PCB assembly service: files to send, DFM checks, and quality standards

What is a PCB assembly service?

A PCB assembly service places and solders components onto your fabricated boards using stencil printing, pick-and-place, reflow (and, if needed, selective/wave), followed by inspection and test to deliver ready-to-evaluate hardware.

What files are needed for PCB assembly?

• Gerber or ODB++ with fabrication notes (stackup, finish, mask legend)

• BOM: MPNs, reference designators, quantities, DNI flags, approved alternates, component heights

• Pick-and-place (CPL/XY): X/Y in mm, rotation, side, origin definition

• Assembly drawing: polarity, pin‑1, keepouts, torque/solder notes, special adhesives or underfill

• Test plan: AOI coverage, X‑ray for BGAs/QFNs as required, ICT/flying‑probe points and netlist, boundary‑scan chain

• Panelization: array size, 5–10 mm rails, break‑away style (v‑score or tabs), tooling hole size/locations

• Stencil preference: thickness (100–150 μm typical), aperture reductions or windowing for thermal pads

• Handling notes: MSL levels, baking requirements, packaging (reel/tray/tube), conformal coat or cleaning needs

DFM rules that prevent rework

For reflow with SAC305, target peak 235–250 °C, 1–3 °C/s ramp, and 30–90 s above liquidus; verify every tall/heavy part’s profile window. Keep at least 0.5 mm component‑to‑component clearance so nozzles and AOI have sightlines. Maintain ≥2 mm from parts to the PCB edge for conveyors and depanelization. Use three global fiducials per panel and two local fiducials near any ≤0.5 mm‑pitch device; fiducials: 1.0 mm bare copper with 3.0 mm clearance. Solder mask dam ≥0.10 mm between pads; mask expansion 0.05–0.10 mm. For QFNs, window the thermal pad to ~50–70% paste coverage; for fine‑pitch gull‑wings, consider 10–20% aperture reduction. Tent through‑vias near pads to avoid wicking; if via‑in‑pad is unavoidable (e.g., BGAs), specify filled and capped. Provide 3.0 mm tooling holes in rails and place fiducials >5 mm from edges. Land patterns per IPC‑7351 reduce variability; for workmanship classify builds per IPC‑A‑610 (many OEMs call out Class 2 or 3).

Which tests should you ask for?

Aim for 100% post‑reflow AOI on both sides. Use X‑ray sampling or 100% on BGAs, LGAs, and bottom‑terminated components. Choose flying‑probe for low volumes and dense nets; move to ICT when volumes justify fixtures and you need fast, high‑coverage testing and power‑up checks. Boundary‑scan is effective on JTAG‑enabled nets; plan test pads (≈0.9–1.0 mm diameter on 2.00–2.54 mm grid) with unobstructed access.

What can HyperPCB commit to on PCBA orders?

HyperPCB operates an ISO 9001:2015 certified quality management system (certificate CN-2023-Q1156, SGS, valid through June 2027). Quotes are returned within 24 hours and DFM feedback within 1 business day, so you can correct risks before parts kit-out. Boards can be built and inspected to IPC Class 2 or IPC Class 3 acceptance criteria, aligning with common commercial and high‑reliability requirements. RoHS and REACH compliance is supported for hazardous substance control when you need restricted‑substance documentation. Our partner factory AEGIS maintains ISO 9001:2015, ISO 14001:2015, and ISO 45001:2018 management systems, plus ISO 13485:2016 for medical and IATF 16949 for automotive quality. For RF programs, our partner factory also manufactures its own high‑frequency laminates and supplies RF PCB fabricators in China, including publicly listed PCB companies.

How to compare PCB assembly quotes?

Normalize on build class (IPC‑A‑610 target), stencil thickness, AOI/X‑ray scope, test coverage, panelization method, and any cleaning/coating. Check that BOM alternates are pre‑approved and that the quote reflects reel/tape attrition and programming/fixture costs; small mismatches here create big variance later.