A preliminary PCBA quote is often based on assumptions. After the supplier validates the BOM, fabrication data, placement file, test requirement, and delivery scope, some assumptions become confirmed costs. A change is not automatically a warning sign—but an unexplained change is.
What legitimately changes a PCBA quote?
- BOM availability: distributor stock, minimum order quantities, packaging quantities, obsolete or long-lead parts, and approved-source restrictions.
- PCB fabrication: layer count, material, copper weight, impedance control, finish, via structure, panel utilization, and inspection requirements.
- Assembly complexity: fine pitch, BGA/QFN, bottom-side placement, press-fit, selective solder, hand operations, masking, cleaning, or coating.
- Test scope: programming, fixtures, ICT/flying probe, functional test, calibration, burn-in, and data retention.
- Commercial scope: quantity breaks, excess material, packaging, export documents, shipment split, currency, and requested lead time.
What should the supplier show?
Ask for a delta, not just a replacement total. The response should identify the changed input, previous assumption, new confirmed condition, one-time cost, recurring cost, lead-time effect, and buyer decision required. For BOM changes, request the affected MPN, quantity, source or availability issue, and alternate-approval status.
When is a quote change a red flag?
Warning signs include repeated unexplained totals, substitutions without approval, missing fixture or test lines that appear only after production starts, and an inability to tie the change to a file revision or scope decision. Another warning is a supplier that prices an incomplete package as fully firm without listing assumptions.
How can buyers reduce revisions?
Send Gerber or ODB++, drill and stackup data, BOM with MPNs, centroid/CPL, assembly drawings, quantity breaks, test notes, firmware/programming needs, labeling, packaging, and target delivery together. Mark no-substitute parts, allowable alternates, and customer-supplied materials. Use one release ID so the supplier prices the same configuration your team intends to build.
What should be fixed before the PO?
Confirm the quotation revision, release-package ID, approved BOM alternates, excess-material treatment, NRE, recurring test time, quality records, packaging, Incoterms, and validity period. Keep provisional items visible instead of hiding them in the unit price.
Bottom line
A good engineering review can change a preliminary quote because it replaces uncertainty with a buildable scope. The buyer should expect transparency: every material change should have a reason, evidence, cost category, schedule effect, and approval path.
Prepare your files with the PCBA quote-package checklist, then send them through the PCBA RFQ page for review.