacity, not wafer capacity, gates the most advanced products today. The companies that patented dense interconnect schemes early were staking position in the exact layer that would later constrain the AI buildout. A 2021 Apple grant is one such stake.
The period framing matters. In 2021, "chiplet" was moving from research term to product strategy across the industry. Reading this grant now shows packaging IP being assembled before the supply crunch made advanced packaging the visible bottleneck it is today.
The caveat we attach: this is a packaging-architecture patent and a defensive asset. It evidences where Apple staked an interconnect claim; it does not prove a specific product uses it or quantify any capacity advantage.
For the period investor, the takeaway is that the bottleneck migrated up the stack, and the IP followed it early. Packaging stopped being plumbing and became strategy — and 2021 grants like this one mark the turn.