PCB Cost Breakdown: Functionality vs Manufacturability
Key Takeaways
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The cost of the stackup and how to gauge it at a glance.
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Fabrication variables: what contributes to the cost of a board?
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The hope of additive manufacturing that could circumvent cost without sacrificing performance.
When faced with a complex layout on a deadline that is stymying every attempt at completion, would it be better to ask for more time or more money to meet the goals set out by the engineer while conserving design intent? To those who picked the former option: try again (after all, time IS money).
While layout designers aren’t directly dealing with the dollars and cents of circuit board manufacturing, their effects are felt at every step of the design. The board size, layer count, component packages, and more are all motivated by engineering factors, but financial motivation often acts as the common denominator. This is by no means surprising, but it can still be vexing when the solution to our layout woes is a small (to us!) additional cost away.
The Heart of PCB Cost Analysis: Feasibility
A PCB cost breakdown entails the immediate cost of materials and procured components as well as the complexity of producing the design. For example, more layers in the stackup, a particularly involved stackup, or board features beyond standard steps that either increase cost due to additional processing or indirectly by reducing yield for more demanding fabrication jobs. Feasibility is at the heart of cost analysis: features, performance, and cost are all competing for engineering resources, and there’s no such thing as a free lunch.
What Does a PCB Cost Breakdown Entail?
To accurately assess PCB cost breakdown, input is needed from many factors, each of which has subcategories and qualifiers. For example, when considering which materials to use, one has to consider what purpose the material serves and how it contributes to the overall board performance. These functions and conditions are further broken down into each material's thermal rating and heat transfer properties, signal transfer performance, and mechanical properties such as the ability to withstand vibrational stress and shock.
Formulating a PCB cost breakdown begins with the size of the board and the number of layers. The size of a board will generally be determined by the number of circuits required for the device in which the board will be utilized. The number of layers is decided by:
- The loads the circuitry will have to withstand
- Whether there will be high-tech components
- Pin density
- The number of signal layers (determined from pin density)
What Are Some of the Variable Cost Drivers?
Some variables influence the overall PCB cost breakdown more than others and must be thoroughly analyzed before commencing production. Some of these critical variables are as follows:
The Number and Size of Holes in a Board
If the holes are super-thin, they require laser drills. Designs that call for drilling through 10 or more layers, or materials that are hard to drill will increase PCB cost.
The Width of Traces (Signal Conductors)
To avoid transient surges and the threat of overheating, the traces must have sufficient width. Board makers will enlarge the trace width and add extra solder mask to traces that might be prone to high capacity, adding to the PCB cost.
Custom Specifications
Even if the board itself is small and consists of only one or two layers, custom specifications will always raise the PCB cost breakdown. What drives the cost up for custom boards is whether special tools or production skills are required. For example, metal edging, extra clearance for solder mask, and rounded edges come with an added cost, as does the use of board finishes with higher grades and longer shelf life. Boards that involve higher frequencies and military-compliant PCBs are going to cost more due to high-grade materials and testing requirements.
Understanding what can affect the cost of a PCB helps control its price
PCB Functionality vs. Manufacturability Cost
Traditionally, a PCB cost breakdown was directed by the manufacturability of its separate parts. When there was a hard choice between two design options, the ease of manufacturability was more often the deciding issue due to less cost rather than optimum functionality.
Recently, however, the advent of additive manufacturing, or 3D printing, is slashing PCB production costs dramatically. Additive manufacturing creates three-dimensional solid objects from a digital file by laying down successive layers of material. As 3D printing scales up and enters the electronics manufacturing industry, highly efficient functionality in design is gaining a foothold over the old supremacy of manufacturability.
Additive manufacturing is one of many ways to save money during the PCB production process
With 3D printing the need for tooling is eliminated - no metal drills or lasers required for vias and heat transfer holes! High-definition trace lines can be built on unlimited numbers of multi-layer boards, measuring up to industry standards of conductivity, strength, thermal stability, and dielectric behavior. Single components can be built that have both rigid mechanical strength and flexibility where bending is required.
In the immediate future, new design freedoms will make their way into mainstream electronics production with the advent of industrial 3D printers. Streamlined functionality and design beauty will render the old manufacturing limitations obsolete. PCB cost breakdowns will be simplified to the choice of materials, functional requirements of the end application, and the creation of digital files.
Calculate the Design Price Before Production
To avoid exceptionally high costs that might stem from unique or custom PCB design requests, designers would be wise to calculate the PCB cost breakdown before production. Determining the specifications of the design and the steps required to bring it to fruition with a PCB cost breakdown will prevent hidden cost overruns.
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If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.