Improving Product Reliability and Software Quality, 2nd Edition

20Product Design Phase

20.1 Product Design Phase

Now that the concept, requirements, and architecture for the product have been completely defined, the design of the product can commence. In the product design phase, everything required to produce a working prototype is developed. At the end of this phase, there will be a complete product documentation package. This will include the schematic, theory of operation, outline drawing, bill of materials (BOM), software, assembly, and mechanical drawings. There will also be a working prototype suitable for design validation, which will be performed in the next phase of product development. The decisions made by the end of this phase will determine the product cost, design, manufacturing, test, and service complexity and will also determine how difficult it will be to ramp production. Unless the product is completely redesigned, 80–90% of the product cost is determined. Cost down efforts to reduce product cost here are usually limited to reducing material cost because redesign at this point is not cost‐effective.

Product cost is emphasized because there is a cost associated with reliability. The cost equation works two ways. First, there is an added material cost associated with using higher reliability components and adding redundancy. The added cost should be evaluated against the improvement expected in reliability and how much the market is willing to pay for increased reliability. There is also a cost saving associated with designing ...