Who makes semiconductor test & burn-in for AI data centers

Test and burn-in happens at multiple points in the chain — wafer-level probing before a die leaves the foundry, and package-level test and burn-in after advanced packaging is complete — using testers, probe cards, sockets, and dedicated burn-in systems from a distinct set of suppliers from the packaging and equipment side (Packaging & bonding equipment). It's the quality gate between every other step in this layer and a shippable, working accelerator, and some OSATs handling overflow packaging work (see the OSAT child part under advanced packaging) also provide test services directly. Investor interest in this sub-layer tends to track how much more test time and how many more test insertions a given AI die needs relative to a conventional logic chip — larger, more complex, higher-value dies raise the cost of letting a defective unit through, which pushes toward more thorough (and more expensive) test and burn-in per unit rather than toward higher unit test cost. Supplier concentration is meaningful in testers specifically, with a more fragmented set of vendors for probe cards, sockets, and handlers.