Limited Knowledge of DFSS and Dfx Can Lead to Sub-Optimal Designs

Articles on Dfx often elaborate on subtopics such as Design for Manufacturability (DFM), Design for Assembly (DFA) and Design for Test (DFT). 

Of course, during the design process, we want to enable manufacturability, simplify assembly and ensure our ability to test the product at critical-points throughout fabrication and assembly. 

However, an optimized design aligns with customer needs and the acknowledges the competitive landscape by clearly defining and validating critical-to-quality (CTQ) requirements. To maximize customer value, we should refine our design using Design for Six Sigma (DFSS) to ensure it meets (or exceeds) what matters most to the customer (and perhaps the customers, customer). This is where DFSS comes in:

DFSS helps ensure a design is optimized to maximize customer value and minimize cost.  Many of the Dfx disciplines only focus on the cost-side of the equation. 

Recall the DFSS thought process:

• Understand Customer Needs
• Define Initial Solution
• Model Design Performance
• Optimize the Design to Maximize Value and Minimize Cost
• Verify
• Control

There are several discussion points embedded in this thought process not typically covered by Dfx. 

With Design for Six Sigma:

1.)	Product performance and product competitiveness is maximized and optimized
2.)	Conceptual design selection tools help ensure product development proceeds with all the best design ideas (integrated into the conceptual design)
3.)	Analytical modeling is leveraged to model and optimize design performance
4.)	Models are verified through testing of prototypes (thereby minimizing the number of redesign / retest iterations)
5.)	Optimization routines can be run on verified models to maximize (or “loosen”) specification limits on difficult-to-manufacture parameters.  Conversely, specification limits can be tightened on easy-to-manufacture parameters.

A Dfx program can indeed emphasize manufacturability, assembly and testability, but this is only one side of the equation…perhaps the less important side.  If the product doesn’t meet customer needs or is not competitive, Dfx may not help

It can be seen that DFSS is a more holistic approach, especially with state-of-the-art design modeling and optimization tools. DFSS should be therefore be emphasized to ensure an optimized, competitive design. Meanwhile, DFSS also minimizes costs. Dfx can supplement these efforts or can be combined in your overall DFSS program.