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Understanding PCB Costs: A Breakdown of Key Factors
Various factors influence PCB manufacturing costs, many of which can be optimized through careful design choices.
One of the most significant cost factors is the size and complexity of the board. Larger boards require more materials and can be more expensive to produce, while complex designs often involve additional steps and components.
For instance, rigid-flex PCBs offer both flexibility and durability but may involve higher costs due to their layered structure. However, the added reliability and space efficiency can make them a cost-effective choice for applications where both flexibility and robust performance are needed.
By understanding these cost drivers, you can make informed decisions that balance performance needs with budget considerations.
Board Size and Complexity
Board size and complexity are key factors influencing material costs and manufacturing difficulty.
The end product’s requirements or PCB’s purpose will ultimately dictate its scale and complexity.
For instance, the ideal size of a PCB for a gaming computer’s motherboard will differ from that of a calculator’s.
The number and complexity of electronic components a board will house are key determinants of its size.
The size and form factor of a motherboard aren’t just for show; they need to accommodate all the components necessary for its purpose.
Layer Count: A Balancing Act
Modern high-end motherboards use multilayer high-density interconnect (HDI) PCBs, whereas most calculators use single-sided boards with one layer.
It would be wasteful to use a multilayer board where a single-layer board would suffice.
Just as with size (board length and width), the more layers (thickness and height) a board has, the more costly it is to manufacture.
Multilayered boards often require different materials, such as additional copper foil or prepreg.
Each additional PCB layer increases the manufacturing complexity and costs almost exponentially.
Multilayer boards require more advanced equipment, expertise, and machinery to assemble.
Material Selection: Balancing Cost and Performance
Different parts of a PCB require different materials. For instance, the substrate and conductive layers are usually made from separate but homogeneous substances.
Your material requirements typically correspond to your application needs, especially concerning the substrate.
For example, rigid PCBs use different laminate materials compared to flexible PCBs.
The material composition of your PCB significantly impacts its cost. As such, always select materials with careful consideration.
Finishing Options: More Than Just Aesthetics
In addition to the base materials, consider which substances to use for the solder mask, PCB surface finish, and silkscreen.
While these elements seem cosmetic, each serves an important purpose.
The solder mask and finish are protective, while the silkscreen marks components and test points.
Epoxy liquid is the cheapest and most commonly used solder mask.
Liquid photo imageable solder masks (LPSM and LPI) and dry-film photo imageable solder masks are also good alternatives.
Hot air solder leveling (HASL) is the least expensive finish. However, many designers and manufacturers have moved away from it due to its use of lead.
Instead, they’ve begun to use Electroless Nickel Immersion Gold (ENIG). While more expensive, ENIG offers a long shelf life and exceptional contact resistance.
Minimum Feature Size and Tolerances
When deciding on tolerances for your PCB, aim for mid-range manufacturing industry tolerances.
This will make it easier to find a manufacturer that can fabricate your boards without incurring additional costs.
Tighter tolerances and smaller feature sizes can complicate the manufacturing process. For instance, smaller drill holes require smaller, less durable drill bits.
Consult the necessary guidelines as you work on your design to ensure the manufacturability of your board and minimize later revisions.
Most engineers and PCB designers recommend reading and adhering to the IPC board design standards, as do we.
Design for Cost Savings: Practical Strategies
Many PCB designers exclusively focus on function and performance, often ignoring cost completely.
Adopting philosophies such as Design for Manufacturing and Assembly (DFM or DFMA) can help create more cost-efficient designs without sacrificing quality.
Principles and practices of DFM include prototyping and testing, review simplification, standardization, and iteration. Let’s explore some of these practices in depth.
Optimizing Board Size and Minimizing Waste
The most common PCB sizes are as follows:
- 457mm x 610mm (18” x 24”)
- 457mm x 533mm (18” x 21”)
- 533mm x 610mm (21” x 24”)
These dimensions typically correspond with PCB panelization standards. If you plan to use panelization to maximize production speeds, efficiency, and cost, you’ll need to design and optimize the board accordingly.
The goal is to fit as many boards on a single panel as possible while keeping panel margins as thin as possible. This helps minimize both waste and material costs.
However, even if you’re not designing boards for mass production (and thus not using panelization), you can still benefit from these practices.
The best approach is to size your board to meet the necessary functional requirements for your application while still adhering to industry standards.
Choosing the Right Number of Layers
Two-layer PCBs are sufficient for most applications. However, if you’re designing PCBs for electronics requiring high-speed circuits, you may benefit from using four layers.
The average multilayer PCB consists of four layers; only increase the layer count if four layers can’t accommodate all your components.
Running circuit and temperature simulations will provide a preliminary assessment of your board’s performance with its current layer count.
Additionally, commissioning a prototype will give you a functional real-world board that you can use to further refine your design.
Selecting Standard and Readily Available Materials
FR-4 is the cheapest and most common material for rigid and rigid-flex PCBs. While sufficient for most uses, it isn’t as resilient or heat-resistant as ceramic-based materials like Beryllium oxide (BeO).
The conductive layer of a PCB usually consists of copper. While alternative materials like gold, silver, and aluminum can be used, they are more expensive and can be harder to source than copper.
As such, your focus should be on the density of the copper.
High-performance PCBs tend to have thick traces, which means they require more copper. This is another instance where the PCB’s purpose affects the amount of material your design uses.
Selecting standard and readily available materials improves turnaround time and ensures that a wide pool of fabricators can manufacture your design.
The less time manufacturers have to spend sourcing your materials, the quicker and less costly fabrication will be.
Balancing Cost and Performance Needs
Look for materials that satisfy the PCB’s use case requirements as inexpensively as possible. Take the time to evaluate how each material impacts cost and performance.
Since you can’t analyze cost and performance in isolation, layer count, board size, and form factor all play a role.
This is why standardization, iteration, and refinement are vital in the design and development process.
Your initial PCB design is unlikely to be perfect and fully representative of the final product.
As such, partnering with a manufacturer who can help assess your design and suggest necessary amendments is vital.
Considering Alternative Finishing Options
Your surface finish must pair well with your PCB, its fabrication method, and its materials.
For instance, immersion tin is ideal for PCBs that utilize press-fit insertion but isn’t environmentally friendly due to its use of the carcinogen Thiourea.
Organic finishing options like organic solderability preservatives (OSP) are more environmentally friendly but have a shorter shelf-life.
Ultimately, it may be better to invest a little more in a gold alloy-based solution like ENIG or ENEPIG. While the upfront costs are higher, these finishes have long shelf lives, which can reduce costs in the long run.
Additionally, environmentally friendly products tend to have greater consumer appeal.
Transparency and Cost-Effectiveness: Our Commitment
WellPCB is committed to transparent pricing and delivering cost-effective manufacturing solutions.
Recognizing that location can impact cost, we operate two factories located in the cities of Jiangmen and Shenzhen in China.
Each factory spans around 15,000 square meters and is equipped with the latest machinery sourced from Japan and Germany. We support production at all scales.
Use our online PCB cost calculator to generate a quote. It supports Rigid PCBs, Flex PCBs, and Rigid-Flex PCBs.
Download Your Free Guide: 9 Proven Strategies for Cost-Effective PCB Design!
Now that you’re familiar with the cost considerations to observe during the PCB design process, how do you put them into action?
We’ve created a guide featuring nine strategies to optimize your PCB design costs. Click here to access your free guide.
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