PCB Quote and Cost Drivers Explained
A board price is the sum of a small number of large factors and a large number of small ones, and only some of them are visible in the quotation. Understanding which factors drive the price allows a design to be changed before the order rather than after.
The most common surprise is that the cheapest quotation is not the cheapest supply. Delivery, yield and the cost of a change often exceed the difference between two quotes by a wide margin.
Panel Utilisation
Fabricators buy laminate in standard panel sizes, so the fraction of the panel that the boards occupy decides the material cost per board. A layout that leaves a large border pays for the border.
Panelisation therefore has a direct cost effect, and a small change in the board outline or the panel arrangement can move the price. The utilisation should be calculated rather than estimated, and the supplier is the best source of the panel size.
Layer Count and Stack Up
Each layer adds imaging, lamination and inspection steps, so the layer count is one of the strongest drivers. A stack up that needs an unusual core thickness or an asymmetric build adds cost beyond the layer count.
Reducing the layer count by better routing is the single most effective cost reduction available, and it is also the one that requires the most work. It should be attempted before the layout is complete.
Feature Size and Tolerance
Fine conductor width and spacing reduce yield, and the fabricator prices that reduced yield into the quotation. A design that uses the finest feature everywhere pays for it everywhere, while the same design with the fine features restricted to where they are needed costs less.
Tolerances work the same way. A tolerance that is tighter than the process capability is either priced at a premium or accepted with a higher rejection rate, and the drawing should state only the tolerances the function requires.
Via Size and Aspect Ratio
Small vias with a large aspect ratio are more difficult to plate and more likely to fail, and the price reflects the added process control. Reducing the board thickness or increasing the via diameter are the two levers.
Via fill and cap, back drilling and via in pad each add a process step and each is priced separately. They should be specified only where the design needs them.
Material and Surface Finish
A standard FR4 laminate is a commodity, while a high frequency or a high glass transition material is a specialty purchase with its own lead time and price. The finish ranges from an inexpensive organic coating to a precious metal.
The material and the finish are the two items most often specified by habit rather than by requirement. Both should be justified against a functional need, particularly where the product is not cost sensitive enough to notice.
Tooling and One Time Charges
Tooling charges cover the films, the drills and the programming, and they are incurred once per design rather than per board. Where the quantity is small they can dominate the piece price, and where the quantity is large they disappear into it.
The tooling list should be reviewed rather than accepted, because it often includes a film for a layer that has not changed or a drill that is not used.
Volume and Lead Time
Volume changes the price because the fixed costs are spread, and lead time changes it because a rush order occupies capacity that could be sold otherwise. Both are commercial factors that can be managed.
Consolidating orders to reach a price break can cost more in inventory than it saves in unit price, so the total cost should be considered rather than the piece price alone.
Test and Inspection Requirements
Electrical test, impedance coupons, cross sections and certification each add cost. Where a requirement is driven by a standard the product must meet, it is unavoidable, and where it is driven by habit it is worth questioning.
The test method also affects the cost, since a flying probe is slower but has no fixture, while a fixture requires tooling. This trade is described in the comparison of flying probe and fixture test.
Cost of a Change
A change after the design has been released invalidates tooling and may require a new first article. The cost of the change is usually many times the cost of the feature that was overlooked.
A complete package at the first release is therefore a cost reduction measure, and the checks that make it complete are described in the design release checklist.
Comparing Quotations
Two quotations should be compared on the same data package, the same quantity, the same lead time and the same test requirements. A quotation that is lower because it assumes a different stack up is not comparable.
The comparison should also include the delivery record and the responsiveness to a question, because those are the factors that decide what the board actually costs when the schedule is tight.
Additional Considerations for This Build
Practical attention to cost drivers pays for itself here, because it decides whether the finished board behaves as the drawing intended. Where the requirement is not stated on the fabrication drawing or in the assembly notes, the shop has to assume a default, and that default is rarely the value the design was simulated with. Stating cost drivers explicitly, together with the tolerance that applies, removes the assumption and keeps the result predictable from batch to batch.
Process Control and Verification
On a design of this kind, layer count is the item that decides how the rest of the board is arranged. Keeping a sample from the panel turns a dispute into a measurement, because the same coupon can be re-examined by both parties without rebuilding the batch. Reviewing the design before the data is released is cheaper than correcting it after the panel is in the tank, because every step downstream inherits the decision made at the front end.
Documenting the assumption is part of the design work, and a short note on the drawing prevents a question that would otherwise arrive a day later and cost a day of schedule. The process window is set by the narrowest step in the flow, so an improvement anywhere else shows up as margin rather than as yield until that step is addressed.
Related reading: our fabrication notes, board quality and design release notes cover the same ground.
Process Control and Verification
On a design of this kind, layer count is the item that decides how the rest of the board is arranged. Keeping a sample from the panel turns a dispute into a measurement, because the same coupon can be re-examined by both parties without rebuilding the batch. Reviewing the design before the data is released is cheaper than correcting it after the panel is in the tank, because every step downstream inherits the decision made at the front end.
A first article check confirms that the process and the drawing agree on the points listed above, and that the coupon data supports the values used in the design.
Where a measurement falls outside the expected window, the sample is retained so that the cause can be established before the balance of the batch is released.
A first article check confirms that the process and the drawing agree on the points listed above, and that the coupon data supports the values used in the design.
Where a measurement falls outside the expected window, the sample is retained so that the cause can be established before the balance of the batch is released.
FAQ
Is a higher layer count always more expensive? It is on the same design, and a design that needs the layers may be cheaper than one that avoids them with tighter features.
Do tooling charges vary between suppliers? They do, because each supplier builds its own films, and the difference is one of the reasons quotations are not directly comparable.
What is the most common avoidable cost? A tolerance tighter than the function needs, which raises the price and the rejection rate at the same time.
Why is the second order cheaper? Because the tooling is already amortised and the process has been proven, which reduces both the setup and the expected yield loss.
