OEM and Contract Manufacturer: The Delicate Dance of Test

When manufacturing today's complex electronics products, both in-circuit and functional test remain the all-important quality gate between an OEM and its contract manufacturer (CM). When that CM is located in China and the OEM in North America, achieving the highest possible quality of test is critical.

Although the actual test process happens on the CM's manufacturing floor, it is invariably the OEM that specifies the test strategy and the pass-fail criteria. Many OEMs also implement the actual test plan, sourcing application software, test fixtures and ancillary equipment, such as functional testers in the U.S. and shipping it all to the CM's factory in China. Traditionally, the OEM's test engineers then traveled to China to oversee installation and conduct the inevitable test plan debugging on the CM's manufacturing floor. The U.S.-based test engineers also often remained in China to supervise the initial testing "shake-down cruise" during pilot production.



Figure 1: Custom functional test system designed and built by SiFO.

Every China-based CM extols both its in-circuit and functional test development and execution skills in its sales pitch to capture and retain an OEM's business. Indeed, numerous local Chinese test personnel are in place to oversee the actual test process during normal production, make minor adjustments to test programs and to maintain the substantial investment in test equipment sitting on the manufacturing floor. 

This division of test responsibility between the CM and OEM usually works quite well. That is, until substantial test plan changes occur, due to product design modifications or introduction of a new product into production. Or, worse, something unexpected goes wrong.

The traditional solution has been for OEM's test engineers to fly to China and remain at the CM's site until the required changes were implemented, new product integration was complete or remaining problems had been diagnosed and repaired. But recessionary pressures on the OEM, resulting in slashed budgets, staff reductions and travel freezes, have killed this tradition.

The upshot: Too often there is an impaired test process in China, and the test engineers who can diagnose and fix it are stuck almost 6,000 miles away in the U.S.