PCB Change Orders:
What an Engineering Change Costs at Each of the Five Process Gates — and the Three-Sentence PO Clause That Puts the Cost Where It Belongs

A change order issued after tooling release has three possible costs, and buyers usually budget for only one of them. The quote for the revised artwork is the visible cost. The invisible ones are the boards already in process that will be scrapped or reworked, and the schedule displacement that pushes every subsequent build. On a six-layer board released ten days before the change, the second and third costs together are typically five to fifteen times the first.

This is a page about which changes can be absorbed at which stage of the fabrication and assembly cycle, what each stage costs to reverse, and how to write a change clause that puts the cost where it belongs. The arithmetic is not complicated, but it is only visible if the supplier reports the process stage at the moment the change arrives, and most do not unless the PO asks them to.

The Five Process Gates and What Each One Costs to Reverse

Fabrication is a sequence of irreversible commitments. Once the drill programme is running, the laminate has been consumed; once the panels are etched, the copper is gone; once they are laminated, the inner layers are sealed. The point at which a change arrives determines what can still be recovered, and the cost gradient is steep.

Gate 3 is where the disputes concentrate. The buyer believes the change arrived before any physical work, because it arrived before the promised ship date. The factory has a lamination book in the press. Neither party is lying, and the difference is the absence of a stated gate in the PO. A clause that says “changes accepted before lamination at no material charge” is short, enforceable and prevents this argument entirely.

The gate definitions must be the supplier's real gates, not a generic checklist. Ask the factory to state, for each build, the date and time each gate is closed. On a standard six-layer build that is usually: artwork release at day zero, lamination at day two, drilling at day four, plating at day six, electrical test at day eight, ship at day ten. A change arriving on day three is at gate 3 and costs full scrap, no matter what the email says.

NRE, Tooling and the Re-Quote Question

Fabrication NRE is dominated by film generation and tooling, and it is charged per change because each change consumes new film. On a four-layer build, a revised inner layer means new film for that layer and a new drill programme if holes moved. The charge is legitimate; the variable is whether it is charged at full rate when only one layer changed.

Assembly NRE behaves differently: stencil, programme, and first-article inspection. A component change that does not affect pad geometry needs no new stencil. A change that moves a pad does. A change that only swaps one resistor for another value should cost a programme edit and a new first article, nothing more. When a supplier re-quotes the full assembly NRE for a component substitution, the question to ask is which line items are actually consumed. Our setup cost amortization page breaks down which assembly charges scale with build size and which do not.

For fabrication, the corresponding question is whether the change re-opens the panelization. Moving one component inside a panel does not; changing board outline does. Panelization changes ripple through the drill programme, the route programme and the assembly panel fixture, which is why outline changes are the single most expensive class of ECO after lamination. The panelization cost reference covers the constraints that make this so.

The Scrap Calculation Buyers Should Do Themselves

When a change arrives mid-build, the quantity to scrap is not the order quantity. It is the number of panels in process plus the panels already completed in the affected revision plus the panels a minimum-run constraint forces the factory to finish. That third term surprises people. A shop running a 50-panel minimum per lamination book may have 32 panels in the book; the change scraps all 32, not the 14 already started.

A worked example. Order 200 boards, four-up panel, so 50 panels plus 5 spares. Change arrives after lamination on a 30-panel book. Cost of that change: 30 panels of laminate and inner-layer labour, plus the remaining 20 panels re-fabricated, plus a new drill programme if holes moved. If the revision change costs one day of schedule, the re-fab runs in parallel with the balance of the order and the ship date moves two to three days. The same change arriving one day earlier, before lamination, costs new film and nothing else.

Two consequences follow. First, the most valuable procedural change a buyer can make is a mandatory “gate notification” from the supplier, sent the day each gate closes, so the buyer knows exactly how much room they have. Second, a change window of three to five days before the build is a rational design-management target, because it keeps most changes at gates 1 and 2 where they are nearly free. Programmes that treat ECOs as free until ship date are the ones that pay gate-3 prices repeatedly.

Writing the Change Clause

A usable change clause has four parts, and each one closes a specific dispute.

The first defines the gates and requires the supplier to notify on gate closure. Without it, the buyer is guessing. Second, it allocates cost by gate: no material charge before gate 2, engineering charge only at gate 2, full material and labour at gates 3 and 4, and a defined split at gate 5 for boards versus components. Third, it caps expedite charges at a stated percentage so that a change cannot silently become a premium-rate rebuild. Fourth, it requires the supplier to report the scrapped quantity with panel count so the buyer can verify the number against the panelization they approved.

The fourth part matters more than it looks. Scrapped-quantity reports are the only way to check whether the factory is booking changes against the correct revision, and they are also how a buyer discovers that a change was implemented on the wrong panel revision across a whole lot. The practice described in waiver and deviation control applies directly: any deviation from the released revision, in either direction, is documented with the revision it was applied to.

First Article and Re-Approval After a Change

Every change that touches the drill programme, the pad geometry, the stackup or the BOM reopens the first article. That is not bureaucracy; the first article is the only checkpoint where a dimensional error introduced by the change is caught before volume. The practical question is scope. A component substitution needs a first article of the affected assembly area, not the full board. A stackup change needs a full stackup verification with sectioned coupons. A silkscreen change needs nothing.

Suppliers who treat all changes as equal either over-inspect the trivial ones or under-inspect the important ones. The classification that prevents both is the same one used for the qualification file: changes affecting electrical function, changes affecting mechanical fit, and changes affecting documentation only. Only the first two reopen dimensional first article; the third requires a document revision and nothing else. The engineering change order process reference covers the classification and the record-keeping, and first article inspection for PCBA covers what a scoped first article has to contain.

Summary

An ECO costs whatever the process gate it arrives at dictates, and that cost is between nearly nothing at gate 1 and more than the order value at gate 4. Define the gates, require notification when each closes, allocate cost by gate in the PO, cap expedite, and require scrapped quantity reported in panels. Classify changes by electrical, mechanical and documentation impact so that re-approval scope matches the change instead of defaulting to full first article every time. The clause takes fifteen minutes to write and typically removes the largest recurring unplanned cost in a fabrication programme.