A lower quoted unit price does not necessarily mean a lower cost for the same eight-layer PCB order. Setup charges, test scope, panel delivery format and logistics can make two apparently comparable offers describe different products. Normalize the scope first, then compare arithmetic on the same quantity and revision.
Freeze the technical baseline
Give every supplier the same controlled archive and drawing revision. Identify laminate restrictions, finished copper, surface finish, impedance requirements, hole technology and acceptance deliverables. Ask each supplier to list exceptions separately. A material substitution or omitted test is not merely a commercial discount; it changes the basis of comparison.
Define delivered quantity as acceptable individual boards or acceptable assembly panels, and state which unit is being priced. If an assembly panel contains six boards, a price per panel and a price per board need explicit conversion before either appears in the comparison sheet.
Separate recurring and non-recurring costs
For an illustrative 100-board order, supplier A offers $4.80 per board plus a $240 setup charge. Supplier B offers $6.10 per board plus a $70 setup charge. Assume, solely for this example, that the manufacturing and inspection scope is identical and that logistics and tax are excluded.
| Quantity | A: 4.80Q + 240 | B: 6.10Q + 70 | Lower modeled total |
|---|---|---|---|
| 50 | $480 | $375 | B by $105 |
| 100 | $720 | $680 | B by $40 |
| 200 | $1,200 | $1,290 | A by $90 |
At 100 boards, the apparent advantage of A’s lower unit price disappears after setup. The effective price is $7.20 per delivered board for A and $6.80 for B. These are invented arithmetic inputs, not market rates, quotes from actual suppliers or a price promise.
Calculate the crossover—and state its assumptions
Set the totals equal: 4.80Q + 240 = 6.10Q + 70. Rearranging gives 170 = 1.30Q, so the algebraic crossover is about 130.77 boards. At whole quantities around that point, compare the actual totals. The result assumes each supplier keeps the same rates across the entire quantity range.
Real quotes may have quantity breaks, minimum charges, different panel usage and yield assumptions. A repeat order may or may not reuse tooling without a new charge. Therefore the algebraic crossover is a negotiation question, not evidence that the same relationship holds at an unquoted quantity. Request explicit repeat-order terms.
Add the commercial terms without hiding uncertainty
Create separate rows for tooling, testing fixtures, packing, freight, duties, tax and currency conversion. Mark unknown items as unresolved instead of entering zero. State the exchange-rate date when currencies differ, and keep recoverable taxes distinguishable from permanent project expense.
Do not compare a dispatch date with an arrival date. Record the lead-time starting event, such as drawing approval or receipt of payment, and identify transit separately. A faster lead-time claim without those definitions cannot be normalized into a reliable delivery comparison.
Use an exception log alongside the cost table
| Question | Supplier response to retain | Decision owner |
|---|---|---|
| Material substitution? | Exact proposed grade and qualification basis | Design engineering |
| Impedance testing included? | Targets, tolerance, coupon and report | Signal-integrity / quality |
| Panel format identical? | Approved array drawing and quantity unit | Assembly engineering |
| Setup repeated on reorder? | Written recurrence terms | Procurement |
| Quote validity and exclusions? | Dated commercial scope | Purchasing |
An exception should be accepted, rejected or returned for clarification. It should not silently disappear when the numbers are copied into a purchasing spreadsheet. Retain the final comparison with the same design revision as the approved order.
Make the decision reproducible
A useful recommendation states the chosen offer, normalized total, unresolved risks and the conditions that would change the result. For the example above, B is lower at 100 boards under identical scope; A is lower at 200 boards under unchanged rates. If a supplier’s inspection scope differs, resolve that difference before treating either result as a purchasing recommendation.
Use the site’s panel cost model to explore dimensional and quantity sensitivity separately. Its illustrative rates are not a substitute for the written offers being normalized here.
References and next step
Würth Elektronik: PCB layout and manufacturing costs
Use the fabrication requirements guide to document the result. For a project-specific review, include the controlled drawing revision and relevant assumptions in your RFQ.