How to Quote PCB Assembly From a Customer BOM

Step 1: Clean and Normalize the BOM

Start by checking the BOM against the Gerber or assembly drawing before pricing anything. Confirm the count of reference designators matches the quantity column on every line, because a mismatch there is the most common source of a quote that loses money. Resolve lines that have a value but no manufacturer part number, separate DNP and customer-consigned lines, and note any lines that allow an approved alternate.

Capture package details that affect process: BGA, QFN with thermal pads, fine-pitch connectors, press-fit parts, and anything that needs selective solder or hand assembly. This is also where you decide if the build needs X-ray inspection, conformal coat, or underfill, since each adds operations that belong in the labor model.

Step 2: Price at the Right Quantity Breaks

Price each line for each quantity the customer asked about, not just one. A 10 piece prototype and a 500 piece run pull entirely different breaks, and reel versus cut tape pricing changes the math on passives. Use your actual sources and discounts, not list price.

Passive components are often bought in full reels for volume builds, so the quote should reflect the reel cost and consider what happens to the leftover quantity. Flag lines where the cost per piece is dominated by a single expensive part such as an FPGA, memory, or RF module, because those lines deserve their own risk treatment and often their own validity window rather than a blanket adder.

• Price at every build quantity on the RFQ, not an average
• Use your negotiated distributor discounts and approved sources
• Separate reel, cut tape, and tray pricing for passives and ICs
• Mark lines over a cost threshold for individual review

Step 3: Availability, Lead Time and Last Time Buy Risk

Check stock depth and factory lead time for every line, and look for lifecycle status. A part marked not recommended for new designs or approaching end of life may be fine for a one time build and a disaster for a three year program. Quote validity should reflect the longest or most volatile line, so a 30 day validity on a BOM with allocated parts is sensible.

For long lead items, quote the schedule honestly: either the customer supplies the parts, you buy at risk with a deposit, or you propose a pre-approved alternate. Writing the lead time risk on the quote protects you from the dispute that follows when delivery slips for reasons that were visible at quoting time.

Step 4: Overage, Attrition and Minimum Buy Quantities

Machines drop parts. Small passives such as 0201 and 0402 components need meaningful overage, while larger ICs need a small spare count, and tape leader and splice waste adds to the total. Overage rules should be a table by package type, not one percentage for the BOM.

Then handle minimum order quantities: if the part comes only in a reel of 3,000 and the job needs 200, someone owns the remaining 2,800 pieces. Decide whether that cost is charged to the customer, absorbed into price, or held for the next order. Quotes that ignore leftover material push cash into excess inventory that never gets billed.

Step 5: Roll Up and Review Before It Goes Out

Add bare board cost, SMT and through-hole labor from your time standards, test and inspection, stencil and programming NRE, packaging and freight, then margin. Review the quote against similar past jobs: if cost per placement or margin is out of line with closed jobs of similar complexity, find out why before sending. Netray can run this comparison as a private AI layer over your ERP, retrieving comparable jobs and their actual costs for the estimator.

It is overkill if you only build a few repeat assemblies; a clean spreadsheet and a good habit of closing the loop on actuals will serve you fine.