QA testing lowers mobile phone fab costs

Staying competitive in the terminal supply market requires continuous innovation, not only in the design of new features but also in driving down cost.

The adoption of intensive automation--offshore manufacturing where labor rates are lower and outsourcing goes to OEMs--is now recognized as a given for any major player in the mobile phone industry. However, further reducing costs requires a more subtle approach.

A closer examination of the costs and benefits of quality assurance testing is an obvious target. Over time, as other costs have been reduced, product testing has become an increasingly significant proportion of the total cost. While efforts to reduce costs associated with testing have been successful, they are countered by increased product complexity and time-to-market pressures, requiring more rather than less testing, as well as higher-priced capital equipment. Where possible, manufacturers have adopted reduced test scenarios backed by batch sampling, but this approach risks product quality.

The era in which quality is assured by using function-based test methodologies is rapidly coming to an end. This test methodology treats the device as a mobile phone and tests it by making and receiving phone calls during which parametric performance is measured. This approach might have been relatively efficient when terminals were just single-band mobile phones, but this is no longer the case. Making and receiving calls requires the test system to emulate a radio base-station supporting various protocols, rendering the test equipment overly complicated and therefore expensive. Moreover, the testing of terminal performance parameters requires the device be placed under the control of a system-specific signal protocol (designed to be a robust communications protocol and not a high-speed manufacturing process control protocol), which is not conducive to the needs of manufacturing.

This type of testing has served the industry well, especially as the market proliferated and manufacturers raced to gain market share and brand value. As cost leadership is now key to future success, one must take a more informed approach to quality assurance testing.

One emerging method is to treat the device as "open." A mobile phone device can be viewed as a computer to which a number of RF and other peripherals can be added. The quality assurance process is no different. Its purpose is to provide assurance that no errors have occurred in the supply chain, component handling or assembly process; it is not a means of re-verifying the design. The difference is that by considering the device as open, one can implement a test process that is optimized for speed. In this approach, the test requirements of the device are an intrinsic part of the design, to the point where a large measure of self-testing can be accomplished.