Key Rules for Design for Excellence Print E-mail
Written by Arbel Nissan   
Monday, 30 April 2012 18:29

Most product cost is determined in design, before it ever reaches production.

OEMs constantly seek ways to cut product cost and time-to-market. The advantages of a shorter time-to-market and lower costs of an end-product are evident: market attraction improves, lifecycle extends, development cost reduces, etc. This is far from a trivial mission, and different managers look for different ways to achieve these objectives. One strategic path leading to attaining these objectives is DfX methodology. DfX (Design for Excellence) is an efficient tool with a proven record of accomplishment with which we can ensure proper execution of electronics products the first time.

Research indicates that OEMs that develop electronics products and have implemented DfX methods stayed within 82% of their development budget, performed 66% less repair rounds and saved $26,000 in those rounds they did perform.1 Other scientific work2 indicates that approximately 75% to 85% of the cost of an electronic product is determined in the design phase, while the actual product costs increase significantly, of all places, during production (Figure 1).



As the design process advances, the window of opportunity to introduce changes becomes smaller, and the cost of introducing change grows, in some cases exponentially. For example, introducing a change after putting together a prototype will entail a new PCB layout round, execution of an engineering change order (ECO), ordering a replacement version, reproduction, inspection of quality and reliability, renewed meeting of standards, delay in supply to customers, etc. In other words, taking into consideration problems that may arise during production and assembly during the design phase proves to be an efficacious method for reducing costs and increasing yield.

It is true that implemention of DfX requires further investment of time by the organization during design, yet research indicates that as a result of this extension of time, the product’s overall time-to-market drops by approximately 40%.3

This requires an understanding that quality control, by itself, does not suffice for the task of prevention of problems. The fundamental of success of an electronics product is a sound design, maintaining an open and productive channel of communication between the designers and production, based on accumulated knowledge and experience. As part of DfX, we remain aware that failure may occur in the future, and implement working methods to prevent it from happening.

Failures in design of the electronics product can take place due to incomplete exchange of information between the electrical, mechanical and PCB layout design; failure to understand the shortcomings and capabilities of production; and unrealistic customer expectations regarding the process of development of a new product in matters of reliability and time-to-market. DfX’s purpose is to ensure consistent and continuous production throughout the supply chain, with a minimal number of failures.

The DfX methodology consists of several sub-topics, according to the various stages in the product lifecycle. Every topic relates to a different stage in the production cycle and is accompanied by instructions pertaining to the actions to be taken in the design stage to prevent failures. These topics include DfM (design for manufacturing), DfT (design for testability), DfR (design for reliability) and DfE (design for environment).

To demonstrate this, following are several key rules how to properly implement DfX.

Learn from the past. Albert Einstein said, “The only source of knowledge is experience.” When developing new products, consult the past. Failure to meet quality, customer complaints, reasons for product recall, and so on are all sources of information to draw from. To this end, we are required to document such incidents in an orderly way, analyze them and implement procedures that will prevent their recurrence. A cross-organizational brainstorming of every element taking part in the project may well be a way to achieve this.

Stick to norms as much as possible. Adhere to standards as much as possible at all stages of product development. This is true when engaged in design, layout, choice of components, procurement, production processes, etc. Developing product using existing standards helps cut time-to-market, simplifies processes and minimizes risk of errors. Take, for example, a non-standard component. If we choose a component failing to meet the norm, we expose ourselves to a higher price tag, because the part is less common among all the suppliers, thus less governed by laws of competition and (likely) produced in smaller batches. Second, as a result of the need to replace the item, the time to deliver may stretch, and consequently, we may presume that the supply chain will be disrupted. It may be difficult to find a substitute component. Avoid reinventing the wheel; stick to norms as much as possible.

Reduce the number of components in a product. One of the best ways to reduce production costs and enhance product quality and reliability is to reduce the number of components. When using fewer components, the cost of acquisition may be reduced by placing a large order of one item, rather than a small order of several items. In addition, as the number of components in an electronic circuit determines the assembly cost, reducing the number used will lower that cost, respectively. Further, reducing the number of components will result with less risk of faulty items and quality issues during assembly. Consider these examples: First, designated component library, including an AVL (approved vendor list), ensures that a new product would use known components. Second, components that can be used in several applications may cause an increase in direct costs, but in general, the overall cost of all the components will decrease. Third, ordering whole assemblies from a subcontractor avoids dealing with putting together these subassemblies.

Design for Lean production. The main principle of designing for Lean production is that whatever does not add to the product’s value is garbage to be discarded.
As part of this design, cut down on production processes as much as possible through use of automatic assembly over manual (e.g., SMT components instead of manual insertion through-hole parts). The manual assembly to be performed should be simplified to such degree as to avoid questions and errors, as well as to help turn assembly automatic at a later stage. Refrain from additional production processes, where possible; e.g., design boards with components on one side instead of both sides by reducing the area of components or increasing the area of the printed circuit board. Design for Lean can help save a great deal of time in production and improve product quality.

When it comes to production, stay away from technological extremes. Make a distinction between the product’s development and its production. When we develop the product, we may be interested in taking the technology to an extreme to differentiate our product from competing products in the marketplace, as well as to offer our customer added value. In its production, we should take the opposite approach. Since production is not added value for us, we should simplify it and base it on existing technologies, ensuring higher quality and reliability. So, for example, choosing a component with a 0.4mm pitch would be preferred over a 0.3mm pitch component; a 0402 package would be a better choice than a 0201 package, and choosing a 10 mil trace width would be better than choosing an 8 mil.

Develop work methods to nullify failure. As we know, Murphy’s Law never rests. If anything can go wrong, it will. Anticipate failures and work to prevent them from happening in the first place. For instance, a clear and comprehensible product assemble file should be prepared for every worker of the production line. To avoid confusion and interference, the instructions should be specified in a methodic and unequivocal way. To prevent duplication, instructions should be listed only in one place in the file. Reduce text use as much as possible; use images and visualization in its place. In this context, it would be advisable to plan the product’s assembly process so it will be assembled in no way but the proper one. Improper assembly should be prevented by employment of asymmetric holes, stops, etc.

Integrate and coordinate design and layout elements and production and assembly elements. Whenever a PCB is designed, its production should be taken into account from the start. The planning and layout teams should be synchronized at the best possible level with the production and assembly teams. To reach a complete optimization of the circuit and electronics product throughout production, initiate thinking processes, combining the planning and PCB layout with production and assembly elements. Ensure that every critical objective of the process is known, considered, controlled and eventually, achieved. These objectives include product cost, desired level of quality, reliability, regulation, time-to-market and customer satisfaction.

The great victors of today’s competitive technological world are those companies that can deliver to their customer an innovative product that holds an added value over their competitors. Development of an innovative product is an imperative but insufficient condition to attain these objectives. Organizations wishing to achieve these goals should reduce their production costs and shorten the product’s time-to-market. Implementation of DfX will improve company performance by ensuring the right job is performed correctly from the beginning.

References

1. Aberdeen Group, “Printed Circuit Board Design Integrity, The Key to Successful PCB Development,” 2007.
2. Martin Tarr, “The DfX Concept,” University of Bolton, 2007.
3. D. E. Carter, and B. S. Baker, Concurrent Engineering: The Product Development Environment for the 1990s, Addison-Wesley Publishing, 1992.

Arbel Nissan is COO at Nistec (nistec.com); This e-mail address is being protected from spambots. You need JavaScript enabled to view it .

Last Updated on Monday, 30 April 2012 20:36
 

Search

Search

Login

CB Login

Language

Language

English French German Italian Portuguese Russian Spanish
 


Printed Circuit Design & Fab Magazine on Facebook