Requesting a PCB Assembly quote is often the first formal step in moving a hardware project from design to production. However, many engineering and purchasing teams experience frustrating delays or receive inaccurate initial pricing. This usually happens because the initial documentation package is incomplete.
When a manufacturer receives partial files, they must make assumptions about materials, stack-ups, or component sourcing. These assumptions often lead to change orders, unexpected engineering fees, or price adjustments later in the process. Providing a complete and standardized file package ensures that the quotation reflects the true cost of manufacturing and prevents avoidable delays.
Core Files for Bare PCB Fabrication
Before any components can be placed, the bare printed circuit board must be fabricated. The manufacturer requires specific data to understand the physical and electrical structure of the board.
Gerber Files and Drill Data The foundation of any fabrication quote is the Gerber data. While older RS-274X formats are still accepted, Gerber X2 is highly recommended because it embeds critical metadata, such as layer functions and pad attributes, directly into the files. Alongside the copper and solder mask layers, you must provide Excellon drill files that clearly distinguish between plated through-holes, non-plated holes, and mechanical slots.
Fabrication Drawing The Gerber files show the geometry, but the fabrication drawing provides the global instructions. This document must specify the final board thickness, surface finish (such as ENIG, Immersion Silver, or HASL), solder mask color, and silkscreen color. It should also highlight any special requirements, such as edge plating, specific routing tolerances, or impedance test coupons.
Stack-Up and Material Requirements For multilayer boards, the stack-up defines the arrangement of copper and dielectric layers. If you do not provide a specific stack-up, the manufacturer will propose a standard one. However, for controlled impedance designs, the dielectric thickness and material type (e.g., standard FR4, High-Tg, or low-loss laminates) must be explicitly defined to calculate the correct trace widths.
Essential Files for PCBA Sourcing and Placement
If you are requesting a turnkey or consigned PCBA processing quote, the manufacturer needs detailed information about the components and their placement on the board.
Bill of Materials (BOM) The BOM is the most critical document for component sourcing. A complete BOM must include the Reference Designator, Quantity, Description, and most importantly, the Manufacturer Part Number (MPN). If the MPN is missing, the procurement team must spend significant time researching alternatives, which can delay the quotation and introduce sourcing risks.
Pick-and-Place File (Centroid Data) To program the automated SMT machines, the manufacturer requires a pick-and-place file. This file provides the exact X and Y coordinates, rotation angle, and side (Top or Bottom) for every surface-mount component. Without this data, the engineering team must manually extract coordinates from the CAD software, adding unnecessary engineering hours to your project cost.
Assembly Drawing The assembly drawing provides visual context that the BOM and centroid files cannot convey. It should clearly indicate the polarity of diodes and electrolytic capacitors, the orientation of connectors, and any specific requirements for conformal coating, potting, or mechanical hardware installation.
Common Pitfalls in File Submission
Even experienced hardware teams can make mistakes when preparing quotation files. Recognizing these common pitfalls can save weeks of back-and-forth communication.
Sending Gerber Files Without Stack-Up Information Gerber files may show the copper layers, but they do not always define the full dielectric structure. For controlled impedance projects, stack-up requirements must be provided or reviewed before production to avoid signal integrity failures and incorrect material pricing.
Incomplete BOM with Missing MPNs Relying on generic descriptions like “10uF 0402 Capacitor” instead of a specific MPN forces the manufacturer to guess the quality and brand of the component. This often results in a quotation based on premium parts, only for the buyer to later demand cheaper alternatives, requiring a complete re-quote.
Ignoring Pick-and-Place Rotation Data Some CAD exports omit the rotation angle or use a different coordinate origin than the Gerber files. If the pick-and-place data does not align perfectly with the Gerber pads, the SMT programmer must manually adjust the component placement, increasing the risk of assembly defects.
Files Required for Quotation
To ensure a fast and accurate quotation, please prepare the following documentation package before contacting the manufacturer.
- Complete Gerber files (RS-274X or Gerber X2 format)
- Drill files and Excellon data
- Fabrication drawing with stack-up and material notes
- Controlled impedance requirements and reference layers
- Complete BOM with Manufacturer Part Numbers (MPN)
- Pick-and-place file with X/Y coordinates and rotation
- Assembly drawing with polarity and special instructions
Planning Your Project
Preparing a complete and accurate file package is the most effective way to control your project timeline and budget. When the manufacturer has all the necessary data, they can provide a precise quotation that reflects the true complexity of your design, rather than a rough estimate padded with risk contingencies.
Before submitting your files, conduct an internal review to ensure all layers are present, the BOM is fully populated with MPNs, and the pick-and-place data aligns with your Gerber outputs. This proactive approach streamlines the PCB design to manufacturing transition and sets the stage for a successful production run.
For engineering review and quotation support, please send your complete file package to sales@toplinecircuit.com.
