Tuesday, September 02, 2008

Testing - From Product Concept to Production

When thinking about testing for a new product what first comes to mind? Is it manufacturing, quality or design validation? If you're a designer I believe you would be most interested in functional validation. Someone from the product management organization would probably consider quality or manufacturing first. Tests to cover this broad scope of validation needs carry similar levels of importance, yet have vastly different approaches.

Manufacturing test focuses on time, defects and electrical requirements; quality testing concentrates on characterizing design margin and reliability; design validation directs attention to functionality and parametric data - "does it meet the customers application?" All three testing categories play a considerable role in a high quality product, however they can place very different demands on the silicon content necessary to fully support them.

When defining a new product are you including all three of the test category types as you develop engineering specifications? If not, then your product is left open to higher product costs, or quality and yield issues once you get into production. I find it best that all silicon expectations for testing reside in the engineering specification, further reinforcing the thought process about silicon requirements in support of testing. This also emphasizes test strategies early in the development process, when something can still be done about it.

Make sure you have a process in place for creating a comprehensive test plan that includes all three testing categories. Complete that strategy for testing during the product definition phase and include any silicon content expectations in support of production testing, validation and characterization. Bear in mind that the test strategy is a multi-disciplined effort. Design knows what needs to be validated and characterized while test and product engineering knows the hardware and software capabilities of the testing environment and will bring the required focus on production test costs to the plan. The output of the test strategy should directly drive the silicon requirements to support those tests. Please see the diagram above for a proposed NPD requirements flow that meets the objective of early test definition to drive the silicon expectations in support of those tests.

The days of testing as an afterthought should be long gone in the development organizations of today. Involve test early, involve test in product definition (test modes) and listen to the test and product engineer's inputs on testability concerns. In today's environment there will be no acceptance of a wasted silicon spin to support testing after the fact, nor will there be any tolerance of quality issues due to silicon characterization or validation limitations. Think through testing up front to prevent an inadequacy in silicon validation capabilities from becoming a surprise, just as you are eagerly anticipating a production ramp.

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