PCBA Manufacturing Data: What Your Assembler Needs for a Quote

Printed circuit board assembly (PCBA) brings together three worlds: the bare board, component sourcing and the production process. For an assembler to quote and build reliably, they need a complete data package. If something is missing, they either ask – or make assumptions that become expensive later. In this second part of our series you will learn which manufacturing data a PCBA quote requires and what to look out for when preparing it.

The PCBA data package at a glance

1. Board data: Gerber, ODB++ or IPC-2581

The most widespread format is Gerber RS-274X: one file per layer (copper, solder mask, silkscreen, solder paste, outline) plus drill data in Excellon format. Modern alternatives such as ODB++ and IPC-2581 bundle all information into one intelligent data set and reduce interpretation errors – for example in layer assignment.

Make sure the solder paste layer is included, as the stencil is made from it. If you have special requirements for stencil thickness or apertures, for example for fine-pitch parts or large ground pads, state them explicitly.

2. Board specification and stack-up

Gerber data describes geometry, not material. These details therefore belong in the request as well:

• Base material (e.g. FR4) and glass transition temperature (Tg)
• Number of layers, final thickness and stack-up
• Outer and inner copper weight
• Surface finish, e.g. ENIG, lead-free HASL or OSP
• Colour of solder mask and silkscreen
• Impedance-controlled traces with target values and tolerances
• Special technologies such as microvias, via-in-pad or rigid-flex

Our PCB page gives an overview of the board technologies we source, from standard FR4 to HDI and rigid-flex.

3. Bill of materials: aligned with the placement data

For assembly, every BOM line must match the reference designators on the board. Check in particular whether parts that are not to be placed (DNP) are marked and whether the package details match the footprint in the layout. What a complete BOM looks like is shown in part 1 of this series.

Also clarify whether the assembler should source all parts (full turnkey) or whether you will supply some components yourself (partial turnkey or consignment). Customer-supplied parts should be marked in the BOM and delivered in production-ready packaging.

4. Placement file (pick-and-place)

The placement file, also called centroid or XY file, contains for each SMD part:

• the reference designator (e.g. U3)
• the X and Y coordinate of the part centre
• the rotation angle
• the side (top or bottom)

A clear statement of the coordinate origin and unit (mm or mil) is essential. The file is exported from the ECAD system and should come from the same revision as the Gerber data and BOM.

5. Panels, fiducials and tooling rails

Small boards are usually manufactured and assembled in panels. Decide whether you specify the panel yourself or let the manufacturer design it. Fiducials on the board and panel allow pick-and-place machines to align precisely. Also state how the individual boards should be separated – for example by V-scoring or milled tabs.

6. Acceptance class according to IPC-A-610

The IPC-A-610 standard defines acceptance criteria for electronic assemblies in three classes:

• Class 1: general electronic products where function is the main requirement
• Class 2: dedicated service electronics with high demands on reliability and service life, typical for many industrial applications
• Class 3: high-reliability electronics where failure cannot be tolerated, e.g. in medical technology or aerospace

The class affects test scope and cost. Without a specification, many manufacturers assume Class 2 – so state the required class explicitly.

7. Testing, programming and box build

Define how the quality of the assembly is to be verified. Common methods are:

• AOI (automated optical inspection) for solder joints and part position
• X-ray inspection for hidden joints, e.g. on BGA or QFN packages
• ICT (in-circuit test) or flying probe for electrical tests
• Functional test with a customer-specific test fixture and test specification

If the assembly is to be programmed, the manufacturer needs the firmware file, the programming interface and instructions if necessary. Conformal coating, enclosure assembly or cable harnesses can also be part of the order and should be named early.

Checklist for your PCBA request

• Gerber or ODB++ data incl. drill data and solder paste layer
• Board specification with stack-up and surface finish
• BOM with MPNs and reference designators
• Placement file with coordinate origin and unit
• Assembly drawing as PDF
• Acceptance class according to IPC-A-610
• Test and programming requirements
• Batch sizes, annual demand and required date
• All documents with identical revision

Intelligent Components supplies printed circuit boards (PCB) and circuit board assembly (PCBA) as a complete package – including component sourcing, testing and logistics. Send us your data package and we will check it for completeness before quoting.

Is your data package ready? Send us your request – we will get back to you with a completeness check and a quote.