Teradyne

Alex d'Arbeloff and Nick DeWolf started Teradyne in Boston in 1960 – in an office above a hot dog stand, as company lore has it. The product is automatic test equipment (ATE): cabinets that push test patterns through every die on a wafer or in a finished package and bin whatever fails.

Testing never appears on a spec sheet, but it sets the yield and therefore the price. Chiplets and HBM stacks have raised the stakes: one bad die discovered after assembly takes all the good ones down with it. The main rival is Japan's Advantest. Since buying Denmark's Universal Robots in 2015, Teradyne also makes collaborative industrial robots, which is an unusual hobby for a test company.