Challenges of Manufacturing RF Products

The test philosophy will be based on many factors including the analysis of past data, confidence in design margins, and looking at the costs of adding test time and complexity. The law of diminishing return comes into play quite quickly, weighing the benefit of expanding the test protocol versus the cost of increased test times and test reliability issues (false fails). Each case is different and there is no single right answer. But an ongoing statistical analysis of your data will tell you where and when to trade off test complexity for test throughput.

A common good practice is to randomly take units from the production line and put these through a stringent environmental stress screening (ESS) and/or a highly accelerated life test (HALT) to identify any detrimental changes in material or process that impact on RF performance. This practice is certainly not unique to RF products, but because of the nature of RF circuitry and its sensitivity to changes in materials and process, an ESS or HALT program can be a good predictor of subtle material or process changes.

Work with engineering to come up with a test plan that understands where the risks and tradeoffs lie. You might start with a stringent, exhaustive test suite while the product is ramping up to production allowing you to gather a full set of data. Then, as results warrant, relax the measurements on secondary parameters to a sample basis or gather fewer data points to increase test throughput. But throughout, make sure you have a clear and realistic appreciation of the accuracy and repeatability of your RF test stand(s). You cannot measure something to 0.2% accuracy when the instrumentation and setup have a 0.5 % accuracy due to combined effects of equipment accuracy and setup calibration and repeatability.

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