Comparing PCB Design-to-Cost and Design-to-Value

As a consumer, you are always confronted with a choice for everything you buy: How much should I spend on this product? The answer to this question is another question: How much value does this purchase have for me? This requires consideration of much more than just dollars and cents. How well does the product meet your needs and for how long? After all, if the product does not meet your needs or will not last, then regardless of the lower cost it was too much. In other words, in most cases, your return is proportional to your investment.

When designing PCBs, you are confronted with a similar situation. Essentially, should I design-to-cost or design-to-value? Some may think there is very little difference between these two board design options. Although it is true that cost is a factor for both, there are distinct differences that will have a significant impact on the design and manufacturing of your boards. Let’s take a look at each from these perspectives and then will be able to answer the question of whether it is better to design-to-cost or design-to-value.

PCB Design-to-Cost

At times, a phrase accurately reflects the process it describes. PCB design-to-cost is such a case. When implementing this strategy, the objective is to achieve the lowest per-unit cost for your boards. The most effective way to reach this goal is by applying the lowest cost criteria throughout the development process. This means designing your PCBs such that the lowest manufacturing costs are incurred. Following the suggestions below will help you in minimizing manufacturing costs. 

How to design-to-cost:

• Choose the least expensive components

In most cases, there are many options for components that will work for your design and the range of cost and quality may be wide. However, when making cost the most important factor you will most likely have to sacrifice quality.

• Keep your design minimally complex

The more complex your design, the more it difficult it is to manufacture and the more it will cost. The number and size of traces, layers and types of vias can all increase complexity. For example, via-in-pad is more difficult than other via options and buried and blind vias are more expensive.

• Select the least expensive board materials

Materials built for high frequency, high power, and high-temperature operation are generally more expensive than generic materials such as base FR4. Minimizing your layer count can also reduce cost when board materials are unavoidably expensive. Your choice of finish can also increase costs.

The list above is not all-inclusive, but does provide important principles that should guide your design decisions.

PCB Design-to-Value

PCB design-to-cost is a simplistic design strategy in that there is essentially only one criterion to guide your decisions. Design-to-value, on the other hand, is a more involved process because the goal is to design your boards so that the fabricated and assembled result is of the best quality for the cost. Implementing this strategy requires that your decisions are guided more by whether your PCB will meet your client’s needs reliably.

Designing to value may result in a higher overall manufacturing cost as compared to the designing to cost method, but ultimately your boards should be of a higher quality and more aligned with the needs of your client. Instituting the following guidelines as part of your design process will aid you in producing the best product.

How to design-to-value:

• Choose the best components

Depending upon your client there may be multiple considerations that should guide your component selections. Obviously, the component must be able to perform its intended function, but it must also reliably do so continuously throughout the lifecycle of the device for which it is intended. Additionally, it is important to ensure that adequate numbers of components will be available for future production. And in some cases, it is mandated that supply chains be verifiable to minimize the possibility of counterfeit or inferior quality components ending up on your boards. These requirements necessitate that you limit your sources to distributors that meet these qualifications.

• Keep your design minimally complex

Just as for design-to-cost, it is best to minimize the complexity of your design to the degree possible. This objective must be balanced against other factors, such as constraints on board size that may mean additional layers and vias to satisfy signal trace needs.

• Select materials based on board type

When selecting board materials, the most important factor is whether the board will be able to maintain its integrity within the environment where it will be deployed. Therefore, your board’s type is critical in selecting the best materials. For example, boards on which high-frequency signals will propagate require that special consideration is given to the dielectric constant.

This design strategy is driven by client requirements, but cost is a factor. The best value is obtained at the cost level that the desired quality is achieved, such as when design is coupled with a lean manufacturing process.  

How to Choose Between PCB Design-to-Cost and Design-to-Value

Now, that we have considered the key attributes of PCB design-to-cost and design-to-value we can address the question of whether it is better to design-to-cost or design-to-value. In order to do so, we need to define a common metric by which we can compare the two strategies. Probably, the best one to use is return on investment or ROI. ROI for product development may be defined by the following equation:

ROI = Profit realized (t) / total development cost

Profit realized (t) is the total profit over a period of time. The time period should be the entire period for which the product is being sold, which will vary for different products. The development cost includes design and manufacturing costs. These costs are higher initially but drop off sharply after the design has been finalized. For design-to-cost, the initial costs will typically be lower than for design-to-value; however, better quality products will typically stay on the market longer and generate more total profit.

Design process focus determines your ROI

Creating a product that is both optimally functional as well as cost efficient can be taxing. PCB design-to-cost requires less expenditure but also yields less return, while the converse is true for design-to-value. From the perspective of your clients, in the vast majority of cases, the quality of your product is going to be the most important factor and will determine the number of products they purchase and projects that you are awarded. Figuring out ways to optimize production goals before the board goes into design and production are what PSpice specializes in.

Irrespective of the strategy that you employ, your development must include good design for manufacturing (DFM) that is tailored to your CM’s (configuration manager’s) capabilities and processes. Cadence provides  PCB design and analysis tools that make it easy to incorporate your CM’s DFM specifications. For example, the DFM Checker allows you to verify compliance with your CM’s manufacturing processes prior to submitting your design.

If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.