AI packaging stocks

The scarce step in making an AI accelerator is often not the transistors but bonding the logic die to its high-bandwidth memory — advanced packaging, of which CoWoS is the best-known flavour. Packaging capacity, the ABF substrates the package is built on, and the test-and-burn-in capacity that qualifies finished parts together form a real ceiling on how many accelerators reach customers each quarter. Because so few suppliers can do leading-edge packaging at volume, it behaves like a bottleneck: when it tightens, chip supply tightens with it regardless of wafer availability. This theme groups the companies most exposed to the advanced-packaging parts of the AI value chain.