SSANMSanmina Corporation

Sanmina assembles complex electronics to other people's designs — for communications, medicine, defence and industry.

A contract manufacturer does not own the product: it buys components, assembles and tests the device. The company deliberately avoids consumer electronics with its thin margins and works where the product is certified and lives for years: medical devices, defence equipment, communications hardware.

Such products require the plant itself to be qualified, and a customer does not leave afterwards — moving production means going through certification again. That makes revenue steadier than at assemblers of mass-market equipment. Risks: customer concentration, working capital tied up in components and manufacturing geography. The company pays no dividend but buys back stock.