Data & stencil review
Compare Gerber pads, stencil openings and CPL coordinates. Flag tombstoning risks on small passives and insufficient paste on large thermal pads.
PCB assembly
SMT PCB Assembly for Fine-Pitch and Production Boards
XFPCB runs SMT PCB assembly for fine-pitch ICs, chip passives, LEDs, QFN and BGA packages. We align stencil design, pick-and-place data and reflow profiles before boards hit the line.
What Makes This an SMT Build
Surface-mount assembly places components on paste-printed pads and solders them in reflow. This page focuses on SMT-specific controls: aperture design, package readiness, moisture-sensitive handling and post-reflow inspection - not a generic PCBA overview.
Send Gerbers, BOM with manufacturer part numbers, centroid data, assembly drawing, polarity marks and DNP notes. We check pad-to-aperture match, rotation, and whether packages need nitrogen reflow or X-ray.
SMT Process Steps at XFPCB
Paste print & SPI check
Print solder paste, verify deposit volume on critical pads, then release the panel to placement.
High-speed placement
Place chip parts and fine-pitch ICs per CPL; confirm polarity and feeder setup for LEDs, diodes and polarized caps.
Reflow, AOI, selective X-ray
Run a board-appropriate reflow profile, inspect with AOI, and add X-ray for BGA/QFN when joints are not visible.
SMT-Specific Build Controls
- Pad geometry vs stencil aperture is reviewed before steel fabrication.
- Moisture-sensitive devices are handled to open-bag limits when MSL data is provided.
- BGA, QFN and LGA builds can include X-ray sampling for voiding and alignment.
- Mixed SMT + through-hole boards are sequenced so SMT reflow happens before THT soldering.
SMT Quotation Focus
| Project Area | XFPCB Guidance |
|---|---|
| Packages supported | Chip passives, SOIC, QFP, QFN, BGA, SMT connectors, LED arrays |
| Process core | Stencil print → placement → reflow → AOI (X-ray optional) |
| Files that speed quoting | BOM + MPN, CPL with rotation, assembly drawing, DNP list |
| Failure modes we watch | Insufficient paste, tombstoning, polarity reverse, BGA voiding |
DFM Checklist Before SMT Release
Stencil Aperture Review
We compare pad size, reductions and paste volume so fine-pitch and large pads print consistently.
Package & Polarity Check
Pin-1 marks, diode/LED orientation and connector keying are checked against the CPL before feeders are set.
Reflow Profile Planning
Lead-free profiles, peak temperature limits and nitrogen preference are confirmed against datasheets you provide.
Useful Terms
- SPI
- Solder paste inspection after printing.
- MSL
- Moisture sensitivity level for baking and floor-life control.
- Centroid / CPL
- XY placement file with rotation and reference designators.
- AOI
- Automated optical inspection after reflow.
Related XFPCB Pages
SMT PCB Assembly for Fine-Pitch and Production Boards FAQs
What files are required to quote SMT assembly?
Provide Gerbers, BOM with manufacturer part numbers, pick-and-place data with rotations, assembly drawing, polarity notes and DNP list. Note any BGA/QFN packages that need X-ray.
Can XFPCB assemble fine-pitch and BGA packages?
Yes. Fine-pitch ICs, QFN and BGA are common on our SMT lines. Share package drawings for unfamiliar parts so aperture and profile planning stay accurate.
Do you fabricate the SMT stencil?
Stencil fabrication can be included with the assembly order. We review apertures against your pads before cutting steel.
How do you reduce SMT defects on first builds?
Complete CPL data, clear polarity marks, realistic paste rules and early DFM feedback on pad/aperture mismatch cut most first-article issues.
Request a Quote for SMT PCB Assembly
Share your SMT package list and placement data so we can quote stencil, placement and inspection as one plan.
- Include BOM MPNs, CPL rotations and any BGA/QFN packages.
- State whether AOI only or AOI + X-ray is required.
- Note lead-free preference and any component peak-temperature limits.