# Semiconductor test & burn-in

Part ID: 1.18 · Layer 1 (Compute silicon & packaging)

The automated test equipment, probe cards, sockets, and burn-in systems used to verify a chip works before and after it's packaged.

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.

**AI delta:** Larger, more complex, and higher-value AI dies raise the cost of letting a defective unit through, pushing more test time and more test insertions onto each unit shipped.

## Companies

| Company | Role | Confidence | Ownership | Ticker | Note |
|---|---|---|---|---|---|
| Advantest | manufacturer | inferred | public | 6857.T | and Teradyne (TER) testers |
| Aehr | manufacturer | inferred | public | AEHR | burn-in |
| Cohu | manufacturer | inferred | public | COHU | handlers |
| FormFactor | manufacturer | inferred | public | FORM |  |
| ISC | manufacturer | inferred | public | 095340.KS |  |
| KYEC | manufacturer | inferred | public | 2449.TW | test services |
| Leeno | manufacturer | inferred | public | 058470.KS | test sockets |
| MPI | manufacturer | inferred | public | 6223.TWO | probe cards |
| Technoprobe | manufacturer | inferred | public | TPRO.MI |  |

Confidence tags: disclosed = company/filing statement; reported = trade press or partner list; inferred = taxonomy lead.