Cost Determining Factors When Quoting PCBs – Part I
Customers and/or buyers who are relatively new to the printed circuit board (PCB) industry may sometimes be confused as to how a particular project is priced by the fabricator. Today we’ll begin to demystify the factors used by fabricators to calculate price, empowering you to better plan and price your next PCB project.
PCB Pricing is a result of many different elements. Every PCB manufacturer will have some similar needs for overhead expenses including the need for a facility, equipment, labor and raw material costs. Additional overhead expenses that affect PCB pricing include chemical processes and waste water treatment systems; which require special (i.e. expensive) approvals, permits, zoning, etc. Every manufacturing industry has raw material costs, but the raw materials used specifically in the printed circuit board fabrication process can be very expensive (examples include gold, silver, copper, nickel, lead, fiberglass, epoxy resin, and a variety of chemicals).
Manufacturing overhead & raw material costs aside, when a fabricator sets out to calculate PCB pricing of a printed circuit board, there are both primary (board size, quantity, layer count, lead time, etc.) and secondary (tooling, finish type, drill type, lamination process, etc.) cost considerations. In this post, we’ll tackle the primary cost considerations.
A panel is one of the raw materials used to produce a printed circuit board. The size of a printed circuit board, or how much “real estate” it uses up on a panel will be a significant factor when calculating cost/price. Seems simple enough but things can get more complicated. For example, depending on the dimensions it’s possible to have a board that takes up less real estate but is actually higher in cost. The reason for this relates to the overall size of the panel used to manufacture the board; one dimension may fit the panel better than the other. For example, consider two parts with the exact same total square inches per board. The first is 2″ x 6″ and the second is 3″ x 4″. A standard production panel will produce more of the 3″ x 4″ board then the 2” x 6” board and therefore, the cost per board would be lower for the 3” x 4” board.
Quantity is important because many manufacturers will have a minimum cost for an order. For instance, a project may only require 10 pieces but the minimum order cost may require 20 pieces. As the quantity increases the cost per board will go decrease until the minimum manufacturing cost has been achieved.
Some manufacturers will provide higher quantity discounts but deliver smaller quantities over time. For example, a 500 piece order may be placed with 100 pieces delivered each month until the order has been completely fulfilled. In this case, the manufacturer achieves manufacturing efficiency by producing all 500 pieces at the same time and the customer achieves cash flow efficiency by only paying for the product that has been delivered.
For PCB Manufacturers, the told adage “Time is Money” rings true as well! The quicker a project needs to be manufactured the more it will cost – frequently between 30 and 200% more. For a manufacturer, there are real costs involved with prioritizing new projects higher than existing work in process and some of that cost is reflected in pricing.
The number of layers is also a significant cost-determining factor. Single-sided or double-sided PCBs are roughly the same cost to manufacture. However multi-layer PCBs create additional costs in the materials and manufacturing process. Typically, moving to a 4 layer PCB from a 2 layer PCB will double the price. Adding additional layers to a multi-layer project will add additional cost but the price increase related to adding more layers is not as pronounced. For example, the cost to go from 4 layers to 6 layers may represent a 50% increase opposed to the 100% increase incurred when moving from a 2 layer to a 4 layer PCB.
Drill Size and Count
Another factor to consider is the smallest hole size to be drilled and the total number of drilled holes. When the hole size is less than 0.015″ the cost of the PCB can increase between 5% and 10%. A large number of holes can increase the cost further by a similar percentage. This is due to the fact that the manufacturing process has to be adjusted for smaller hole sizes and large hole counts and the number of panels that can be drilled at one time decreases.
Material Type and Thickness
There are many material types that can be used to manufacture a PCB, the most common of which is called FR-4. FR-4 is simply fiberglass and material woven together with an epoxy resin that includes fire-resistant properties. Higher temperature FR-4, Polyimide, Hybrid Capable, High Copper Weight, and Flex are some other material types that could be selected to create high copper weight, hybrid capable PCBs or more. The most common material thickness is 0.062″. Selecting different material types and thicknesses can both have a significant impact on price.
Many of today’s designs/projects require components that are very small. To accommodate, the spacing between copper features on a board need to be smaller. To keep board costs in check it’s important to leave as much space as possible. Trace/space that drops below 0.006” may see a 5% to 10% increase in costs.
These are the primary variables a fabricator will consider when preparing a price quotation for a customer but there are many more. To help you design smarter, more cost-effective printed circuit boards, it is helpful to understand the considerations and calculations behind a quoted price. Check back next week when we’ll wrap up by diving deeper into some of the secondary cost-determining factors.